JPH08321381A - Organic electroluminescent element - Google Patents

Abstract

PURPOSE: To provide an easy-to-watch organic EL element by keeping reflected light from a rear cathode, so as not to be transmitted outside via the installation of a circularly light-polarizing plate on a transparent electrode. CONSTITUTION: An ITO film is formed on a glass substrate 3, and a desired pattern is applied to the film. A transparent electrode 4 is thereby formed. Thereafter, an electron hall injection layer 5 is deposited on the substrate 3 and, then, a luminous layer 6 is deposited thereon. An electron injection and transport layer 7 is, then, deposited on the luminous layer 6. At this stage, a vacuum condition is eliminated and a deposition source for both silver and magnesium is prepared. Then, a bath is again evacuated for the co-deposition of silver and magnesium, thereby forming a cathode 8. The organic EL element so formed is taken out from the vacuum bath, and sealed whenever necessary for the prevention of deterioration. Then, a circularly light-polarizing plate is bonded to a linear polarizing plate 1, so as to keep the optical axis of a phase substrate 2 at 45 degrees with the polarization axis of the polarizing plate, and the product so prepared is bonded to the substrate 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device (hereinafter abbreviated as organic EL device) used for a flat light source or a flat display.

[0002]

2. Description of the Related Art Organic EL devices are Japanese Journal of Applied Physics, Vol. 25, p. 773 (1986), Applied Physics Letters, vol. 51, p. 913 (1987), JP-A-57-517.
No. 81, No. 59-194393, No. 63-264692, No. 63-295696
According to the newsletter, etc., it is generally made as follows. A transparent electrode (ITO) is formed on a transparent insulating substrate such as glass or resin substrate by a method such as vapor deposition or spattering. Next, polymorphyllines represented by copper phthalocyanine, N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-biphenyl-4,
A hole injecting and transporting layer is formed by vapor deposition of a triphenylamine derivative such as 4′-diamine or 1,1′-bis (4-di-para-tolylaminophenyl) cyclohexane by a vapor deposition method or another method to form a layer having a thickness of 1 μm or less. And Then, a light emitting layer having a thickness of 1 μm or less is formed on the hole injecting and transporting layer with an organic phosphor such as a quinolinol complex, tetraphenylbutadiene, or a quinolinol complex doped with quinacridone. Further, if necessary, an electron injecting and transporting layer such as an oxadiazole derivative is formed with a thickness of 1 μm or less. Finally, a single metal such as magnesium / aluminum / indium or magnesium / silver or aluminum / magnesium alloy is laminated by vapor deposition or other method to form an electrode. In the organic EL device thus manufactured, when a DC voltage of 3 to 20 V is applied with a transparent electrode as an anode and magnesium or the like as a cathode, holes are injected from the anode and electrons are injected into the organic material layer from the cathode to generate holes. The organic substance emits light by recombination of the electrons with and the brightness of 10,000 Cd / m ² or more can be obtained, which is a brightness level that can be sufficiently put to practical use as a display device or a lighting device. However, since the film thickness of the organic compound used for the organic EL element is very thin, external light reaches the back negative electrode. The electrode surface formed by vapor deposition or the like is very smooth and has a mirror surface. Therefore, there is a drawback in that the external scenery is reflected on the element due to the reflected light of the external light from the electrode, and the external scenery and the display are overlapped, which makes it very difficult to see.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides an easy-to-see organic EL device by preventing the light reflected from the back negative electrode from going outside. It was made for the purpose.

[0004]

That is, the present invention provides at least a transparent substrate, an anode, an organic light emitting layer, a cathode or at least a transparent substrate, an anode, a hole injecting and transporting layer, an electron injecting and transporting light emitting layer, a cathode or at least a transparent substrate, Anode, hole injecting and transporting light emitting layer, electron injecting and transporting layer, cathode or at least transparent substrate, anode, hole injecting and transporting layer, organic light emitting layer,
An organic EL device comprising an electron injecting and transporting layer and a cathode in this order, wherein a circularly polarizing plate is provided on the surface of an anode side transparent substrate (the surface of the transparent substrate opposite to the anode).
It is an L element.

