JPH03216997A - Electro-luminescent element - Google Patents

Abstract

PURPOSE:To improve a packaging process by using a fluorescent sintered ceramics plate which is concurrently used for an emission layer and a substrate, formed out of at least a kind of sulfuric fluorescent body containing a 0.01-10% of I group metal copper and sintered in the temperature range of 850 deg.C-1250 deg.C, and forming a pair of electrodes only on the front surface of the fluorescent ceramics plate. CONSTITUTION:On the surface of fluorescent sintered ceramics 1 which is concurrently used for an emission layer and a substrate, formed out of at least a kind of sulfuric fluorescent body containing a 0.01-10% of copper and sintered in the temperature range of 850 deg.C-1250 deg.C, at least a pair of electrodes 2, 3 are formed without facing each other. At least one of the paired electrodes 2, 3 is selected as a transparent electrode 2, an emission is taken out through the transparent electrode 2 by applying a voltage between the paired electrodes 2, 3. In this method, an element-mounting process is improved and the causes associated with deteriorated elements and the like are suppressed, while a higher quality and an additional new function are obtainable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to an electroluminescent device formed with counter electrodes that do not face each other.

[Prior art 1 Electroluminescent device (hereinafter referred to as EL device)
has been studied for a long time for its application to flat solid state light emitting display devices, and there are deep-rooted expectations for its practical application. This EL
The device is structurally characterized by forming a crystalline thin film of phosphor on a substrate. The organic dispersion type is characterized by uniformly dispersing and mixing the phosphor powder in an organic dielectric binder, and the inorganic dispersion type is characterized by binding the phosphor powder with an inorganic binder such as glass. Can be divided. Inorganic dispersion type EL is often ceramic type EL.
Although it is sometimes called phosphor powder, it is simply phosphor powder particles dispersed in this inorganic binder. All of the EL devices that have been developed so far have a light-emitting layer or an insulating layer appropriately placed and supported between a pair of opposing electrodes (formed on both sides) (at least one is a transparent electrode for light extraction). It is based on structure.

Recently, the inventors have developed manganese-doped zinc sulfide (ZnS
: A phosphor sintered ceramic plate made by sintering phosphor powder (referred to as ``n'') at a high temperature of 850°C or higher is used as the substrate and light emitting layer, and this is simply sandwiched between a pair of opposing transparent electrodes and a counter electrode. By using an element with a simple structure, we have realized a DC high brightness EL element (hereinafter referred to as a PCEL element) that achieves several thousand cd/s+'' despite being driven at a low DC voltage of several tens of V (Japanese Patent Laid-Open No. 61-224291) [ [Problems to be Solved by the Invention] All EL devices that have been proposed to date are planar light emitting devices that emit light by applying a voltage between opposing electrodes. The lead wires for supplying the product are always taken out from two sides.

That is, electrode wiring is also required on the back side of the light emitting surface of the EL element. This is a fatal drawback in terms of device fabrication and device mounting, since it conflicts with the brainer technology used to fabricate the device.

Now that high-performance PCEL devices have been realized, in order to be widely used as a practical device, the characteristics of the device over time must be stable, and when considering the application of EL devices, electrode patterning and , it is a necessary condition that the device must be easy to implement. f) In a CEL element using a phosphor sintered ceramic plate, the thick ceramic is sandwiched between a transparent heavy pole and a counter electrode,
Father forming, which is one of the deterioration mechanisms of DC EL elements, progresses while the element is being driven, so there is a problem with the aging characteristics, but with the conventional PCEL element structure, there is no solution other than using a driving method such as pulse voltage driving. . As a result, there is a problem that the scope of application is significantly narrowed.

[A Thousand Steps to Solve the Problems] As a means for solving the above-mentioned problems, the present invention provides a PCEI.
In the device, copper, which is a Group I metal, is used as both the light-emitting layer and the substrate.
．． Since a phosphor sintered ceramic plate made of at least one kind of sulfide-based phosphor containing 01 to 10% and sintered in the range of 850 to 1250 degrees Celsius is used, the ceramic in its virgin state has low resistance. By focusing on this point, mounting efficiency is significantly improved by forming a counter electrode consisting of a transparent electrode and a counter electrode only on one surface side of the phosphor ceramic plate. Furthermore, by forming a current control layer or an electric field control layer by modifying or deforming the portion of the surface of the phosphor ceramic where electrodes are not formed, it is possible to improve the aging characteristics and achieve higher performance. can.

[Action] The present invention has the following effects. That is, PCE
In the case of the L element, a bulk material (thickness 0.1 mm to 0.8 ms) is a phosphor sintered ceramic plate containing copper (Cu) that has low resistance and can serve as both the light emitting layer and the substrate.
Therefore, an element configuration that cannot be imagined from the common sense of conventional EL elements, in which driving is possible by forming a counter electrode whose electrode surfaces do not face each other, becomes possible.

The effects of the PCEL device according to the present invention will be explained below using an example in which ZnS:Iin is used as the phosphor.
[It goes without saying that the present invention is not limited to n and its device manufacturing method. ZnS: Mn phosphor particles,
The counter electrode is formed on a phosphor sintered ceramic plate that is coated with Cu in a solution containing Cu, which is a group I metal, and then formed through a molding and sintering process. When a DC voltage is applied so that the electrode side becomes the negative electrode, a large current flows because the ceramic made of Cu-coated phosphor particles has a low resistance. If this voltage is continued to be applied, Cu ions will move (migration) along the direction of the furnace to the negative electrode.
Therefore, a high resistance Zn depleted of Cu is placed under the transparent electrode.
S: I[n A light-emitting layer is generated, and as the current decreases, a high electric field begins to be applied to this phosphor layer and it emits light. Once the resistance increases, the current flows through the part with lower resistance, so the light-emitting part also spreads accordingly, and eventually a high-resistance ZnS:l[n phosphor layer is formed over the entire lower part of the transparent electrode, leading to full-surface light emission. . This is the forming phenomenon.

However, in the EL element according to the present invention, if the element is continuously driven with direct current for a long time after forming is completed, this high resistance layer becomes wider over time and the element resistance increases. A deterioration mode (father-feeding) may occur in which the amount of energy gradually decreases.

In the device structure of the present invention, the counter electrode is on the same plane, and the phosphor ceramic that serves as the light emitting layer and substrate is [f
Since it is also a ULK material, it can be easily processed.
It becomes possible to freely control the moving path of Cu. If necessary, the DC electric field of the high-resistance ZnS:l[n phosphor layer can be controlled by etching, coating, doping, or other treatments on the portion of the ceramic where the counter electrode is not attached. That is, by intentionally injecting a third element from the outside into the area corresponding to the Cu movement path, Cu
It is possible to control the moving speed of the current limiting layer (
By forming this part), stable operation and long life of the element can be realized even during the above-mentioned continuous driving.

On the other hand, between a counter electrode formed on one surface of the phosphor ceramic and an electrode made of metal etc. formed on the other surface facing both of these electrodes, the former is made positive and the latter is made negative. By applying a DC bias voltage and performing forming, high-resistance ZnS:lln is formed directly under the counter electrode.
By forming a phosphor layer and then applying an alternating current voltage between the counter electrodes, light emission can be achieved at both electrodes, and since the direction of movement of Cu changes depending on the direction of the electric field, deterioration due to γ-forming etc. can be achieved. can be suppressed.

As described above, since the EL element according to the present invention applies a voltage to the counter electrode on the same plane, that is, the electrodes only need to be formed on one surface, it can be easily manufactured, and the wiring can be taken out by wire bonding etc. This is not only extremely advantageous in terms of mounting on surface-emitting type illuminated lamps, flat-type solid-state light-emitting display devices, etc., but also makes it possible to improve the performance and functionality of the EL characteristics. Therefore, the element structure according to the present invention deviates from the conventional concept and can be said to be revolutionary.

The present invention will be explained below using examples.

[Example 1] Copper chloride (CuCl
z) was added at 0.38%, and furthermore, 8.5% of paraffin was added as a binder. After mixing uniformly, the mixture was molded into a disk shape with a diameter of 25 mI1 and a thickness of 0.6 mm using a press pressure of 4 t/cm", and the mixture was depressurized. The binder was removed at 600°C for 5 hours, and then sintered at 950°C for 1 hour in a mixed atmosphere of argon and carbon disulfide to produce a phosphor sintered ceramic plate 1 as shown in Figure 1. On the center of one side of this ceramic plate, a piece of aluminum (A
I) A circular transparent electrode 2 made of added zinc oxide (ZnO:Al) is formed, and a doughnut-shaped AI counter electrode 3 having an inner diameter of 21 mm, an outer diameter of 25 mm, and a thickness of about 30 ounces is formed around it by vacuum evaporation. A PCEL device having a counter electrode on the same surface as shown in FIG. 1 was fabricated. After forming by applying a DC bias voltage with the transparent electrode 2 as the positive electrode and the counter electrode 3 as the negative electrode, the EL characteristics were measured, and as shown in FIG. /■
2) Brightness (L + oo) 2000 cd/m” when applying 50 V and 100 V (7) Yellow-orange light emission, which is comparable to the characteristics obtained with conventional device structures, was achieved. Furthermore, equivalent EL characteristics were obtained even when the drive voltage was half-wave rectified or in a DC pulse waveform, and the aging characteristics of the EL characteristics were improved.

