KR100682866B1 - Organic electroluminescent device using metal phthalocyanine dendrimer polymer as a hole injecting layer or a hole transporting layer - Google Patents

Abstract

An organic electroluminescent device is provided to have improved luminous efficiency and luminous brightness by using metal phthalocyanine dendrimer polymer as a hole injecting layer or a hole transporting layer. The organic electroluminescent device comprises an anode layer, a light emitting layer, and a cathode layer. The organic electroluminescent device further includes a hole injecting layer or a hole transporting layer comprising metal phthalocyanine dendrimer polymer between the anode layer and the light emitting layer. The metal phthalocyanine dendrimer polymer is obtained by reacting a metal compound with at least one compound selected from compounds represented by the following formula 1 or derivatives thereof. In the formula 1, Rs as a divalent organic group which are identical to or different from one another, comprises O, S, CH2, CO, SO2, or NHCO.

Description

Organic electroluminescent device using metal phthalocyanine dendrimer polymer as a hole injecting layer or a hole transporting layer}

1 is a cross-sectional view of a conventional organic electroluminescent device.

2 is an optical electron micrograph showing that crystallization occurs when conventional copper phthalocyanine is used as the hole injection layer or the hole transport layer.

3 is a view illustrating a process of synthesizing a copper phthalocyanine dendrimer according to an embodiment of the present invention.

4 is a view showing the structure of a copper phthalocyanine hyper branched polymer according to an embodiment of the present invention.

5 is a view showing the structure of a copper phthalocyanine dendrimer according to an embodiment of the present invention.

FIG. 6 is a graph showing the efficiency with respect to the voltage of the organic light emitting display device according to Example 1 and Comparative Example 1. FIG.

7 is a graph showing luminance versus voltage of organic light emitting diodes according to Example 1 and Comparative Example 1. FIG.

8 is a graph showing current density versus voltage of the organic light emitting display device according to Example 1 and Comparative Example 1. FIG.

9 is a graph showing absorption spectra of an organic light emitting display device according to Example 1;

<Description of Major Symbols in Drawing>

11: substrate 12: anode

13: hole injection layer 14: hole transport layer

15: light emitting layer 16: electron transport layer

17: electron injection layer 18: cathode

The present invention relates to an organic light emitting device using a metal phthalocyanine dendrimer polymer as a hole injection layer or a hole transport layer, and more particularly, to improve the luminous efficiency and brightness by reducing the energy barrier difference between the anode layer and the light emitting layer, the crystals are not good The present invention relates to an organic electroluminescent device using a compound in a hole injection layer or a hole transport layer, which has a high solubility in organic solvents and is easy to process.

An organic light emitting display is a self-luminous display that uses light to generate light when electrons and holes are combined in an organic film when a current flows through a fluorescent or phosphorescent organic film. Active research is currently being conducted due to various advantages such as high color purity, low power consumption, and perfect video implementation.

In the organic light emitting device as described above, it is common to laminate multiple organic films such as a hole injection layer, an electron transporting layer, a hole transporting layer, and a light emitting layer in order to improve efficiency and lower driving voltage without using only a single light emitting layer as an organic film. The multiple organic films may be basically classified into a hole related layer, an electron related layer, and an emission layer. FIG. 1 is a cross-sectional view of a conventional organic electroluminescent device (for a system employing a low molecular weight light emitting layer), in which an anode or anode electrode 12 is stacked on a substrate 11, and a hole related layer thereon. As a hole injection layer (HIL) 13 and a hole transfer layer (HTL) 14 are laminated, and an emission layer 15 (EML) 15 is laminated, and electrons thereon. After the Electron Transfer Layer (ETL) 16 and the Electron Injection Layer (EIL) 17 are stacked as the related layer, the cathode or cathode electrode 18 is finally stacked. It can be seen that.