FIG. 1 shows a typical example of an organic EL device according to the present invention, which is composed of a circularly polarizing plate, a transparent substrate, an anode, a hole injecting and transporting layer, an organic light emitting layer, an electron injecting and transporting layer, and a cathode in this order. Is. The circular polarization plate is composed of a linear polarization plate and a retardation plate. By tilting the angle between the deflection axis of the linear polarizing plate and the optical axis of the retardation plate ± 45 °, right-handed and left-handed circular deflections can be obtained. The characteristic of the circular deflection is that the peeling of the circular deflection is changed by the reflection. That is, the right circular deflection is reflected to become the left circular deflection, and the left circular deflection is reflected to become the right deflection. Light entering from the outside and passing through the circularly polarizing plate undergoes right or left circular polarization, is reflected by the metal electrode on the back surface, and travels toward the outside of the element. However, since it is circularly polarized in the opposite direction to the incident light,
Since the circularly polarizing plate does not pass the reflected light, the outside scenery due to the reflection cannot be seen.

If the circularly polarizing plate is not installed, the external light is reflected as it is and enters the eyes, so that the external scenery is reflected as it is. As a result, when the organic EL element is used for pattern display or matrix display, the display and the external scenery overlap and the display is very difficult to see. However, when the circularly polarizing plate is installed as described above, the circularly polarizing plate cuts the light reflected by the negative electrode, so that the outside scenery cannot be seen and only the pattern to be displayed by the organic EL element becomes visible. The display element can be made very easy to see.
At this time, the outermost surface of the organic EL element is subjected to the non-glare treatment which is performed in the liquid crystal display, so that the display can be seen better.

[0007]

EXAMPLE An example of the organic EL device of the present invention will be described below with reference to FIG. An ITO thin film is attached to the glass substrate (3) by vapor deposition or another method, and desired patterning is performed to form a transparent electrode (4). This substrate was thoroughly washed, dried and then placed in a vacuum chamber, 1000 copper phthalocyanine was vapor-deposited as a hole injecting and transporting layer (5), and then 8-aluminum quinolate was 500 as a light emitting layer (6).
Vapor deposition. Further, as the electron injecting and transporting layer (7), 2-
(4'-t-Butylphenyl 9-5- (4'-biphenyl) -1,3,4-oxadiazole is vapor-deposited 500. Here, the vacuum is broken, a vapor deposition source of silver and magnesium is prepared, and again. The inside of the chamber is evacuated, and the vapor deposition rate of silver and magnesium is set to 1:10 to co-evaporate to form the cathode (8). The organic EL device thus prepared is taken out from the vacuum chamber and, if necessary, , In order to prevent deterioration. In this state, the metallic luster of the cathode can be seen as it is because the film thickness of the evaporated organic material is thin. Therefore, the element is like a mirror. The circular polarizer is a linear polarizer (eg Sumitomo Chemical Co., Ltd.)
A polarizing plate (SG-1812AP, etc.) manufactured by the company, (1) is coated with a pressure-sensitive adhesive or an adhesive on the optical axis of the retardation plate (2) (for example, SEF-057M, a retardation plate manufactured by Sumitomo Chemical Co., Ltd.). It is made by adhering or adhering so as to form an angle of 45 ° with the polarization axis of. The circularly polarizing plate thus prepared is adhered or adhered to the glass substrate (3). By installing the circularly polarizing plate on the surface of the glass substrate of the organic EL element in this way, it is possible to block the reflected light from the back metal electrode and prevent the outside scenery from being captured, and it is very possible even in bright places. We were able to obtain an element that was easy to see.

[0008]

As described above, the organic EL device of the present invention is extremely useful as a flat light source or a light emitting device for display, the display is very easy to see, and the drawbacks of the conventional organic EL device can be compensated. Its industrial utility value is high.

[Brief description of drawings]

FIG. 1 is a schematic view of an organic EL element.

[Explanation of symbols]

 1 linear polarizing plate 2 retardation plate 3 glass substrate 4 anode 5 hole injecting and transporting layer 6 light emitting layer 7 electron injecting and transporting layer 8 cathode

Claims (2)

[Claims] 1. An organic electroluminescent device having an organic thin film sandwiched between a pair of electrodes, at least one of which is transparent, wherein a circularly polarizing plate is provided on the transparent electrode side. 2. A transparent substrate, an anode, an organic light emitting layer, a cathode or at least a transparent substrate, an anode, a hole injecting and transporting layer, an electron injecting and transporting light emitting layer, a cathode or at least a transparent substrate, an anode, a hole injecting and transporting light emitting layer, In an organic electroluminescent device composed of an electron injecting and transporting layer, a cathode or at least a transparent substrate, an anode, a hole injecting and transporting layer, an organic light emitting layer, an electron injecting and transporting layer, and a cathode in this order, an anode side transparent substrate (the surface of the transparent substrate) An organic electroluminescent device characterized in that a circularly polarizing plate is provided on the surface opposite to the anode.