JP2005276667A - Organic el element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent leakage current from flowing via an organic compound layer between electrodes arranged with a spacing to each other in an organic EL element. <P>SOLUTION: In the organic EL element provided with the insulating substrate 10, a plurality of first electrodes 11 arranged with the spacing to each other on the substrate, the organic compound layers 12, 13 including at least a light-emitting layer formed in a state that these first electrodes 11 are covered from the above, and a second electrode 14 arranged so that it is intersected with and opposed against the first electrode 11 pinching these organic compound layer 12, 13, the organic compound layer 12, 13 are divided between the mutual plurality of first electrodes 11, and in this divided part, an insulating layer 15 is embedded in a state that end faces 12, 13 of the organic compound layer are not exposed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic EL (electroluminescence) element and a manufacturing method thereof.

  Conventionally, as shown in Patent Documents 1 and 2, for example, an insulating transparent substrate, a plurality of transparent anodes disposed on the substrate at intervals, and a state in which the transparent anode is covered from above An organic EL element comprising an organic compound layer including at least a light-emitting layer and a metal cathode disposed so as to cross and face the transparent anode with the organic compound layer interposed therebetween is known. Yes.

In this organic EL element, when a current is passed between the transparent anode and the metal cathode, the light emitting layer included in the organic compound layer emits light, and the emitted light is extracted through the transparent anode and the transparent substrate. In other words, in the organic EL element, the intersection between the transparent anode and the metal cathode is used as one light emitting part, and light emission and non-light emission can be controlled for each light emitting part. Such an organic EL element has a characteristic that is excellent in wavelength stability.
Japanese Patent No. 2911552 Japanese Patent No. 3016808

  In an organic EL element having the above basic configuration, for example, disclosed in Patent Document 1, generally, a metal cathode is a scanning electrode, a transparent anode is a signal electrode, and a plurality of transparent anodes intersecting with a selected metal electrode are provided. Each is independently connected to a drive current source, and the light emitting portion between the transparent anode and the metal cathode connected to the drive current source emits light.

  Here, regarding a certain transparent anode, when it is connected to a drive current source, the adjacent transparent anode can be connected to the drive current source or not connected. In a conventional organic EL element, when one transparent anode is connected to a driving current source, light emission is formed from the one transparent anode depending on whether or not the adjacent transparent anode is connected to the driving current source. The problem that the brightness of the part fluctuates is recognized. This problem is that the current that should flow between the one transparent anode and the cathode facing it leaks to the adjacent transparent anode side through the organic compound layer formed so as to extend between the anodes. It is due to that. The magnitude of the leaked current (leakage current) depends on the potential difference between the anode connected to the drive current source and the adjacent anode, and is inversely proportional to the distance between the two anodes, so it flows to the light emitting section. The current changes according to the potential state of the adjacent anode, which leads to luminance fluctuation.

  Patent Document 2 shows a configuration in which the hole transport layer at the light emitting site and the metal cathode are close to each other. In such a configuration, current leaks to the adjacent anode through the metal cathode. Has become difficult.

  The problem in the organic EL device in which the anode is formed on the substrate side and the cathode is formed on the opposite side of the organic compound layer has been described above. However, the cathode and the anode may be formed opposite to the above example. It is possible and a similar problem can occur.

  In view of the above circumstances, an object of the present invention is to provide an organic EL element capable of preventing leakage current from flowing through an organic compound layer between electrodes arranged at intervals.

  Another object of the present invention is to provide a method capable of efficiently producing such an organic EL device.

The organic EL device according to the present invention, as described above,
An insulating substrate;
A plurality of first electrodes spaced apart from each other on the substrate;
An organic compound layer including at least a light-emitting layer formed to cover these first electrodes from above;
In the organic EL element comprising the second electrode disposed so as to cross and face the first electrode with the organic compound layer interposed therebetween,
An organic compound layer is divided between the plurality of first electrodes;
An insulating layer is embedded in the divided portion so that the end face of the organic compound layer is not exposed.

  In many cases, the first electrode is a transparent anode, and the second electrode is a metal cathode.

On the other hand, the manufacturing method of the 1st organic EL element by this invention is:
A method for manufacturing the organic EL device according to the present invention described above,
Forming a plurality of first electrodes spaced apart from each other on the substrate;
In a state of covering these first electrodes from above, an organic compound layer having a discontinuous pattern between the first electrodes is formed,
In the portion where the organic compound layer is not formed, an insulating layer is embedded in a state where the end face of the organic compound layer is not exposed,
Next, the second electrode is formed.

