JPS6012696A - Thin film electroluminescent element - 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 The present invention relates to the structure of a thin film electroluminescent device (hereinafter referred to as a thin film EL device) that exhibits electroluminescence upon application of an alternating current electric field.

In order to improve the brightness and luminous efficiency and to obtain stability of operation over a long period of time, in the thin film EL cell for AC operation, 0.5-3 mo1% of h or ThFs # SmF3 pP is used as the luminescent center. z added with rF3 etc.
ns+Zn5e etc. semiconductor layer is Y, 03 or Al1
0stPATiO.

A thin-film KL element with a so-called double insulation structure sandwiched from both sides by insulating layers such as BαTies + Sim O4 was used.

An example of the basic structure of a conventional double-insulated thin film EL element is shown in the first example.
As shown in the figure.

In Figure 1, 1 is a glass substrate, 2 is In2O5+S
3 is a transparent conductive film made of nO, ITO or metal thin film, etc. Y20B m A40S z P A is deposited thereon by electron beam or sputter deposition method.
Insulator layer such as T i Os rBaTi03, S is Na, 4 is Mn1ThF deposited on it,
*This is a ZnS semiconductor layer containing luminescent centers such as SmF and tPrF3. This semiconductor layer 4 is also manufactured by a vapor deposition method or a sputtering method.

5 is an insulating layer deposited on the semiconductor layer 4, and the deposition method and material are the same as those for the insulating layer 3. 6 is a back electrode made of A/shade deposited on it, 7 is an AC power source that drives EL hydrogen atoms, and 7 is an AC power source that drives EL hydrogen atoms, which connects the transparent conductive film 2 and the back electrode 6.
and is connected to.

Next, the principle of EL hydrogen light emission will be briefly explained for an element having the structure shown in FIG.

The semiconductor layer 4 is considered to be a simple capacitor before the start of light emission. Therefore, when an AC voltage from a power source 7 is applied between the electrodes 2 and 6, a voltage corresponding to the capacitance of each layer is applied to the semiconductor layer 4 and the insulating layer 3.5.

The electric field applied to the semiconductor layer 3 is sufficiently high (approximately 1 (7'V)
/cm or more), electrons are excited in the conduction band of the semiconductor layer 3. These 7m2 molecules are accelerated by the electric field and collide with the luminescent center with sufficient energy to collisionally excite the luminescent center. As a result, when the electrons in the luminescent center that have risen to an appropriate excited state return to the ground state, light with an energy value unique to the luminescent center is emitted. When the actual thickness is 11, the emission spectrum has a certain degree of broadening 9 due to interaction with the lattice.

The luminescent center Mn or ThFs r SmF mentioned above
@ HP rF.

etc., their emission energy is in the visible light range, so they emit strong light. I will be on the I2 side.

At least one transparent conductive film is used in a thin film EL device. In the example of FIG. 1, only the transparent conductive film 2 is used, but the transparent conductive film (1) may also be used for the back electrode 6. The conductive film sufficiently transmits visible light and Since low resistance is required, conventionally In4 o3t SnO,...
Until now, metal thin films and the like have been used. However, these films inevitably have a large resistance when they can sufficiently transmit light emitted from the semiconductor layer 4. For this reason, in a large-area device, there is a voltage drop due to the resistance of the transparent conductive film between the peripheral part and the central part or between the parts near and far from the external electrode connected to the transparent conductive film. This has the disadvantage that the applied voltage changes depending on the location within the plane, resulting in uneven brightness.

The present invention aims to solve the problem of uneven brightness caused by non-uniform distribution of voltage applied to a semiconductor layer in a plane. A metal electrode is provided to sufficiently reduce the voltage drop across the transparent conductive film, thereby uniformizing the in-plane distribution of the voltage applied to the semiconductor layer and eliminating uneven brightness due to non-uniformity of the voltage. That is.

The present invention will be explained in detail below with reference to the drawings.

Figure 2 shows a double-insulated AC-driven thin Jl with a non-explosion system.
t,j EL hydrogen element cross-sectional view. In the figure, ITO
A linear A/gold 1'? i'ffl pole 8 is formed. The resistance of the electrode 8 is sufficiently lower than that of the ITO film 2.