In the conventional organic light emitting device, oxygen diffusion occurs in an anode, for example, an indium tin oxide (ITO) electrode, and the work function of the anode is not so high as 4.7 to 4.8 eV, and its surface roughness is a problem. In order to improve the problem, by using a polythiophene-based conductive polymer such as polyaniline (polyaniline), polypyrrole, and polyethylene dioxythiophene (PEDOT) as a polymer, Methods have been studied to have work functions near 5.0 eV (Y. Yang, J. Appl. Phys. 77, 694 (1995); J. Gao et al., Syn. Met. 82, 221 (1996); And PCT WO 00/65653 and the like). However, the method of using the conductive polymer as the hole injection layer has a disadvantage in that the conductive polymer is hydrophilic, so that the amount of water absorption is large, easily dissolved in water or an organic solvent, and combined with electrons to form a salt.

In order to overcome the above problems, a method of using a low molecular copper phthalocyanine as a hole injection layer has been developed (J. Marks et al, Adv. Mater. 14, 565 (2002)).

However, the copper phthalocyanine lacks heat stability as can be seen in FIG. 2 of the accompanying drawings, and crystallization easily occurs (FIG. 2 shows that crystallization occurs when annealed at 80 ° C. for 30 minutes). Due to its low solubility in solution, a solution process was impossible and a complex deposition process had to be adopted.

The present invention is to solve the problems of the prior art, the technical problem to be achieved by the present invention is to reduce the energy barrier between the anode layer and the light emitting layer to increase the luminous efficiency and brightness, and the crystals do not form well for the organic solvent It is to provide an organic light emitting device using a metal phthalocyanine dendrimer polymer having a high solubility and easy solution process as a hole injection layer or a hole transport layer.

The present invention to achieve the above technical problem,

In an organic light emitting device comprising an anode layer, a light emitting layer and a cathode layer,

An organic electroluminescence further comprising a hole injection layer or a hole transport layer comprising a metal phthalocyanine dendrimer polymer obtained by polymerizing a metal compound with at least one compound selected from the compound represented by the following Chemical Formula 1 and derivatives thereof between the anode layer and the light emitting layer The device is provided:

Wherein R is a divalent organic group comprising O, S, CH ₂ , CO, SO ₂ or NHCO, all of which may be the same or different.

Hereinafter, the present invention will be described in more detail.

The present invention relates to the use of a dendritic oligomer or polymer of the compound represented by the formula (1) having high solubility in organic solvents and high dielectric constant properties as a hole injection layer or hole transport layer of an organic light emitting device.

In the present invention, the compound represented by Chemical Formula 1 and its derivatives are not particularly limited, and examples thereof include 1,3,5-tri (3,4-dicyanophenoxy) benzene and 1,3,5-tri (3). , 4-dicyano benzoyl) benzene, 1,3,5-tri (3,4-dicyano phenyl imino) benzene, 1,3,5-tri (3,4-dicyanopentthiol) benzene, 1, 3,5-tri (3,4-dicyanobenzyl) benzene, 1,3,5-tri (3,4-dicyanobenzylthio) benzene, 1,3,5-tri (3,4-dicyanobenzoyl Imino) etc. are mentioned.

In the present invention, a compound having three dicyano phenyl groups having two adjacent cyano groups represented by Formula 1 and derivatives thereof may include a polymer containing a dendrimer oligomer or a polymer while forming metal ions such as copper and metal phthalocyanine. Forming is known by Japanese Patent Laid-Open No. 2005-105193, which is incorporated herein by reference.

In the present invention, the dendrimer polymer is a concept including a hyper branch polymer or a dendrimer. The hyper-branched polymer refers to a multi-branched polymer synthesized by a self-condensation reaction of a compound having three or more two kinds of substituents in one molecule, and a dendrimer is a branched constant unit structure repeatedly extending from a core. It refers to the spherical polymer that came out. The dendrimer appears to increase generation according to the addition of a repeating unit structure.

