JP2005100781A - Organic el element and organic el display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molecular dispersion type organic EL element and an organic EL display wherein heat resistance, a life, and light emitting efficiency can be achieved at high levels in all. <P>SOLUTION: An organic layer 3 containing a star polymer and a light emitting dopant wherein a plurality of polymer chains are formed of polyvalent functional groups as starting points is installed between two electrodes 2, 4 of the organic EL element 9 which are arranged so as to oppose each other. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an organic EL (electroluminescence, electroluminescence) element and an organic EL display.

  In the field of organic EL elements used for organic EL displays and the like, various types of devices have been prototyped based on a technique for forming an organic layer using a low molecular weight compound by a vacuum deposition method (for example, see Non-Patent Document 1). It is about to reach the stage of conversion.

On the other hand, development of an organic EL element using a polymer material as a constituent material of the organic layer is underway. Such an organic EL element generally has a π-conjugated type using a π-conjugated polymer (for example, see Patent Document 1) and a molecular dispersion type in which a dye is dispersed in a non-conjugated polymer. (See, for example, Non-Patent Documents 2 and 3). Among these, the non-conjugated organic EL device has an advantage that a desired color can be obtained with high color purity by mixing a predetermined dopant into the host polymer.
Japanese Patent Laid-Open No. 10-92576 Applied Physics Letters, vol.51, pp913 (1987) Polymer, vol.24, pp748 (1983) Applied Physics Letters, vol.75, No.1, pp4 (1999)

  However, since polymer materials used in conventional molecular dispersion type organic EL elements are not necessarily sufficient in terms of carrier transportability and stability, conventional molecular dispersion type EL elements are advantageous in terms of luminous efficiency, heat resistance and lifetime. There is room for improvement.

  The present invention has been made in view of the above-mentioned problems of the prior art, and provides a molecule-dispersed organic EL element and an organic EL display that can achieve all of heat resistance, life and luminous efficiency at a high level. With the goal.

  In order to solve the above-mentioned problems, an organic EL device of the present invention includes two electrodes arranged opposite to each other, a star formed between the electrodes, and a plurality of polymer chains formed from polyvalent functional groups as starting points. And an organic layer containing a light-emitting dopant.

  According to the organic EL device of the present invention, the luminescent dopant is sufficiently contained in the organic layer by including in the organic layer, together with the luminescent dopant, a star polymer in which a plurality of polymer chains are formed based on the polyvalent functional group. It is held uniformly and stably. Moreover, since the star polymer contained in the organic layer has high heat resistance and excellent stability, a high level of luminous efficiency can be stably obtained over a long period of time.

  The polyvalent functional group which is the starting point of the polymer chain of the star polymer according to the present invention is preferably one containing an aromatic group having 10 or more carbon atoms derived from a luminescent compound. By introducing a polyvalent functional group containing such an aromatic group into the star polymer, the luminous efficiency of the organic EL device can be further increased. Among such polyvalent functional groups, those having a structure represented by the following formula (1) or (2) are particularly preferable.

［式（１）中、ｍは１〜３の整数を表し、ベンゼン環及びアントラセン環を構成する炭素原子それぞれは置換又は未置換のいずれであってもよく、ベンゼン環及びアントラセン環を構成する炭素原子又は該炭素原子に結合した置換基の構成原子にはポリマー鎖の一端が結合する。］

[In the formula (1), m represents an integer of 1 to 3, carbon atoms constituting the benzene ring and the anthracene ring may be either substituted or unsubstituted, and carbon constituting the benzene ring and the anthracene ring. One end of the polymer chain is bonded to the constituent atom of the substituent bonded to the atom or the carbon atom. ]

［式（２）中、フルオランテン環を構成する炭素原子それぞれは置換又は未置換のいずれであってもよく、フルオランテン環を構成する炭素原子又は該炭素原子に結合した置換基の構成原子にはポリマー鎖の一端が結合する。］
また、星型ポリマーのポリマー鎖はポリビニル鎖であることが好ましい。これにより、耐熱性、寿命及び発光効率に優れた有機ＥＬ素子を有効に実現することができる。

[In the formula (2), each carbon atom constituting the fluoranthene ring may be substituted or unsubstituted, and the constituent atom of the carbon atom constituting the fluoranthene ring or the substituent bonded to the carbon atom is a polymer. One end of the chain binds. ]
The polymer chain of the star polymer is preferably a polyvinyl chain. Thereby, the organic EL element excellent in heat resistance, lifetime, and luminous efficiency can be effectively realized.

  The polymer chain of the star polymer is preferably formed by polymerization of a monomer having an aromatic group having 10 or more carbon atoms and a polymerizable functional group derived from a luminescent compound. By forming a polymer chain by polymerization of such a monomer, the luminous efficiency of the organic EL element can be further increased. Among such polymer chains, those formed by polymerization of a vinyl monomer having a structure represented by the following formula (3) are particularly preferable.

［式（３）中、Ｌは２価の基を表し、Ｘ^１、Ｘ^２、Ｘ^３、Ｘ^４及びＸ^５は同一でも異なっていてもよく、それぞれアルキル基、アルコキシ基、アリール基、アリールオキシ基、複素環基、ハロゲン原子、シアノ基、水酸基又はアミノ基を表し、ａ、ｂ、ｃは及びｄはそれぞれ０〜４の整数を表し、ｅは０〜５の整数を表し、ｎは０又は１を表し、ｐは０又は１を表し、ｑは１〜３の整数を表し、Ｘ^１〜Ｘ^５で表される置換基はそれぞれ互いに結合して環を形成していてもよい。］
なお、発光性化合物から誘導される炭素数１０以上の芳香族基を、多価官能基及びポリマー鎖のそれぞれに導入することで上記の効果が得られる理由は必ずしも明確でないが、本発明者らは以下のように推察する。すなわち、本発明にかかる星型ポリマーにおいては上述のように多価官能基を起点とするポリマー鎖が複数形成されるが、多価官能基及びポリマー鎖のそれぞれに上記特定の芳香族記が導入されることによって、星型ポリマーのキャリア輸送性が高められるものと考えられる。より具体的には、星型ポリマーの多価官能基に電荷が集まりやすくなり、この多価官能基がホールと電子との再結合中心となりやすいものと考えられる。そして、この再結合中心が発光効率の向上に寄与しているものと考えられる。

[In Formula (3), L represents a divalent group, and X ¹ , X ² , X ³ , X ⁴ and X ⁵ may be the same or different, and each represents an alkyl group, an alkoxy group, an aryl group, an aryl group. Represents an oxy group, a heterocyclic group, a halogen atom, a cyano group, a hydroxyl group or an amino group, a, b, c and d each represents an integer of 0 to 4, e represents an integer of 0 to 5, and n represents It represents 0 or 1, p represents 0 or 1, q represents an integer of 1 to 3, and the substituents represented by X ^{1 to} X ⁵ may be bonded to each other to form a ring. ]
The reason why the above effect can be obtained by introducing an aromatic group having 10 or more carbon atoms derived from a luminescent compound into each of the polyvalent functional group and the polymer chain is not necessarily clear. Guesses as follows. That is, in the star polymer according to the present invention, a plurality of polymer chains starting from a polyfunctional group are formed as described above, but the specific aromatic group is introduced into each of the polyfunctional group and the polymer chain. By doing so, it is considered that the carrier transport property of the star polymer is enhanced. More specifically, it is considered that charges are easily collected in the polyvalent functional group of the star polymer, and this polyfunctional group is likely to be a recombination center between holes and electrons. And it is thought that this recombination center is contributing to the improvement of luminous efficiency.

In addition, the organic EL display of the present invention includes two electrodes arranged opposite to each other, a star polymer and a luminescent dopant formed between the electrodes and having a plurality of polymer chains starting from a polyvalent functional group A display unit in which a plurality of organic EL elements including the organic layer are arranged, a power supply unit that is electrically connected to each of the two electrodes and supplies voltage or current to the electrodes, And a switching unit for turning on or off each of the organic EL elements,
It is characterized by providing.

  As described above, the organic EL elements of the present invention are arranged in the display unit, and the display unit is driven by the power supply unit and the switching unit, whereby the luminance and color display functions are excellent, and the heat resistance is high. A long-life organic EL display can be realized.

  According to the present invention, it is possible to realize a molecular dispersion type organic EL element and an organic EL display which can achieve all of heat resistance, life and luminous efficiency at a high level.

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

  First, in the organic EL device of the present invention, a star polymer (hereinafter sometimes referred to as “star polymer according to the present invention”) contained in the organic layer will be described.

  The star polymer according to the present invention has a structure in which a plurality of polymer chains are formed starting from a polyvalent functional group.

  The polyvalent functional group is not particularly limited as long as it can form a plurality of polymer chains. Specifically, an aliphatic chain hydrocarbon group, an aliphatic cyclic hydrocarbon group, an aromatic hydrocarbon group, or Examples thereof include organic groups in which some of the carbon atoms constituting these hydrocarbon groups are substituted with nitrogen atoms, oxygen atoms, or the like. The valence of the polyvalent functional group, that is, the number of polymer chains formed in the polyvalent functional group is preferably 2 to 10, more preferably 3 or 4.

  Among these, it is preferable that the polyvalent functional group includes an aromatic group having 10 or more carbon atoms derived from a luminescent compound. By using such a polyvalent functional group containing an aromatic group as the base point of the star polymer, the luminous efficiency of the organic EL device can be further increased. The aromatic group may contain a nitrogen atom, an oxygen atom or the like. Specific examples of preferred aromatic groups include naphthalene ring, anthracene ring, naphthacene ring, pyrene ring, perylene ring, fluorene ring, fluoranthene ring, phenanthrene ring, carbazole ring, quinoline ring, quinoxaline ring, phenanthroline ring, and these 2 An aromatic group having a structure in which more than one type is combined is exemplified.

  Among such polyvalent functional groups, those having a structure represented by the following formula (1) or (2) are preferable.

［式（１）中、ｍは１〜３の整数を表し、ベンゼン環及びアントラセン環を構成する炭素原子それぞれは置換又は未置換のいずれであってもよく、ベンゼン環及びアントラセン環を構成する炭素原子又は該炭素原子に結合した置換基の構成原子にはポリマー鎖の一端が結合する。］

[In the formula (1), m represents an integer of 1 to 3, carbon atoms constituting the benzene ring and the anthracene ring may be either substituted or unsubstituted, and carbon constituting the benzene ring and the anthracene ring. One end of the polymer chain is bonded to the constituent atom of the substituent bonded to the atom or the carbon atom. ]

［式（２）中、フルオランテン環を構成する炭素原子それぞれは置換又は未置換のいずれであってもよく、フルオランテン環を構成する炭素原子又は該炭素原子に結合した置換基の構成原子にはポリマー鎖の一端が結合する。］

[In the formula (2), each carbon atom constituting the fluoranthene ring may be substituted or unsubstituted, and the constituent atom of the carbon atom constituting the fluoranthene ring or the substituent bonded to the carbon atom is a polymer. One end of the chain binds. ]

Each of the carbon atoms constituting the benzene ring and the anthracene ring in the formula (1) and the fluoranthene ring in the formula (2) may be substituted or unsubstituted. Examples of the substituent include an alkyl group, an alkoxy group, an aryl group, an aryloxy group, a heterocyclic group, a halogen atom, a cyano group, a hydroxyl group, and an amino group exemplified in the description of X ^{1 to} X ^{5 in} the formula (3) described later. Etc. These substituents may be bonded to each other to form a ring.

  Introduction of the polyvalent functional group into the star polymer according to the present invention can be performed by using a compound having the target polyvalent functional group and a reactive group for forming a polymer chain. Such a reactive group can be appropriately selected according to the kind of the polymerizable functional group which the constituent monomer of the polymer chain has. For example, as a reactive group in the case of forming a polyvinyl chain in a polyvalent functional group, a halogen group such as a chloro group and a bromo group is exemplified.

  Preferable examples of the compound having a polyvalent functional group and a reactive group include compounds represented by the following formulas (4) to (8). X in the formulas (4) to (8) each represents a halogen atom (preferably a chlorine atom or a bromine atom).

  The polymer chain of the star polymer can be formed by polymerization of a monomer having a predetermined polymerizable functional group. The polymerizable functional group may be one kind of polymerizable group such as a vinyl group or an epoxy group, or may be two kinds of functional groups capable of forming an ester bond or an ether bond. Examples of the reaction of the two types of functional groups include a dehydration reaction between a hydroxyl group and a carboxylic acid group, a transesterification reaction between a hydroxyl group and an ester group, a deoxidation reaction between a hydroxyl group and a halogen group. Among these, when a polyvinyl chain is formed using a monomer having a vinyl group (vinyl monomer), an organic EL device having excellent heat resistance, lifetime, and luminous efficiency can be effectively realized.

  Moreover, it is preferable to form a polymer chain using the monomer which has a C10 or more aromatic group induced | guided | derived from a luminescent compound from the point which improves the carrier transport property of the star polymer concerning this invention. Such aromatic groups may contain nitrogen atoms, oxygen atoms, and the like. Specific examples of preferred aromatic groups include naphthalene ring, anthracene ring, naphthacene ring, pyrene ring, perylene ring, fluorene ring, fluoranthene ring, phenanthrene ring, carbazole ring, quinoline ring, quinoxaline ring, phenanthroline ring, and these 2 An aromatic group having a structure in which more than one type is combined is exemplified.

  In addition, since the degree of freedom in molecular design of the star polymer can be increased and desired characteristics can be easily and reliably imparted to the organic layer, a monomer that can form a non-π conjugated polymer is used. A monomer having a polymerizable functional group (preferably a vinyl group) and an aromatic group as described above is preferable, and is represented by the following general formula (3) from the viewpoint that all of heat resistance, lifetime and luminous efficiency can be achieved at a high level. Particularly preferred are the compounds

In the formula, L represents a divalent group, and X ¹ , X ² , X ³ , X ⁴ and X ⁵ may be the same or different, and each represents an alkyl group, an alkoxy group, an aryl group, an aryloxy group, a complex It represents a ring group, a halogen atom, a cyano group, a hydroxyl group or an amino group, and these substituents may be bonded to each other to form a ring. A, b, c and d each represent an integer of 0 to 4, e represents an integer of 0 to 5, n represents 0 or 1, p represents 0 or 1, q represents 1 to An integer of 3 is represented.

  Examples of the divalent group represented by L include an alkylene group such as a methylene group, an ethylene group, and a propylene group, and an arylene group such as a phenylene group. These divalent groups may have a substituent or may be unsubstituted. N represents 0 or 1, and when m is 0, a structure in which a vinyl group is directly bonded to a carbon atom constituting a benzene ring is obtained.

When X ^{1 to} X ⁵ are alkyl groups, the alkyl group may be linear or branched. The alkyl group is preferably unsubstituted, but may have a substituent. As for carbon number of an alkyl group, 1-30 are preferable. Preferred alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, pentyl and the like.

When X ^{1 to} X ⁵ are alkoxy groups, the alkyl group constituting the alkoxy group may be linear or branched. The alkoxy group is preferably unsubstituted, but may have a substituent. As for carbon number of an alkoxy group, 1-30 are preferable. Preferred alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, s-butoxy, t-butoxy and the like.

When X ^{1 to} X ⁵ are aryl groups, the aryl group may be substituted or unsubstituted, but the total carbon number of the aryl group is preferably 6 to 20. Preferable aryl groups include phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, biphenylyl group and the like.

When X ^{1 to} X ⁵ are aryloxy groups, the aryl group constituting the aryloxy group may be either substituted or unsubstituted, but the total number of carbon atoms of the aryloxy group is preferably 6 to 20. Preferable aryloxy groups include phenoxy group, o-tolyloxy group, m-tolyloxy group, p-tolyloxy group and the like.

When X ^{1 to} X ⁵ are heterocyclic groups, the heterocyclic group is preferably a 5-membered ring group or a 6-membered ring group. The heterocyclic group may have a condensed ring and may have a substituent. The heterocyclic group may have aromaticity or may not have aromaticity. Preferable heterocyclic groups include pyrrolyl group, pyridyl group, quinolyl group, thienyl group, furyl group and the like.

When X ^{1 to} X ⁵ are halogen atoms, examples of the halogen atom include fluorine, chlorine, bromine and iodine.

When X ^{1 to} X ⁵ are amino groups, the amino group may be substituted or unsubstituted, and may have, for example, the above-described alkyl group or aryl group. As for the total carbon number of an amino group, 0-20 are preferable. Preferred amino groups include a narrowly defined amino group (—NH ₂ ), a methylamino group, an ethylamino group, a phenylamino group, a dimethylamino group, and a diphenylamino group.

  Among the compounds represented by the general formula (3), it is more preferable to use a compound represented by the following general formula (9) or (10).

  In general formulas (9) and (10), R represents an alkyl group, an alkoxy group or an aryl group. Moreover, e in a formula represents the number of the substituents R, and is an integer of 1-5. The substitution position of R is not particularly limited, but it is preferable to use a compound in which R is bonded to the p-position.

  The carbon number of the alkyl group represented by R is preferably 1-30, more preferably 1-20, and still more preferably 1-12. The alkyl group represented by R may be linear or branched. Preferred examples of the alkyl group represented by R include n-butyl group, t-butyl group, hexyl group, ethylhexyl group, n-heptyl group, isoheptyl group, n-octyl group, isooctyl group, n-nonyl group, Examples include isononyl group, n-decyl group, isodecyl group, n-undecyl group, isoundecyl group, n-dodecyl group, isododecyl group and the like.

  Moreover, carbon number of the alkoxy group represented by R becomes like this. Preferably it is 1-30, More preferably, it is 1-20, More preferably, it is 1-12. The alkoxy group represented by R may be linear or branched. Preferable examples of the alkoxy group represented by R include a butyroxy group, a hexyloxy group, an ethylhexyloxy group, an octyloxy group, a dodecyloxy group, a hexadecyloxy group, an eye coloxy group, and the like.

  Moreover, the total carbon number of the aryl group represented by R is preferably 6-30, more preferably 6-20. The aryl group may be substituted or unsubstituted. Preferable examples of the aryl group represented by R include phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, biphenylyl group, naphthyl group and the like.

  Examples of the monomer represented by the general formula (9) include 10′-biphenyl-2-yl-10- (4-vinylphenyl)-[9,9 ′] bianthracenyl represented by the following formula (11), And 10- (4-dodecylphenyl) -10 ′-(4-vinylphenyl)-[9,9 ′] bianthracenyl represented by the following formula (12). Examples of the monomer represented by (10) include 9-biphenyl-2-yl-10- (4-vinylphenyl) -anthracene represented by the following formula (13), and the following formula (14). 9- (4-octylphenyl) -10- (4-vinylphenyl) -anthracene, 9- (2,4-hexadecyloxyphenyl) -10- (4-vinyl represented by the following formula (15) Phenyl) -anthracene and the like.

  The method for forming the polymer chain of the star polymer can be appropriately selected from a radical polymerization method, a cationic polymerization method, an anionic polymerization method, and the like depending on the type and combination of the polymerizable functional groups. Further, when forming the polymer chain, the polymer chain may be extended from the reactive group of the polyvalent functional group as a starting point, and after forming the polymer chain of a predetermined length, the polymer chain is May be combined.

  The ratio of the compound having a polyfunctional group and a reactive group and the monomer for forming the polymer chain is determined by the valence of the polyfunctional group, the type of raw material compound, and the molecular weight of the target star polymer. It is adjusted according to etc. For example, the number of units per polymer chain (the number of constituent monomers) is preferably 10 to 500, and the blending ratio of the two is selected so that the number of units is within the range. Further, from the viewpoint of solubility in the solvent used in the coating solution for forming an organic layer, the number of units is more preferably in the range of 10 to 100. Further, the molecular weight of the obtained star polymer is not particularly limited, but the weight average molecular weight is 10,000 to 200 from the viewpoint that the device characteristics (heat resistance, lifetime and light emission efficiency) and solubility during production can be balanced. Within the range of 1,000.

  In the above description, the case where the star polymer is a non-π conjugated polymer has been described in detail. However, higher efficiency and longer life by crosslinking can also be applied to a π conjugated polymer. Specific examples of the π-conjugated polymer include polymers having a polyparaphenylene vinyl structure, a polyparaphenylene structure, a polyamine structure, a polythiophene structure, a polyfluorene structure, and the like.

  Next, the organic EL device of the present invention and the manufacturing method thereof will be described.

  FIG. 1 is a schematic cross-sectional view showing a preferred embodiment of the organic EL device of the present invention. In the organic EL element 9 shown in FIG. 1, the anode layer 2 (first electrode layer) and the insulator layer 6 are laminated in this order on the substrate 1, and correspond to the light emitting region of the insulator layer 6. An opening is provided in the portion so that the anode layer 2 is exposed. Then, the organic layer 3 and the cathode layer 4 (second electrode layer) are laminated in this order on the exposed anode layer 2, and the laminated structure of substrate 1 / anode layer 2 / organic layer 3 / cathode layer 4 is obtained. Is formed. The organic layer 3 contains the star polymer according to the present invention and a dopant for light emission. The surface of the organic EL element 9 on the cathode layer 2 side is sealed with a sealing plate 5 via a spacer 7 provided on the insulator layer in the non-light emitting region.

