JP5125039B2 - Rare earth oxynitride phosphor and light emitting device using the same - Google Patents

Description

  The present invention relates to rare earth oxynitride phosphors that emit light when excited by electromagnetic waves such as light, electron beams, X-rays, heat, etc., in particular, general lighting such as fluorescent lamps, in-vehicle lighting, backlights for liquid crystals, displays, etc. Rare earth oxynitride phosphors used in light emitting devices and light emitting devices using the same, for example, rare earth oxynitride phosphors used in white and multicolor light emitting devices using semiconductor light emitting elements And a light emitting device using the same.

  Currently, fluorescent lamps are the mainstream of white lighting, but light emitting devices that use light emitting elements consume less power and do not use mercury compared to fluorescent lamps. It is predicted that the lighting of the light emitting device will be mainstream. In addition, a light-emitting device using a light-emitting element emits light with a small color, high power efficiency, and bright colors. In particular, a semiconductor element such as a light emitting diode (LED) or a semiconductor laser (LD: Laser Diode) does not have a fear of a broken ball. In addition, it has excellent initial drive characteristics and is strong against vibration and repeated on / off lighting. Semiconductor light-emitting elements having such excellent characteristics are used as various light sources. For example, the emission color of a light emitting device using a current white semiconductor light emitting element can be obtained by the principle of color mixing of light. In order to obtain high-brightness white light with excellent color rendering and brightness, and to expand the color reproduction range, high-brightness LEDs of the three primary colors red, blue, and green are required. . However, since the luminous efficiency of the green LED is inferior to that of red and blue at present, there is a problem that the luminous efficiency of white is lowered due to this influence.

  Therefore, with the development of green LEDs, research on phosphors that emit green light with high brightness is underway. As a method of obtaining green light using the latter phosphor, (1) a method of obtaining a green wavelength by exciting a phosphor with a light emitting element that emits light in a blue region, and (2) a method for obtaining visible light from ultraviolet rays. There is a system in which a phosphor is excited by a light emitting element that emits light in a short wavelength side region to obtain a wavelength-converted green wavelength.

As a phosphor according to (1), an oxynitride phosphor has been reported (see Patent Document 1). Specifically, the Ca-alpha sialon phosphor in which both Eu ²⁺ ions and Dy ³⁺ ions are activated is excited by an excitation light source having an emission spectrum near 450 nm and emits an emission spectrum having a peak wavelength near 570 nm. To do. In a light emitting device including the above phosphor and a blue LED that is a light emitting element, a mixed color of light that has been excited and excited by the excitation light source from the blue LED and blue light from the excitation light source that is not converted is emitted. .

  However, since the phosphor of oxynitride glass is a glass body, it is generally difficult to process. Furthermore, due to color variations of the excitation light source due to manufacturing variations of blue LEDs and differences in input current, the color mixture ratio between the blue color of the excitation light source and the color after wavelength conversion is easily shifted, and the color emitted from the light emitting device varies. There was a problem that occurred.

  On the other hand, in the method (2), a light emitting element in the short wavelength side region from ultraviolet to visible light is used as an excitation light source. In this wavelength region, since the sensitivity of the color is low and is difficult to visually recognize, there is no color shift of the excitation light source due to manufacturing variations. Therefore, there is an advantage that the change in the emission spectrum of the excitation light source hardly affects the color of the light emitting device.

Thus, there has been reported a phosphor that uses light from a light emitting element in the near-ultraviolet to visible light short wavelength side region as an excitation light source and converts the wavelength thereof to green (see Patent Document 1). Specifically, the Yb ²⁺ alpha sialon phosphor is excited by an excitation spectrum near 240 nm and emits light having a peak wavelength near 510 nm. Further, the Er-alpha sialon phosphor has a broad peak at 263 nm and a line peak excitation spectrum near 400 nm, and exhibits an emission spectrum of 500 nm to 600 nm.

