JPH04249095A - Electroluminescence element - Google Patents

Abstract

PURPOSE:To suppress the cost and enhance the reliability. CONSTITUTION:On a base board 15 of glass, a film-form color filter 16 is in layers formed which provides a large transmittance only in the P, G, B wavelength region of multi-layer thin film, and a transparent electrode 17 is formed on this color filter 16. On this transparent electrode 17, light emitting elements 18, 19, 20 are formed which emit R, G, B light through the action of the electric field generated by the transparent electrode 17 and metal electrodes 21, 22. 23.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EL device that emits light upon application of an electric field.

0002

BACKGROUND OF THE INVENTION Research on EL in organic compounds began with the discovery of an EL emission phenomenon due to carrier injection in single crystals such as anthracene, which has strong fluorescence, and has been developed into thin film type devices. Recently, a stacked organic thin film EL device in which a hole transport layer and an electron transport layer are inserted between a light emitting layer and an electrode has been developed to produce 10,000 cd/m2.
The above-mentioned high-intensity light emission and operation at a driving voltage of 10 V or less have been reported. Incidentally, in an EL light emitting element using an organic compound, in order to improve the color purity of the emitted light color especially when colorization is desired, a color filter is provided individually for each emitted color.

FIG. 8 shows an example of such an EL light emitting element, and is an enlarged view of one pixel. As shown in the figure, the upper surface of the glass substrate 1 has R and R, respectively.
Color filters 2, 3, and 4 that emit G and B colors are formed by a printing process or the like. Each color filter 2, 3
, 4, a transparent electrode 5 is formed on the upper surface of the glass substrate 1 including the glass substrate 1. . On the upper surface of the transparent electrode 5, light-emitting layers 6, 7, and 8 are formed to correspond to the color filters 2, 3, and 4, respectively, and emit the respective colors of R, G, and B. Metal electrodes 9, 10, 11 are formed on the upper surface of each light emitting layer 6, 7, 8. And transparent electrode 5 and metal electrode 9,
When an electric field is applied by 10, 11, each light emitting layer 6,
7 and 8 emit R, G, and B colors, respectively. Each light emitting layer 6
, 7, 8 passes through the glass substrate 1 via the transparent electrode 5 and the respective color filters 2, 3, 4. At this time, the gradation level, etc. of one pixel is controlled by changing the electric field applied to each of the light emitting layers 6, 7, and 8.

0004

[Problems to be Solved by the Invention] However, in the conventional EL light emitting device described above, the color filters 2, 3, 4
are formed by printing or the like to correspond to each of the light emitting layers 6, 7, 8, which increases the number of manufacturing steps and reduces the E.
This results in an increase in the cost of the L light emitting element. Also, Figure 8
As shown in FIG. 2, the color filters 2, 3, and 4 have rectangular cross sections, and the thickness of the transparent electrode 5 is extremely thin. There is a risk that a disconnection or the like may occur in the portion 5a of the electrode 5. If a disconnection or the like occurs in the transparent electrode 5 in this way,
There is a risk that the pixel will not perform a normal light emitting operation, resulting in a lack of reliability.

The present invention has been made in response to the above circumstances, and an object of the present invention is to provide an EL light emitting element that can reduce costs and improve reliability.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the EL light emitting device of the present invention has a multilayer thin film on a glass substrate that has a high transmittance only in the R, G, and B wavelength regions. A color filter is formed in multiple layers, a transparent electrode is formed on this color filter, and light emitting elements that emit colors of R, G, and B, respectively, are formed on this transparent electrode by an electric field caused by the transparent electrode and the metal electrode. It is characterized by being

[0007]

[Function] In the EL light emitting device of the present invention, a multilayer thin film color filter is formed on a glass substrate and has a high transmittance only in the R, G and B wavelength regions, and a transparent color filter is formed on the color filter. In addition to forming electrodes, light emitting elements that emit colors of R, G, and B were formed on the transparent electrodes by the electric fields generated by the transparent electrodes and the metal electrodes. There is no need to form color filters, and the formation of color filters is greatly simplified. In addition, in this example, since a multilayer thin film color filter having high transmittance only in the R, G, and B wavelength regions was formed on a glass substrate in multiple layers, the cross section was similar to that of a conventional EL light emitting element. However, there is no fear of disconnection of the transparent electrode due to the rectangular color filter, and normal light emitting operation of the pixel is performed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, details of embodiments of the present invention will be explained based on the drawings. FIG. 1 shows an enlarged view of one pixel according to an embodiment of the EL light emitting device of the present invention. As shown in the figure, each R, G,
A thin film color filter 16 corresponding to B is formed. Here, as shown in FIG. 2, the color filter 16 is a thin film multilayer filter, for example, S with a refractive index of 1.45.
It is made by repeatedly laminating iO2 and ZnS with a refractive index of 2.3. FIG. 6 shows an example of this, and it has wavelength transmittance characteristics as shown in FIG. 4.

