JP2009191093A - Fluorescent substance and light emission apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a red light emission fluorescent substance with high brightness having sufficient performance even in an aspect of color reproducibility and color rendering property, and a light emission apparatus using those. <P>SOLUTION: The red light emission fluorescent substance represented by the general formula: A<SB>1-x</SB>Ag<SB>x</SB>Eu<SB>y</SB>Ln<SB>1-y</SB>W<SB>2</SB>O<SB>8</SB>and the light emission apparatus using it are provided. Wherein A is selected from the group consisting of Li, Na, K, Rb and Cs, 0<x<0.3, Ln is selected from the group consisting of Y, Gd, La and Sm, and 0<y≤1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a phosphor used in a light emitting device, and in particular, a display such as a vacuum fluorescent display (VFD) and a plasma display panel (PDP), and a light emitting device using a blue light emitting diode or an ultraviolet light emitting diode as a light source. The present invention relates to a phosphor that can be used for the above.

LED lamps using light emitting diodes are used in various display devices such as portable devices, PC peripheral devices, OA devices, various switches, backlight light sources, and display boards. As a red phosphor for an LED lamp using the above-described light emitting diode, it was introduced in Non-Patent Documents 1 to 3 and the like, and it has been known for a long time that it has excitation in the vicinity of 400 nm in addition to the ultraviolet region of 300 nm or less. A study using a well-known phosphor represented by a composition formula of AEuM ₂ O ₈ (A is an alkali metal, M is Mo or W) is introduced in Patent Document 1. However, in light of market demand, there is still room for improvement in terms of luminance, and further higher luminance is desired.
JP 2003-41252 A L. G. Van Uitert: 'Luminescence of Inorganic Solids', p488-p502 (1966) J. et al. P. M.M. Van Vliet & G. Blasse: Journal of Soil State Chemistry 76, 160 (1988) J. et al. P. M.M. Van Vliet & G. Blasse: Journal of Solid State Chemistry 85, 56-64 (1990)

  The present invention has been made in view of such circumstances, has high luminance by excitation of light in the near ultraviolet or blue wavelength region of 250 to 500 nm, and has sufficient performance in terms of color reproducibility and color rendering. An object of the present invention is to provide a red light emitting phosphor that emits red light, and a light emitting device using the same.

The red light emitting phosphor according to the present invention has the following general formula (1):
A _1-x Ag _x Eu _y Ln _1-y W ₂ O ₈ (1)
(In the formula, A is at least one selected from the group consisting of Li, Na, K, Rb, and Cs, 0 <x <0.3, and Ln consists of Y, Gd, La, and Sm. At least one selected from the group, 0 <y ≦ 1)
It is characterized by being represented by.

The light emitting device according to the present invention is
A light emitting element that emits light having a wavelength of 250 nm to 500 nm;
And a phosphor layer including the phosphor disposed on the light emitting element.

  Further, according to the present invention, there is provided a method for producing the red light emitting phosphor, wherein the carbonate or oxide of the metal element A, the oxide of Ag, the oxide or carbonate of Eu, the oxide or carbonate of the metal element Ln, and Mixing an oxide or carbonate of W and firing at 500 to 1300 ° C. under a pressure of atmospheric pressure or higher.

  According to one embodiment of the present invention, red light emitting fluorescence that emits red light with high brightness and no problem in color reproducibility and color rendering by excitation of light in the near ultraviolet or blue wavelength region of 250 to 500 nm. A body and a light emitting device using the same are provided. A white light-emitting phosphor or a light-emitting device is also provided by combining this phosphor with another phosphor as required. This phosphor does not require any harmful substances such as mercury as a constituent element, so it can be used as a light source for lighting, display, and liquid crystal backlight as an alternative to conventional fluorescent lamps that can achieve high safety and low power consumption. Is.

  An embodiment of the present invention will be described as follows.