3 is a view illustrating a process of forming a copper phthalocyanine hyper branched polymer or a copper phthalocyanine dendrimer according to an embodiment of the present invention. Referring to FIG. 3, a first generation is formed by the reaction of the compound represented by Chemical Formula 1 and its derivatives with copper, and then a copper phthalocyanine hyper branch polymer or a copper phthalocyanine dendrimer is formed by successive reactions. Herein, an example of a process of forming the copper phthalocyanine hyper branched polymer or the copper phthalocyanine dendrimer by the reaction of the compound represented by Chemical Formula 1 and its derivatives with copper is described as follows. First, the compound represented by Chemical Formula 1 and copper are dissolved in a solvent. Herein, the copper may be copper chloride or copper powder. When copper chloride is used, the ratio of the compound represented by Chemical Formula 1 and copper chloride is preferably used in a molar ratio of 2: 1 to 3: 2, and copper When using a powder, it is preferable to use the ratio of the compound represented by Formula 1 and copper powder in a molar ratio of 4: 1 to 3: 1. If less copper is used outside the range of the above ratio, copper phthalocyanine may not be sufficiently formed to form copper phthalocyanine hyperbranched polymer or copper phthalocyanine dendrimer, and if too much copper is used, the solvent is poorly soluble and the reaction is not smooth. Not desirable Acetone, tetrahydrofuran, dimethyl acetamide, N-methyl-2-pyrrolidone and the like can be used as the solvent. A solution prepared by dissolving the compound represented by Formula 1 and copper in the solvent was reacted at a high temperature of about 160 ° C. for 6 hours to 20 hours, and then the solution was added dropwise to excess distilled water or methanol to dry the resulting precipitate. Can be obtained. The product produced by the above process is a copper phthalocyanine hyper branched polymer or a copper phthalocyanine dendrimer according to the present invention. Usually, the copper phthalocyanine hyper branched polymer and copper phthalocyanine dendrimer are simultaneously formed and present in the product.

4 is a view showing the molecular structure of a copper phthalocyanine hyper branched polymer according to an embodiment of the present invention, Figure 5 is a view showing the molecular structure of a copper phthalocyanine dendrimer according to an embodiment of the present invention. Referring to FIG. 4, the copper phthalocyanine hyperbranched polymer according to an embodiment of the present invention combines four compounds represented by the formula (1) using copper as a center element to form a metal phthalocyanine structure, and is then continuously combined with the metal phthalocyanine structure. It can be seen that the compound represented by the formula (1) is bonded to form a huge branched structure. Referring to FIG. 5, the copper phthalocyanine dendrimer according to an embodiment of the present invention may have a spherical structure in which a metal is present in a core and a hyperbranched polymer is bonded around the core. The molecular weight of the metal phthalocyanine dendrimer may be adjusted according to polymerization conditions, but is preferably about 2,000 to 100,000.

Although it does not specifically limit as a core metal of the said metal phthalocyanine dendrimer in this invention, Cu, Co, Ni, Ti, Fe, Ru, Zn is preferable, More preferably, it is Cu.

In the present invention, the metal phthalocyanine dendrimer polymer does not crystallize upon annealing due to the bulky structure connected by the organic spacer.

The present invention relates to an organic electroluminescent device using the metal phthalocyanine dendrimer polymer as a hole injection layer or a hole transport layer.

The organic light emitting device according to the present invention can be divided into two types of systems in which a polymer light emitting layer is employed and a low molecular light emitting layer is employed.

In the case of a system employing a polymer light emitting layer, an organic light emitting display device according to the present invention includes an anode formed on a substrate; A hole injection layer (or hole transport layer) formed on the anode; An emission layer formed on the hole injection layer (or hole transport layer); And a cathode formed on the light emitting layer.

In the organic light emitting device employing the polymer light emitting layer according to the present invention, the substrate is a substrate used in a conventional organic light emitting device, an organic substrate or a transparent plastic substrate excellent in transparency, surface smoothness, ease of handling and waterproofing This is preferred.

In the organic light emitting device employing the polymer light emitting layer according to the present invention, as the anode formed on the substrate, a metal film, which is a reflective film, is used for the top light emitting structure, and in the case of the bottom light emitting structure, oxidation is transparent and excellent in conductivity. Materials such as indium tin (ITO), indium zinc oxide (IZO), tin oxide (SnO ₂ ), zinc oxide (ZnO), or mixtures thereof may be used.