[Example 2] On one side of a phosphor sintered ceramic plate 1 having a thickness of about 0.51 mm as shown in FIG. 3 and manufactured under the same conditions as in Example 1,
The sputtered ZnO:AL transparent electrode 2 was made of English letters or segment patterns, and the counter electrode 3 was a doughnut-shaped ZnO:Al with an inner diameter of 21 mm, an outer diameter of 25 mm, and a thickness of 1000 mm.
A PCEL device with a spatter film formed thereon was manufactured. After forming by applying a DC voltage with the transparent electrode 2 as the positive electrode and the counter electrode 3 as the negative electrode, the EL characteristics of each pattern were measured. As a result, each pattern emitted light uniformly over the entire surface, vth was 55 V, and l+oo was 2100 cd. /cm'', which showed almost the same characteristics as Example 1. Even when the driving voltage was half-wave rectified or a DC pulse waveform, the same EL characteristics were obtained, and the stability over time was improved.

[Example 3] On one side of the 0.51 mm thick phosphor sintered ceramic plate 1 produced under the same conditions as in Example 1, a 16 mm diameter and 400 mm thick plate was formed by magnetron sputtering as shown in FIG.
nm of ZnO: A 1 circular transparent electrode 2 and its surroundings with an inner diameter of 21 l. A PCEL for a surface-emitting illuminated lamp in which a donut-shaped opposed transparent electrode 3 with an outer diameter of 25 l is formed, and an AI metal layer or conductive paint layer 4 is formed as an electric field control layer on the opposite surface of the phosphor ceramic plate. The device was fabricated. As shown in the figure, forming was performed by applying a DC bias voltage between the counter electrodes 2 and 3 and the Al metal layer 4, with the former being positive and the latter being negative. After completion of footing, a 400 II z AC voltage was applied between the counter electrodes to cause the device to emit light. As a result of measuring the EL characteristics, Lh exhibited yellow-orange luminescence of 40 V and L+oo of 5500 cd/c+*''.The luminance half-life time reached 6000 hours.In addition, two of the counter electrodes in the same figure were 3 and metal f!
14 is connected and a DC voltage is applied to make it negative, or similarly, when a DC voltage is applied that makes 2 of the counter electrodes positive and 3 negative, electrode 3 is made positive and metal layer 4 is made negative at the same time. As a result of applying a DC voltage, almost the same EL characteristics as in the case of AC drive described above were obtained in both cases. In the case of the above-mentioned DC drive, equally good EL characteristics were obtained in both half-wave rectification and DC pulse drive, and the aging characteristics were improved.

[Example 4] A counter electrode having the same shape and size as in Example 1 was formed on one side T of a phosphor ceramic plate with a thickness of 0.41 cm, which was manufactured under the same conditions as in Example 1, and each electrode was As a mask, oxygen was implanted into the space between the inner and outer electrodes by ion implantation to form a high-resistance current limiting layer 5, as shown in FIG. 5, to produce a PCEL element for a surface-emitting illuminated lamp. After forming by applying a DC voltage between the counter electrode or between the counter electrode and the back electrode 4, the EL characteristics were measured.
? Atta. In addition, this method made it possible to significantly improve the aging characteristics. Furthermore, equivalent EL characteristics were obtained even when the driving voltage was set to a half-wave rectified waveform or a DC pulse waveform.

[Example 5] A counter electrode having the same shape and size as in Example 1 was formed on one side of a phosphor ceramic plate with a thickness of 0.4■■ manufactured under the same conditions as in Example 1, and each electrode By masking the space between the inner and outer electrodes, a ring-shaped groove 6 with a width of 2 cm and a depth of 0.2 l is dug by sputter etching as shown in Fig. 6 to increase the current resistance. A limiting layer was formed to produce a PCEL element for a surface-emitting illuminated lamp. After applying a DC voltage between the counter electrode or between the counter itII and the back electrode 4 and completing 7 warmings, the EL characteristics were measured, and the result was that V+k was 50V, t, I o o was 57
00Cd/lI! Teatta.

Further, as in Example 4, the aging characteristics could be significantly improved. Furthermore, almost similar EL characteristics were obtained even when the driving voltage was set to half-wave rectification or a DC pulse waveform.