The present inventors have found that a phosphor having excellent emission intensity can be obtained by adding Ag as a luminescent center element to an oxide compound having a limited composition. The phosphor in the present invention is an oxide compound and is represented by the following composition formula (1).
A _1-x Ag _x Eu _y Ln _1-y W ₂ O ₈ (1)
(In the formula, A is at least one selected from the group consisting of Li, Na, K, Rb and Cs, 0 <x <0.3, and Ln is a group consisting of Y, Gd, La, and Sm. At least one selected from 0 <y ≦ 1)

That is, in the phosphor according to the present invention, in the composite oxide AEuW ₂ O ₈ of the group IA metal A, europium, and tungsten, 0 to 30% of the group IA metal site is substituted with Ag serving as the luminescent center element, It can also be said that a part of the europium site is substituted with Y, Gd, La, or Sm as necessary. In the present invention, it is particularly important that an Ag element is contained, thereby realizing a stronger emission intensity.
The compounding amount of Ag needs to satisfy 0 <x <0.3, but 0.1 ≦ x ≦ 0.2 is preferable in order to obtain stronger emission intensity. This is because if x exceeds 0.3, the emission intensity tends to decrease.

  If necessary, a part of Eu can be replaced with at least one element Ln selected from the group consisting of Y, Gd, La, and Sm. However, Eu is sensitized and emission intensity is increased. It is preferable to use Sm as the element Ln because the effect is strong. The compounding ratio of Ln is determined by the relationship between 1-y and the compounding ratio y of Eu. The compounding ratio of y needs to satisfy 0 <y ≦ 1, but preferably 0.90 <y ≦ 0.98.

  The phosphor according to the embodiment of the present invention including the specific oxide compound as described above has peak wavelengths in the vicinity of 590, 610, 650, and 700 nm when excited with light having a wavelength of 250 nm to 500 nm. A plurality of narrow-band emission peaks are shown. In other words, it can be said that it emits light in the red region when excited with light having a wavelength of 250 nm to 500 nm. In addition, the narrow band here means that the half width of the emission spectrum is narrow.

  The phosphor according to the embodiment of the present invention exhibits good emission intensity because the composition of each constituent element is defined within the range specified by the present invention. A phosphor having such a composition and a high emission intensity has been obtained for the first time by the present inventors.

The phosphor according to the embodiment of the present invention includes each metal element, specifically, an oxide or carbonate of each of A, Ag, Eu, Ln, and W, for example, a carbonate or oxide of the metal element A, Ag. , Eu oxides or carbonates, and W oxides or carbonates, and if necessary, oxides or carbonates of the metal element Ln can be synthesized as starting materials. Ag carbonate can also be used, but an oxide is preferably used from the viewpoint of easy handling because it is easily denatured by natural light. Although salts other than oxides or carbonates can be used, in that case, it is necessary to select a raw material or a synthesis condition in which unnecessary elements do not finally remain in the phosphor. More specifically, Li ₂ CO ₃ , Ag ₂ O, Eu ₂ O _3, Sm ₂ O is used for a phosphor containing Li as the metal element A and Sm as the metal element Ln. ₃ and WO ₃ can be used as starting materials. These starting materials are weighed and mixed so that the amount of elements other than oxygen is the same as the ratio in the composition of the desired phosphor, and the obtained mixed powder is fired to obtain the target phosphor. At this time, W may be mixed relatively excessively. This is because the single oxide of W has little adverse effect on the phosphor. In mixing, for example, a method of mixing in a mortar can be mentioned. Alternatively, mixing may be performed by a wet mixing method.

  When the raw materials are mixed in a solid state, the obtained mixed powder is generally filled in a crucible and fired. The material of the crucible is not particularly limited, and may be platinum, boron nitride, silicon nitride, silicon carbide, aluminum nitride, sialon, aluminum oxide, carbon, molybdenum, tungsten, or the like.

  By firing such a raw material mixture for a predetermined time, a phosphor having a desired composition can be obtained. The firing is desirably performed at a pressure of atmospheric pressure or higher. The range of 500-1300 degreeC is preferable for a calcination temperature, More preferably, it is 900-1000 degreeC. When the firing temperature is less than 500 ° C., it becomes difficult to form an oxide. On the other hand, if it exceeds 1300 ° C., the material or product may sublime. Moreover, in order to suppress the reduction | restoration of a raw material, baking in an oxidizing atmosphere or air | atmosphere is preferable.

  After firing, the powder obtained as necessary can be subjected to post-treatment such as washing to obtain the fluorescence according to the embodiment of the present invention. When washing is performed, for example, pure water washing or acid washing can be performed.

  The phosphor according to the present invention can be used in any conventionally known light-emitting device. FIG. 1 shows a cross section of a light emitting device according to an embodiment of the present invention.

