JPS62108497A - Thin film el device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a thin film EL device, and particularly to improvements in device structure.

[Conventional technology]

FIG. 4 is a sectional view showing the structure of a conventional general thin film EL cord. As shown in FIG. 4, this thin film EL element is
An electrode 2 is placed on the substrate 1. Insulator layer 3゜EL light emitting layer 4. Insulator layer5. The electrode 6 is laminated. In other words,
Two insulator layers 3 and 5 are arranged on both sides of the EL light emitting layer 4,
Electrodes 2 and 6 are attached to the outside of this insulating layer 3.5, which is fixed to the substrate 1. Thus,
When a voltage is applied between the two electrodes 2 and 6, the EL light emitting layer 4
It has a structure that emits light.

The EL light emitting layer 4 in the above EL light emitting device has 0, . 1~
2.0% by weight of Mn or Cu, A, f'.

These are semiconductors such as ZnS and Zn5e doped with Br, Tb, etc. (hereinafter referred to as ZnS:Mn). I x 10' V/CT11 in this EL light emitting layer 4
When a certain electric field is applied, the EL light emitting layer 4 and the insulating layer 3
．． Electrons are tunnel-injected into the conduction band of the EL light emitting layer 4 from the interface level at the interface with the EL layer 5 . Regarding the basic technology in this regard, please refer to the document “G,0°Muller, Phys.
ica 5tatusSolidi (a) 8
1 597 (1984). The injected electrons are further accelerated in the conduction band and have obtained sufficient energy. ゛The electrons directly excite luminescent centers such as Mn, and when the excited luminescent centers return to the ground state, they emit light. .

Ideally, the insulator layers 3 and 5 do not cause leakage current. If an insulator layer that does not cause such leakage current is used, the current flowing through the thin film EL element will be only the capacitive displacement current, and the EL light emitting layer 4 will not be heated more than necessary, improving the stability of the element. do. Furthermore, in order to increase the effective electric field strength applied to the EL light emitting layer 4, the insulator layer 3.5 is desirably made of a material with a high dielectric constant, and it is also important that the dielectric breakdown voltage is high. .

Conventionally, the insulator layers 3 and 5 are made of Sin.

S i02, GeO2+ Y203, TiO2.

Al103. Si3 N4. Films made of silicon oxynitride or the like have been formed by electron beam evaporation, sputtering, or the like, but none of these films meet the requirements for an insulator layer as described above. A particular problem is that since there are pinholes or microcracks in the film, if moisture intrudes into these areas, the dielectric strength drops and discharge phenomena are likely to occur. When a discharge phenomenon occurs, thermal Ii scratches occur on the thin film EL element, degrading the element characteristics.

In order to solve this problem, a method has been proposed in which the thin film EL cord is housed in an envelope and an insulating liquid is injected into the envelope to prevent moisture from penetrating into pinholes, microcracks, etc. has been done. According to this means, the infiltration of moisture into pinholes, microcracks, etc. is prevented, and there is an effect that the discharge phenomenon when electricity is applied can be prevented.

[Problem that the invention seeks to solve]

However, the method described above, that is, the method of accommodating the thin-film EL element in an envelope and injecting an insulating liquid into the envelope, increases the number of manufacturing steps, and therefore requires a lot of time and troublesome effort to manufacture. ” Second, it has the disadvantage of high cost.

Furthermore, since it is difficult to completely seal the small hole provided in the envelope for injecting insulating liquid, liquid leakage is likely to occur. Note that if the insulating liquid penetrates into pinholes, microcracks, etc., it will not only have the effect of preventing moisture from entering, but may also increase the dielectric strength of the area. However, in the above means, only thin film EL
Since the insulating liquid was simply injected around the element, the insulating liquid did not actively penetrate into pinholes, microcracks, etc., and no improvement in dielectric strength could be expected.

Therefore, the present invention provides (1) a pinhole in an insulator layer;

Discharges caused by cracks, etc. are suppressed, and the device has excellent stability and life characteristics. (2) Moreover, the manufacturing process of the device is simple, does not require much time, and is easy and inexpensive. (3) In addition, there is no risk of insulating liquid leaking, and in particular, the insulating liquid sufficiently penetrates into pinholes, microcracks, etc.
The object of the present invention is to provide a thin-film EL device that can improve the dielectric strength of that part, and (4) in addition, vibrations caused by application of an AC voltage are alleviated, and there is no risk of peeling or cracking of the device-constituting films. .

[Means for solving problems]

The present invention has taken the following measures to solve the above problems and achieve the object.

(1) Provide a thin film light-emitting layer doped with an active substance.

(2) An insulator layer is provided on at least one side of the thin film light emitting layer.

(3) An electrode for applying an electric field is provided on the outside of the insulating layer.

(4) An insulating liquid layer is provided between the electrode and the insulator layer.

