JPS6042600B2 - Electrominessance device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an electroluminescence device,
In particular, it relates to an assembly for use in an electroluminescent device and to an electroluminescent device including such an assembly.

Such electroluminescent devices are made by depositing a transparent layer of conductive material, such as tin oxide, on the surface of a transparent substrate, such as glass.

The unnecessary parts of this transparent layer are then removed and an electrode of the desired shape with a surface area constituting the area of the electroluminescent device necessary for emitting light and a conductive strip close to the edge of the substrate are formed. A configuration is obtained of a flaky strip and a lead suitably connecting this strip to the area of the electrode. An electroluminescent layer consisting of a paint containing electroluminescent powder mixed with a suitable adhesive is applied to the exposed surface of the electrode. After the paint is cured or dried, it is coated with a conductive layer, such as aluminum, to form the other electrodes of the device, and the device is then encapsulated for safety. At this stage, the device does not emit light, and in order to generate electroluminescence, it is necessary to carry out a formation step to appropriately change the structure of the electroluminescence layer. This formation process uses the transparent layer as a positive electrode and applies a unidirectional voltage to the device until the desired structure is obtained, increasing the resistance of specific parts of the electroluminescent layer and decreasing the current, allowing light to escape from said areas. It is something that radiates. Immediate emission of light is then effected by applying a suitable relatively small voltage to the electrodes. The process of forming this electroluminescent layer as well as the operation of the electroluminescent device has been described in detail in numerous articles and other publications.

Two such articles are mentioned: One is the DC electroluminescence in zinc monosulfide described in IEEE Newsletter Vol. 61, No. 7, published in July 197, from 902 to 90. Sans State of the Artho, and the others are 196CPr. r'Zns described in the British journal Applied Physics, No. 2, Volume 2, pages 953 to 966
and Mn, Cn, Cl, an editorial entitled Material Control and Direct Current Electroluminescence in Powdered Phosphorus. Typical forming current is 100 per square centimeter
In milliamperes, the voltage is approximately 15 to 80 volts, depending on the structure and geometry of the layers of the device, especially the geometry of the transparent electrodes. For example, high forming voltages are required, especially when transparent electrodes have relatively long leads connecting conductive strips to both sides of the electrodes that constitute the light emitting area of the device; In some cases, especially if the light emitting area is relatively large, the heat distributed in the connecting leads can lead to burning out of the transparent electrode as well as the electroluminescent layer, as well as overheating or cracking of the substrate. It is an object of the invention to provide an electroluminescent device in which the above-mentioned electroluminescent formation can be achieved with relatively little electrical power, in particular with substantially low currents.

To achieve the above objects, the present invention comprises a multilayer assembly having a pair of electrodes and a layer of conductive electroluminescent material disposed between the electrodes, and a transparent substrate; In an electroluminescent device in which a substrate supports the multilayer assembly with one of the electrodes disposed between the substrate and the layer of conductive electroluminescent material, one electrode a first layer of conductive material formed transparent and adjacent to the substrate; and a second layer of semiconductor or insulating material adjacent to the layer of electroluminescent material; The present invention is characterized in that a plurality of separation regions through which the current flows are formed in the one electrode by changing the resistance to the current between the electrode and the layer of the tsusansu material.

By forming the separation region as described above, the electroluminescent material can be formed with less power than conventional power, reducing the risk of damage to the substrate, electroluminescent material, and transparent electrode during the formation process. be able to.

The surface portion of the electrode close to the electroluminescent layer may have properties that substantially inhibit the flow of impurities.

The electrode includes a first layer of conductive material adjacent to the substrate;
a second layer of semiconductor or insulator.

In such a case, the second layer is provided with an opening to constitute the above-mentioned separation region. Alternatively, the second layer can completely cover the first layer. According to another embodiment of the assembly, the electrode comprises a metal oxide and the isolation region is in substantially pure form of the metal. The metal oxide is doped and the dopant level is different in the electrode surface area than in the rest of the electrode.

As described above, according to the present invention, it is possible to reduce the electric power during the formation process, thereby preventing overheating and damage to the substrate, the first layer, and the electroluminescent layer, and also preventing the substrate, the first layer, and the electroluminescent layer from being damaged. Further, it is possible to prevent impurities in the first layer from diffusing into the electroluminescent layer, thereby extending the life of the electroluminescent device.