  In the illustrated light emitting device, the resin stem 200 includes a lead 201 and a lead 202 formed by molding a lead frame, and a resin portion 203 formed integrally therewith. The resin portion 203 has a concave portion 205 whose upper opening is wider than the bottom portion, and a reflective surface 204 is provided on the side surface of the concave portion.

  A light emitting chip 206 is mounted with Ag paste or the like at the center of the substantially circular bottom surface of the recess 205. As the light emitting chip 206, for example, a light emitting diode, a laser diode, or the like can be used. Furthermore, other materials that emit ultraviolet light can be used and are not particularly limited. In addition to ultraviolet light, chips capable of emitting wavelengths such as blue, blue-violet, and near ultraviolet light can also be used. For example, a GaN-based semiconductor light emitting element or the like can be used. The electrodes (not shown) of the light emitting chip 206 are connected to the leads 201 and 202 by bonding wires 207 and 208 made of Au or the like, respectively. The arrangement of the leads 201 and 202 can be changed as appropriate.

  A fluorescent layer 209 is disposed in the recess 205 of the resin portion 203. The phosphor layer 209 can be formed by dispersing or precipitating the phosphor 210 according to the embodiment of the present invention at a rate of 5 wt% to 50 wt% in a resin layer 211 made of, for example, a silicone resin. . Further, if necessary, other phosphors may be combined with the phosphor layer 209, or other phosphor layers may be used in combination, so that a light emitting device other than red light, for example, white light can be obtained.

  As the light emitting chip 206, a flip chip type having an n-type electrode and a p-type electrode on the same surface can be used. In this case, problems caused by the wire such as wire breakage and peeling and light absorption by the wire are solved, and a highly reliable and high-luminance semiconductor light-emitting device can be obtained. In addition, an n-type substrate may be used for the light emitting chip 206 to have the following configuration. Specifically, an n-type electrode is formed on the back surface of the n-type substrate, a p-type electrode is formed on the upper surface of the semiconductor layer on the substrate, and the n-type electrode or the p-type electrode is mounted on a lead. The p-type electrode or the n-type electrode can be connected to the other lead by a wire. The size of the light emitting chip 206 and the size and shape of the recess 205 can be changed as appropriate.

  The light emitting device according to the embodiment of the present invention is not limited to the package cup type as shown in FIG. 1, and can be appropriately changed. Specifically, also in the case of a bullet-type LED or a surface-mounted LED, the light emitting device of this embodiment can be obtained by applying the phosphor of this embodiment. Since the phosphor of this embodiment has good temperature characteristics, it is particularly suitable for high power input LEDs. Note that the high power input LED refers to an LED to which a power of 0.5 W or more is input.

  The present invention will be described below with reference to examples, but the present invention is not limited to the embodiments exemplified in the following examples.

Example 1
Ag ₂ O 0.811g
Li ₂ CO ₃ 2.328 g
Eu ₂ O ₃ 11.702 g
Sm ₂ O ₃ 0.610 g
WO ₃ 32.459g
The phosphors of Example 1 were obtained by sufficiently dry-mixing the above raw materials, filling them in an alumina crucible, and firing in the atmosphere at 900 ° C. for 6 hours. The composition formula of the obtained phosphor was Li _0.9 Ag _0.1 Eu _0.95 Sm _0.05 W ₂ O ₈ .
The phosphor after firing was a sintered powder having a red body color. As a result of excitation with a black light and an LED having a peak wavelength of 400 nm, red light emission was observed.

Example 2
A phosphor was produced in the same manner as in Example 1 except that the amount of Ag ₂ O was changed to 1.622 g and the amount of Li ₂ CO ₃ was changed to 2.069 g. Formula of the obtained phosphor _{was Li 0.8 Ag 0.2 Eu 0.95 Sm 0.05} W 2 O 8.
The phosphor after firing was a sintered powder having a red body color. As a result of excitation with a black light and an LED having a peak wavelength of 400 nm, red light emission was observed.

Comparative Example 1
A phosphor was produced in the same manner as in Example 1 except that the amount of Ag ₂ O was changed to 0 g and the amount of Li ₂ CO ₃ was changed to 2.586 g. The composition formula of the obtained phosphor was LiEu _0.95 Sm _0.05 W ₂ O ₈ .
The phosphor after firing was a sintered powder having a red body color. As a result of excitation with a black light and an LED having a peak wavelength of 400 nm, red light emission was observed.

