JP3231816B2 - Electrode manufacturing method for electroluminescent device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for fabricating an electrode of an organic electroluminescent device, and more particularly to a method for fabricating an electrode of an organic electroluminescent device having good bonding to a substrate on which the electrode is formed.

[0002]

2. Description of the Related Art An organic electroluminescent device basically has a shape in which an organic light emitting layer is sandwiched between positive and negative electrodes. Excitons (excitons) formed when electrons and holes injected as carriers from the positive and negative electrodes are recombined emit light when returning from the excited state to the ground state. It is also known that a hole transport layer is further interposed between the positive electrode and the organic light emitting layer, or an electron transport layer is interposed between the negative electrode and the organic light emitting layer in order to improve the luminance (particularly). 63-46969
No. 2, JP-A-63-295695, JP-A-2-250
No. 292, J.I. J. Appl. Phys. , 27, L2
69 (1988)). That is, as shown in FIG. 1, the glass substrate 1, the transparent positive electrode 2, the hole transport layer 3, the organic light emitting layer 4, the electron transport layer 5, and the negative electrode 6 are laminated in this order. Then, a voltage is applied from the DC power supply 7 to emit light. Of course, one or both of the electron transport layer and the hole transport layer may be omitted. Further, not only organic compounds but also inorganic compounds may be used for the electron transporting layer and the hole transporting layer.

[0003]

The organic light emitting layer, the hole transporting layer, or the electron transporting layer is easily degraded under the influence of moisture, oxygen, and certain kinds of molecules in the use environment. Need to shut off. As shown in FIG. 1, since electrodes are laminated on the organic light emitting layer, the hole transport layer, or the electron transport layer, if the electrode has low adhesion or bonding property to these layers, the bonding force with time will increase. Becomes loose or peels off,
Moisture and oxygen enter from there, and the hole transport layer, the organic light emitting layer, or the electron transport layer is deteriorated, and the light emission characteristics such as luminance and color are reduced. Generally, an organic light emitting layer, a hole transport layer,
Alternatively, the adhesion of the metal electrode to the electron transport layer is poor, and loosening or peeling of the bond is likely to occur over time. Therefore, an object of the present invention is to provide an organic electroluminescent device, an organic light-emitting layer,
An object of the present invention is to improve the bonding force of a positive or negative electrode to a hole transport layer or an electron transport layer, thereby improving the durability of a light emitting device and stabilizing light emitting characteristics.

[0004]

According to the present invention, there is provided a method for manufacturing an electrode of an organic electroluminescent device, comprising a substrate layer which is an organic light emitting layer, a hole transport layer or an electron transport layer, and a grid electrode arranged on the surface side thereof. for example a metal mesh, leave biased together negative potential, ionized metal to form the electrodes, which was accelerated by the negative potential, a method of forming a film on the substrate layer, the base layer After the surface is subjected to plasma or reverse sputtering, an electrode is subsequently formed on the surface of the base layer in a vapor phase without being exposed to air . According to the present invention, the bonding force with the electrode is large, moisture and oxygen do not enter the electron transporting layer, the organic light emitting layer or the hole transporting layer,
The electrode acts as an excellent shielding layer.

FIG. 2 shows an embodiment of the present invention.
After a transparent positive electrode 2, a hole transport layer 3, an organic light emitting layer 4, and an electron transport layer 5 are sequentially formed on the surface of a glass substrate 1 by a conventional method, a negative electrode 6 is formed.

[0006] The plasma treatment is carried out as a pre-treatment. In this case, the laminate is accommodated inside a known electrode film forming apparatus, and the organic light emitting layer 4 is connected to a predetermined negative power supply 8 when the electron transport layer 5 or the electron transport layer is not provided. However, since the conductivity of these layers is not sufficient, the mesh grid 9
Is placed close to layer 5 (or layer 4 if layer 5 is absent) and is at the same negative potential. The distance between the grid 9 and the base layer is preferably several mm, and a negative potential of, for example, about -150 volts or less to about -10 kV is applied. As a plasma gas to be used, an inert gas such as He, Ar, Ne, or Xe, or a gas such as hydrogen or nitrogen is turned into plasma. Positive ions in the plasma gas are accelerated by the negative potential applied to the grid 9 to activate the surface of the organic light emitting layer or the electron transport layer, thereby improving the bonding force with the electrode to be formed next. Instead of the plasma treatment, the surface of the base may be activated by a well-known reverse sputtering method in the same arrangement as in FIG. The present invention also includes such a case, since a positive electrode may be formed last after forming a hole transport layer.