(substrate)
As the substrate 1, an amorphous substrate such as glass or quartz, a crystal substrate such as Si, GaAs, ZnSe, ZnS, GaP, or InP, or a metal substrate such as Mo, Al, Pt, Ir, Au, Pd, or SUS is used. Can be used. In addition, a thin film made of crystalline or amorphous ceramic, metal, organic material or the like formed on a predetermined substrate may be used.

  When the substrate 1 side is the light extraction side, it is preferable to use a transparent substrate such as glass or quartz as the substrate 1, and it is particularly preferable to use an inexpensive glass transparent substrate. The transparent substrate may be provided with a color filter film, a color conversion film containing a fluorescent material, a dielectric reflection film, or the like for adjusting the color light.

(Anode layer)
The anode layer 2 functions as a hole injection electrode to the organic layer 3. Therefore, the material of the anode layer 2 is preferably a material that can efficiently inject holes into the organic layer, and more specifically a material having a work function of 4.5 to 5.5 eV.

  Further, when the substrate 1 side is the light extraction side, the transmittance at a wavelength of 400 to 700 nm, which is the emission wavelength region of the organic EL element, particularly the transmittance at the wavelength of each RGB color is preferably 50% or more, It is more preferably 80% or more, and further preferably 90% or more. If the transmittance of the anode layer 2 is less than 50%, the light emission from the organic layer 3 is attenuated, and it is difficult to obtain the luminance necessary for image display.

The anode layer 2 having a high light transmittance can be configured using a transparent conductive film composed of various types of oxides. As such a material, indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), zinc oxide (ZnO), tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), and the like are preferable. It is particularly preferable in that a thin film having a uniform in-plane specific resistance can be easily obtained. The ratio of SnO ₂ to In ₂ O _{3 in} ITO is preferably 1 to 20% by weight, and more preferably 5 to 12% by weight. The ratio of ZnO to In ₂ O ₃ in IZO is preferably 12 to 32% by weight. One kind of the above materials may be used alone, or two or more kinds thereof may be used in combination.

Note that the composition of the oxide constituting the anode layer 2 may be somewhat deviated from the stoichiometric composition. For example, ITO usually contains In ₂ O ₃ and SnO _{2 in a} stoichiometric composition, but when the composition of ITO is represented by InO _x · SnO _y , x is in the range of 1.0 to 2.0. , Y may be in the range of 0.8 to 1.2.

Further, the work function of the anode layer 2 can be adjusted by adding a transparent dielectric such as silicon oxide (SiO ₂ ) to the anode layer 2. For example, the work function of ITO can be increased by adding about 0.5 to 10 mol% of SiO ₂ with respect to ITO, and the work function of anode layer 2 can be within the above-mentioned preferable range.

  The film thickness of the anode layer 2 is preferably determined in consideration of the above light transmittance. For example, when using an oxide transparent conductive film, the film thickness is preferably 50 to 500 nm, more preferably 50 to 300 nm. When the thickness of the anode layer 2 exceeds 500 nm, the light transmittance becomes insufficient and the anode layer 2 may be peeled off from the substrate 1 in some cases. Further, the light transmittance is improved as the film thickness is reduced. However, when the film thickness is less than 50 nm, the efficiency of hole injection into the organic layer 3 is lowered and the strength of the film is lowered.

  FIG. 1 shows an example of an organic EL element in which the anode layer 2 is disposed on the substrate 1 and the cathode layer 4 is disposed on the side far from the substrate 1 with the organic layer 3 interposed therebetween. The position of the layer 4 may be reversed. When the cathode layer 4 is disposed on the substrate 1, the cathode layer 4 side can be the light extraction side. In this case, the cathode layer 4 preferably satisfies the optical conditions and film thickness conditions described above. .

(Insulator layer)
In the organic EL device of the present invention, it is preferable to provide an insulator layer 6 in the non-light emitting region on the anode layer 2 as shown in FIG. By providing the insulating layer 6, it is possible to control the light emission area and suppress color bleeding. As a material of the insulating layer 6, a general insulating film material such as SiO ₂ or Al ₂ O ₃ can be appropriately selected and used. The thickness of the insulator layer 6 is preferably about 1 to 7 μm. An opening is provided in a portion corresponding to the light emitting region of the insulator layer 6 by photolithography and etching so that the anode layer 2 is exposed. On the exposed anode layer 2, an organic layer 3 and a cathode layer are provided. 4 (second electrode layers) are laminated in this order. Thereby, electrical conduction between the anode layer 2 and the organic layer 3 is ensured.

(Organic layer)
As described above, the organic layer 3 is a light emitting layer containing the star polymer according to the present invention and a light emitting dopant.

The dopant contained in the organic layer 3 can be appropriately selected according to the intended emission color. For example, as a phosphorescent dopant, an iridium complex such as tris (2-phenylpyridine) iridium (Ir (ppy) ₃ ), 2,3,7,8,12,13,17,18-octaethyl-21H, 23H-porphyrin A platinum complex having a porphyrin ring such as platinum (PtOEP) can be used. Further, as the blue light emitting dopant, tetraphenylbutadiene and its derivatives, styrylamine derivatives, fluoranthene derivatives and the like can be used. The proportion of the dopant for light emission is preferably 1 to 15% by weight with respect to the total amount of monomers before polymerization.

  The organic layer 3 contains the star polymer according to the present invention and a luminescent dopant, but may further contain other carrier transporting materials such as a hole transporting material and an electron transporting material.

  As the hole transporting material, either a low molecular material or a high molecular material can be used. Examples of the hole transporting low molecular weight material include pyrazoline derivatives, arylamine derivatives, stilbene derivatives, and triphenyldiamine derivatives. Examples of the hole transporting polymer material include polyvinyl carbazole, polyethylene dioxythiophene / polystyrene sulfonic acid copolymer (PEDOT / PSS), polyaniline / polystyrene sulfonic acid copolymer (Pani / PSS), and the like. One of these hole transporting materials may be used alone, or two or more thereof may be used in combination.

  As the electron transporting material, either a low molecular material or a high molecular material can be used. Examples of the electron transporting low molecular weight material include oxadiazole derivatives, anthraquinodimethane and derivatives thereof, benzoquinone and derivatives thereof, naphthoquinone and derivatives thereof, anthraquinones and derivatives thereof, tetracyanoanthraquinodimethane and derivatives thereof, and fluorene. And a derivative thereof, diphenyldicyanoethylene and a derivative thereof, phenanthroline and a derivative thereof, and a metal complex taking care of these compounds. Examples of the electron transporting polymer material include polyquinoxaline and polyquinoline. One of these electron transporting materials may be used alone, or two or more thereof may be used in combination.

  As for the low molecular weight material and its usage, for example, JP-A-63-70257, JP-A-63-175860, JP-A-2-135359, JP-A-3-37992, JP-A-3-37792. The technique disclosed in Japanese Patent Laid-Open No. 3-152184 can be used.