  In the first method, the organic compound layer having a discontinuous pattern between the first electrodes is formed by depositing a mask at the discontinuous portion and depositing the organic compound layer by vapor deposition or the like. It is possible to form by doing, and it is also possible to form by an inkjet system.

Moreover, the manufacturing method of the 2nd organic EL element by this invention is as follows.
Similarly, a method for producing the organic EL device according to the present invention,
Forming a plurality of first electrodes on an insulating substrate spaced apart from each other;
On these first electrodes, an organic compound layer continuously extending so as to cover all of the first electrodes is formed,
Etching removes the portion of the continuously extending organic compound layer between the first electrodes,
In the part where the organic compound layer is removed, an insulating layer is embedded in a state where the end face of the organic compound layer is not exposed,
Next, the second electrode is formed.

  More specifically, it is desirable to apply laser etching or dry or wet etching using photolithography as the etching.

  In the organic EL device according to the present invention, the organic compound layer is divided between the plurality of first electrodes, and the insulating layer is embedded in the divided portions. Leakage current is prevented from flowing through the compound layer. In addition, since the insulating layer is embedded without exposing the end face of the organic compound layer, the second electrode is electrically connected to the end face of the organic compound layer, and a leakage current flows through the second electrode. There is no such thing.

  If so, since all of the current originally used for light emission flows between the first electrode and the second electrode constituting the light emitting section to emit light, the luminance reduction of the light emitting section is prevented. It becomes possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a schematic sectional shape of a part of the organic EL device according to the first embodiment of the present invention, and FIG. 2 shows a schematic perspective shape of the organic EL device. Note that FIG. 2 is for showing the combination of the elements constituting the organic EL element, and the cross-sectional shape of each layer is schematically shown.

  This organic EL element includes a transparent glass substrate 10, a plurality of strip-like transparent anodes (first electrodes) 11 disposed on the glass substrate 10 at intervals, and these transparent anodes 11 from above. A hole transport layer 12 formed in a covering state, a light emitting layer 13 formed on the hole transport layer 12, and the transparent anode 11 with the light emitting layer 13 and the hole transport layer 12 interposed therebetween And a plurality of strip-shaped metal cathodes (second electrodes) 14 arranged so as to cross each other. In FIG. 2, the hole transport layer 12 and the light emitting layer 13 are shown integrally.

The hole transport layer 12 and the light emitting layer 13 which are organic compound layers are divided between the plurality of transparent anodes 11, and the end surfaces of the hole transport layer 12 and the light emitting layer 13 are not exposed to the divided portions. An insulating layer 15 made of SiO ₂ or the like is embedded in the state.

  The plurality of metal cathodes 14 are arranged in a direction perpendicular to the transparent anode 11 with a space between each other. As a result, the intersecting portions of the transparent anode 11 and the metal cathode 14 are arranged in a two-dimensional matrix, and the hole transport layer 12 and the light emitting layer are disposed between the transparent anode 11 and the metal cathode 14 for each intersecting portion. A light-emitting portion is formed by arranging 13. In such a configuration, when a predetermined current flows between the transparent anode 11 and the metal cathode 14, the light emitting layer 13 emits light in units of the light emitting units, and the emitted light passes through the transparent anode 11 and the glass substrate 10. To be taken out.

  The transparent anode 11 preferably has a light transmittance of at least 50 percent or more, preferably 70 percent or more, in the visible light wavelength region of 400 nm to 700 nm. As a material for the transparent anode 11, conventionally known compounds such as tin oxide, indium tin oxide (ITO), and zinc indium oxide can be appropriately used, but other metals having a high work function such as gold and platinum. You may use the thin film which consists of. In addition, organic compounds such as polyaniline, polythiophene, polypyrrole, or derivatives thereof can also be used. Supervised by Yutaka Sawada, “New Development of Transparent Conductive Film”, published by CMC Co., Ltd. (1999), there is a detailed description of the transparent conductive film, and what is shown there can be applied to the present invention. It is.

  The organic EL device of the present embodiment has a hole transport layer 12 and a light emitting layer 13 as organic compound layers, but other layers such as a hole injection layer, an electron injection layer, and an electron transport layer are provided as appropriate. May be.