Furthermore, as another phosphor, an oxynitride phosphor represented by La ₃ Si ₈ N ₁₁ O ₄ or a general formula La ₃ Si _8-x Al _x N _11-x O _{4 + x} (0 <x ≦ 4) Has been reported to emit green light with the optically active element Tb as the center of light emission (see Patent Document 2). Specifically, the excitation wavelength peak for the phosphor of La ₃ Si ₈ N ₁₁ O ₄ to which Tb is added is 256 nm, and the excitation wavelength peak for the phosphor of La ₃ Si ₇ AlN ₁₀ O ₅ is disclosed as 258 nm. The In other words, since all phosphors have an excitation wavelength peak in the ultraviolet region, these phosphors have a wavelength of a light emitting device including a semiconductor light emitting element having a light emission peak in the short wavelength region or the blue region from near ultraviolet to visible light. It cannot be used as a conversion material.

  Accordingly, it is desired to develop a phosphor that combines the above (1) and (2) and is excited by a wide range of wavelengths from the ultraviolet to the short wavelength region of visible light and the blue region and emits green light. As an example, a Y-Si-ON: Ce-based phosphor is disclosed (Non-Patent Document 1). This phosphor is excited by a wavelength in a blue region from ultraviolet to visible light, and has a broad emission spectrum having a peak wavelength in the vicinity of 423 nm to 504 nm.

However, when a light emitter is used as a light source for a display device such as a transmissive color liquid crystal display device, a sharp emission spectrum is required. This is because in the broad emission spectrum, the bottom area of the waveform overlaps with the emission spectra of other colors, resulting in color mixing. When color mixing occurs, the color purity deteriorates and vivid colors cannot be displayed. Therefore, the transmitted light component is limited by the color filter. This makes it possible to transmit the emission spectrum of only the desired region, but on the other hand, the light transmittance decreases. When the light transmittance decreases, the light output that can be taken out as a whole decreases. Therefore, for example, in a transmissive color liquid crystal display device, a three-wavelength cold cathode fluorescent tube having a sharp emission spectrum is usually used as a white light source. In addition, the use of light emitters such as LEDs has been developed as light sources for transmissive color liquid crystal display devices, and the importance of LEDs having a sharp emission spectrum is increasing.
JP 2002-363554 A JP 2005-112922 A Journal of Alloys and Compounds 268 (1998) 272-277

  The present invention has been made in view of such conventional problems. The first object of the present invention is to provide a rare earth oxynitride phosphor that can be excited by an excitation light source in a wide range from ultraviolet to visible light, and can emit green light sharply by wavelength conversion, and a light emitting device using the same. It is to provide. Another object of the present invention is to provide a rare earth oxynitride phosphor having high luminous efficiency and excellent reproducibility, and a light emitting device using the rare earth oxynitride phosphor.

The rare earth oxynitride-based phosphor according to the present invention has a general formula of J _x L _y O _a N _b : Ce, Tb, and x, y, a, b are in the following ranges, and is shared by cerium and terbium. It is activated and absorbs ultraviolet or blue light and emits green light.
J is Sc, Y, La, Pr, Nd, Sm, Gd, Dy, Ho, Er, Tm, Yb, Lu, and L are at least one selected from the group of Si, Ge, Ti, Zr, and Hf. O is oxygen and N is nitrogen, and 0.5 ≦ x ≦ 8.5, 0.5 ≦ y ≦ 12, 0.5 ≦ a ≦ 16, and 0.5 ≦ b ≦ 16.

The rare earth oxynitride phosphor according to the present invention has a general formula of Y ₄ Si ₂ O ₇ N ₂ : Ce, Tb, is co-activated with cerium and terbium, and absorbs ultraviolet or blue light. Can emit green light.

  The rare earth oxynitride phosphor is excited by excitation light from an excitation light source having an emission peak wavelength of 460 nm or less, and can emit fluorescence having a peak wavelength in a wavelength range of 530 nm to 570 nm.