  Formation of the organic layer 3 can be suitably performed by a coating method. In such coating, a coating solution in which a light emitting dopant, the star polymer according to the present invention, or other carrier transporting material used as necessary is added to a predetermined solvent is used. The solvent of the coating solution is not particularly limited as long as the star polymer according to the present invention is dissolved and no obstacle is caused during coating. For example, organic solvents such as alcohols, hydrocarbons, ketones, and ethers can be used. Of these, chloroform, methylene chloride, dichloroethane, tetrahydrofuran, toluene, xylene, cyclohexanone, dimethylformamide, N-methylpyrrolidone, and the like are preferable. The amount of the star polymer according to the present invention dissolved in the solvent is appropriately selected according to the structure and molecular weight of the vinyl polymer, but is preferably 0.1% by weight or more.

  The organic layer 3 is formed by applying the coating solution so as to cover the opening where the anode layer 2 of the insulator layer 6 is exposed, and removing the solvent from the coating solution by heating. A coating method for the coating solution is not particularly limited, and for example, a spin coating method, a spray coating method, a dip coating method, an ink jet method, a printing method, and the like are applicable.

  Further, when removing the solvent from the coating solution, by heating at a heating temperature equal to or higher than the glass transition temperature of the star polymer according to the present invention, a very high level of residual solvent reducing effect and adhesion improving effect can be obtained. it can. The above heating is preferably performed under reduced pressure or in an inert gas atmosphere.

  The film thickness of the organic layer 3 is not particularly limited, and varies depending on the forming method, but is preferably 5 to 500 nm, more preferably 10 to 300 nm.

  FIG. 1 shows an example of an organic EL element having a single layer structure in which the organic layer 3 is composed only of a light emitting layer containing a star polymer and a light emitting dopant according to the present invention. As long as it has a layer containing a star polymer and a light emitting dopant, a multilayer structure in which a plurality of layers such as a light emitting layer, a carrier transport layer, and a carrier block layer are laminated may be used.

  For example, a hole transport layer is disposed between the light emitting layer and the anode layer, and an electron transport layer is disposed between the light emitting layer and the cathode layer, and the star polymer according to the present invention is provided in each of the hole transport layer and the electron transport layer. Can be contained. Thereby, the transportability of holes and electrons injected into the organic layer is enhanced, and the luminous efficiency can be further improved. Furthermore, the heat resistance and lifetime of the organic EL element are also increased.

  Further, an electron blocking layer is disposed between the light emitting layer and the anode layer, and a hole blocking layer is disposed between the light emitting layer and the cathode layer, and the electron blocking layer and the hole blocking layer are respectively incorporated with the star polymer according to the present invention. be able to. Thereby, so-called electron traps are suppressed, the hole density in the light emitting layer is increased, and the light emission efficiency can be further improved. Furthermore, the heat resistance and lifetime of the organic EL element are also increased.

  When the carrier block layer is provided, the star polymer according to the present invention may be used alone, or may be used in combination with the above-described hole transporting material or electron transporting material as necessary. Further, light emission from a plurality of layers can be obtained by adding a light emitting dopant to the carrier block layer to form a light emitting layer / carrier block layer and laminating the light emitting layer separately provided.

(Cathode layer)
The cathode layer 4 functions as a layer for injecting electrons into the organic layer 3. Specific examples of the cathode layer 4 include an inorganic electron injection layer, an electron injection layer composed of a coating film of an organometallic complex, and an electron injection layer composed of a coating film of a metal salt. A laminate in which an auxiliary electrode layer is laminated on these electron injection layers may be used as the cathode layer 4. In the case of such a laminate, the inorganic electron injection layer, the coating film of the organometallic complex, and the coating film of the metal salt are disposed on the side close to the organic layer 3, and the auxiliary electrode layer is disposed on the side far from the organic layer 3.

  When forming an inorganic electron injection layer, it is preferable to select an inorganic material having a low work function so that electron injection into the organic layer 3 is facilitated. Examples of such inorganic materials include alkali metals such as Li, Na, K, and Cs, alkaline earth metals such as Mg, Ca, Sr, and Ba, and alkali halides such as LiF and CsI. Alternatively, a metal having properties similar to those of an alkali metal or an alkaline earth metal such as La, Ce, Sn, Zn, or Zr can be used. Among these, Ca is particularly preferable because it has a very low work function.

  The film thickness of the inorganic electron injection layer is not particularly limited as long as electrons can be injected into the organic layer 3, but preferably 0.1 to 100 nm, more preferably 1 when an alkali metal or an alkaline earth metal is used. 0.0 to 50 nm. In addition, when using an alkali halide, the film thickness is preferably as thin as possible from the viewpoint of the ability to inject electrons into the organic layer 3, and is specifically preferably 10 nm or less and more preferably 1 nm or less.

  Moreover, the electron injection layer which consists of a coating film of an organometallic complex is prepared by, for example, applying a coating solution obtained by adding an organometallic complex to a predetermined solvent on the organic layer 3 by a coating method such as a spin coating method. It can be formed by removing. As such organometallic complexes, β-diketonato complexes, quinolinol complexes, and the like can be used. The metal included in the organometallic complex is not particularly limited as long as it has a low work function. For example, alkali metals such as Li, Na, K, and Cs, alkaline earth metals such as Mg, Ca, Sr, and Ba, Includes metals having properties similar to those of alkali metals or alkaline earth metals such as La, Ce, Sn, Zn, and Zr. Further, by further including an electron transporting polymer material or the like in the coating film of the organometallic complex, the electrical properties of the electron injection layer and the adhesion to the organic layer 3 can be further improved. The thickness of the electron injection layer made of the coating film of the organometallic complex is preferably as thin as possible from the viewpoint of the ability to inject electrons into the organic layer 3, and is specifically preferably 10 nm or less and more preferably 1 nm or less.

  The total film thickness of the electron injection layer composed of the coating film of the organometallic complex and the protective electrode layer, that is, the total film thickness of the cathode layer 4 is not particularly limited as long as electron injection into the organic layer 3 is possible. The film thickness of the entire layer 4 is preferably 50 to 500 nm. If the thickness of the protective electrode layer relative to the electron injection layer is too thin, the above effect cannot be obtained sufficiently. If the thickness of the auxiliary electrode is too thick, the stress due to the auxiliary electrode layer increases and dark spots grow. The speed tends to increase.

  In addition, the electron injection layer formed of a metal salt coating film is formed by applying a coating solution obtained by adding a metal salt to a predetermined solvent onto the organic layer 3 by a coating method such as a spin coating method, and removing the solvent from the coating solution. Can be formed. Examples of the metal contained in the metal salt include Ag, Al, Au, Be, Bi, Co, Cu, Fe, Ga, Hg, Ir, Mo, Mn, Nb, Ni, Os, Pb, Pd, Pt, Re, Ru, Sb, Sn, Ti, Zr, etc. are mentioned.

  The metal salt may be either an organic metal salt or an inorganic metal salt. Examples of organometallic salts include substituted or unsubstituted aliphatic carboxylates, divalent carboxylates, aromatic carboxylates, alcoholates, phenolates, dialkylamides, and the like. Examples of the inorganic metal salt include halides.

  The aliphatic carboxylic acid of the aliphatic carboxylate may be either a saturated aliphatic carboxylic acid or an unsaturated aliphatic carboxylic acid. Examples of the saturated aliphatic carboxylate include metal salts such as acetic acid, propionic acid, octanoic acid, isooctanoic acid, decanoic acid, and lauric acid. Examples of the unsaturated aliphatic carboxylate include metal salts such as oleic acid, ricinoleic acid, and linoleic acid.