[Example 6] A film with a thickness of 0.0 mm as shown in FIG. 7 was manufactured under the same conditions as in Example 1. On one side of a 5m phosphor ceramic plate 1,
Diameter 16l, thickness 45cm by magnetron sputtering method
On-ZnO:A1 circular transparent turtle electrode 2 and a donut-shaped transparent electrode 3 having an inner diameter of 21 g++s and an outer diameter of 25 mm were formed around it. Furthermore, a doughnut-shaped counter electrode 7 with an inner diameter of 18 mm and an outer diameter of 19 mm is formed in the space between the heavy poles 2 and 3 by vacuum evaporation to form a P for a surface-emitting illuminated lamp.
A CEL device was produced. The electrodes 2 and 3 are connected, and a DC bias voltage is applied with positive voltage and At counter electrode 7 negative, and after forming, a DC voltage is applied between the transparent electrodes 2 and 3 and the opposite electrode 7. As a result of applying the driving voltage and measuring the EL characteristics, Lh is 34V, L+oo is 6400cd/s"
Met. Almost the same EL characteristics were exhibited even when the waveform of the driving voltage was changed to either half-wave rectification or DC pulse. Also,
The ellipse shown in FIG. 7 could also be produced by first forming a ZnO.Al transparent electrode with a diameter of 25 mm and then patterning it by sputter etching.

The EL properties in this case were equal to or better than the above properties, and the aging properties were also improved.

[Example 7] Under the ceramic manufacturing conditions of Example 1, a phosphor sintered ceramic plate l having a thickness of 0.5 mm was manufactured without containing any CuCl2, and the entire surface of one side was coated as shown in FIG. The metal Cu layer 8 is formed to a thickness of 2000 nm by spatter method.
ZnO with an outer diameter of 16 m was deposited by sputtering on the phosphor sintered ceramic plate 9 shown in FIG.
:A 1 A circular transparent electrode 2 is surrounded by sputtered ZnO as a counter electrode 3 with an inner diameter of 21mm and an outer diameter of 25mm.
A counter electrode consisting of :^l was formed.

When forming was performed by applying a DC voltage with the circular transparent electrode 2 as the positive electrode between the counter electrodes, yellow-orange light emission was obtained, and as a result of measuring the EL characteristics, V+b was 35L L+oo
was 4000 cd/m''T:. In addition, similar EL characteristics were obtained in both half-wave rectification and DC pulse driving.
Introducing Cu into n-sintered ceramics is done by using copper sulfate (C
There was no problem at all when replacing Cu by introducing Cu by immersing ceramics in an aqueous solution of IISO4) or a methanol solution of copper chloride (CuCLz).

C to ZnS:In phosphor as shown in this example
It goes without saying that the EL element manufacturing methods shown in Examples 2 to 6 are also effective in the case of phosphor sintered ceramics using the method of introducing u.

[Example 8] A phosphor ceramic plate 1 with a diameter of 24 l and a thickness of 420 nm was fabricated under the same conditions as in Example 1 and had a thickness of 0.4 mm as shown in FIG. 10 by magnetron scattering.
As shown in FIG. 10, 10 PCEL elements for surface-emitting illuminated lamps were fabricated, each having a ZnO:A1 circular transparent electrode 2 and a counter electrode 3 coated with conductive paint on the outer periphery of the side surface of the ceramic plate 1. By arranging them on top of each other and driving them in parallel, we fabricated a large-area light-emitting illuminated lamp panel. The EL characteristics of each element were almost the same as those obtained in Example 1. Additionally, this panel can be driven with direct current, half-wave rectified waves, or direct current pulses.
Moreover, it was possible to improve the aging characteristics.

It should be noted that the shape and arrangement of the opposing electrodes 3 of each element shown in FIG. There was no problem in using Layer 4 together or in combination.

In Examples 1 to 8 above, ZnS:lln was used as the phosphor, but this phosphor was used as ZnS:Tb. F, ZnS: Ss, P
ZnS-based, strontium sulfide (SrS)-based, calcium sulfide (CaS)-based, and barium sulfide (BaS), etc.
It was confirmed that exactly the same effects and performance can be expected even if the system is replaced with a new one.

[Example 9] 8.0% of paraffin was added as a coating material to a commercially available green-emitting ZnS:Cu phosphor powder and mixed uniformly.
ZnS:C as shown in FIG. 11 under the same conditions as Example 1.
A u-phosphor sintered ceramic plate 10 was produced.