Furthermore rare earth oxynitride-based fluorescent material is represented by the general formula is _{J x L y M z O a} N b: Ce, represented by Tb, J is Sc, Y, La, Pr, Nd, Sm, Gd, Dy, Ho, Er, Tm, Yb, Lu, and L are at least one selected from the group of Si, Ge, Ti, Zr, Hf, and M, B is Al, Ga, and In, O is oxygen, and N is nitrogen. Yes, the ranges of x, y, z, a, b are 0.5 ≦ x ≦ 8.5, 0.5 ≦ y ≦ 12, 0.001 ≦ z ≦ 5, 0.5 ≦ a ≦ 16, 0 5 ≦ b ≦ 16, which is co-activated with cerium and terbium, and can emit green light by absorbing ultraviolet light or blue light.

The rare earth oxynitride phosphor has a general formula Y ₄ Si _2−m Al _m O _{7 + m} N _2−m : Ce, Tb, and the range of m is 0 <m ≦ 0.2. It is co-activated with cerium and terbium and can absorb ultraviolet light or blue light to emit green light.

  The rare earth oxynitride phosphor can be excited by excitation light from an excitation light source having an emission peak wavelength of 460 nm or less and emit fluorescence having a peak wavelength in a wavelength range of 530 nm to 570 nm.

  Further, the rare earth oxynitride phosphor preferably has an average particle size of 2 μm or more and 20 μm or less.

  On the other hand, the light-emitting device is an excitation light source having a first emission spectrum that emits a wavelength of 460 nm or less, and one or more types that absorb at least part of the first emission spectrum and emit a second emission spectrum. The above-described rare earth oxynitride phosphor can be used as the wavelength conversion member.

  As described above, the rare earth oxynitride phosphor and the light-emitting device using the same are excited by light in the short wavelength region from near ultraviolet to visible light of 460 nm or less and have a very good light emission efficiency for line emission in the green region. A light emitting device can be realized. In addition, a crystalline rare earth oxynitride phosphor that is easy to manufacture and process or a rare earth oxynitride phosphor excellent in stability can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a rare earth oxynitride phosphor and a light emitting device using the same for embodying the technical idea of the present invention. Nitride-based phosphors and light-emitting devices using the same are not specified as follows. In addition, the member shown by the claim is not what specifies the member of embodiment. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the embodiments are not intended to limit the scope of the present invention unless otherwise specified, and are merely explanations. It's just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing.

  The short wavelength region from near ultraviolet to visible light in this specification is not particularly limited. The region is preferably 240 nm to 480 nm. As the excitation light source, one having an emission peak wavelength at 240 nm to 430 nm can be used. Among these, it is preferable to use an excitation light source having an emission peak wavelength in the vicinity of 240 nm to 280 nm and 350 nm to 430 nm. In particular, it is preferable to use an excitation light source having a wavelength of 350 nm to 420 nm that is used in semiconductor light emitting devices.

  The relationship between the color name and chromaticity coordinates, the relationship between the wavelength range of light and the color name of monochromatic light, and the like comply with JIS Z8110. Specifically, 380 nm to 455 nm is blue purple, 455 nm to 485 nm is blue, 485 nm to 495 nm is blue green, 495 nm to 548 nm is green, 548 nm to 573 nm is yellow green, 573 nm to 584 nm is yellow, 584 nm to 610 nm is yellow red , 610 nm to 780 nm is red.

(Phosphor)
The rare earth oxynitride phosphor in the embodiment is excited by light from an excitation light source having an emission peak wavelength of 460 nm or less, and has a fluorescence emission peak wavelength longer than the emission peak wavelength of excitation light. More preferably, the range of the excitation light source having the emission peak wavelength is set to 240 nm to 460 nm. This is because a phosphor with high luminous efficiency can be provided by using an excitation light source in this range. In particular, it is preferable to use an excitation light source having an emission peak wavelength at 240 nm to 430 nm, and it is preferable to use an excitation light source having an emission peak wavelength at 240 nm to 280 nm or 350 nm to 420 nm. At this time, the rare earth oxynitride phosphor in the embodiment of the present invention has higher emission luminance when the latter range is used as the excitation light source.

