JP2009256573A - Phosphor for collision excitation type el, manufacturing method of phosphor for collision excitation type el, thin film el device, thin film el display, and thin film el lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phosphor for a collision excitation type EL realizing novel full color light emission using as the base material a chemically extremely stable compound or composite oxide, a manufacturing method of a thin film of the phosphor, a thin film EL device using a thin film of the phosphor for a light emitting layer, a thin film EL display using the thin film EL device, and an EL lamp. <P>SOLUTION: The phosphor for a collision excitation type electroluminescence contains a base material including a compound or a composite oxide having at least lanthanum (La) and oxygen (O) as its constituent elements, and at least one or more of metal elements as an activator. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a phosphor suitable for an electroluminescence element and an electroluminescence element.

  As a conventional phosphor for a collision excitation type thin film electroluminescent element (hereinafter referred to as a thin film EL element), a sulfide mainly composed of zinc sulfide (ZnS) has been used for a long time.

  However, since the above-described sulfide-based phosphor is chemically unstable and particularly extremely unstable with respect to moisture, a special sealing for completely removing moisture at the time of manufacturing a thin film EL device. There is a fatal disadvantage that it must be processed, which raises the cost of fabricating the device.

  In view of such circumstances, the present invention provides a collision excitation type EL phosphor capable of realizing novel full-color light emission using a chemically extremely stable compound or composite oxide as a base material, and a method for producing the phosphor thin film. It is an object of the present invention to provide a thin film EL element using the phosphor thin film as a light emitting layer, a phrase film EL display using the thin film EL element, and an EL lamp.

  The first aspect of the present invention for solving the above-described problem is that a base material comprising a compound or composite oxide containing at least lanthanum (La) and oxygen (O) as constituent elements is used as an activator. A phosphor for collision excitation type electroluminescence (hereinafter abbreviated as EL) characterized by containing the above metal element.

According to a second aspect of the present invention, in the first aspect, the base material comprising LaNbO ₄ or a composite oxide containing LaNbO ₄ contains at least one metal element as an activator. It is in the phosphor for excitation type EL.

According to a third aspect of the present invention, in the first aspect, the base material comprising lanthanum oxide (La ₂ O ₃ ) contains at least one metal element as an activator. It is in the phosphor for EL.

  According to a fourth aspect of the present invention, in the second or third aspect, La is selected from among gadolinium (Gd), yttrium (Y), boron (B), indium (In), aluminum (Al), and scandium (Sc). A collision excitation type EL phosphor comprising: a base material composed of a compound or a complex oxide substituted with at least one of the above, and at least one metal element as an activator.

  According to a fifth aspect of the present invention, there is provided the collision excitation type EL phosphor according to the first to fourth aspects, wherein bismuth (Bi) is contained as an activator.

  According to a sixth aspect of the present invention, in the first to fifth aspects, the activator contains at least one selected from the group consisting of Bi, a transition metal element, and a rare earth metal element. It is in the phosphor for excitation type EL.

  According to a seventh aspect of the present invention, there is provided the phosphor for collision excitation type EL according to any one of the first to fifth aspects, wherein the metal element as an activator is contained in an amount of 0.1 to 10 atomic% relative to La. It is in.

  According to an eighth aspect of the present invention, in the first to seventh aspects, after the collision excitation type EL phosphor is formed as a thin film on an arbitrary substrate using an arbitrary film forming method, an inert gas or weak oxidation is performed. In the method for producing a phosphor thin film for collision excitation type EL, heat treatment is performed at 1050 ° C. or lower in a reactive gas atmosphere.

  According to a ninth aspect of the present invention, there is provided a thin film EL device according to the eighth aspect, wherein the collision excitation type EL phosphor thin film is used as a light emitting layer.

  According to a tenth aspect of the present invention, in the ninth aspect, a carrier acceleration layer is laminated or inserted on one or both sides of the light emitting layer of the thin film EL element for the purpose of improving excitation efficiency. The thin film EL element is characterized by being.

  An eleventh aspect of the present invention is the thin film EL element according to the tenth aspect, wherein the carrier acceleration layer is zinc sulfide (ZnS).

According to a twelfth aspect of the present invention, an insulating substrate, a light emitting layer formed on the substrate using the phosphor for collision excitation EL of the first to seventh aspects, and a light emitting layer are formed. And a protective layer.
A thirteenth aspect of the present invention is the thin film EL element according to the twelfth aspect, wherein the protective layer contains zinc sulfide (ZnS).
A fourteenth aspect of the present invention resides in a thin film EL display using the thin film EL element in the ninth to thirteenth aspects.

  A fifteenth aspect of the present invention resides in a thin film EL lamp using the thin film EL element in the ninth to thirteenth aspects.