Embodiments of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, the DC electroluminescence device of the present invention includes a transparent substrate 10 made of glass or polymer material, with a transparent conductive layer 11 provided on one side of the substrate to provide a positive electrode for the device. is forming. This layer 11 is made of, for example, antimony-doped tin oxide, indium oxide, titanium dioxide, tin-doped cadmium oxide, cadmium stannate, or silver-doped bismuth oxide. Tin oxide layer 11 is formed by well-known processes such as evaporation, sputtering or chemical vapor deposition. Alternatively, layer 11 can be formed by electrolytically depositing a thin metal film layer onto substrate 10 using an electrolytic process. Unwanted parts of this layer 11 are then removed by a conventional etching process, resulting in an electrode having a surface area constituting the area of the electroluminescent device necessary for the emission of light, the edge of the substrate 10 being removed. The electrode area and the conductive strip are suitably interconnected by one or more conductive strips and conductive tracks in close proximity to the conductive strip. Next, a continuous layer 12 of copper sulfide is formed by an evaporation process on the exposed surface of the electrode layer 11 so that the above formation process can be accomplished with low power.

The thickness of this layer 12 is less than 5 microns, preferably on the order of 1 micron. Various other semiconductor or insulating materials can be used as the material for the above layer.

For example, it is made from zinc sulfide, copper oxide, zinc oxide, copper selenide, zinc selenide, aluminum oxide, silicon monoxide, or oxyytrium sulfide. Layer 12 preferably has a functionality ranging from 2 to 6 electron volts. This layer 12 is coated with an electroluminescent layer 13 of a powdered phosphorus mixture having a thickness of the order of 30 to 50 microns, for example.

This mixture, each containing phosphorus powder coated with copper and mixed with adhesive, is applied to the desired thickness on layer 12 and cured or dried. Specifically, this mixture is of the type described in the editorial article mentioned above. After this, a conductive layer such as aluminum or copper is applied on the exposed surface of the electroluminescent layer. A layer 14 is obtained which forms a layer of transparent material and constitutes another electrode for the electroluminescent device.

As shown in FIG. 1, a substrate 10, an electrode 11 and a layer 12 are combined with an electroluminescent layer 13 and an electroluminescent layer 13. ``Beyond the pole 14 and forming a step with the exposed upper surface of the protruding layer 12.''

The electroluminescent layer 13 and the electrodes 14 are covered by a glass sheet 16 mounted on a strip of butyl rubber 17, which strip 17 is mounted on the layer 12 and covers the electroluminescent layer 13 and the electrodes 14.
It constitutes a closed volume in which the A desiccant agent is placed in this volume, and the outer surfaces of the sheet 16 and the strip 17 are optionally covered with a layer 18 of encapsulating material. At this stage, the electroluminescent device has layers 11 and 14.
Even if a DC voltage is applied to the electrode made of the above, it does not emit light, and it is necessary to form an electroluminescent layer 13. For this purpose, a unidirectional voltage is applied to the device with layer 11 as the positive electrode and layer 14 as the negative electrode, and the electroluminescent layer 1
Give the required structure to 3. At this time, the resistance of the electroluminescent layer 13 increases, the current flowing through the layer decreases, and light is emitted from the above-mentioned region of the layer 13 composed of the layer 11. Light emission is then immediately effected by the device by applying a suitable relatively low unidirectional voltage, either continuous or pulsed. If pulses are used, preferably the pulses are 1:2.
It has a space ratio mark of 00th place and a repetition frequency of 125 kHz. By providing a layer 12 between the electrode layer 11 and the electroluminescent layer 13, which effectively constitutes an additional layer of the electrode, less power is required to form the electroluminescent layer. cloud”
It has been found that

As a result, the substrate 10 and the layer 11 during the above-mentioned formation process
, 13 is substantially reduced.
It has been found that this is due to the fact that the surface area of the electrode 11 is modified by the semiconductor or insulating layer 12 so that the current flowing into the surface of the electrode layer 11 tends to be confined to the separation region. This area is extremely small, for example 2 to 3
It has a maximum transverse diameter on the order of microns, although this dimension can be as small as 1110 microns or less. The surface of the electrode 11 farther from the substrate 10 has a wavy shape, the peak of which protrudes into the electroluminescent layer 13, and the continuous layer 12 has two differences as shown in FIGS. 2 and 3. Consists of ivy form.

In the case of FIG. 2, the continuous layer 12 covers only the slightly smaller peak formed by the wavy surface of the electrode 11, through which the large peak 20 of the electrode 11 extends, and the electroluminescent material is electrically engaged with. In this embodiment, the current is limited to the peak portion 20. In the manner of FIG. 3, the continuous layer 12 completely covers the electrode 11;
and the electroluminescent layer 13 serves to confine the current to the separated region. A thin resistive region of layer 12 between the electroluminescent layer 13 and the large peak 20 of layer 11 constitutes a separation region, which when initially applied with a forming voltage between electrodes 11, 14 , a preferential high field region is obtained.
Furthermore, this layer 12 inhibits impurities in the substrate 10 and electrodes 11 from diffusing into the electroluminescent layer 13, resulting in an increased lifetime of the electroluminescent device.