In the case of M, its specific resistance is approximately 3
．． 3Ω/mouth. In order to sufficiently reduce the amount of light blocked by Al, the width of the six helical electrodes 80 is set to 1730 mm, which is the width of the part without the electrodes 8, and the sheet resistance in the linear direction is 9°9Ω/■. On the other hand, since the sheet resistance of commonly used ITO is 50Ω/hole,
It can be seen how low the sheet resistance of the linear Al electrode 8 is. Therefore, most of the current will flow through the linear Al electrode 8, but since the resistance of the electrode 8 is sufficiently small, the voltage drop will be about 115 compared to the case without the linear AI electrode 8, and in addition to the semiconductor) The uniformity of the in-plane voltage distribution is greatly improved.

Therefore, in such an EL hydrogen element, uneven light emission due to non-uniformity of the voltage applied to the semiconductor layer 4 is eliminated, and a hydrogenated element having extremely uniform light emission is obtained.

In this case, the area covered by the sandy A/electrode 8 is about 3 circles of the entire transparent conductive film 2, so the linear A
The average transmittance of only the l electrode 8 is 97, which is almost negligible. On the other hand, if an ITO film 2 of 10 Ω/1 is used, the transmittance deteriorates by about 10%, so it can be seen that the linear A7 electrode 8 is still effective.

It is quite possible to make the width of the linear Al electrode less than 100 microns, so this increases the distance of clear vision +'I
It is possible to substantially eliminate the perception of flocculent Al type (;A8) in Ht.

In the above example, a linear AA group electrode is used, but this electric body is not limited to a linear shape, and may be in a net shape or the like. This J15 example is shown in the third example.
As shown in the figure. Instead of the linear Al electrodes 8, mesh-like AJfii 9 that are orthogonal to each other are used.

In the above example, A/ was used as the material of the linear electrode, but the material of the electrode is not limited to Al, but other old materials may be used.

Further, in the above example, the linear Al' electrode 8 is connected to the ITO film 2 and the Y
Although it is provided between the insulating film 3 made of 2O3, the linear AI electrode may be provided between the ITO film 2 and the glass substrate 1.
Furthermore, both may be used together. Alternatively, the back electrode 6 may be a transparent conductive film and a linear electrode may be provided on one or both surfaces thereof.

Although the present invention has been explained above using a double-insulated thin film EL element as an example, the present invention is not limited to this example, but can be applied to all EL elements having a transparent conductive film to achieve uniform brightness in the same way as described above. It is possible to bring about

Furthermore, by applying the present invention, the current flowing through the light-transmitting conductive film can be significantly reduced and made uniform, so that thermal destruction of the light-transmitting conductive film due to Ih current can be prevented.

In addition, even if thermal destruction does not occur, it is effective in preventing distortion and peeling of the interface due to thermal expansion during energization.
This can greatly contribute to improving the reliability of the L element. In addition, since the electric current in the light-transmitting conductive film is reduced and made uniform, the thickness of the four-electric conductive film can be made thinner than conventional ones, which has the effect of improving light-transmitting properties. It is.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a basic double-insulated thin-film EL device, and FIG. 2 is a double-insulated thin-film E having a mesh metal scrap electrode according to the present invention.
FIG. 813 is a partial cross-sectional perspective view of a double-insulated thin film EL element having a mesh metal scrap electrode. In the figure, 1 is a glass substrate, 2 is a transparent conductive film made of ITO etc., 3 and 5 are insulating films made of Y2O3 etc., 4
6 is a semiconductor layer such as ZnS containing a luminescent center such as Mn, and 6 is A.
/ etc., 7 is a working AC power source for an El element, 8 is a glandular gold electrode made of A1 etc. of the present invention, 9
is a mesh metal electrode. Patent applicant: NEC Corporation

Claims (1)

[Claims] (1) In a thin film electroluminescent device having at least one light-transmitting conductive film, a linear metal electrode may be provided on at least one surface of the light-transmitting conductive film.
FXflA electroluminescent device with F'j characteristic.