  Examples of the divalent carboxylate include metal salts of divalent carboxylic acids such as citric acid, malic acid, and oxalic acid.

  Examples of the aromatic carboxylate include benzoic acid, o-tert-butylbenzoic acid, m-tert-butylbenzoic acid, p-tert-butylbenzoic acid, salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid and the like. Examples of the metal salt include salicylic acid.

  An alcoholate is a metal salt of an alcohol. Examples of the alcohol component constituting the alcoholate include primary alcohols such as ethanol, n-propyl alcohol, and n-butyl alcohol, secondary alcohols such as isopropyl alcohol and isobutyl alcohol, and tertiary alcohols such as tert-butyl alcohol. It is done.

  Phenolate is a metal salt of phenols. The number of hydroxyl groups contained in the phenol component constituting the phenolate is not particularly limited, but is preferably 1 to 2. Such a phenol component may have a substituent (preferably a linear or branched alkyl group having 1 to 8 carbon atoms) in addition to the hydroxyl group. In the present invention, phenol, naphthol, 4-phenylphenol and the like are preferably used.

  Examples of the halide that is an inorganic metal salt include metal salts such as chlorine, fluorine, bromine, and iodine.

  It is preferable to provide an auxiliary electrode layer on these electron injection layers. Thereby, the electron injection efficiency to the organic layer 3 can be improved, and the penetration | invasion of the water | moisture content or the organic solvent to the organic layer 3 or an electron injection layer can be prevented. As a material for the auxiliary electrode layer, a general metal can be used because there is no restriction on work function and charge injection capability. However, it is preferable to use a metal having high conductivity and easy handling. In particular, when the electron injecting layer contains an organic material, it is preferable to select appropriately according to the type and adhesion of the organic material. Specific examples of the material used for the auxiliary electrode layer include Al, Ag, In, Ti, Cu, Au, Mo, W, Pt, Pd, and Ni. Among them, low resistance such as Al and Ag. The use of these metals can further increase the electron injection efficiency. Further, higher sealing properties can be obtained by using a metal compound such as TiN. These materials may be used alone or in combination of two or more. Moreover, when using 2 or more types of metals, you may use as an alloy.

(Spacer and sealing plate)
As shown in FIG. 1, the organic layer 3, further, the anode layer 2 and the cathode layer 4 can be prevented from being deteriorated by sealing the cathode layer 4 side of the organic EL element 9 with the sealing plate 5. . At this time, the spacer 7 is disposed in the non-light emitting region on the insulating layer 6, and the spacer 7 and the sealing plate 5 are adhered to each other, thereby contacting the surface of the organic EL element 9 on the cathode layer 4 side with the sealing plate 5. Can be prevented. The spacer 7 may be an organic material or an inorganic material (including a metal material). Alternatively, the spacer 7 can be formed by a technique such as photolithography using a photosensitive material such as a photoresist or photosensitive polyimide. Further, an adhesive and an insulator such as a glass spacer may be mixed, and the mixture may be applied to the formation region of the spacer 7.

  It is preferable to encapsulate a sealing gas in a space formed by the surface of the organic EL element 9 on the cathode layer 4 side, the sealing plate 5 and the spacer 7. As such a sealing gas, it is preferable to use an inert gas such as Ar or He. The moisture content of the sealing gas is preferably 100 ppm or less, more preferably 10 ppm or less, and even more preferably 1 ppm or less. The lower limit of the moisture content of the sealing gas is not particularly limited, but if it is about 0.1 ppm, the deterioration preventing effect of the organic layer 3, the anode layer 2, the cathode layer 4, and the like is high, which is very preferable.

  According to the said embodiment, the organic EL element by which element characteristics, such as luminous efficiency, heat resistance, and lifetime, were achieved by the high level by including the star polymer concerning this invention and the dopant for light emission in the organic layer 3 was obtained. It becomes feasible. Such an organic EL element is very useful in the field of various optical application devices such as an organic EL display, an optical pickup used for memory reading and writing, a relay device provided in an optical communication transmission path, and a photocoupler. is there.

  Next, the organic EL display of the present invention will be described.

  FIG. 2 is a block diagram showing a preferred embodiment of the organic EL display of the present invention. The organic EL display shown in FIG. 2 is a passive drive type, and is a color conversion type organic EL display using a blue light emitting element as an excitation light source. The color conversion method is a method of exciting three color fluorescent elements by visible light emission of high energy rays. In the case of the color conversion method, blue light emission is often generated in the organic layer of the organic EL element, and green light and red light are obtained by exciting the green and red phosphor screens using the blue light emission as excitation light energy rays. Since blue is converted into green and red, it is called a color conversion method.

  In FIG. 2, the display unit 14 includes a substrate 1, an anode layer 2 (first electrode layer) formed on one side of the substrate 1, an organic layer 3 formed on the anode layer 2, and the organic layer 3. A plurality of organic EL elements 9 composed of the formed cathode layer 4 (second electrode layer) are two-dimensionally arranged. Here, in each of the organic EL elements 9, three organic layers containing the star polymer and the blue light emitting dopant according to the present invention correspond to the three light emitting regions (for example, 13a, 13b, and 13c). 3 (light emitting layer) is formed. Of the three light emitting areas, one is a blue light emitting area, and the remaining two are a green light emitting area and a red light emitting area.

  As a material of the substrate 1, for example, a transparent or translucent material such as glass, quartz, or resin is preferable.

  On the substrate 1, as described above, a fluorescence conversion filter film is provided in a region corresponding to two of the three light emitting regions formed in one organic EL element. The emission color is controlled so that a green emission region and a red emission region are obtained. The light emitting region where the fluorescence conversion filter film is not provided is a blue light emitting region.

  The fluorescence conversion filter film absorbs light generated by electroluminescence in the organic layer 3 and emits light of a color different from the absorbed light from the phosphor in the film, and performs color conversion of emission color. Includes a phosphor, a light absorber, and a binder. The fluorescence conversion filter film can be formed by patterning using a technique such as photolithography or printing. In this case, the material for the fluorescence conversion filter film is preferably one that can form fine patterning, and one that is less susceptible to damage in the formation process of the upper layer (the anode layer 2 or the like).

  As the phosphor contained in the fluorescence conversion filter film, one having a high fluorescence quantum yield is preferable, and one having a high light absorption in the emission wavelength region of the light emitting element such as a laser dye is preferable. Such phosphors include, for example, rhodamine compounds, perylene compounds, cyanine compounds, phthalocyanine compounds including subphthalo, naphthalimide compounds, condensed ring hydrocarbon compounds, condensed heterocyclic compounds, styryl compounds, Examples include coumarin compounds. In addition, when the light absorption property of fluorescent substance itself is inadequate, it is preferable to use a light absorber together, and as this light absorber, what does not quench fluorescence is preferable.

  The binder is not particularly limited as long as it does not quench the fluorescence, and can be appropriately selected from known binders.

  Moreover, it is preferable to combine the constituent material of the organic EL element 9 or a color filter that cuts off short-wavelength external light that can be absorbed by the fluorescence conversion filter film with the fluorescence conversion filter film because the light resistance and display contrast of the element are further improved. .