The insulating or semiconducting material comprising this layer 12 may be of many different forms, and may be any metal chalcogen compound, the compositional metal being different from the metal in the electrode 11, and the material being an electroluminescent material. Sansu wood is compatible.

More specifically, the material of layer 12 is a metal chalcogen compound selected from the group consisting of oxygen, sulfur, and selenium. Although in this embodiment the semiconductor or insulating layer 12 of the electroluminescent device is formed separately from the layer 11, it is also conceivable for the two layers 11, 12 to be integrated with each other.

For example, a transparent electrode 11 is deposited on a substrate 10 and then a layer 1
The surface of layer 11 can be treated to suitably change the properties of the surface of layer 11 such that the surface further away from substrate 10 exhibits the properties of layer 12. Alternatively, layer 11 can also be formed in two different stages. That is, the first step consists in forming on the substrate 10 a first part of the layer 11 having the necessary properties to obtain a transparent electrode for the device, for example by depositing, and the second step consists in forming on the substrate 10 a first part of the layer 11 having the necessary properties to obtain a transparent electrode for the device; This is a step of forming other parts of layer 11 so that the surface part of layer 11 has the properties obtained by layer 12. In the case of a second embodiment of the electroluminescence device, a layer 11 of antimony-doped tin oxide is formed on a glass substrate 10, and then this layer 1
Evaporate a layer of aluminum into the surface of 1.

This is shown in Figure 4, where the layer of aluminum is 21
with reference number. This layer 21 is then removed using a tin chloride solution by immersing the device in the solution. It has been found that upon removal of this aluminum layer 21, an insulating layer of aluminum oxide is formed on the surface of the tin oxide. This insulating layer is shown at 22 in FIG. 5, and layer 22 completely covers electrode 11 and has a constant thickness. In the case of a third embodiment of the electroluminescence device, a layer 11 of antimony-coated tin oxide is formed on a glass substrate 10, and the device thus formed is then exposed to water such as tap water or slightly oxidized distilled water. It is immersed in an electrolytic solution 23 shown in FIG.

This tin oxide layer 11 is connected to the negative electrode of a power source (not shown), and the positive electrode of the power source is connected to an electrode 24 immersed in an electrolyte.
An electrolytic current flows from electrode 24 to layer 11 . Electrode 24 is comprised of a suitable inert material such as graphite, platinum, tin oxide, or the like. Both during the removal of the aluminum layer 21 used in the second and third embodiments of the electroluminescence device and during the electrolytic process, the separated portion of the tin oxide layer 11 close to the surface remote from the substrate 10 is reduced to tin. It has been found that during the formation step the above-mentioned isolation regions are formed in which the current is substantially confined.

Furthermore, in the deformation step of both the second and third embodiments of the present device, the proportion of antimony dopant in the surface of layer 11 opposite substrate 10 is changed to form an insulating surface portion on layer 11, whereby Impurities are prevented from flowing into the electroluminescent layer 13 from the substrate 10 and layer 11. Also in the second embodiment of the device, this flow of impurities is further inhibited by an insulating layer 22 of aluminum oxide. Upon completion of the method of the second and third embodiments of the device, electroluminescent, conductive layers 13 and 14 are formed as described above.

The regions of the electroluminescent device to be illuminated can be excited simultaneously or sequentially.

In this simultaneous case, the areas of the layer 11 constituting the regions are each connected by a conductive track to a conductive strip provided near the edge of the substrate 10. In the sequential case, the conductive strips are omitted and each conductive track is connected to layer 1.
1, the rails extend to the edges of the device and make it possible to connect the husband's rails to the terminals of the corresponding voltage supply.

However, if the areas of layer 11 are to be excited in groups, each group is provided with a conductive strip, and each area is connected by a conductive track to the appropriate one of the strips. Although the present invention has been described with respect to a DC electroluminescence device, it is equally applicable to an AC electroluminescence device.

[Brief explanation of the drawing]

FIG. 1 is a sectional side view showing a first form of the electroluminescence device, FIGS. 2 and 3 are fragmentary sectional views showing different structures of the first form of the device, and FIG. 4 is a side view of the device. Second
FIG. 5 is a cross-sectional side view of the assembly used in the fabrication of the second embodiment of the present invention; FIG.
The figure is a schematic diagram showing a method of manufacturing a third embodiment of the present device. 10... Substrate, 11... Electrode or transparent layer or first layer, 12... Electrode or second layer, 21...
...Metal layer, 22...Insulating material layer, 23...
... Electrolyte, 24 ... Positive electrode.

