JPS6142894A - Thin film el panel - 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] Industrial Application Field The present invention relates to a thin film EL panel among flat display panels that will become increasingly necessary in the future, especially in the field of office automation, in line with the trend of information society. be. EL panels differ from liquid crystal and electrochromic display panels in that they are all-solid-state, self-luminous, easy to see even in the dark, and less dependent on viewing angle. It is also thin, lightweight, and has a high screen f.
# Because it is easy to refine and has the characteristics of no flicker, it is ideal for character and graphic displays for personal computers and word processors.

Conventional Structure and Problems Generally, an EL flat panel has a structure in which a transparent electrode, a first insulating layer, a phosphor layer, a second insulating layer, and a back electrode are laminated in this order on a glass substrate.

The transparent electrode is a mixed crystal oxide of In and Sn, and the insulator layer is Y2O3, Ta205. A12o3. Si3N
4°T iO2, S r T 103. B a T
tO3 and PbTiOs have been conventionally used. In addition, as the phosphor layer, ZnS:Mn or Z
n S ', T b F 3 are often used.

In the above configuration, when an orthogonal matrix is formed with striped transparent electrodes and back electrodes and operated in a line-sequential driving method, the brightness of the panel decreases as the number of scan side, ie, horizontal line electrodes increases. If there are more than 50 horizontal lines, the brightness is insufficient for practical use.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a thin film EL panel that has higher brightness than the prior art.

For example, when using a ZnS:Mn phosphor layer and assuming a constant thickness, the brightness of an EL panel according to the structure of the invention depends on the concentration of Mn,
Interface state between ZnS:Mn layer and insulator layer and ZnS:M
It depends on the crystallinity of the n-layer. Although there are many unknowns regarding the interface state, the optimal Mn concentration is approximately 0.8 atoms, and the better the crystallinity, the higher the brightness can be obtained.

The present invention focused on this crystallinity, and found that if the formation conditions of the ZnS:Mn thin film are the same, the crystallinity is greatly influenced by the underlying compound for forming the ZnS:Mn, that is, the type of the first insulating layer. As a result of the study, it was found that BeO as the base is extremely effective in improving the crystallinity of the ZnS:Mn film, and by applying this, they succeeded in improving the brightness of EL panels. The entire first insulating layer may be formed of this BeO thin film, or it is also effective to form the first insulating layer of two or more layers only in a portion in contact with the ZnS:Mn thin film. In the latter case, the first insulating layer is formed in combination with an insulating film with high dielectric breakdown voltage, resulting in stable EL.
You can create panels.

Description of examples Examples of the present invention will be described in detail below.

Example 1 1n, Sn mixed crystal oxide transparent electrode (ITO).

Two substrates formed on glass by direct current activated sputtering using a Sn alloy as a target were prepared. On the one hand, a 12,500 Y2O3 thin film was formed using the EB active evaporation method using Y metal, and on the other hand, a BeO thin film of the same thickness (2,500 A) was formed using a high-frequency sputtering method targeting BeO oxide.The substrate temperature for both was 200C. The gas and its pressure are 02, B, where Y2O3 is 4X10 torr.
e O is 6 x 10 torr Ar+5040
It is 2.

In the subsequent preparation process, the above two substrates were prepared at the same time. First, O, S atoms - Mn
ZnS:Mn phosphor thin film containing
Formed to human thickness and then heated at 560°C in vacuum for 1
Time annealing was performed.

Next, 2,600 Y2O3 films were formed again using the same manufacturing method, and A7 metal was deposited as a final back electrode.

The EL panel prepared as described above was driven with a 5 KHz sine wave, and its voltage and brightness characteristics are shown in FIG. Curve 1 in the figure is glass/ITo/Y2O3/ZnS
: Mn/Y2O3/A, 1 panel, 2 is glass/ITo/BeO/ZnS: Mn/Y2O3/Al
The characteristics of the panel were shown. Although the thickness of the ZnS:Mn phosphor film is the same, the brightness of the panel using the BeO thin film as the first insulating layer is about 1.5 times higher.

As a result of examining both ZnS:Mn thin films by X-ray diffraction, the first
When the insulating layer was BeO, the intensity of the 111 peak was about twice as high. This good crystallinity is linked to improved brightness.

Example 2 S was placed on the same ITO-coated glass substrate as in Example 1.
The rTiO3 thin film was subjected to ESOO using the high-frequency sputtering method at a substrate temperature of 400°C in Ar gas containing 80% O2 at 8X10 torr using its oxide ceramic as a target.
It was formed to a thickness of O. After applying the 5rTiQ3 thin film, it was divided into two parts, and one part was further coated with BeO in the same manner as in Example 1.
600 people laminated the thin film.

Thereafter, both ZnS:Mn sheets were processed in the same manner as in Example 1.
.

By stacking it with Y2O3 and Al, an EL panel was completed. Their voltage and brightness characteristics are shown in the 3°4 curve in the figure. Curve 3 is /77 S/ I T O/ S r
'r 103/ZnS:Mn/Y20
s/A l, 4 is glass/ITO/5rTio
/Bed/ZnS:Mn/Y2O3/A/ The characteristics of the panel were shown. The dielectric constant of SrTiO3 thin film is about 14
0, the emission start voltage is lower than that in the case of using Y2O3 or Boo as the first insulating layer in Example 1.

From the comparison of curves 3 and 4, S with Boo on the ZnS:Mn side
The bilayer type first insulating layer of r T 103+ B e O has a brightness about 1.5 times higher than that of just 5rTiOs.

Generally, when ZnS:Mn is formed on SrTiO3, Y
The 111 X-ray peak of ZnS:Mn is considerably weaker than that of 2O3. However, as mentioned above, ZnS: 1vl
In the case of a two-layer first insulating layer with BeO on the side in contact with n, the 111 diffraction peak of ZnS:Mn layered thereon is B
It becomes about 4 times stronger than when there is no eO. This leads to improved brightness of the EL panel.

Example 3 The structure was exactly the same as in Example 2, but a green-emitting ZnS:TbFs phosphor thin film was used instead of ZnS:Mn. Using a powder containing 2% by weight of TbF3 with respect to ZnS as a target, Zn was sputtered using high frequency sputtering at a substrate temperature of 200°C in Ar at 2X10 torr.
S'', T b Fs thin film was created.The subsequent annealing temperature was 400°C for 1 hour.The voltage and brightness characteristics of the EL panel are shown in curve 6.6 in Figure 1. 6 is a glass x/ I T O/ S r T 103/ Z
n S: T b F s/Y20s/AI I 6 is glass/ITo/SrTiO3/BeO/ZnS:Tb
The characteristics of the EL panel with F3/Y2o3/Ag structure were shown. Similar to Example 1.2, the effect of eO was observed.

Effects of the Invention As described above, according to the present invention, as shown in Examples 1 and 2.3, by using a composite first insulating layer in which BeO or Boo and another insulating layer are stacked, the brightness of an EL panel can be improved. can be increased by about 1.6 times, which is effective for increasing the size of the panel, and can further improve the practicality of the EL panel.

[Brief explanation of the drawing]

The figure is a characteristic diagram for explaining the thin film EL panel of the present invention.

Claims (1)

[Claims] A transparent electrode is placed on a glass substrate, and a first green layer is placed on top of the transparent electrode.
A ZnS-based phosphor layer is laminated thereon, and a second insulating layer and a back electrode are laminated thereon, and all or part of the first insulating layer is made of BeO, and this BeO is always in contact with the phosphor layer. A thin film EL panel characterized by: