JP2879707B2 - Multi-color EL element - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a multicolor EL device useful for a multicolor EL display.

[Prior art] Thin-film EL devices can be used as flat, thin, large-area display panels, and are expected to be used in a wide range of applications from numeric display to graphic display and image display. In order to display, a multi-color display is required, and many studies have been made on a base material and a luminescent center for realizing the display.

Conventionally, as a multicolor EL element, as shown in FIG. 6, a ZnS: Mn light-emitting layer (d ₁ ) that emits yellow-orange light and a ZnS: TbF light-emitting layer (d ₂ ) that emits green light are alternately arranged. A device formed side by side has been proposed (for example, Japanese Patent Application Laid-Open No. 1-222191).
No.). With this configuration, two types of emission colors can be obtained by selecting a pixel to which a voltage is applied.

[Problems to be solved by the invention]

However, in order to realize this, a transparent electrode (b) such as ITO and a first insulating film (c) made of a dielectric material are sequentially stacked on a glass substrate (a), and then ZnS: Mn (or ZnS: : TbF) and photolithography,
It is necessary to pattern by etching and then perform the same process for ZnS: TbF (or ZnS: Mn),
After that, the second insulating film (e) and the back electrode (f) are laminated. Therefore, the process of forming the light emitting layer becomes complicated, and this method generally has a problem that red light emission with good color purity used for warning color display or the like cannot be obtained.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned conventional problems and to provide a multi-color EL element having a wide range of display colors from red to green with high color purity by simple steps.

[Means for solving the problem]

In the multicolor EL device of the present invention, in order to achieve the above object, ZnS is used as a base material, and Tb, M
n is Tb 0.2 to 0.8 at% (atomic%, the same applies hereinafter), Mn
A single layer film doped with 0.1 to 0.4 at% and F as a co-activator at 0 to 0.3 at% is used for a light emitting layer, and a red filter and a green filter are combined. At this time, the two filters are arranged on a light extraction path.

[Function of the invention]

From the ZnS: Tb, Mn, F light emitting layer, light emission in which green light emission caused by Tb ³⁺ ions and red light emission considered to be caused by Mn ²⁺ ions are synthesized is obtained. At this time, the F ^-1 ion increases the intensity of green light emission by the Tb ³⁺ ion, and shifts the emission spectrum of the Mn ⁺² ion to a longer wavelength side. Therefore, a broad emission spectrum from red to green is obtained.

Originally, Mn ²⁺ ion emits yellow-orange light. However, since this is light emission due to transition of 3d electrons, the light emission color is easily affected by the surrounding crystal field. Also in the light emitting layer of the present invention,
Red light emission is considered to be the result of being affected by the crystal field of Tb ³⁺ ion or F ⁻¹ ion.

The emitted light having a broad spectrum from red to green is separated by red and green color filters, and extracted outside as red light and green light with good color purity. Of course, in this case, an intermediate color can be obtained by using the gradation display.

FIG. 3 shows a ZnS: Tb, Mn, F light emitting layer (Mn concentration: 0.2 at%, F:
FIG. 4 is a graph showing the relationship between the Tb concentration of the EL element of 0 at% and the green luminance separated by the filter, and FIG. 4 shows ZnS: Tb, Mn, F.
EL element of light emitting layer (Tb concentration is 0.4at%, F concentration is 0at%)
5 is a graph showing a relationship between Mn concentration and red luminance separated by a filter. FIG. 5 shows the F concentration of the EL element of the ZnS: Tb, Mn, F light emitting layer (Tb concentration: 0.4 at%, Mn concentration: 0.2 at%) and green light (solid line) and red light (solid line) separated by a filter. It is a graph which shows the relationship of the freshness of a broken line).

As shown in FIGS. 3 to 5, the concentrations of Tb, Mn, and F were 0.2 to 0.8 at%, 0.1 to 0.4 at%, and 0 to 0.3 at%, respectively.
In this case, the above-mentioned action is effectively performed, and high-luminance red light emission and green light emission are obtained.

In addition, F has a meaning of charge compensation of Tb (compensating for the valence difference between Zn ²⁺ and Tb ³⁺ which replaces it, and maintaining electrical neutrality), and the life of the EL element is extended. Contribute.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to examples. However, it goes without saying that the present invention is not limited to the following examples.

FIG. 1 shows a first embodiment of the present invention. First, a color filter (2) and a transparent electrode (3) made of ITO are sequentially laminated on a glass substrate (1). The color filter is
The red filter is indicated by R and the green filter by G. Next, the first insulating film (4) is formed by sputtering.
After forming 5000 _{2 of} Ta ₂ O ₅ , 6000Z of Z by vacuum evaporation
An nS: Tb, Mn, F light emitting layer (5) is formed, a second insulating film (6) is formed in the same manner as the first insulating film, and finally a back electrode (7) made of aluminum is formed.

When a voltage is applied between the transparent electrode (3) and the back electrode (7), red light is extracted through the red filter (R) and green light is extracted through the green filter (G).

The method of combining the filters is not limited to the above method, but may be the method shown in FIG. In this case, the back electrode (7) is laminated on the glass substrate (1), while the transparent electrode (3) is the second electrode.
The color filter (2) is laminated on the insulating film (6). The red light and the green light are respectively extracted upward through a red filter (R) and a green filter (G) disposed at the top.

〔The invention's effect〕

As described above, the multicolor EL device of the present invention has ZnS:
Tb, Mn, is a combination of a single-layer light-emitting layer and a green filter and a red filter, F- ¹ ion is Tb ³⁺
In addition to increasing the green emission intensity of the ions, they act on Mn ²⁺ ions to shift the emission spectrum to longer wavelengths, so that a wide range of display colors with good color purity from red to green can be obtained, and By using the tonal display, these intermediate colors can also be obtained. Moreover, since the light emitting layer is a single layer,
Compared to conventional multi-color EL elements, it can be manufactured with simpler processes and has excellent productivity.

Also, among them, Tb, Mn, F are 0.2 to 0.8, 0.1 to 0.4, 0 to 0.3
In the case of at%, the above effects are particularly remarkable.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of the multicolor EL device of the present invention, FIG. 2 is a schematic diagram showing another embodiment, and FIGS. 3 to 5 are ZnS: Tb, Mn, respectively. EL with F light emitting layer
A graph showing the relationship between the Tb concentration of the device and the green luminance separated by the filter, a graph showing the relationship between the Mn concentration and the red luminance separated by the filter, and the relationship between the F concentration and the luminance of the green light and the red light separated by the filter. FIG. 6 is a schematic configuration diagram of a conventional multicolor EL device. 1 is a glass substrate, 2 is a color filter, 3 is a transparent electrode, 4 is a first insulating film, 5 is a ZnS: Tb, Mn, F light emitting layer, 6 is a second insulating film, and 7 is a back electrode.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H05B 33/14 H05B 33/22

Claims (2)

(57) [Claims] 1. A luminescent material comprising ZnS as a base material and Tb, Mn,
A multicolor EL device comprising a combination of a light-emitting layer comprising a single-layer film containing F as a coactivator, a green filter and a red filter. 2. A single layer containing ZnS as a base material, containing Tb and Mn of 0.2 to 0.8 at% and Mn of 0.1 to 0.4 at% as emission centers and F of 0 to 0.3 at% as a co-activator, respectively. A multicolor EL device comprising a combination of a light emitting layer comprising a film, a green filter and a red filter.