  In the present invention, the collision-excited EL thin film phosphor is formed by sputtering in an inert gas atmosphere, chemical vapor deposition (CVD), electron beam evaporation, activated reactive evaporation (ARE), cluster, Utilizing ion beam (ICB) method, ion beam sputtering (IBS) method, atomic layer epitaxial (ALE) growth method, molecular beam epitaxial growth (MBE) method, gas source MBE (or CBE) method, electron cyclotron resonance (ECR) plasma Produced by using a known thin film deposition technique such as a crystal growth method, and heat-treated at 700 to 1050 ° C., preferably about 900 to 1000 ° C. in an inert gas or weakly oxidizing gas atmosphere, and a good polycrystalline film By forming the layer, it becomes possible to provide a sufficient function as a light-emitting layer for a collision excitation type EL element. Wherein the can realize brightness to withstand. In addition, a conventional wet chemical film formation method, for example, a film application method using a solution coating method or a sol-gel method is also effective by taking advantage of the chemical stability of the collision excitation type EL thin film phosphor.

  In a thin film EL device produced by making full use of a production method in which the Bi-doped lanthanum oxide-based oxide phosphor thin film according to the present invention is heat-treated in an inert gas atmosphere at about 700 to 1050 ° C., preferably about 900 to 1000 ° C. Blue light emission was realized. In addition, in the thin film EL element produced by laminating a zinc sulfide (ZnS) thin film on the Bi-doped lanthanum oxide-based phosphor thin film as a carrier acceleration layer, it was realized that the luminance of blue light emission was greatly improved.

  A combination of the above-described elements as appropriate can also be included in the scope of the invention for which patent protection is sought by this patent application.

  As a result of various investigations on manufacturing methods and manufacturing conditions of oxide phosphor thin films to which various metal elements are added as an emission center material, the inventors have developed a compound containing La and oxygen and a composite oxide as a base material. The phosphor thin film formed by adding Bi as a luminescent center material is heat-treated in an inert gas or weakly oxidizing atmosphere to produce a high-quality polycrystalline lanthanum oxide phosphor thin film, The present invention has invented a new collision-excited EL thin-film phosphor having the effect of realizing blue light emission and a thin-film EL device using the phosphor thin film as a light-emitting layer. In addition, it is possible to greatly improve the luminance of blue light emission in a thin film EL element produced by laminating a zinc sulfide (ZnS) thin film on the Bi-doped lanthanum oxide-based phosphor phosphor thin film as a carrier acceleration layer, There is an effect that it is extremely advantageous for increasing the luminance of the EL element. Moreover, the effect of changing the emission spectrum can be expected by co-adding a plurality of other emission centers in addition to Bi.

  Hereinafter, the embodiments of the present invention will be described by way of examples. However, the embodiments are merely examples, and the present invention is not limited thereto.

(Example 1)
After sufficiently mixing lanthanum oxide (La ₂ O ₃ ) powder with bismuth oxide (Bi ₂ O ₃ ) powder as a luminescent center material so that Bi contains 1.0 atomic% with respect to La, argon (Ar) gas Bi-doped lanthanum oxide phosphor powder was produced by firing at 1000 ° C. for 1 hour in an atmosphere. A sputtering target was prepared by using the oxide phosphor powder, and a sintered barium titanate (BaTiO ₃ ) ceramic substrate / insulator layer was coated with argon gas (Ar) gas pressure 6 Pa, sputtering input power 100 W, substrate. A Bi-doped lanthanum oxide phosphor thin film light emitting layer was formed under the conditions of a temperature of 275 ° C. and a substrate-target distance of 25 mm. Thereafter, annealing treatment was performed at 1000 ° C. for 1 hour in an Ar gas atmosphere.

  FIG. 1 shows a photoluminescence (PL) spectrum of the phosphor thin-film light emitting layer. As shown in the figure, strong blue PL having a peak at about 450 nm was shown.

  An EL element was prepared by forming an aluminum-added zinc oxide (ZnO: Al) transparent electrode on the light emitting layer thin film and a metal Al electrode on the back surface. When a 1 kHz sine wave AC voltage was applied to the EL element, a blue EL having peaks at wavelengths of about 450 nm and about 490 nm as shown in FIG. 2 was realized. FIG. 3 shows typical luminance (L) -applied voltage (V) characteristics when the EL element is driven with a 1 kHz sine wave AC voltage. As shown in the figure, blue light emission of about 1.7 cd / m 2 was realized at an applied voltage of 600V. As a result, the Bi-doped lanthanum oxide phosphor thin film light emitting layer sufficiently functioned as a light emitting layer thin film for an EL element.

(Example 2)
After sufficiently mixing lanthanum oxide (La ₂ O ₃ ) powder with bismuth oxide (Bi ₂ O ₃ ) powder as a luminescent center material so that Bi contains 1.0 atomic% with respect to La, argon (Ar) gas Bi-doped lanthanum oxide phosphor powder was produced by firing at 1000 ° C. for 1 hour in an atmosphere. A sputtering target was prepared by using the oxide phosphor powder, and a sintered barium titanate (BaTiO ₃ ) ceramic substrate / insulator layer was coated with argon gas (Ar) gas pressure 6 Pa, sputtering input power 100 W, substrate. A Bi-doped lanthanum oxide phosphor thin film light emitting layer was formed under the conditions of a temperature of 275 ° C. and a substrate-target distance of 25 mm. Thereafter, annealing treatment was performed at 1000 ° C. for 1 hour in an Ar gas atmosphere. Thereafter, a sputtering target was prepared using zinc sulfide (ZnS) powder, and a ZnS thin film was formed on the Bi-doped lanthanum oxide phosphor thin film light emitting layer. After film formation, heat treatment was performed at 500 ° C. in an Ar atmosphere to provide a function as a carrier acceleration layer.