In the organic light emitting device employing the polymer light emitting layer according to the present invention, the hole injection layer (or hole transport layer) is a metal phthalocyanine dendrimer obtained by polymerizing at least one compound selected from a compound represented by the following formula (1) and derivatives thereof It consists of a polymer.

[Formula 1]

Wherein R is a divalent organic group comprising O, S, CH ₂ , CO, SO ₂ or NHCO, all of which may be the same or different.

In the present invention, the hole injection layer or the hole transport layer may be used alone of the metal phthalocyanine dendrimer polymer, it is also possible to use a blend of the metal phthalocyanine dendrimer polymer and the thermoplastic resin, thermosetting resin or a mixture thereof.

Examples of the thermoplastic resins that can be used in the present invention include polyimide, polyamide, polyamide imide, polystyrene imide, polyester, benzoxazole, polystyrene, polyvinylcarbazole and polymethylmethacrylate. At least one selected from the group, but is not limited thereto.

Examples of the thermosetting resin that can be used in the present invention include at least one selected from the group consisting of an epoxy resin, a polyimide resin, a cyanate resin, a phenol resin, a benzo cyclobutene resin and a dicyclopentadiene resin, but It is not limited.

In the present invention, the thermoplastic resin or the thermosetting resin is preferably used in 10 to 90 parts by weight, more preferably 20 to 80 parts by weight based on 100 parts by weight of the dendrimer polymer according to the present invention. If the content is less than 10 parts by weight, the mechanical properties of the blended resin may be deteriorated. If the content is more than 80 parts by weight, the high dielectric constant effect is insignificant, which is not preferable.

In the present invention, the method for depositing the metal phthalocyanine dendrimer polymer on the anode may use methods commonly used in the art to which the present invention pertains, for example, thermal deposition and spin coating. In particular, in the present invention, since the metal phthalocyanine dendrimer polymer includes a polar group, such as a cyan group, at the end thereof, the metal phthalocyanine dendrimer polymer may be dissolved in 20% by weight or more in a polar organic solvent having a boiling point of 50 to 210 ° C. Therefore, by dissolving in the solvent it is possible to deposit by solution casting (solution casting). Examples of the polar organic solvent that may be used in the present invention include acetone, tetrahydrofuran (THF), dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, and the like.

Preferably, the hole injection layer or the hole transport layer has a thickness of 100 kPa to 500 kPa. If the thickness of the hole injection layer or the hole transport layer is less than 100 kPa, the hole injection characteristic or the hole transport characteristic is lowered, and if it exceeds 500 kPa, It is not desirable because of the voltage rise.

In the case of the polymer system, phosphorescent and fluorescent materials may be used as the light emitting layer.

In addition, an electron injection layer (EIL) may be selectively stacked on the emission layer, and the electron injection layer material is not particularly limited, and materials such as LiF, Li, Ba, BaF ₂ / Ca may be used.

Finally, a cathode is laminated on the light emitting layer (when the electron injection layer is not included) or the electron injection layer (when the electron injection layer is included).

On the other hand, in the case of a system employing a low molecular light emitting layer, the organic light emitting display device according to the present invention includes an anode formed on a substrate; A hole injection layer formed on the anode; An emission layer formed on the hole injection layer; An electron injection layer formed on the light emitting layer; It includes a cathode formed on the electron injection layer.

In the organic electroluminescent device employing the low molecular weight light emitting layer according to the present invention, as the hole injection layer or the hole transport layer, metal phthalocyanine obtained by reacting at least one compound selected from a compound represented by the following formula (1) and derivatives thereof with a metal compound It consists of a dendrimer polymer.

[Formula 1]

Wherein R is a divalent organic group comprising O, S, CH ₂ , CO, SO ₂ or NHCO, all of which may be the same or different.