Claims (1)

[Claims] 1. A multilayer assembly consisting of a pair of electrode layers and a layer of conductive electroluminescent material disposed between the electrode layers, and one transparent electrode layer of the multilayer assembly. In an electroluminescent device comprising a supporting transparent substrate, a layer of a semiconductor or insulating material is disposed between the transparent electrode layer and the layer of electroluminescent material, the layer of insulating material comprising: A plurality of electrically conductive isolation regions are formed between the transparent electrode layer and the layer of electroluminescent material, which are electrically insulated from each other, and a current flows substantially through the isolation regions and a high electric field is applied to the isolation regions. An electroluminescence device characterized in that: 2. The surface of the transparent electrode layer adjacent to the semiconductor or insulating material layer is roughened to form a plurality of peak portions, and the peak portions penetrate through the semiconductor or insulating material layer to form the separation region for energization. An electroluminescence device according to claim 1, characterized in that the electroluminescence device is formed with: 3 The surface of the transparent electrode layer adjacent to the semiconductor or insulating material layer is roughened to form a plurality of peak portions, and the peak portions protrude into the semiconductor or insulating material layer to form separation regions for conducting current. 2. An electroluminescent device according to claim 1, characterized in that the electroluminescent device is formed of: 4. Claims according to any one of the preceding claims, characterized in that the layer of semiconductor or insulating material substantially prevents impurities from flowing from the transparent electrode layer into the layer of electroluminescent material. electroluminescence device. 5 The layer of semiconductor or insulating material is approximately 2 electron volts to 6 electron volts
An electroluminescent device according to any one of the preceding claims, characterized in that it has an electron volt actuation function. 6. An electroluminescent device according to any one of claims 1 to 5, characterized in that the semiconductor or insulating material layer contains copper sulfide. 7. The electroluminescent device according to any one of claims 1 to 5, characterized in that the semiconductor or insulating material layer contains zinc sulfide. 8. An electroluminescent device according to any one of claims 1 to 5, characterized in that the semiconductor or insulating material layer contains copper oxide. 9. An electroluminescent device according to any one of claims 1 to 5, characterized in that the semiconductor or insulating material layer contains zinc oxide. 10. An electroluminescent device according to any one of claims 1 to 5, characterized in that the semiconductor or insulating material layer contains selenium copper. 11. The electroluminescent device according to any one of claims 1 to 5, characterized in that the semiconductor or insulating material layer contains selenium zinc. 12. Electroluminescence device according to any one of claims 1 to 5, characterized in that the semiconductor or insulating material layer contains aluminum oxide. 13. Electroluminescent device according to any one of claims 1 to 5, characterized in that the semiconductor or insulating material layer contains silicon monoxide. 14. Claims 1 to 5, characterized in that the semiconductor or insulating material layer contains oxyyttrium sulfide.
The electroluminescence device according to any one of the items. 15. Electroluminescent device according to any one of claims 1 to 14, characterized in that the layer of semiconductor or insulating material has a thickness of less than 5 microns. 16 The transparent electrode layer contains a metal oxide, and the surface of the transparent electrode layer in contact with the semiconductor or insulating material layer is treated to reduce metal oxide, so that the surface of the transparent electrode layer contains a metal oxide. 2. An electroluminescent device according to claim 1, characterized in that a plurality of isolation regions are formed consisting of electrically conductive metal parts surrounded by oxide. 17. Electroluminescent device according to claim 16, characterized in that the surface of the one electrode remote from the substrate is covered with a layer of insulating material. 18. Claim 16, characterized in that the layer of semiconductor or insulating material is formed as a metal oxide on the surface of the transparent electrode layer, both layers being doped to different levels. The electroluminescence device described. 19 The transparent electrode layer consists of a transparent layer of metal oxide provided on the substrate and another layer of metal oxide provided on the transparent layer of metal oxide, and this layer of another metal oxide 18. The electroluminescence device according to claim 16 or 17, wherein the electroluminescence device is formed by chemically treating a metal layer. 20. The electroluminescence device according to claim 19, wherein the metal oxide is tin oxide and the metal of the other metal oxide layer is aluminum. 21 The metal oxide layer is provided on top of a substrate, the substrate is immersed in an electrolyte, and a current is passed through the electrolyte from the positive electrode to the metal oxide layer to reduce the metal oxide. An electroluminescent device according to claim 16 or 17.