  The rare earth oxynitride phosphor in the embodiment uses a light emitting element in the short wavelength side region from near ultraviolet to visible light as an excitation light source. The light in this wavelength region has low visibility. Visibility refers to a wavelength function indicating the relationship between the sensation of brightness given by monochromatic light and the energy of light. The relationship between the human eye feeling and the light wavelength is based on the visibility characteristic, and the visibility of the light at 555 nm is the highest, and the visibility decreases toward the short wavelength and the long wavelength. For example, light in the ultraviolet region used as an excitation light source belongs to a portion having low visibility, and the light emission color of the light emitting device is substantially determined by the light emission color of the fluorescent material used. Further, even when a color shift of a light emitting element due to a change in input current or the like occurs, a color shift of a fluorescent material that emits light in the visible light region can be suppressed to be extremely small. As a result, a light emitting device with little color tone change is provided. Can do. Although the ultraviolet region generally has a wavelength shorter than 380 nm or 400 nm, light having a wavelength of 420 nm or less is hardly visible in terms of visual sensitivity, so that the color tone is not greatly affected. Therefore, it is preferable to use an excitation light source of 420 nm or less.

  Further, it is preferable that at least a part of the rare earth oxynitride phosphor has a crystal. In particular, the rare earth oxynitride phosphor has at least 50% by weight, more preferably 80% by weight or more of crystals. This indicates the proportion of the crystalline phase having luminescent properties, and if it has a crystalline phase of 50% by weight or more, light emission that can withstand practical use can be obtained. Therefore, the more crystal phases, the better. As a result, the luminance can be increased, and the production and processing of the rare earth oxynitride phosphor can be facilitated.

  Furthermore, it is preferable that the rare earth oxynitride phosphor absorbs light in a short wavelength region of ultraviolet light or visible light and emits fluorescence having a peak wavelength in a wavelength range of 530 nm to 570 nm.

(Method for producing rare earth oxynitride phosphor)
Next, a method for producing a rare earth oxynitride phosphor will be specifically described with reference to examples. Formula rare earth oxynitride-based phosphor according to Examples 1-4 _{J x L y O a N b} : Ce, represented by Tb. Here, J is Sc, Y, La, Pr, Nd, Sm, Gd, Dy, Ho, Er, Tm, Yb, Lu, L is at least one selected from the group of Si, Ge, Ti, Zr, and Hf It is. O is oxygen, N is nitrogen, and 0.5 ≦ x ≦ 8.5, 0.5 ≦ y ≦ 12, 0.5 ≦ a ≦ 16, and 0.5 ≦ b ≦ 16. This rare earth oxynitride phosphor contains a rare earth element in its composition formula, and is co-activated with Ce and Tb.

(Comparative example 1, Examples 1-4)
Among the rare earth oxynitride phosphors, phosphors Y ₄ Si ₂ O activated by Ce and Tb and having J = Y, L = Si, x = 4, y = 2, a = 7, and b = 2 _{7 A} method for producing N ₂ : Ce, Tb is shown. Further, the phosphors thus produced were designated as Examples 1 to 4 by changing the mixing ratio of Ce and Tb to be added.

  First, each of a raw material compound of a rare earth metal element, a group 4 element compound, a nitride, and an activator is pulverized. The average particle size of the pulverized raw material is preferably in the range of 0.1 μm or more and 10 μm or less from the viewpoints of reactivity with other raw materials, control of particle size at the time of firing and after firing, etc., but limited to this range Not. Moreover, although it is better to use these purified raw materials having high purity, commercially available products may be used. Specifically, in Examples 1 to 4, yttrium oxide was used as the rare earth metal element compound, silicon oxide as the group 4 element compound, silicon nitride as the nitride, and cerium oxide and terbium oxide as the coactivator. In addition, carbonates, nitrides, hydroxides, nitrates, oxalates, imide compounds and amide compounds of rare earth metal elements can also be used.

The above raw materials are weighed and mixed so as to have the composition described in Example 1 of Table 1 ((Y _0.945 Ce _0.005 Tb _0.05 ) ₄ Si ₂ O ₇ N ₂ ). However, this composition is a representative composition estimated from the blending ratio, and has sufficient characteristics to withstand practical use in the vicinity of the ratio. Moreover, the composition of the target phosphor can be changed by changing the blending ratio of each raw material.