High-resistance ZnS:1 [niil
ll11 was formed. Furthermore, Zn having the same shape and size as in Example 1 was deposited on top of it by the same magnetron sputtering method.
A counter electrode consisting of an O:A1 circular transparent electrode 2 and an At counter electrode 3 was formed. When a DC voltage with the circular transparent electrode 2 as the positive electrode was applied between the counter electrodes, light emission that changed from green to yellow-orange was obtained by changing the voltage value. E
As a result of measuring the L characteristic, Ytb is 30V, L+oJ;
There was 12000cd/l”l? Also, the F!4u
Even when ii was replaced with SrS-based or CaS-based blue and red phosphors containing alkaline earth elements, EL characteristics with acceptable luminance were obtained. By selecting the thin film and changing the value of the applied voltage, it was possible to realize a PCEL element with a desired emission color.

Furthermore, almost the same EL characteristics were obtained whether the drive voltage waveform was a half-wave rectified wave or a DC pulse wave.

In the above examples, the sintering temperature of the phosphor ceramics was set at 95%.
Although the temperature was set at 0°C, it was possible to produce phosphor ceramics that could be used as the light emitting layer of the present invention within the temperature range of 850°C to 1250°C. Further, in the embodiment, the horizontal structure of the device is circular, but the shape of the PCEL device according to the present invention is completely arbitrary and is not limited to the above embodiment. Furthermore, at least one type of transparent electrode implemented in the present invention is ZnO-based, ITO-based, or tin oxide (CSnOt).
Any system may be used, and if necessary, the element can be sealed before use.

[Effects of the Invention] In the PCEL element according to the present invention, since the counter electrode is formed only on one side of the ceramic, mounting performance is significantly improved, and deterioration of the element can be prevented by performing various external processing on the space between the two electrodes. It is also possible to suppress the factors that lead to this, improve performance, and add new functions. The above-mentioned processing is completely impossible with thin film type EL elements, and was also impossible with conventional parallel plane counter electrode type EL elements.
This was made possible for the first time by using thick bulk ceramics and forming a counter electrode on one side.

The PCEL element according to the present invention uses light emitting diodes (LEDs) to display various patterns that take advantage of the characteristics of being a surface light emitter.
Since it can be realized by making full use of ordinary wire bonding mounting technology, it is possible to provide an inexpensive planar solid state light emitting device driven by direct current or alternating current.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a PCEL element for a surface-emitting illuminated lamp according to the present invention, and FIG. 2 shows changes in emission brightness with respect to applied voltage when the PCEL element shown in FIG. Figure 3 shows a PC for a flat solid state light emitting display device according to the present invention.
Figure 4 is a cross-sectional view of a PCEL element in which a metal layer is provided as an electric field control layer on the surface of the sintered ceramic plate on which the counter electrode is not formed, and Figures 5 and 6 are cross-sectional views of the EL element. Figure 7 shows a cross-sectional view of a PCEL element with a current limiting layer formed in the space between the electrodes, Figure 7 is a cross-sectional view of a PCEL element with a counter electrode formed in the space between the transparent electrodes, Figure 8 does not contain Cu. FIG. 9 is a cross-sectional view of a ceramic in which metal Cu is coated on one side of a phosphor sintered ceramic plate, and FIG. 9 is a cross-sectional view of a PCEL element in which the counter electrode is formed on the Cu shown in FIG. 8 after thermal expansion treatment. , Fig. 10 is a schematic diagram of a PCEL element in which a counter electrode is provided on the side surface of the ceramic plate, and Fig. 11 is an r'cEL element in which a phosphor luminescent layer is further formed on a ZnS:Cu phosphor sintered ceramic plate.
A cross-sectional view of the element. ■...phosphor sintered ceramic plate, 2... transparent electrode, 3... counter electrode, 4... metal electric field control layer,
5... Current limiting layer implanted with oxygen ions, 6...
Spatter-etched groove, 7... At electrode, 8...
-Metallic Cu layer, 9...phosphor sintered ceramic plate with Cu thermally diffused on one side, 10...ZnS: C
u Phosphor sintered ceramic plate, 11... Phosphor thin film Fig. 1 Fig. 2 O 50 Applied voltage 100 150 Y [Y] 0T3 Fig. 4 Fig. 5 Fig. 7 Fig. 9 Fig. 11

Claims (2)

[Claims] (1) 850, which serves both as a light-emitting layer and a substrate, and is made of at least one sulfide-based phosphor containing 0.01 to 10% copper.
At least one counter electrode whose electrode surfaces do not face each other is formed on the surface of phosphor sintered ceramics sintered in the range of ℃ to 1250℃, at least one of the counter electrodes is a transparent electrode, and there is a gap between the counter electrodes. An electroluminescence device characterized in that luminescence is extracted through the transparent electrode by applying a voltage. (2) The electroluminescent device according to claim 1, which is used for manufacturing a surface-emitting illuminated lamp or a flat solid-state light-emitting display device.