A transparent electrode 17 is formed on the upper surface of the color filter 16. On the upper surface of the transparent electrode 17, light emitting layers 18, 19, and 20 that emit colors of R, G, and B are formed, respectively. Metal electrodes 21, 22, 23 are formed on the upper surface of each light emitting layer 18, 19, 20. Here, the chemical formula of each light emitting layer 18, 19, 20 is, for example, shown in FIG.
As shown. Moreover, each light emitting layer 18, 19,
20 consists of an organic EL layer, which has a two-layer structure of hole transport layer/emissive layer, a two-layer structure of electron transport layer/emissive layer, or a three-layer structure of hole transport layer/emissive layer/electron transport layer. There is. The EL light emitting element having such a configuration operates as follows. First, the transparent electrode 17 and each metal electrode 21, 2
When an electric field is applied by 2, 23, each light emitting layer 18,
19 and 20 emit light in R, G, and B colors, respectively. Light emitted from each light emitting layer 18 , 19 , 20 passes through a transparent electrode 17 , a color filter 16 , and a substrate 15 .

At this time, the R, G, and B lights emitted from the respective light emitting layers 18, 19, and 20 have wavelengths shown in FIG. 5, for example. In other words, as you can see from the figure, R, G,
B is in the wavelength range near 630 nm, 520 nm, and 460 nm, respectively. Further, FIG. 4 shows the transmittance of the multi-layered thin film color filter 16, which shows high values near each of the above-mentioned wavelength regions. Furthermore, FIG.
This shows the emission spectra of each of R, G, and B that has passed through the color filter 16, and the wavelength width of the portion where the light intensity of each R, G, and B is low is narrowed. As a result, the light emitted from each light emitting layer 18, 19, 20 is
Color filter 16 with enhanced color purity of G and B
It can be seen that the light passes through the substrate 15.

As described above, in this embodiment, a multilayer thin film color filter having high transmittance only in the R, G, and B wavelength regions is formed on a glass substrate in multiple layers, and a multilayer thin film color filter is formed on the glass substrate. In addition to forming a transparent electrode, we also formed light emitting elements on this transparent electrode that emit the colors of R, G, and B by the electric field generated by the transparent electrode and the metal electrode. Since there is no need to form a color filter, and the formation of the color filter is greatly simplified, the cost of the EL light emitting element does not increase. Furthermore, in this example,
Since a multilayer thin film color filter with high transmittance only in the R, G, and B wavelength regions is formed on a glass substrate in multiple layers, it is possible to use a color filter with a rectangular cross section like a conventional EL light emitting device. Reliability is improved because the pixel performs normal light emitting operation without the risk of disconnection of the transparent electrode.

0012

[Effects of the Invention] As explained above, according to the EL light emitting device of the present invention, a multilayer thin film color filter having high transmittance only in the R, G, and B wavelength regions is formed on a glass substrate. , a transparent electrode was formed on this color filter, and a light emitting element that emitted each color of R, G, and B was formed on this transparent electrode by an electric field generated by this transparent electrode and a metal electrode. There is no need to form color filters corresponding to the elements, and the formation of the color filters is greatly simplified, making it possible to reduce the cost of the EL light emitting element. In addition, since we formed a multilayer thin film color filter with high transmittance only in the R, G, and B wavelength regions on a glass substrate, we created a color filter with a rectangular cross section like a conventional EL light emitting device. Since there is no fear of disconnection of the transparent electrode due to the filter, and normal light emitting operation of the pixel occurs, reliability can be improved.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view of one pixel according to an embodiment of the EL light emitting element of the present invention.

FIG. 2 is an enlarged view showing a thin film-like color filter having high transmittance only in the R, G, and B wavelength regions, which is provided on the top surface of the glass substrate of the EL light emitting element in FIG. 1;

FIG. 3 is a diagram showing a chemical formula of the light-emitting layer of FIG. 1.

FIG. 4 is a diagram showing the transmittance of the multilayer thin film color filter of FIG. 1;

5 is a diagram showing R, G, and B emission spectra in each light emitting layer in FIG. 1. FIG.

6 is a diagram showing the relationship among the number of layers, refractive index, and thickness in transmittance of the multilayer thin film color filter of FIG. 4; FIG.

[Figure 7] Each R, G, and B passed through the color filter in Figure 1
It is a figure showing the emission spectrum of.

FIG. 8 is an enlarged view of one pixel of an example of a conventional EL light emitting element.

[Explanation of symbols]

15 Glass substrate 16 Color filter 17 Transparent electrode 18, 19, 20 Luminescent layer 21, 22, 23 Metal electrode

Claims (1)

[Claims] [Claim 1] A multilayer thin film of R, G, B on a glass substrate.
A thin film-like color filter whose transmittance is high only in the wavelength region is formed in multiple layers, a transparent electrode is formed on this color filter, and R ,G,
An EL light-emitting element characterized by comprising a light-emitting element that emits the color B.