WO2008050923A1

WO2008050923A1 - Electroluminescent device and the substrate therefor and method of making the same

Info

Publication number: WO2008050923A1
Application number: PCT/KR2006/004569
Authority: WO
Inventors: Dae Hyun Park; Je Seok Kim
Original assignee: Lg Electronics Inc.
Priority date: 2006-10-24
Filing date: 2006-11-03
Publication date: 2008-05-02
Also published as: KR100767680B1

Abstract

An electroluminescent device capable of achieving improved light emission efficiency, a substrate for the electroluminescent device, and a method for manufacturing the electroluminescent device are disclosed. The electroluminescent device includes a metal substrate and a luminous layer formed on the metal substrate.

Description

[DESCRIPTION]

[invention Title]

ELECTROLUMINESCENT DEVICE AND THE SUBSTRATE THEREFOR AND METHOD OF MAKING THE SAME

[Technical Field]

The present invention relates to an electroluminescent device, a substrate for the electroluminescent device, and a method for manufacturing the electroluminescent device, and more particularly, to an electroluminescent device capable of improving the emission efficiency of light, a substrate for the electroluminescent device, and a method for manufacturing the electroluminescent device.

[Background Art] ' Electroluminescence phenomenon is widely used in luminous devices and display apparatuses using the same, and more particularly, in flat-panel display apparatuses.

Among electroluminescent devices, an inorganic electroluminescent device using an inorganic thin film can be used in a flat display panel. The inorganic electroluminescent device causes the emission of light as electrons, which were accelerated by a high electric field, collide with phosphors to excite the phosphors. The inorganic electroluminescent device has advantages of high- brightness, long lifespan, high resolution, etc. Considering the configuration of the inorganic electroluminescent device, a luminous layer structure is formed on a substrate. The luminous layer structure includes a phosphor layer, and dielectric layers and electrodes located at both sides of the phosphor layer. More specifically, the dielectric layers serve to protect the device from dielectric breakdown and external foreign substances, thereby contributing to the stability of the device. Further, the dielectric layers perform an important role in the determination of light-emission efficiency and brightness according to the condition of interfaces between the phosphor layer and the dielectric layers .

Conventionally, a glass or ceramic substrate is used as the substrate for the electroluminescent device. The above described dielectric layers, electrodes, and phosphor layer are sequentially laminated on the glass or ceramic substrate, and then, the resulting structure is fired partially or wholly. In this way, the electroluminescent device is completed. Among glass and ceramic substrates, the ceramic substrate has a high price and is easily broken. Therefore, the ceramic substrate needs meticulous care during a process and has a disadvantage of increasing manufacturing costs.

On the other hand, when using glass as a material of the substrate, it has a limit in the firing temperature of the substrate. More specifically, when using a conventional glass substrate similar to that used in a liquid crystal display (LCD) or plasma display panel (PDP) , it is difficult to raise a firing temperature beyond 600^°C or more. However, using high-fusion-point glass causes a great increase in manufacturing costs.

It is noted that the phosphor layer used in the above described electroluminescent device has an increase in the particle size of a phosphor when it is fired at a high temperature. This can increase the light emission efficiency of the phosphor.

In conclusion, the above described conventional substrate has a disadvantage of increasing manufacturing costs and suffers from a difficulty in handling. Further, the conventional substrate cannot attain the increased light emission effect of a phosphor caused by a high- temperature firing process. [Disclosure] [Technical Problem]

An object of the present invention devised to solve the problem lies on an electroluminescent device, which can assure a high-temperature firing process and achieve an improved mass-productivity and light emission efficiency, a substrate for the electroluminescent device, and a method for manufacturing the electroluminescent device.

[Technical Solution] The object of the present invention can be achieved by providing an electroluminescent device comprising: a metal substrate/ and a luminous layer formed on the metal substrate.

In a second aspect of the present invention, provided herein is an electroluminescent device comprising: a substrate including a metal layer; and a luminous layer formed on the substrate.

In a third aspect of the present invention, provided herein is a substrate for an electroluminescent device comprising: a metal layer; and an insulating layer located on the metal layer and including an additive to fit a thermal expansion coefficient of the insulating layer to a thermal expansion coefficient of the metal layer.

In a fourth aspect of the present invention, provided herein is a method for manufacturing an electroluminescent device comprising: forming an insulating layer on a metal substrate; forming a luminous layer on the insulating layer; and firing the resulting structure including the metal substrate.

[Mode for Invention!

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

The present invention may, however, be embodied in many alternate forms and should not be construed as limited to the embodiments set forth herein. Accordingly, while the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the claims.

