JPS62143394A - 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] <Industrial Field of Application> The present invention relates to a thin film EL device that emits EL light by applying an alternating current electric field, and in particular, by limiting the material composition of the substrate glass of the thin film EL device. The present invention relates to an element structure that realizes a thin-film EL element with high performance.

Summary of the invention> As a glass substrate, the volume resistivity is IQ9Ω at 350°C.
α or more, 1060・α or more at 600℃, but ,
A highly reliable thin film EL element is obtained using a non-alkali type glass having a strain point temperature of 600° C. or higher and an alkali component content of 0.5% by weight or less.

<Prior art> The manufacturing process of thin-film EL devices includes several high-temperature vapor deposition, sputtering processes, and high-temperature heat treatment processes.
The glass substrate is exposed to high temperatures several times before the EL element is completed.

As a glass substrate for an EL element, high-purity molten silica (quartz glass) is most suitable because it is extremely stable even at high temperatures, but cannot be used because its manufacturing cost is extremely high. Therefore, low-alkali borosilicate glass is usually used.

<Problem that the invention seeks to solve> However, alkali ions (Li”) contained in glass.

Depending on the volume resistivity (volume electrical conductivity) of the glass, Na+, Ni+) precipitates on the substrate surface during the high temperature process of the EL element manufacturing process, significantly degrading the characteristics of the EL element. In particular, as the substrate temperature rises during insulating film sputtering, the alkali ions precipitate on the substrate surface, and a transparent electrode (ITO) is formed by the charge incident on the substrate from the plasma.
) The interaction between the current flowing through the stripes and the alkali ions alters the ITO composition, resulting in extremely high electrode resistance and extremely poor characteristics of the EL device.

The present invention has been made in view of the above problems, and its purpose is to obtain a highly reliable EL element by limiting the alkaline component content and volume resistivity of the substrate glass. That is.

<Means for Solving the Problems> The thin film EL device of the present invention comprises a pair of electrode layers formed on a glass substrate and an electroluminescent layer sandwiched between these electrode layers. The glass substrate has a volume resistivity of IOΩ at 350° C. on a steel plate, a strain point temperature of 600° C. or more, and an alkali component content of 0. It is characterized by using a non-alkali type glass containing 5% by weight or less.

<Function> As described above, the rate of change in resistance of ITO at 600°C is small and can be formed without altering the ITO composition, and the rate of change in resistance due to the alkali component of the glass can also be made small. Furthermore, by having a strain point temperature of 600° C. or higher, a thin film EL device with even better performance characteristics can be obtained.

<Example> Figure 1 shows the relationship at each temperature between the amount of alkali contained (weight percent) and the volume resistivity of borosilicate glass used as a glass substrate of an EL element. It is. In Figure 1, the glass with a lower alkali content generally has a higher volume resistivity, but the glass with a lower alkali content has a higher volume resistivity.
This relationship is reversed for 2%, 1.5% and 3%, respectively. This is a glass matrix (B20.A
This is due to the component ratio of 4203°5i02) and the mixing ratio of added Alka'J (Na20°K2O) (mixed alkali effect). With a content of 0.5% or less, 35
Volume resistivity at 0℃ is 100・a or more and 600℃
A material with a volume resistivity of 10 Ω·- or more can be obtained.

FIG. 2 shows the relationship between the volume resistivity of glass and the rate of change in resistance of ITO (substrate temperature 600° C.). Second
As shown in the figure, when the glass has a volume resistivity of 106 Ω·C or less at 600°C, the rate of change in resistance of ITO at 600°C becomes extremely large.

Figure 3 also shows the alkaline component of glass (Na20°K).
2O) content and the resistance change rate of ITO. When the alkali content is 0.5% by weight or more, the resistance change rate increases.

Furthermore, the strain point temperature of the glass substrate needs to be 600° C. or higher. As mentioned above, the manufacturing process of thin film EL devices includes several high-temperature deposition, sputtering, and high-temperature heat treatment processes, and the glass substrate needs to be able to withstand these high temperatures. The following points can be cited as advantages that the glass substrate can be used at high temperatures of 600° C. or higher. Transparent electrode (ITO)
Since the annealing temperature can be raised, the crystallinity of the ITO film can be improved and the specific resistance can be lowered. Also EL
The dielectric strength of the element is also improved. Furthermore, since the annealing temperature of the light emitting layer can be raised, the crystallinity of thin film polycrystalline particles such as ZnS can be improved, and Mn (active impurity element) as a light emitting center can be added to the crystal lattice at an appropriate concentration. It can be diffused and improves the 85 emission characteristics.

From the above, the volume resistivity is 109Ω・at 350°C.
(up to) or above, non-alkali material with a temperature of 1060・a or above at 600'C, a strain point temperature of 600°C or above, and an alkali content of 0.5% by weight or below.
By using this type of glass as the substrate glass, it is possible to obtain an EL element with high display quality and reliability.

Table 1 shows the properties of the glass according to this example.

Table 1 Glass Properties of Examples (Effects of the Invention) As explained above, according to the present invention, it is possible to obtain an EL element with high display quality and reliability.

[Brief explanation of drawings]

Figure 1 shows the amount of alkali (% by weight) contained in the borosilicate glass used as the glass substrate of the EL element.
Figure 2 is a diagram showing the relationship between the volume resistivity of glass and the ITOΩ resistance change rate at each temperature. IT
FIG. 3 is a diagram showing the relationship between O and the resistance change rate. Agent Patent attorney Aihiko Fuku (and 2 others) Temperature (0C
) ITOt, Far North Lower Margin (σ Utsugen Figure 5)

Claims (1)

[Claims] 1. In a thin film EL device consisting of a pair of electrode layers formed on a glass substrate and an electroluminescent layer sandwiched between these electrode layers, the glass substrate has a volume resistivity of 10^9 Ω at 350°C. cm or more, 600℃
is 10^6Ω・cm or more, and the strain point temperature is 600
1. A thin film EL device characterized by using non-alkali type glass having a temperature of 0.degree. C. or higher and an alkali component content of 0.5% by weight or less.