The method for depositing the metal phthalocyanine dendrimer polymer on the anode in the organic light emitting device employing the low molecular weight light emitting layer according to the present invention, for example, thermal deposition, spin commonly used in the technical field to which the present invention belongs Coating methods and the like can be used. In particular, the metal phthalocyanine dendrimer polymer in the present invention can be dissolved by more than 20% by weight in a polar organic solvent having a boiling point of 50 to 210 ℃ can be deposited by solution casting (solution casting). Examples of the polar organic solvent that may be used in the present invention include acetone, tetrahydrofuran (THF), dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, and the like.

In the present invention, since the metal phthalocyanine dendrimer polymer is deposited and crosslinked to the tin indium oxide (ITO) in the firing process, the metal phthalocyanine dendrimer polymer is stable since it is insoluble in an organic solvent thereafter.

In the present invention, the thickness of the hole injection layer or the hole transport layer is preferably 100 kPa to 500 kPa. If the thickness of the hole injection layer or the hole transport layer is less than 100 kPa, the hole injection characteristic or the hole transport characteristic is lowered, and exceeds 500 kPa. In this case, an increase in driving voltage is not preferable. The same substrate and anode as in the polymer light emitting layer system may be used as the substrate and the anode.

In the system employing a low molecular weight light emitting layer, a red light emitting material, a green light emitting material, and a blue light emitting material are patterned in R, G, and B areas of the pixel areas on the hole injection layer or the hole transport layer to form an emission layer (EML) as a pixel area. . The light emitting material may use two or more mixed host materials.

It is preferable that the thickness of a light emitting layer is 100-800 GPa, More preferably, it is 300-600 GPa. If the thickness of the light emitting layer is less than 100 kV, the efficiency and lifespan are lowered.

In addition, an electron transport layer (ETL) is formed on the light emitting layer, and as the electron transport layer material, a material generally employed as an electron transport layer in the art may be used, for example, Alq ₃ may be used. On the other hand, it is preferable that the thickness of the electron transport layer is 50 to 600 kV, but if the thickness of the electron transport layer is less than 50 kW, the lifespan characteristic is lowered.

In addition, an electron injection layer EIL may be selectively stacked on the electron transport layer. The electron injection layer material is not particularly limited, and materials such as LiF, NaCl, CsF, Li ₂ O, BaO, Liq, and Ba may be used. The thickness of the electron injection layer is preferably 1 to 100 kV. If the thickness of the electron injection layer is less than 1 kW, the electron injection layer does not serve as an effective electron injection layer, and the driving voltage is high. High drive voltage is not preferred.

Finally, a metal for a cathode, which is a second electrode, is stacked on the electron transport layer, and as the cathode metal, lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al-Li), and calcium (Ca) ), Magnesium-indium (Mg-In), magnesium-silver (Mg-Ag) and the like can be used.

The organic electroluminescent device using the metal phthalocyanine dendrimer polymer according to the present invention as the hole injection layer or the hole transport layer has been described above. The organic electroluminescent device according to the present invention uses a dendrimer polymer having a metal, preferably copper as a core, as a hole injection layer or a hole transport layer, so that the work function is high, the luminous efficiency and luminance can be increased, and conventional copper phthalocyanine is injected into the hole. There is no problem of crystallinity and complicated deposition, which is a problem when used as a layer (or a hole transport layer).

Hereinafter, a preferred embodiment of the present invention. However, the following examples are merely to aid the understanding of the present invention, and the present invention is not limited to the following examples.

Example

Example  One

The anode was cut into Corning 15Ω / cm ² (1600Å) ITO glass substrates of 50mm x 50mm x 0.7mm, ultrasonically cleaned in isopropyl alcohol and pure water for 5 minutes, and then UV and ozone cleaned for 30 minutes. Used.

The metal phthalocyanine dendrimer polymer was dissolved in N-methyl-2-pyrrolidone by dissolving 1,3,5-tri (3,4-dicyanophenoxy) benzene and copper chloride in a molar ratio of 3: 2 and stirred at 160 ° C. After reacting for 12 hours, the reaction solution was dropped into excess distilled water to precipitate, and the resultant precipitate was dried by vacuum drying for about 3 hours.

A copper phthalocyanine dendrimer polymer having a molecular weight of 10,000 prepared according to the above method was dissolved at 1.2% by weight in dimethylformamide, an organic solvent.

The copper phthalocyanine dendrimer polymer was coated to a thickness of 20 nm by spin coating, and calcined at 200 ° C. for 1 hour. The copper phthalocyanine dendrimer polymer thin film manufactured as described above was used as a hole injection layer, and then GP223 manufactured by Dow, a green light emitting material, was coated on the hole injection layer to a thickness of about 80 nm.

Subsequently, Ba and Al were sequentially vacuum deposited on the light emitting layer to a thickness of 5 nm and 150 nm, respectively, to prepare an organic light emitting display device according to the present invention.

Comparative example  One

The same process as in Example 1 was carried out except that the organic light emitting display device was manufactured without forming a hole injection layer.

Performance experiment

6 shows the efficiency according to the voltage of the organic light emitting device according to Example 1 and the organic light emitting device according to Comparative Example 1, Figure 7 shows the organic light emitting device according to Example 1 and the organic according to Comparative Example 1 The luminance according to the voltage of the electroluminescent device is illustrated. 8 shows current densities according to voltages of the organic light emitting diode according to Example 1 and the organic light emitting diode according to Comparative Example 1, and FIG. 9 shows absorption spectra of the organic light emitting diode according to Example 1. Shown.

The experimental results for Example 1 and Comparative Example 1 are summarized in Table 1.

division Emission characteristics Maximum Efficiency (cd / A) Turn-on voltage (V) Work function CIE color coordinates (x, y) Example 1 ITO / HBCuPc / GP223 / Ba / Al 3.57 3.8 5.2-5.3 0.30, 0.58 Comparative Example 1 ITO / GP223 / Ba / Al 0.173 3.4 4.8 0.29, 0.57

HBCuPc = copper phthalocyanine dendrimer polymer

As can be seen in the drawing and Table 1, the organic electroluminescent device using the copper phthalocyanine dendrimer polymer according to the present invention as the hole injection layer has a large work function and a very good luminous efficiency according to the voltage, The current density is low, it can be confirmed that the efficiency is excellent.

According to the present invention, when the metal-based dendrimer polymer is used as the hole injection layer or the hole transport layer, an organic electroluminescent device having a high work function and a low current density and excellent luminous efficiency can be manufactured, and the dendrimer polymer Since the polar group may be dissolved in a polar organic solvent, an easy deposition such as a solution deposition method may be performed.

Although the present invention has been described above through specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the technical idea of the present invention, and such changes and modifications belong to the appended claims.

Claims (6)

In an organic light emitting device comprising an anode layer, a light emitting layer and a cathode layer, An organic electroluminescence further comprising a hole injection layer or a hole transport layer comprising a metal phthalocyanine dendrimer polymer obtained by reacting at least one compound selected from a compound represented by the following Chemical Formula 1 and a derivative thereof and a metal compound between the anode layer and the light emitting layer. device: [Formula 1]

Wherein R is a divalent organic group comprising O, S, CH ₂ , CO, SO ₂ or NHCO, all of which may be the same or different. The method of claim 1, Organic metal light emitting device, characterized in that the metal is Cu, Co, Ni, Ti, Fe, Ru or Zn. The method of claim 1, And the hole injection layer or the hole transport layer further comprises a thermoplastic resin or a thermosetting resin. The method of claim 3, The thermoplastic resin is at least one member selected from the group consisting of polyimide, polyamide, polyamide imide, polyether imide, polyester, benzoxazole, polystyrene, polyvinylcarbazole and polymethylmethacrylate. An organic electroluminescent device. The method of claim 3, The thermosetting resin is at least one member selected from the group consisting of an epoxy resin, a polyimide resin, a cyanate resin, a phenol resin, a benzo cyclobutene resin and a dicyclopentadiene resin. The method of claim 1, An organic light emitting display device, characterized in that the metal phthalocyanine dendrimer polymer is a substance of the following formula:

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