The same reference numbers will be used throughout the drawings to refer to the same or like parts. In the drawings, dimensions of layers and regions are exaggerated for clarity of description.

It will be understood that, when an element such as a layer, region or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present.

It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. Finally, the term "directly" means that there are no intervening elements. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms.

The above terms first, second, etc. are used simply to discriminate any one element, component, region, layer, or area from other elements, components, regions, layers, or areas. Accordingly, the term first region, first layer, first area, etc., which will be described hereinafter, may be replaced by the term second region, second layer, or second area.

As shown in FIG. 1, an electroluminescent device of the present invention is formed on a substrate 100 including a metal. The substrate 100 including a metal, as shown in FIG. 1, may include a metal layer 110, and an insulating layer 120 located on the metal layer 110.

The metal layer 110 of the substrate 100 may be made of one of titanium (Ti) , nickel (Ni) , and cobalt (Co) . Of course, the metal layer 110 may be made of an alloy including at least one of titanium (Ti) , nickel (Ni) , and cobalt (Co) , or may be made of an alloy including one of titanium (Ti) , nickel (Ni) and cobalt (Co) as a main component and other metals. The insulating layer 120 is provided for insulation with a luminous layer (See reference numeral 200 in FIG. 3) to be formed on the substrate 100. The insulating layer 120 may include dielectrics such as ceramic, glass, or the like. The insulating layer 120 may be formed on the metal layer 110 of the substrate 100 by use of a green sheet. Here, the green sheet may include dielectric powder, a binder, a dispersant, a solvent, a plasticizer, etc. When using a green-sheet method, the insulating layer 120 can be formed as the green sheet is laminated on the metal layer 110 of the substrate 100. The laminated green sheet to form the insulating layer 120 can be fired at the following process. Meanwhile, the insulating layer 120 may include an additive to fit a thermal expansion coefficient of the insulating layer 120 to a thermal expansion coefficient of the metal layer 110 when the insulting layer 120 has a temperature variation. This is because the metal layer 110 has a fixed thermal expansion coefficient determined based on the kind of a constituent material thereof, but the thermal expansion coefficient of the insulating layer 120 can be changed according to a temperature of the insulating layer 120. For example, when the substrate 100 including the metal layer 110 and the insulating layer 120 or the electroluminescent device including the substrate 100 is fired, the substrate 100 or the electroluminescent device may have a thermal expansion according to a firing temperature thereof. In this case, the additive can be added to provide the insulating layer 120 with the same thermal expansion coefficient as that of the metal layer 110. In particular, it is advantageous that the optimum fitting of the thermal expansion coefficient can be accomplished at a firing temperature of the device.

For example, the metal layer 110 may have a temporary deformation, such as bending, expansion, etc., in one direction or the other direction according to the variation range of temperature. In this case, with the fitting of the thermal expansion coefficient, the insulating layer 120 can be deformed in the same direction as the deforming direction of the metal layer 110. The additive may include at least one of alumina, zirconia (ZrO₂) , titanium dioxide (TiO₂) , and forsterite (Mg₂SiO₄) .

In addition to adding the additive into the insulating layer 120, fitting the thermal expansion coefficient of the insulating layer 120 to the thermal expansion coefficient of the metal layer 110 can be accomplished by changing the content of parent dielectric powder included in the insulating layer 120.

Also, it will be appreciated that fitting the thermal expansion coefficient of the insulating layer 120 to the thermal expansion coefficient of the metal layer 110 can be accomplished only by changing the content of parent dielectric powder included in the insulating layer 120 without providing the insulating layer 120 with the additive .

Meanwhile, as shown in FIG. 2, a coupling layer 130 may be located between the insulating layer 120 and the metal layer 110, for the coupling of the two layers 120 and 110.

The coupling layer 130 may be made of low-fusion- point glass powder. As the glass powder is fired, the coupling layer 130 can act to firmly couple the insulating layer 120 and the metal layer 110 to each other. The substrate 100 having the above described configuration may be fired individually, or may be fired together with a part or all of the luminous layer 200 formed on the substrate 100.

As described above, the substrate 100 including the metal layer 110 can be fired at a high temperature, for example, at a temperature of 600^°C or more. Generally, since metal has a higher fusion point than glass, the firing temperature of the substrate 100 including the metal layer 110 can be raised greatly. This allows the substrate 100 to sufficiently attain characteristics obtainable by the raised firing temperature.

Further, by virtue of superior heat conductive characteristics of metal, the substrate 100 including the metal layer 110 can easily emit heat generated from the device. Accordingly, it can be said that the above described configuration of the substrate 100 is advantageous for emitting heat.