  The metal cathode 14 is made of an alkaline metal such as Li or K having a low work function, an alkaline earth metal such as Mg or Ca, and a metal material such as an alloy or a mixture of these metals with Ag or Al. Is preferred. In order to achieve both storage stability and electron injectability at the cathode, the electrode formed of the above material may be further coated with Ag, Al, Au, or the like having a high work function and high conductivity. Note that, similarly to the transparent anode 11, the metal cathode 14 can also be formed by a known method such as a vacuum deposition method, a sputtering method, or an ion plating method.

  Next, with reference to FIG. 3, the manufacturing method of the said organic EL element is demonstrated. First, as shown in FIG. 1A, a plurality of strip-shaped transparent anodes 11 are formed on a glass substrate 10 at intervals. Such a transparent anode 11 can be formed by, for example, a vacuum deposition method, a sputtering method, an ion plating method, or the like.

  Next, as shown in FIGS. 2 (2) and (3), the hole transport layer 12 and the light emitting layer 13 are sequentially formed so that each transparent anode 11 is covered from above and its left and right end faces are completely covered. . At this time, the hole transport layer 12 and the light emitting layer 13 are formed in a pattern separated from each other so that the objects covering the adjacent transparent anodes 11 do not continue. The hole transport layer 12 and the light emitting layer 13 having such a pattern can be formed, for example, by forming a film by disposing a mask in a discontinuous portion. Alternatively, the hole transport layer 12 and the light-emitting layer 13 can be formed in the above-described pattern by forming a film by an inkjet method.

  Next, as shown in FIG. 4 (4), an insulating layer 15 is embedded in a portion where the hole transport layer 12 and the light emitting layer 13 are not formed in a state where the end faces of those layers are not exposed. Next, when the metal cathode 14 is formed as shown in FIG. 5 (5), the organic EL device of this embodiment is completed.

  Instead of forming the hole transport layer 12 and the light emitting layer 13 in the above pattern from the beginning, first, the hole transport layer 12 and the light emitting layer 13 are formed so as to continuously extend over the plurality of transparent anodes 11. Then, the hole transport layer 12 and the light emitting layer 13 in the portion between the transparent anodes 11 may be removed by etching. As the etching, laser etching, dry or wet etching using photolithography can be applied. It is also possible to remove the hole transport layer 12 and the light emitting layer 13 with a sharp needle. However, among them, laser etching is most preferable in that it does not damage the hole transport layer 12 and the light emitting layer 13 left on the transparent anode 11.

  In the organic EL device of the present embodiment, the hole transport layer 12 and the light emitting layer 13 are divided between the plurality of transparent anodes 11, and the end surfaces of the hole transport layer 12 and the light emitting layer 13 are divided into the divided portions. Since the insulating layer 15 is embedded in a state in which the exposed layer is not exposed, leakage current is prevented from flowing between the adjacent transparent anodes 11 via the hole transport layer 12. In addition, since the insulating layer 15 is embedded in such a manner that the end face of the hole transport layer 12 is not exposed, the metal cathode 14 is electrically connected to the end face of the hole transport layer 12, and the metal cathode 14 is interposed therebetween. Leakage current does not flow.

  If so, since all of the current originally used for light emission flows between the transparent anode 11 and the metal cathode 14 constituting the light emitting portion to emit light, the luminance reduction of the light emitting portion is prevented. It becomes possible.

  Next, an organic EL device according to the second embodiment of the present invention will be described with reference to FIG. In FIG. 4, the same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted unless particularly required. The organic EL element shown in FIG. 4 is basically different from that shown in FIG. 1 in that an insulating layer 20 is formed between a plurality of transparent anodes 11.

  The organic EL device of the second embodiment can be manufactured by the following steps. First, a plurality of strip-shaped transparent anodes 11 are formed on the glass substrate 10 at intervals. Next, a strip-shaped insulating layer 20 is formed so as to cover the end of each transparent anode 11. The insulating layer 20 and the insulating layer 15 may be formed from either an inorganic material or an organic material. The insulating layer 20 having a belt-like pattern can be formed by a known method such as a vacuum deposition method using a mask, a sputtering method, or an ion plating method.