As the composition, a tubular furnace, a small furnace, a high-frequency furnace, a metal furnace or the like can be used. Firing can be performed in the range of 1200 ° C. to 2200 ° C., but a firing temperature of 1400 ° C. to 2000 ° C. is preferable. More preferably, baking is performed at about 1800 ° C. for about 2 hours. The firing is preferably performed by gradually raising the temperature and firing at 1200 ° C. to 2200 ° C. for several hours, but the first stage firing is carried out at 800 ° C. to 1200 ° C. and gradually heated. Two-stage baking (multi-stage baking) in which the second baking is performed at 1200 to 2200 ° C. can also be used. The phosphor material is preferably fired using a boron nitride (BN) crucible or boat. In addition to a crucible made of boron nitride, a crucible made of alumina (Al ₂ O ₃ ) or Mo can be used.

  The starting material may also contain a flux that promotes the reaction of the starting material during the firing step of forming the phosphor. Preferably, the flux includes a halogen compound such as a fluoride or chloride compound. The halogen compound includes magnesium fluoride, aluminum, strontium, magnesium chloride, or ammonium chloride. However, the phosphor may be fired without adding flux. The fired mixture is then coated on a substrate such as a lamp bulb. Preferably, the substrate is coated with a suspension of mixture particles and liquid.

By grinding after firing, a rare earth oxynitride phosphor represented by the chemical formula ((Y _0.945 Ce _0.005 Tb _0.05 ) ₄ Si ₂ O ₇ N ₂ ) can be obtained. However, this chemical formula is obtained from the blending ratio of the raw materials used. In Examples 2 to 5, phosphors were synthesized in the same manner as in Example 1 except that the mixing ratio of the raw materials was changed so that the phosphors described in Examples 2 to 5 in Table 1 were obtained. The reaction formula of the basic constituent elements by this firing is shown in chemical formula 1.

In the above chemical formula, δ indicates that oxygen of CeO ₂ and Tb ₄ O ₇ is eliminated and Ce and Tb are reduced to trivalent.
Further, as Comparative Example 1, a phosphor was synthesized using only terbium oxide as an activator and not adding cerium oxide.

  In Table 1, the preparation compositions of Examples 1 to 4 and Comparative Example 1 and the emission characteristics when the obtained phosphors were excited at a wavelength of 253.7 nm were evaluated. Similarly, Table 2 shows emission characteristics when the phosphor is excited to a wavelength of 365 nm. Further, Table 3 shows emission characteristics when the phosphor is excited to a wavelength of 400 nm. The light emission luminance of the rare earth oxynitride phosphors shown in Examples 1 to 4 and Comparative Example 1 is set to 100% in Example 1, and is expressed as a relative value based on this. FIG. 1 shows emission spectra when the rare earth oxynitride phosphors of Comparative Example 1 and Examples 1 to 4 are excited at 253.7 nm. Similarly, FIG. 2A shows emission spectra when the rare earth oxynitride phosphors of Comparative Example 1 and Examples 1 to 4 are excited at 365 nm. Furthermore, each emission spectrum when the comparative example 1 and Examples 1-4 are excited at 365 nm is shown in FIGS. 2 (b), (c), (d), (e), and (f). FIG. 3A shows emission spectra when the rare earth oxynitride phosphors of Comparative Example 1 and Examples 1 to 4 are excited at 400 nm. Furthermore, each emission spectrum when the comparative example 1 and Examples 1-4 are excited at 400 nm is shown in FIGS. 3 (b), (c), (d), (e), and (f). FIG. 4 shows excitation spectra of Comparative Example 1 and Examples 1 to 4. FIG. 5A is a 1000 × magnified photograph of the rare earth oxynitride phosphor of Example 1, and FIG. 5B is a 5000 × magnified photograph of the rare earth oxynitride phosphor of Example 1.

  In the rare earth oxynitride phosphors of Examples 1 to 4, four peak wavelengths were observed as shown in FIGS. That is, each peak wavelength is 480 nm to 510 nm, 530 nm to 570 nm, 580 nm to 610 nm, and 610 nm to 640 nm. Among them, the peak wavelength at 530 nm to 570 nm and the half width of 25 nm is the strongest. That is, the rare earth oxynitride phosphors of Examples 1 to 4 have a sharp emission peak near 545 nm, and emit light in green with chromaticity coordinate values near x = 0.30 and y = 0.54. doing. Further, as can be seen from the excitation spectrum of FIG. 4, excitation is possible with a light source of around 430 nm or less.

By the way, in order to synthesize a phosphor that emits a desired emission color, it is important to select a rare earth ion according to the emission wavelength. For example, if the wavelength is green, Tb ³⁺ which is a trivalent rare earth ion can be used. However, the rare earth oxynitride-based phosphor (Y _0.95 Tb _0.05 ) ₄ Si ₂ O ₇ N ₂ containing Tb shown in Comparative Example 1 has the emission spectra shown in FIGS. 2 (b) and 3 (b). Although an emission spectrum is observed near 545 nm, its intensity is weak. Further, the excitation spectrum shown in FIG. 4 has a peak only in the vicinity of 240 nm to 304 nm, does not have a sufficient excitation wavelength in the near ultraviolet to blue wavelength region, and has a very small spectrum in the target emission wavelength region. However, it has only been observed.

  On the other hand, as shown in FIGS. 2 (c), (d), (e), (f) and FIGS. 3 (c), (d), (e), (f), Tb and In the rare earth oxynitride phosphor in which Ce was co-activated, an emission spectrum near 545 nm was strongly observed, and an excitation spectrum was observed in a desired wavelength region as shown in FIG. That is, it can be said that Ce acted as a sensitizer for Tb luminescence by co-activation of Tb and Ce.

(Particle size)
The particle size of the rare earth oxynitride phosphor is preferably in the range of 2 μm to 20 μm, more preferably 3 μm to 15 μm. A phosphor having a particle size smaller than 2 μm tends to form an aggregate. On the other hand, a phosphor having a particle size range of 3 μm to 15 μm has a high light absorption rate and conversion efficiency. In this manner, the mass productivity of the light-emitting device is improved by including a phosphor having a large particle diameter and having optically excellent characteristics.

Here, the particle size refers to the average particle size obtained by the air permeation method. Specifically, in an environment with an air temperature of 25 ° C. and a humidity of 70%, a sample of 1 cm ³ is weighed and packed in a special tubular container, then a constant pressure of dry air is flowed, and the specific surface area is read from the differential pressure. It is a value converted into an average particle diameter. The average particle diameter of the phosphor used in the present embodiment is preferably in the range of 2 μm to 15 μm. Moreover, it is preferable that the phosphor having this average particle diameter value is contained frequently. In addition, it is preferable that the particle size distribution is distributed in a narrow range. As described above, by using a phosphor having a small variation in particle size and particle size distribution, color unevenness is further suppressed, and a light emitting device having a good color tone can be obtained.

  As will be described later, the fluorescent material in the light emitting device can be arranged at various locations in the positional relationship with the light emitting element. For example, a phosphor can be contained in a mold that covers the light emitting element. In addition, the light emitting element and the phosphor may be arranged with a space therebetween, or the phosphor may be directly placed on the light emitting element.

  The reducing atmosphere is an atmosphere containing at least one of nitrogen, hydrogen, argon, carbon dioxide, carbon monoxide, and ammonia. However, firing can be performed in a reducing atmosphere other than these.

_{(J x L y M z O} a N b: Ce, Tb)
Next, another rare earth oxynitride phosphor will be specifically described with reference to examples. Formula rare earth oxynitride-based phosphor according to Example 5-8 _{J x L y M z O a} N b: Ce, represented by Tb. Here, J is Sc, Y, La, Pr, Nd, Sm, Gd, Dy, Ho, Er, Tm, Yb, Lu, L is Si, Ge, Ti, Zr, Hf, M is B, Al, Ga , In. At least one selected from the group of In. O is oxygen, N is nitrogen, 0.5 ≦ x ≦ 8.5, 0.5 ≦ y ≦ 12, 0.001 ≦ z ≦ 5, 0.5 ≦ a ≦ 16, 0.5 ≦ b ≦ 16 This rare earth oxynitride phosphor contains a rare earth element in its composition formula, and is co-activated with Ce and Tb.