As shown in FIG. 3, the luminous layer 200 including a phosphor layer to emit light under the influence of an electric field is formed on the substrate 100. Now, the formation of the luminous layer 200 will be described.

First, a lower electrode 210 is formed on the substrate 100. The lower electrode 210 may have a specific pattern, for example, a stripe pattern.

The lower electrode 210 may be formed by sputtering a metal such as copper (Cu) , chrome (Cr) , or gold (Au) , or may be made of silver (Ag) or an alloy of Ag.

When using silver (Ag) or an alloy of Ag, the lower electrode 210 may be formed by a printing method or green- sheet method. Accordingly, when the lower electrode 210 is made of silver (Ag) or an alloy of Ag, the lower electrode 210 can attain a thicker thickness by a more simplified process. More specifically, as compared to the sputtering method, the printing method or green-sheet method has no need for expensive equipment and can assure a more simplified manufacturing process of the electrode. Moreover, the electrode formed by the printing method or green-sheet method can attain a thicker thickness than that formed by the sputtering method.

Then, a lower dielectric layer 220 is formed on the lower electrode 210. The formation of the lower dielectric layer 220 may be performed one time or several times by a printing method, a green-sheet method, a table-coating method, or the like.

Next, as shown in FIG. 5, a phosphor layer 230 is formed on the lower dielectric layer 220. The phosphor layer 230 may be configured such that a red phosphor 231, a green phosphor 232, and a blue phosphor 233 are arranged sequentially or patterned, to constitute light-emitting cells.

The above three phosphors may constitute a single pixel. Specifically, the red phosphor 231, the green phosphor 232, and the blue phosphor 233 may serve as sub pixels arranged sequentially.

After completing the formation of the phosphor layer 230, as shown in FIG. 6, an upper dielectric layer 240 and an upper electrode 250 are formed sequentially on the phosphor layer 230.

The upper dielectric layer 240 can be formed by the same method as the above described lower dielectric layer 220.

The upper electrode 250 may have a pattern intersecting the lower electrode 210. For example, the upper electrode 250 may have a stripe pattern intersecting, at a right angle, a pattern of the lower electrode 210. As shown in FIG. 7, a color compensating layer 300 may be located on the luminous layer 200. The color compensating layer 300 serves to compensate for light, emitted from the phosphor layer 230 on the basis of a color coordinate. Also, a protective layer 400 may be formed on the luminous layer 200 or the color compensating layer 300, to protect the luminous layer 200 and the substrate 100 from an external shock.

<Second Embodiment> As shown in FIG. 8, the luminous layer 200 is formed on the substrate 100 including the metal layer 110.

More specifically, the lower electrode 210 and the lower dielectric layer 220 of the luminous layer 200 are formed sequentially. The insulating layer 120 may be located between the metal layer 110 and the luminous layer 200. This is equal to the above described first embodiment. In the present embodiment, as shown in FIG. 8, the phosphor layer 230, which is wholly made of the blue phosphor 233, may be formed on the lower dielectric layer 220.

Blue light emitted by the blue phosphor 233 is converted into red light and green light by a color converting layer (See reference numeral 260 in FIG. 9) that will be described hereinafter, to assure the representation of all colors.

The upper dielectric layer 240 and the upper electrode 250 are formed sequentially on the phosphor layer 230. The upper dielectric layer 240 may be formed by the same method as the above described lower dielectric layer 220.

The upper electrode 250 may have a pattern intersecting the lower electrode 210, and for example, may have a stripe pattern intersecting, at a right angle, a pattern of the lower electrode 210.

The color converting layer 260 is formed on the upper electrode 250. The color converting layer 260, as described above, can convert the blue light emitted from the blue phosphor 233 into red light and green light.

FIG. 10 schematically illustrates the operation of the color converting layer 260. Specifically, the color converting layer 260 includes a red converting portion 261, a green converting portion 262, and a blue converting portion 263. The red converting portion 261 converts blue light B into red light R, and the green converting portion 262 converts blue light B into green light G.

The green converting portion 263 can compensate for blue light, and as occasion demands, may directly pass blue light without conversion.

Although a color compensating layer may be located on the color converting layer 260, it may be unnecessary to provide the color compensating layer so long as the color converting layer 250 can output respective colors on the basis of an optimum color coordinate.