  Next, the hole transport layer 12 and the light emitting layer 13 are formed so as to be located on the exposed transparent anodes 11 and separated from each other at a portion above the insulating layer 20. Such a hole transport layer 12 and a light emitting layer 13 can also be formed by a known method such as a vacuum evaporation method using a mask, a sputtering method, or an ion plating method.

  Next, when the hole transport layer 12 and the light emitting layer 13 are not formed, the insulating layer 15 is embedded in a state where the end faces of those layers are not exposed, and then the metal cathode 14 is formed, the organic layer of this embodiment An EL element is completed.

  Also in this organic EL element, the hole transport layer 12 and the light emitting layer 13 are divided between the plurality of transparent anodes 11, and the end faces of the hole transport layer 12 and the light emitting layer 13 are not exposed to the divided portions. Since the insulating layer 15 is buried in the state, basically the same effect as in the first embodiment can be obtained.

Note that the organic EL element of the first embodiment described above, the hole transport layer 12 and the light emitting layer 13 are not divided and the insulating layer 15 is not formed thereon, and the other points are the same as those of the first embodiment. The conventional organic EL element formed in the same manner as the organic EL element was compared for the presence or absence of leakage current. In comparison, the voltage between one selective transparent anode 11 and the metal cathode 14 facing it is fixed at 15 V, and the same voltage at the transparent anode 11 adjacent to it is changed in four ways. The measurement was performed by measuring the luminance of light emitted from the anode 11 (unit: cd / m ² ). The results are shown in Table 1 below.

  As shown in Table 1, in the conventional example, the light emission luminance decreases as the voltage of the adjacent anode is lowered, that is, as the potential difference from the selected anode is increased. This indicates that leakage current tends to flow as the potential difference increases. On the other hand, in the organic EL device according to the present invention, even if the potential difference is changed, no significant change in the emission luminance appears (the numerical value variation is within the measurement error range), and it is clear that no leakage current occurs. is there.

1 is a schematic sectional view showing an organic EL device according to a first embodiment of the present invention. Schematic perspective view of the organic EL element Schematic explaining the manufacturing method of the said organic EL element Schematic sectional view showing an organic EL device according to a second embodiment of the present invention

Explanation of symbols

10 Glass substrate
11 Transparent anode
12 Hole transport layer
13 Light-emitting layer
14 Metal cathode
15, 20 Insulation layer

Claims (8)

An insulating substrate;
A plurality of first electrodes spaced apart from each other on the substrate;
An organic compound layer including at least a light-emitting layer formed to cover these first electrodes from above;
In the organic EL element comprising the second electrode disposed so as to cross and face the first electrode with the organic compound layer interposed therebetween,
The organic compound layer is divided between the plurality of first electrodes;
An organic EL element, characterized in that an insulating layer is embedded in the divided portion so that the end face of the organic compound layer is not exposed.   2. The organic EL device according to claim 1, wherein the first electrode is a transparent anode and the second electrode is a metal cathode. A method for producing the organic EL device according to claim 1, comprising:
Forming a plurality of first electrodes spaced apart from each other on the substrate;
In a state of covering these first electrodes from above, an organic compound layer having a discontinuous pattern between the first electrodes is formed,
In the portion where the organic compound layer is not formed, an insulating layer is embedded in a state where the end face of the organic compound layer is not exposed,
Next, the second electrode is formed. A method for manufacturing an organic EL element.   4. The organic compound layer having a discontinuous pattern between the first electrodes is formed by forming an organic compound layer by disposing a mask in the discontinuous portion. The manufacturing method of the organic EL element of description.   4. The method of manufacturing an organic EL element according to claim 3, wherein the organic compound layer having a pattern discontinuous between the first electrodes is formed by an ink jet method. A method for producing the organic EL device according to claim 1, comprising:
Forming a plurality of first electrodes on an insulating substrate spaced apart from each other;
On these first electrodes, an organic compound layer continuously extending so as to cover all of the first electrodes is formed,
Etching removes the portion of the continuously extending organic compound layer between the first electrodes,
In the part where the organic compound layer is removed, an insulating layer is embedded in a state where the end face of the organic compound layer is not exposed,
Next, the second electrode is formed. A method for manufacturing an organic EL element.   The method of manufacturing an organic EL element according to claim 6, wherein the etching is laser etching.   7. The method of manufacturing an organic EL element according to claim 6, wherein the etching is dry or wet etching using photolithography.

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