JP3172555B2 - 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 base layer which is an organic light emitting layer, a hole transport layer, or an electron transport layer; After a grid electrode, for example, a metal mesh, disposed on the substrate layer is biased to a negative potential and the surface of the base layer is plasma- or reverse-sputtered, an electrode is continuously formed on the surface of the base layer without being exposed to air. It is characterized by forming a film. According to the present invention, the bonding force between the electrode and the organic light emitting layer, the hole transport layer, or the electron transport layer is large, and moisture and oxygen do not enter the organic light emitting layer, the hole transport layer, or the electron transport 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 a surface of a glass substrate 1 by a conventional method, and before forming a negative electrode 6, a plasma is formed according to the present invention. Perform processing. In the plasma processing, the laminate is housed in a known plasma processing 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 further connected to the layer 5 (or the layer 5).
If not, it is placed close to layer 4) 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 is applied. The plasma gas used is He, Ar, Ne,
An inert gas such as 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. The material of the negative 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.
1, Mg-Ag alloy and the like can be used. Any method such as vapor deposition and sputtering can be used for forming the electrode. The materials of 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. Examples of the organic light emitting layer include a condensed polycyclic aromatic hydrocarbon dye, a condensed polycyclic dye containing a hetero atom such as O, N, and S, and a metal complex dye. Examples thereof include perinone derivatives, quinoline complex derivatives, thiadiazolopyridine derivatives, tetraphenylbutadienes, bisstyrylbenzene derivatives and the like (Japanese Patent Laid-Open No. 1-2).
No. 45087, No. 2-88689, No. 2-25029
No. 2 and No. 2-261889).

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described below. In the following examples, an In—Sn oxide electrode layer was formed on the surface of a glass substrate, and then a hole transport layer, an organic light emitting layer, or an electron transport layer was formed. Next, grids were arranged in parallel at a distance of 5 mm from these layers, and voltages shown in Table 1 were applied to these layers and the grids. Ar or H ₂ plasma or ions were generated in the vacuum chamber of 0.05 Torr by the method shown in Table 1 to perform surface treatment. Next, an Mg-Ag electrode was deposited.
The results obtained are shown in the same table. However, in Example 1, N, N'-diphenyl-N, N'-bis (3-
Methylphenyl) -1,1′-biphenyl-4,4′-
In Example 2, an 8-quinolinol Al complex was used as the organic light emitting layer adjacent to the diamine and the electrode.

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

Embedded image It was used. Table 1 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.

[0008]

[Table 1]

[0009]

The electroluminescent device treated by plasma or reverse sputtering according to the present invention has a higher bonding force with the electrode than the non-treated device, thereby improving the durability and stabilizing the luminous characteristics. did. On the other hand, adhesion was not obtained by the treatment in the oxygen atmosphere or the treatment in the hydrogen atmosphere.

[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

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Nakatani 1-1-13 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation (56) References JP-A-3-84892 (JP, A) JP-A-4 14795 (JP, A) JP-A-5-347188 (JP, A) JP-A-5-101885 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 33/00

Claims (4)

(57) [Claims] 1. A method for producing 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 disposed on the surface side of the substrate layer. An organic electroluminescent device, wherein a bias is applied to a negative potential, and after plasma or reverse sputtering is performed on the surface of the base layer, an electrode is continuously formed on the surface of the base layer without being exposed to air. Electrode fabrication method. 2. The method according to claim 1, wherein an electrode is formed on the organic light emitting layer. 3. The method for producing an electrode of an organic electroluminescent device according to claim 1, wherein an organic light emitting layer, an electron transport layer, and an electrode are laminated in this order. 4. 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.