The protective layer 400 may be formed on the color converting layer 260, to protect the substrate 100 and the luminous layer 200 from an external shock. As described above, the substrate 100 including the metal layer 110 can be fired at a high temperature, for example, at a temperature of 600^°C or more. Generally, since metal has a higher fusion point that glass, the firing temperature of the substrate 100 including the metal layer 100 can be raised greatly. This allows the substrate 100 to have a sufficient effect obtainable by the raised -firing temperature.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

[industrial Applicability]

According to the present invention, a substrate for an electroluminescent device includes a metal layer. This has the effect of allowing a luminous structure formed on the substrate to be fired at a high temperature and consequently, the high-temperature firing can improve the light emission efficiency of a phosphor. Further, the present invention can assure easy handling of the substrate and a structure formed on the substrate, resulting in improved mass-productivity and low manufacturing costs.

16 /

Claims

[CLAIMS]

[Claim l] An electroluminescent device comprising: a metal substrate; and a luminous layer formed on the metal substrate.

[Claim 2] The electroluminescent device according to claim 1, wherein the luminous layer comprises: a phosphor layer; dielectric layers located on both surfaces of the phosphor layer; and an electrode located on each dielectric layer.

[Claim 3] The electroluminescent device according to claim 2, wherein the phosphor layer emits red light, green light, and blue light.

[Claim 4] The electroluminescent device according to claim 2, wherein the phosphor layer emits blue light.

[Claim 5] The electroluminescent device according to claim 4, further comprising: a color converting layer formed on the phosphor layer, to convert the blue light into red light and green light.

[Claim 6] The electroluminescent device according to claim 5, wherein the color converting layer is located on the electrode.

[Claim 7] The electroluminescent device according to claim 2, wherein the electrode is made of silver (Ag) or an alloy of Ag.

[claim 8] The electroluminescent device according to claim 2, further comprising: a color compensating layer to compensate for the color of light emitted from the phosphor layer.

[claim 9] The electroluminescent device according to claim 1, wherein the metal substrate includes one of titanium (Ti) , nickel (Ni) , and cobalt (Co) .

[Claim lθ] The electroluminescent device according to claim 1, wherein the metal substrate is made of an alloy including at least one of titanium (Ti) , nickel (Ni) , and cobalt (Co), or an alloy including one of titanium (Ti), nickel (Ni), and cobalt (Co) as a main component.

[claim ll] The electroluminescent device according to claim 1, further comprising: an insulating layer between the metal substrate and the luminous layer.

[Claim 12] The electroluminescent device according to claim 11, wherein the insulating layer includes an additive to fit a thermal expansion coefficient of the insulating layer to a thermal expansion coefficient of the metal substrate.

[Claim 13] The electroluminescent device according to claim 12, wherein the optimum fitting of the thermal expansion coefficient of the insulating layer to the thermal expansion coefficient of the metal layer is accomplished at a firing temperature of the electroluminescent device.

[Claim 14] The electroluminescent device according to claim 12, wherein the additive includes at least one of alumina, zirconia (ZrO∑) , titanium dioxide (Tiθ₂) , and forsterite (Mg₂SiO₄) .

[Claim 15] The electroluminescent device according to claim 11, further comprising: a coupling layer located between the metal substrate and the insulating layer, to couple the metal substrate and the insulating layer to each other.

[Claim 16] The electroluminescent device according to claim 15, wherein the coupling layer is made of low- fusion-point glass.

[Claim 17] An electroluminescent device comprising: a substrate including a metal layer; and a luminous layer formed on the substrate.

[Claim 18] A substrate for an electroluminescent device comprising: a metal layer; and an insulating layer located on the metal layer and including an additive to fit a thermal expansion coefficient of the insulating layer to a thermal expansion coefficient of the metal layer.

[Claim 19] The substrate according to claim 18, wherein the insulating layer is a green sheet including dielectrics .

[Claim 2θl The substrate according to claim 18, further comprising: a coupling layer located between the metal layer and the insulating layer, to couple the metal layer and the insulating layer to each other.

[Claim 2l] The substrate according to claim 20, wherein the coupling layer is made of low-fusion-point glass .

[Claim 22] A method for manufacturing an electroluminescent device comprising: forming an insulating layer on a metal substrate; forming a luminous layer on the insulating layer; and firing the resulting structure including the metal substrate .

[Claim 23] The method according to claim 22, wherein the formation of the insulating layer comprises: laminating a green sheet including dielectrics.

[Claim 24] The method according to claim 22, wherein the insulating layer includes an additive to fit a thermal expansion coefficient of the insulating layer to a thermal expansion coefficient of the metal layer.

[Claim 25] The method according to claim 22, further comprising: forming an electrode between the metal substrate and the luminous layer.

[Claim 2β] The method according to claim 25, wherein the electrode is made of silver (Ag) or an alloy of Ag.

[Claim 27] The method according to claim 25, wherein the electrode is formed by a printing method or green- sheet method.