After the surface treatment by plasma or reverse sputtering is completed, the negative electrode 6 is subsequently formed in the same vacuum. As the material of the negative electrode, a material selected from a metal having a work function of 4 eV or less or an alloy containing at least one metal having a work function of 4 eV or less is used. For example, Mg, Al, and Mg-Ag alloy can be used. The electrode is formed by ionizing the electrode material, using a grid and a substrate at a negative potential of about -100 to -10 kV as described above, and depositing a metal on the substrate while maintaining the acceleration voltage at this level. I do. The transparent positive electrode 2, the hole transport layer 3, the organic light emitting layer 4, the electron transport layer 5, and the negative electrode 6
Are all known. For example, the transparent positive electrode includes an In-Sn oxide, the hole transport layer includes a triphenyldiamine derivative, a stilbene derivative, a pyrazoline derivative, and the like, and the electron transport layer includes an oxadiazole derivative. As the organic light-emitting layer, a condensed polycyclic aromatic hydrocarbon dye, a condensed polycyclic dye containing a hetero atom such as O, N, or S;
There are metal complex dyes and the like. Examples thereof include perinone derivatives, quinoline complex derivatives, thiadiazolopyridine derivatives, tetraphenylbutadienes, bisstyrylbenzene derivatives and the like (Japanese Patent Application Laid-Open No. 1-245087,
2-88689, 2-250292, 2-2
No. 61889).

There are various well-known methods for forming ions of a metal. For example, ion plating, R
There are an F ion plating method, a multi-cathode method, an HCD method, a bias probe method, a low voltage plasma deposition method, a cluster ion beam (CIB) method, an arc ion plating (AIP) method and the like, and an appropriate method can be selected. In an embodiment of the present invention, a cluster ion beam method (a metal vapor is formed in a closed container and is ejected as cluster ions from a narrow nozzle. For example, Applied Physics Vol. 55, No. 8 (1985), Takagi, "Cluster Ion Beam Technology" And its application "), ion plating (metal vapor is ionized by the action of an arc discharge.
9-4050, JP-A-1-96367), RF
Ion plating method (Ionization by applying inert gas excited by high frequency to heated and vaporized metal)
It was adopted.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described below. In the following example, an In-Sn oxide electrode layer is formed on the surface of a glass substrate,
Next, a hole transport layer, an organic light emitting layer, or an electron transport layer was formed. Next, grids were arranged in parallel with each other at a distance of 6 mm from these layers, and currents and voltages were applied to these layers and the grids at the degree of vacuum shown in Tables 1, 2 and 3. The left column shows general conditions that can be used, and the right column shows conditions used in Examples. The anode side was set to 0V. However, in Example 1, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl- was used as the hole transport layer.
In Examples 2 and 3, stilbene derivatives were used as the organic light-emitting layer, using 4,4′-diamine and an 8-quinolinol Al complex as the organic light-emitting layer adjacent to the electrode.

Embedded image Using an oxadiazole derivative as the electron transport layer adjacent to the electrode

Embedded image It was used. Table 4 shows the results. However, in the peel test, according to JIS K5400, cut 100 squares in a grid pattern, apply adhesive tape so as to cover them all, adhere well, peel off quickly in the direction of 90 degrees with the coated surface, Indicate the number remaining for the first line. The scratch test was measured with a CSR-02 testing machine manufactured by Rhesca, and was expressed as a relative value with the untreated sample taken as 1.0.
For comparison, a conventional deposition method and a film formation by a sputtering method are also described.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

[Table 4]

[0014]

According to the present invention, the ion beam is accelerated by the negative voltage of the grid, so that not only the adhesion of the electrode to the base layer of the organic electroluminescent device is improved, but also the
Adhesion as a result of body layer being activated by pretreatment
The performance is further improved . For this reason, the durability of the organic electroluminescent element against invasion of moisture, oxygen, and the like is improved, and the light emitting characteristics are stabilized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a configuration of an organic electroluminescent device.

FIG. 2 is a diagram illustrating a method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Transparent positive electrode 3 Hole transport layer 4 Organic light emitting layer 5 Electron transport layer 9 Grid electrode

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tetsuji Inoue TDC Corporation, 1-13-1 Nihombashi, Chuo-ku, Tokyo (56) References JP-A-5-41286 (JP, A) JP-A Sho56 -169770 (JP, A) JP-A-4-19993 (JP, A) JP-A-4-363896 (JP, A) "Basics of thin film preparation (2nd edition)" by Tatsuo Asamaki, Nikkan Kogyo Shimbun 1984) p. 145 -149 “Chapter 7 Ion Plating” (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 33/00-33/28

Claims (3)

(57) [Claims] In a method of manufacturing an electrode of an organic electroluminescent device, a substrate layer, which is an organic light emitting layer, a hole transport layer or an electron transport layer, and a grid electrode disposed on the surface thereof are both biased to a negative potential. In a method of ionizing a metal to form an electrode and accelerating the ion by the negative potential to form a film on the base layer, the metal layer before forming the electrode layer
The surface of the substrate layer was subjected to plasma or reverse sputtering.
Thereafter, the surface of the base layer is continuously exposed without being exposed to air.
A method for producing an electrode of an organic electroluminescent device, comprising forming an electrode in a vapor phase on a surface . 2. The method according to claim 1, wherein the ionization is performed by a method selected from an ionization deposition method, an ion plating method, and a cluster ion beam method. 3. The organic electroluminescence according to claim 1, wherein the electrode is selected from a metal having a work function of 4 eV or less or an alloy containing at least one metal having a work function of 4 eV or less. A method for producing an electrode of a device.