Example 3
A phosphor was produced in the same manner as in Example 1 except that the amount of Ag ₂ O was changed to 2.433 g and the amount of Li ₂ CO ₃ was changed to 1.810 g. The composition formula of the obtained phosphor was Li _0.7 Ag _0.3 Eu _0.95 Sm _0.05 W ₂ O ₈ .
The phosphor after firing was a sintered powder having a red body color. As a result of excitation with a black light and an LED having a peak wavelength of 400 nm, red light emission was observed.

Comparative Example 2
A phosphor was produced in the same manner as in Example 1 except that the amount of Ag ₂ O was changed to 3.244 g and the amount of Li ₂ CO ₃ was changed to 1.552 g. The composition formula of the obtained phosphor was Li _0.6 Ag _0.4 Eu _0.95 Sm _0.05 W ₂ O ₈ .
The phosphor after firing was a sintered powder having a red body color. As a result of excitation with a black light and an LED having a peak wavelength of 400 nm, red light emission was observed.

Measurement of emission spectrum The red powders of Examples 1 and 2 were taken out of the crucible and crushed in a mortar. This was excited by a light emitting diode having a peak wavelength of 400 nm, and an emission spectrum was observed. The red powders of Comparative Examples 1 and 3 were also crushed in the same manner, and then excited with 400 nm light to observe an emission spectrum. The emission spectrum was measured using an IMUC7000 type spectrophotometer (trade name, manufactured by Otsuka Electronics Co., Ltd.).

  The obtained result was as shown in FIG. From any of the red powders, a plurality of narrow-band luminescences having peak wavelengths near 590, 610, 650, and 700 nm were obtained. Here, by comparing the peaks in the vicinity of 610 nm of each example, the emission intensity of the phosphors of Examples 1 and 2 exceeds the emission intensity of the phosphor of Comparative Example 1, that is, the phosphor not containing Ag. I understand that.

  When the emission intensity at 612 nm of the phosphors of Examples 1 and 2 and Comparative Examples 1 and 2 at 400 nm excitation was plotted against the substitution rate x of Ag in the Li site, it was as shown in FIG. It can be seen that the emission intensity is improved when the Ag substitution rate x to the Li site is within the range specified in the present invention.

Schematic showing the structure of the light-emitting device concerning one Embodiment of this invention. The emission spectrum by 400 nm light excitation of the fluorescent substance obtained in Examples 1, 2 and Comparative Example 1. The graph which shows the relationship between the emitted light intensity of a 612 nm peak by the 400 nm light excitation of the fluorescent substance obtained in Example 1, 2 and Comparative Example 1, and Ag substitution rate x.

Explanation of symbols

200 Resin system 201 Lead 202 Lead 203 Resin portion 204 Reflecting surface 205 Recessed portion 206 Light emitting chip 207 Bonding wire 208 Bonding wire 209 Fluorescent layer 210 Fluorescent substance 211 Resin layer.

Claims (5)

The following general formula (1):
A _1-x Ag _x Eu _y Ln _1-y W ₂ O ₈ (1)
(In the formula, A is at least one selected from the group consisting of Li, Na, K, Rb, and Cs, 0 <x <0.3, and Ln consists of Y, Gd, La, and Sm. At least one selected from the group, 0 <y ≦ 1)
A red light-emitting phosphor characterized by being represented by:   The red light emitting phosphor according to claim 1, wherein A is Li and Ln is Sm.   3. The red light-emitting phosphor according to claim 1, wherein x is 0.1 ≦ x ≦ 0.2 and y is 0.90 <y ≦ 0.98. A light emitting element that emits light having a wavelength of 250 nm to 500 nm;
A phosphor layer comprising the phosphor layer according to claim 1 disposed on the light emitting element.   A metal element A carbonate or oxide, Ag oxide, Eu oxide or carbonate, metal element Ln oxide or carbonate, and W oxide or carbonate are mixed, and the pressure is higher than atmospheric pressure. The manufacturing method of the red light emission fluorescent substance of any one of Claims 1-3 which comprises baking below at 500-1300 degreeC.

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