  In the display unit 14, the two anode layers 2 are formed in parallel with each other on the substrate 1 and the fluorescence conversion filter film so as to pass through the three light emitting regions 13a to 13c of the organic EL element 9, respectively. Has been. Here, the anode layer 2 is disposed so that a part of each of the light emitting regions 13a to 13c is exposed without completely covering the light emitting regions 13a to 13c. The anode layer 2 is a common electrode for a plurality (two in FIG. 2) of organic EL elements, and a power supply unit 8 (described later) is electrically connected to one end of each anode layer 2. Such a striped anode layer 2 can be formed, for example, by forming an ITO film on the substrate 1 on which the fluorescence conversion filter film is patterned, and then performing patterning and etching.

Although not shown in detail, it is preferable to provide an insulator layer such as a SiO ₂ layer or an Al ₂ O ₃ layer on the anode layer 2 after the anode layer 2 is formed. And it is preferable to open the area | region of the insulator layer corresponding to a light emission area | region by an etching etc., and to form the organic layer 3 in this opening part.

  Further, in the display unit 14, the organic layer 3 containing the star polymer according to the present invention and the blue light emitting dopant corresponds to each light emitting region of the organic EL element 9 and extends the light emitting region across the anode layer 2. It is formed to cover. Such an organic layer 3 can be suitably formed by a coating method such as a spin coating method. Further, by heating the coating liquid, it is possible to reduce the residual solvent and achieve high adhesion between the organic layer 3, the anode layer 2, and the cathode layer 4.

  Further, in the display unit 14, six cathode layers 4 are formed so as to pass over the organic layer 3 corresponding to the light emitting regions of the organic EL element 9. Each of the cathode layers 4 is a common electrode of a plurality (two in FIG. 2) of organic EL elements, and a switching unit 10 described later is electrically connected to one end of each cathode layer 4.

  In the case of a passive drive type organic EL display as in the present embodiment, it is preferable that the stripe-shaped anode layer 2 and the stripe-shaped cathode layer 4 are arranged so as to be orthogonal to each other as shown in FIG. . At this time, the intersection of the anode layer 2 and the cathode layer 4 in each light emitting region corresponds to one pixel of the display.

  A spacer 7 is provided for each organic EL element 9 in the non-light emitting region of the display unit 14. The surface on the cathode layer 4 side is sealed by adhering a sealing plate (not shown) to the spacer 7.

  In the organic EL display shown in FIG. 2, the drive unit 11 that controls display on the display unit 14 blinks on the organic EL element 9 and the power supply unit 8 that supplies current or voltage to the anode layer 2 and the cathode layer 4. A switching unit 10 for sending a control signal and these control logic circuits 12 are included. The power supply unit 8 is electrically connected to the anode layer 2, and the switching unit 10 is electrically connected to the cathode layer 4, and the power supply unit 8 and the switching unit 10 are electrically connected via the control logic circuit 12. Has been. The driving method of the organic EL element 9 in the display unit 14 is not particularly limited, and for example, DC driving, pulse driving, AC driving, and the like are applicable. In driving, it is preferable to supply a direct current, pulse or alternating current or voltage, and the applied voltage is preferably about 2 to 30V.

  According to the above embodiment, by including the star polymer and the blue light emitting dopant according to the present invention in the organic layer 3, it is possible to obtain blue light emission with high color purity in the light emitting region, and to stabilize the characteristics over a long period of time. Can be maintained. This blue light emission is extracted from the substrate 1 side as it is in the blue light emission region. Further, in the green light emission region and the red light emission region, green light and red light are emitted from the substrate 1 side by exciting the phosphors corresponding to green and red in the fluorescence conversion filter film using blue light emission as excitation light energy rays, respectively. Taken from. Therefore, according to the present embodiment, it is possible to realize an organic EL display that is excellent in luminance and color display function and has high heat resistance and a long life.

  The organic EL display of the present invention is not limited to the above-described embodiment, and can be determined in consideration of brightness, life, power consumption, cost, and the like necessary for an assumed display product. For example, FIG. 2 shows a so-called passive drive type organic EL display, but the organic EL display of the present invention may be an active drive type full color display using a polysilicon TFT or the like.

  When the organic EL display of the present invention is a full color display, full color display is realized by forming light emitting elements of three primary colors of red, green, and blue (RGB). The full color display method is the same as that in the above embodiment. In addition to the color conversion method shown, any of the RGB three-color juxtaposition method and the white light emission method may be used. The RGB three-color juxtaposition method is a display method in which each of the RGB three-color light emitting elements emits light. The white light emission method is a method of performing full color display by cutting a part of the wavelength of white light emission using a three-color filter used in a liquid crystal display device or the like. In the case of the white light emission method and the color conversion method, it is not necessary to prepare light emitting elements of three colors, the formation of the light emitting elements can be simplified, and an increase in area can be easily handled.

  In the organic EL display of the present invention, any color display method described above can be applied by appropriately selecting a light emitting dopant to be added to the light emitting layer of the organic EL element. For example, the color conversion method can be preferably applied by including a blue light emitting dopant in the organic layer of the organic EL element to form a light emitting layer. In addition, by incorporating a phosphorescent light emitting dopant into the light emitting layer of the organic EL element, the RGB three-color juxtaposition method using phosphorescent light emission can be preferably applied.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

[Example 1]
First, 9-biphenyl-2-yl-10- (4-vinylphenyl) -anthracene was synthesized according to the reaction route shown in the following reaction formula (A). Specifically, 2-bromobiphenyl was dissolved in a 1: 1 mixed solvent of toluene and ether, and n-butyllithium was added dropwise to the solution under a nitrogen atmosphere, followed by stirring at room temperature for 1 hour. The reaction solution was cooled to −20 ° C., anthrone was added, and pure water was further added after 20 hours to stop the reaction. The solvent was removed from the reaction solution after the reaction, and the residue was redissolved in THF, and dehydrated by adding hydrochloric acid and refluxing to obtain 9-biphenyl-2-yl-anthracene. The obtained 9-biphenyl-2-yl-anthracene was dissolved in DMF, N-bromosuccinimide (NBS) was added, and bromination reaction was performed at 50 ° C. for 20 hours. The resulting bromide was purified by column chromatography, and then dissolved in a mixed solvent of toluene, ethanol and 2M sodium carbonate solution (mixing ratio 4: 1: 2), and 4-vinylphenylboronic acid and tetrakistris as the catalyst were used. Phenylphosphine palladium was added and reacted at 90 ° C. for 24 hours to obtain 9-biphenyl-2-yl-10- (4-vinylphenyl) -anthracene. The obtained 9-biphenyl-2-yl-10- (4-vinylphenyl) -anthracene was purified by column chromatography and subjected to a polymerization reaction described later.