An EL element was fabricated by forming an aluminum-added zinc oxide (ZnO: Al) transparent electrode on the ZnS thin film and a metal Al electrode on the back surface. FIG. 4 shows typical luminance (L) -applied voltage (V) characteristics when the EL element is driven with a 1 kHz sine wave AC voltage. As shown in the figure, high luminance blue light emission of about 23 cd / m ² was realized at an applied voltage of 600V. By forming a ZnS thin film as a carrier acceleration layer on the Bi-doped lanthanum oxide phosphor thin film light emitting layer, a significant improvement in luminance was realized.

(Presence or absence of peeling)
The present inventors have found that there is a difference in the tendency of peeling between the substrate and the light emitting layer depending on the presence or absence of a protective layer that protects the light emitting layer from impurities in the atmosphere. In other words, the inventors have found that the reliability and stability of the device can vary depending on the presence or absence of a protective layer that suppresses or blocks the transmission of impurities from the following examination results. Specifically, the presence or absence of peeling between the substrate and the light emitting layer in the EL element on which the above-described ZnS thin film, which is a semiconductor material that transmits light, and the EL element on which the ZnS thin film is not formed were examined.

  When the ZnS thin film was not formed on the Bi-doped lanthanum oxide phosphor thin film light emitting layer, a phenomenon was observed in which the light emitting layer was peeled from the substrate in some EL devices when left in air for several days. On the other hand, when a ZnS thin film is formed on the Bi-doped lanthanum oxide phosphor thin film light emitting layer as shown in Example 2, peeling between the substrate and the light emitting layer does not occur when left in air for several days. It was. The reason for this difference is that the ZnS thin film blocked the intrusion of moisture in the air into the EL element, and the amount of moisture reaching the interface between the substrate and the light emitting layer was suppressed. It is done. That is, the ZnS thin film functions as a protective layer that protects the light emitting layer and the like from the intrusion of impurities in the atmosphere.

La ₂ O _3: is a graph showing a PL spectrum of a Bi thin film. La ₂ O _3: is a graph showing the EL spectrum of the Bi thin film EL element. La ₂ O _3: luminance of Bi thin-film EL device - is a graph showing the applied-voltage characteristic. ZnS _/ La ₂ O 3: luminance of Bi thin-film EL device - is a graph showing the applied-voltage characteristic.

Claims (15)

  For collision-excited EL, wherein at least one metal element is contained as an activator in a base material composed of a compound or composite oxide containing at least lanthanum (La) and oxygen (O) as constituent elements Phosphor. 2. The collision-excited EL phosphor according to claim 1, wherein the base material made of a composite oxide containing LaNbO ₄ or LaNbO ₄ contains at least one metal element as an activator. Excitation EL phosphor. The collision excitation type EL phosphor according to claim 1, wherein the matrix material comprising lanthanum oxide (La ₂ O ₃ ) contains at least one metal element as an activator. Type EL phosphor.   The collision excitation type EL phosphor according to claim 2 or 3, wherein La is selected from gadolinium (Gd), yttrium (Y), boron (B), indium (In), aluminum (Al) or scandium (Sc). A phosphor for collision excitation type EL, wherein the matrix material comprising a compound or composite oxide substituted with at least one of the above contains at least one metal element as an activator.   5. The collision excitation type EL phosphor according to claim 1, further comprising bismuth (Bi) as an activator.   6. The collision excitation type EL phosphor according to claim 1, wherein the activator contains at least one selected from the group consisting of Bi, a transition metal element, and a rare earth metal element. Collision excitation type phosphor for EL.   6. The collision excitation type EL phosphor according to claim 1, further comprising 0.1 to 10 atomic% of a metal element as an activator with respect to La. Phosphor.   8. The collision-excited EL phosphor according to claim 1 is formed as a thin film on a substrate and then heat-treated at 1050 ° C. or lower in an inert gas or weakly oxidizing gas atmosphere. A method of manufacturing a phosphor thin film for collision excitation type EL.   9. A thin film EL device comprising the collision excitation type EL phosphor thin film according to claim 8 as a light emitting layer.   10. The thin film EL device according to claim 9, wherein a carrier acceleration layer is inserted on one side or both sides of the light emitting layer of the thin film EL device for the purpose of improving excitation efficiency.   The thin film EL device according to claim 10, wherein the carrier acceleration layer is zinc sulfide (ZnS). An insulating substrate;
A light emitting layer formed on the substrate using the phosphor for collision excitation EL according to any one of claims 1 to 7,
A protective layer formed on the light emitting layer;
A thin film EL device comprising:   The thin film EL device according to claim 12, wherein the protective layer contains zinc sulfide (ZnS).   A thin film EL display using the thin film EL element according to claim 9.   A thin film EL lamp using the thin film EL element according to claim 9.

Images