(Examples 5 to 8)
Among the rare earth oxynitride phosphors, activated by Ce and Tb, J = Y, L = Si, M = Al, and the general formula is Y ₄ Si _2−m Al _m O _{7 + m} N _2−. Examples 5 to 8 show rare earth oxynitride phosphors represented by _m : Ce, Tb and having a range of m of 0 <m ≦ 0.2. More preferably, the range of m is 0.01 ≦ m ≦ 0.1. If m is in this range, it will be a rare earth oxynitride phosphor that is excited by an excitation light source in a wide range from ultraviolet to visible light and can emit light sharply in a green color by wavelength conversion. In the rare earth oxynitride phosphors of Examples 5 to 8, the Si / Al ratio and the O / N ratio in the composition were changed, and specifically, the value of m in the general formula of the phosphor was m = 0.01, 0.02, 0.05, and 0.1.

  In the method for manufacturing the phosphors of Examples 5 to 8, AlN synthesized by direct nitridation of Al or the like is further added to the raw material of Example 1, and the production method and conditions are the same as those of Example 1. Tables 4, 5 and 6 show the emission characteristics when the phosphors of Examples 5 to 8 were excited at wavelengths of 253.7 nm, 365 nm and 400 nm. The light emission luminance in each example is expressed as a relative value with reference to 100% in Example 1. FIG. 6A shows emission spectra when the rare earth oxynitride phosphors of Examples 5 to 8 are excited at 253.7 nm. Furthermore, each emission spectrum when Example 5-8 was excited by 253.7 nm is shown to FIG.6 (b), (c), (d), (e). Similarly, FIG. 7A shows emission spectra when the rare earth oxynitride phosphors of Examples 5 to 8 are excited at 365 nm. Further, FIGS. 7B, 7C, 7D, and 7E show the emission spectra of Examples 5 to 8 when excited at 365 nm. FIG. 8A shows emission spectra when the rare earth oxynitride phosphors of Examples 5 to 8 are excited at 400 nm. Further, FIGS. 8B, 8C, 8D, and 8E show emission spectra when Examples 5 to 8 are excited at 400 nm, respectively. Moreover, the excitation spectrum of Examples 5-8 is shown to Fig.9 (a). Furthermore, the excitation spectrum of each of Examples 5-8 is shown in FIGS. 9B, 9C, 9D, and 9E.

The rare earth oxynitride phosphors of Examples 5 to 8 are similar to the emission peaks of Examples 1 to 4. That is, as shown in FIGS. 6 to 8, four peak wavelengths were observed, and each peak wavelength was 480 nm to 510 nm, 530 nm to 570 nm, 580 nm to 610 nm, and 610 nm to 640 nm. Among them, the peak wavelength at 530 nm to 570 nm and the half width of 25 nm is the strongest. That is, the rare earth oxynitride phosphors of Examples 5 to 8 have a sharp emission peak near 545 nm, and the chromaticity coordinate values are green where x = 0.31 and y = 0.54. Emitting light. Further, as can be seen from the excitation spectrum of FIG. 9, excitation is possible with a light source of around 430 nm or less.
(Aluminum effect)

Rare earth oxynitride phosphors of the general formula (Y _0.93 Ce _0.02 Tb _0.05 ) ₄ Si _2-x Al _x O _{7 + x} N _2-x (0 <x ≦ 0.2) shown in Examples 5 to 8 are The composition contains aluminum.
Generally, when aluminum is included in the composition of the phosphor, it is possible to increase the particle size or shorten the afterglow. However, the larger the average particle diameter of the phosphor, the higher the emission luminance. However, when the particle diameter of the rare earth oxynitride phosphor is 20 μm or more, it becomes difficult to apply when used in a light emitting device. On the other hand, the smaller the average particle size of the phosphor, the more uniform light is emitted when it is applied to the light emitting surface of the light emitting device, but there are problems that the light emission luminance is low and that it is difficult to handle during application and manufacturing. Therefore, by adjusting the addition amount of aluminum, light emission luminance, quantum efficiency, light emission characteristics such as afterglow, particle size, and the like may be adjusted.