[Effect]

Since the insulating liquid layer is interposed between the electrode and the insulator layer, the insulating liquid can cause pinholes in the insulator layer.

It easily penetrates into microcracks and the like, suppressing discharges caused by pinholes, cracks, etc. Moreover, since there is no need to provide a special envelope, the manufacturing process of the element is simplified. In addition, since the insulating liquid layer is sandwiched between the electrode and the insulating layer, there is no risk of insulating liquid leaking due to capillary action. It penetrates into the inside of the parts and improves the dielectric strength of the parts. Further, since the insulating liquid layer is interposed between the electrode and the insulating layer, this acts as a cushioning material, and vibrations caused by application of an alternating current voltage are alleviated.

The present invention will be described in detail below using the drawings. FIG. 1 is a sectional view showing the concept of the thin film EL device of the present invention. As shown in FIG. 1, this thin film EL element is basically a thin film EL element with a double insulation structure similar to that shown in FIG. 16 is characterized by the presence of an insulating liquid layer 10 between them.

In FIG. 1, 11 is a substrate, 12 is an electrode, 13 is an insulator layer, 14 is an EL light emitting layer, 15 is an insulator layer, 16 is an electrode,
17 is a substrate.

As the insulating liquid layer 10, polybutene synthetic insulating oil, chlorine-substituted paraffin, silicone oil, fluorinated oil, sulfone thread surface, etc. are preferable.

The thin film EL element having such a configuration has the following effects. In the conventional structure in which the entire element is sealed with an insulating liquid, as mentioned above, it is difficult for the insulating liquid to sufficiently penetrate into pinholes, microcracks, etc. According to the configuration shown in FIG. 1, the insulating liquid layer 10 is sandwiched between the electrode 16 and the insulating layer 15, so that it sufficiently penetrates into the insulating layer 15. Furthermore, since the insulating liquid layer 10 only requires a simple process of coating, the process is significantly simplified compared to conventional ones. Further, since the insulating liquid layer 10 is mechanically sandwiched between the insulating layer 15 and the electrode 16, it is supported by capillary action and there is no risk of leakage to the outside.

Further, in this structure, since the insulating layer 15 and the electrode 16 are not in close contact with each other, the insulating liquid layer 10 existing between them acts as a buffer material. That is, the vibrations generated when an alternating current voltage is applied between the electrodes 12 and 16 are alleviated by the insulating liquid layer 10, and as a result, it is possible to prevent the occurrence of peeling or cracking of the element constituent films caused by the vibrations.

Note that if the insulator layer is formed of a highly crystalline material, it will become a polycrystalline film and the occurrence of pinholes will increase.
Conventionally, an amorphous material has been used for the insulating layer to prevent deterioration of device characteristics due to discharge. For example, when silicone nitride or silicone oxynitride is formed into a film by sputtering, it becomes amorphous, resulting in a film with stable dielectric properties and good withstand voltage, and has been praised as being suitable for thin-film EL devices. However, when an EL emitting layer is fabricated on such an amorphous film by means such as vaporization or sputtering, crystallization is completely hindered, and a large number of lattice defects that become donor levels are generated, resulting in the formation of an EL layer. The resistance of the light emitting layer is reduced. As a result, electrons no longer have sufficient kinetic energy to excite the luminescent center, resulting in a significant drop in luminous efficiency. Therefore, in order to promote crystallization of the EL light emitting layer,
The insulating layer is required to have good crystallinity. Therefore, the insulating layer 13, which serves as the base for producing the EL light emitting layer, is made of a highly crystalline material. In this way, the crystallinity of the EL light emitting layer 14 can be ensured by the insulating layer 13, and a decrease in light emitting efficiency can be prevented. As a result, the occurrence of discharge is suppressed by the insulating liquid layer 10, and the insulating liquid layer 13
As a result, the crystallinity of the EL light emitting layer 14 is ensured, and a layer with excellent dielectric strength and crystallinity can be obtained.

In addition, in the conventional structure shown in FIG. 4, when the back electrode 6 of the element is of a segment type or matrix type, an electrode film is uniformly formed on the insulator layer 5, and then
Patterns were formed by etching. At that time, in order to immerse the entire element in the etching solution, the insulator layer 3,
5 and the EL light emitting layer 4 are unavoidable, and there is a risk that moisture will be adsorbed and remain in the pinholes and microcracks. However, in the case of the present invention, after etching the electrode 12, an insulating layer 13, an EL light emitting layer 14, and an insulating layer 15 are formed thereon, and the other electrode 16 is etched and patterned on the substrate 17 in advance. The EL light emitting layer 14. will be produced later by being pressed onto the insulating liquid layer 10. None of the insulator layers 13, 15, etc. are immersed in the etching solution.

Thus, the thin film EL stringer of the present invention compensates for various drawbacks of conventional devices.

〔Example〕

FIG. 2 is a sectional view showing a first embodiment of the present invention. As the substrate 21, 7059 glass is used. Then, an ITO transparent electrode 22 was formed on the surface of the cleaned substrate 21 by electron beam evaporation to a thickness of 1500 nm.

Furthermore, the above-mentioned ITO transparent electrode 2 was formed by photoetching.
2 was etched into a suitable display pattern. Thereafter, Afo3 was deposited as an insulator layer 23 on top of the insulator layer 23 by high frequency reactive sputtering to a film thickness of about 0.5 J! It was generated to be IR. Furthermore, the second EL light emitting layer 24
As a result, a ZnS;Mn layer was fabricated to have a film thickness of about 1 p by electron beam evaporation using a sintered pellet made of ZnS and Mn as a target. Furthermore, AJO3 was formed thereon as an insulator layer 25 by high frequency reactive sputtering to a thickness of about 0.5 μ.

Further, silicone oil was applied thereon as an insulating liquid layer 20 and left for about 1 hour.

On the other hand, on the glass substrate 27 made of 7059 glass,
An f-electrode is formed into a film and subjected to appropriate etching processing, and this is pressed onto the insulating liquid layer 20 made of silicone oil, and an epoxy resin 28 is formed between the front glass substrate 21 and the back glass substrate 27. It was fixed.

With this configuration, the insulating liquid layer 20
A, II where the silicone oil is the insulating layer 25
It fully penetrated the pinholes and cracks of '03. As a result, discharge phenomena caused by pinholes, microcracks, etc. in the A103 layer were completely suppressed, and the durability of the device was dramatically improved. Further, there was no occurrence of peeling or cracking of the element-constituting thin film due to vibration when an alternating current voltage was applied between the electrodes.

FIG. 3 is a sectional view showing a second embodiment of the present invention. This embodiment differs from the previous embodiment in that the A103 layer as the insulator layer 23 in FIG. 2 is omitted, and all other structures are the same as those of the previous embodiment. Conventionally, the insulating properties of the insulating layer were insufficient, so it was necessary to provide two insulating layers on both the upper and lower sides of the EL light-emitting layer to compensate for the incomplete insulation. However, when silicone oil is interposed as shown in the figure, the insulation properties are dramatically improved, so even if one side of the insulator layer is omitted as in this example, rIi1
There are no problems. In fact, even in the jFi structure shown in FIG. 3, sufficient insulation was maintained and there was no problem with durability. Note that in the case where two insulating layers are provided, the applied electric field is distributed between the two insulating layers and the EL light emitting layer. However, in the case where one of the insulator layers is omitted as in this embodiment, the distributed electric field for one insulator layer is
It will be added to the electric field applied to 4. In other words, the ratio of the electric field distributed to the EL light emitting layer 24 becomes high. As a result, there is an advantage that sufficient luminance can be obtained with a lower voltage application than in the embodiments described above. Furthermore, since the manufacturing process for one layer can be omitted, the manufacturing process is simplified accordingly, which has the advantage of reducing costs.

Note that the present invention is not limited to the above embodiments,
Of course, various modifications can be made without departing from the spirit of the invention.

〔Effect of the invention〕

According to the present invention, since the insulating liquid layer is provided between the electrode and the insulator layer, (1) discharge caused by pinholes, cracks, etc. in the insulator layer is suppressed, and the stability of the device is improved. and excellent life characteristics.

(2) Moreover, the manufacturing process of the element is simple, does not require much time for manufacturing, and can be manufactured easily and inexpensively.

(3) In addition, there is no risk of insulating liquid leaking, and in particular, the insulating liquid can sufficiently penetrate into pinholes, microcracks, etc., thereby improving the dielectric strength of those parts.

(4) In addition, vibrations caused by application of an alternating current voltage are alleviated, and there is no risk of peeling or cracking of the element-constituting films.

It is possible to provide a thin film EL element that exhibits the following effects.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the concept of the present invention, Fig. 2 is a sectional view showing the structure of a first embodiment of the invention, and Fig. 3 is a sectional view showing the structure of a second embodiment of the invention. , FIG. 4 is a sectional view showing the configuration of a conventional example. 1.11.21 and 17.27...Substrate, 2.12
．． 22 and 6.16.26... electrode, 3.13.2
3 and 5, 15.25...insulator layer, 4.14.2
4...EL light emitting layer, 28...Epoxy resin. Applicant's agent Patent attorney Atsushi Tsuboi Figure 1 Figure 2

Claims (1)

[Claims] A thin film light emitting layer doped with an active substance, an insulating layer formed on at least one side of the thin film light emitting layer, an electrode for applying an electric field provided on the outside of the insulating layer, and this electrode and the insulating layer. A thin film EL device comprising an insulating liquid layer provided between the body layer and the body layer.