  Next, 2 g of 9-biphenyl-2-yl-10- (4-vinylphenyl) -anthracene was dissolved in toluene, and 3 mol with respect to 9-biphenyl-2-yl-10- (4-vinylphenyl) -anthracene. % S-butyllithium was added, and a living polymerization reaction was performed in a nitrogen atmosphere. Further, 30 mg of 1,3,5-trischloromethylbenzene was added to this reaction solution, and 9-biphenyl-2-yl-10- (4-vinylphenyl) was started from three methylene groups bonded to the benzene ring. ) -Anthracene polymerization was performed to synthesize a star polymer having polymer chains extending in three directions. After completion of the reaction, reprecipitation was performed 3 times using THF as a good solvent and methanol as a poor solvent, and further reprecipitation was performed 3 times by changing the poor solvent to ethyl acetate to obtain a white star polymer. .

  The obtained star polymer had a weight average molecular weight (Mw) of 33,000 and a number average molecular weight (Mn) of 30,000. From the amount of the monomer used and the average molecular weight of the star polymer, it was suggested that in the obtained star polymer, the number of units per polymer chain was about 25 (average value).

  Next, a 2% by weight toluene solution of the obtained star polymer was prepared. Further, tetraphenylbutadiene was added to the solution so as to be 3% by weight with respect to 9-biphenyl-2-yl-10- (4-vinylphenyl) -anthracene, thereby obtaining a light emitting layer coating solution. Using this coating solution, an organic EL device was produced according to the following procedure.

  First, a coating solution containing polyethylene dioxythiophene / polystyrene sulfonic acid (PEDOT / PSS) is applied onto a substrate on which an ITO film as an anode layer is formed by spin coating, and 5 ° C. in a nitrogen atmosphere at 200 ° C. A hole transport layer having a thickness of 500 mm was formed by drying for 5 minutes. Next, the light emitting layer forming coating solution was applied onto the hole transport layer and dried at 180 ° C. for 1 hour in a nitrogen atmosphere to form a light emitting layer having a thickness of 1000 mm. Further, on this light emitting layer, a layer LiF (film thickness 6 mm) as an electron injection layer and an Al layer (film thickness 2500 mm) as an auxiliary electrode are vacuum-deposited in this order to form a cathode layer. The target organic EL element was obtained by sealing the surface.

In the obtained organic EL element, blue light emission derived from tetraphenylbutadiene was obtained. The current efficiency of the organic EL element was 1.8 cd / A when driven at a constant current of 10 mA / cm ² . Furthermore, when a lifetime test was performed by driving at a constant current of 10 mA / cm ² , the lifetime until the luminance was reduced by half (luminance half-life, the same applies hereinafter) was 150 hours.

[Example 2]
A star polymer was synthesized in the same manner as in Example 1 except that the compound represented by the above formula (6) was used instead of 1,3,5-trischloromethylbenzene. Next, a light emitting layer coating solution was prepared and an organic EL device was produced in the same manner as in Example 1 except that the obtained star polymer was used.

In the obtained organic EL element, blue light emission derived from tetraphenylbutadiene was obtained. The current efficiency of the organic EL element was 1.9 cd / A when driven at a constant current of 10 mA / cm ² . Further, when a life test was performed by constant current driving at 10 mA / cm ² , the luminance half life was 180 hours.

[Example 3]
A star polymer was synthesized in the same manner as in Example 1 except that the compound represented by the above formula (8) was used instead of 1,3,5-trischloromethylbenzene. Next, a light emitting layer coating solution was prepared and an organic EL device was produced in the same manner as in Example 1 except that the obtained star polymer was used.

In the obtained organic EL element, blue light emission derived from tetraphenylbutadiene was obtained. The current efficiency of the organic EL element was 2.1 cd / A when driven at a constant current of 10 mA / cm ² . Further, when a life test was performed by driving at a constant current of 10 mA / cm ² , the luminance half life was 200 hours.

[Comparative Example 1]
A homopolymer was synthesized by conducting the same polymerization reaction as in Example 1 using 9-biphenyl-2-yl-10- (4-vinylphenyl) -anthracene. Next, a light emitting layer coating solution was prepared and an organic EL device was produced in the same manner as in Example 1 except that the obtained homopolymer was used.

In the obtained organic EL element, blue light emission derived from tetraphenylbutadiene was obtained. The current efficiency of the organic EL element was 1.5 cd / A when driven at a constant current of 10 mA / cm ² . Further, when a life test was performed by driving at a constant current of 10 mA / cm ² , the luminance half life was 110 hours.

It is a schematic cross section which shows suitable one Embodiment of the organic EL element of this invention. It is a block diagram which shows suitable one Embodiment of the organic electroluminescent display of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Anode layer (1st electrode layer), 3 ... Organic layer, 4 ... Cathode layer (2nd electrode layer), 5 ... Sealing plate, 6 ... Insulator layer, 7 ... Spacer, 8 DESCRIPTION OF SYMBOLS ... Power supply part, 9 ... Organic EL element, 10 ... Switching part, 11 ... Drive part, 12 ... Control logic circuit, 13 ... Light emission area | region, 14 ... Display part.

Claims (7)

Two electrodes arranged opposite each other;
An organic layer containing a star polymer and a luminescent dopant disposed between the electrodes and having a plurality of polymer chains formed starting from a polyvalent functional group;
An organic EL device comprising: 2. The organic EL device according to claim 1, wherein the polyvalent functional group includes an aromatic group having 10 or more carbon atoms derived from a luminescent compound. The organic EL device according to claim 1 or 2, wherein the polyvalent functional group has a structure represented by the following formula (1) or (2).

[In the formula (1), m represents an integer of 1 to 3, carbon atoms constituting the benzene ring and the anthracene ring may be either substituted or unsubstituted, and carbon constituting the benzene ring and the anthracene ring. One end of the polymer chain is bonded to the constituent atom of the substituent bonded to the atom or the carbon atom. ]

[In the formula (2), each carbon atom constituting the fluoranthene ring may be substituted or unsubstituted, and the constituent atom of the carbon atom constituting the fluoranthene ring or the substituent bonded to the carbon atom is a polymer. One end of the chain binds. ] The organic EL device according to claim 1, wherein the polymer chain is a polyvinyl chain. The polymer chain is formed by polymerization of a monomer having an aromatic group having 10 or more carbon atoms and a polymerizable functional group derived from a light-emitting compound. Organic electroluminescent element as described in any one of these. The organic polymer according to any one of claims 1 to 5, wherein the polymer chain is formed by polymerization of a vinyl monomer having a structure represented by the following formula (3). EL element.

[In Formula (3), L represents a divalent group, and X ¹ , X ² , X ³ , X ⁴ and X ⁵ may be the same or different, and each represents an alkyl group, an alkoxy group, an aryl group, an aryl group. Represents an oxy group, a heterocyclic group, a halogen atom, a cyano group, a hydroxyl group or an amino group, a, b, c and d each represents an integer of 0 to 4, e represents an integer of 0 to 5, and n represents It represents 0 or 1, p represents 0 or 1, q represents an integer of 1 to 3, and the substituents represented by X ^{1 to} X ⁵ may be bonded to each other to form a ring. ] Two electrodes disposed opposite to each other, and a star polymer in which a plurality of polymer chains are formed starting from a polyvalent functional group and an organic layer containing a light-emitting dopant. A display unit in which a plurality of configured organic EL elements are arranged;
A power supply unit that is electrically connected to each of the two electrodes and supplies a voltage or current to the electrodes; and a switching unit that turns on or off each of the organic EL elements;
An organic EL display comprising:

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