Example 9
Next, a light emitting device using the rare earth oxynitride phosphor as a wavelength conversion member will be described. The rare earth oxynitride phosphor of the present invention can be used in many different applications. For example, it can be used as a phosphor, a display device such as a lamp, a cathode ray tube, a plasma display, a radar, or a liquid crystal display. The material can also be used as an electromagnetic calorimeter, gamma camera, computed tomography scanner, or laser scintillator. These uses are merely exemplary and are not meant to be exhaustive.

  A semiconductor light emitting element is used as an excitation light source for the wavelength conversion member. Here, the light emitting element is used to include not only an element that emits visible light but also an element that emits near ultraviolet light, far ultraviolet light, or the like. In addition to the semiconductor light emitting element, an excitation light source having an emission peak wavelength in the short wavelength region from ultraviolet to visible light, such as a mercury lamp used in an existing fluorescent lamp, can be appropriately used as the excitation light source.

  Here, as Example 9 of the light-emitting device, a bullet-type semiconductor light-emitting device including a light-emitting element that emits light in a short wavelength region from near ultraviolet to visible light is used as an excitation light source. The light emitting element is small in size, has high power efficiency, and emits bright colors. In addition, since the light emitting element is a semiconductor element, there is no fear of a broken ball. In addition, it has excellent initial drivability and is strong against vibration and repeated on / off lighting. Therefore, a light-emitting device that combines a light-emitting element and a rare earth oxynitride phosphor is preferable.

  Specifically, the light emitting element is preferably a nitride semiconductor element containing In or Ga. Thereby, the light emitting element emits light having an emission peak wavelength in the vicinity of 360 nm to 410 nm, and the rare earth oxynitride phosphor is excited by the light from the light emitting element, and exhibits a predetermined emission color. This is because the rare earth oxynitride-based phosphor emits light strongly in the vicinity of 360 nm to 410 nm, and thus a light emitting element in the wavelength region is required. In addition, since the emission spectrum width can be narrowed, the rare earth oxynitride-based phosphor can be excited efficiently, and the light emission from the light emitting device does not substantially affect the color tone change. A spectrum can be emitted.

  Thus, by using the light emitted from the light emitting element as an excitation light source, an efficient light emitting device with low power consumption compared to a conventional mercury lamp can be realized.

  The rare earth oxynitride phosphor also has an advantage that it is easier to process than an oxynitride glass having a conventional glass body (amorphous) structure. Since the glass body has a loose structure, if the reaction conditions in the production process cannot be controlled so as to be strictly uniform, the component ratio in the phosphor is not constant, and chromaticity unevenness occurs. On the other hand, the rare earth oxynitride-based phosphor according to the present embodiment is not a glass body but a powder or granule having crystallinity, and thus is easy to manufacture and process. In addition, since the rare earth oxynitride phosphor can be uniformly dissolved in an organic medium, it is easy to adjust the light emitting plastic or the polymer thin film material.

(Light emitting device)
Next, a bullet-type light emitting device is shown in FIG. 10 as a light emitting device according to Example 9 of the present invention. The light-emitting device 1 is in a concave cup 10 formed by a lead frame 4 made of a conductive member. The light-emitting device 2 is placed on the lead frame 4 and is emitted from the light-emitting element 2. A phosphor 3 that converts the wavelength of at least a part of the emitted light. Positive and negative electrodes 9 formed on the light emitting element 2 are electrically connected to the lead frame 4 via conductive bonding wires 5. Further, the light emitting element 2, the lead frame 4, and the bonding wire 5 are covered with a shell-shaped mold 11 so that the lead frame electrode 4 a which is a part of the lead frame 4 protrudes. The mold 11 is filled with a light-transmitting resin 6, and the resin 6 contains a phosphor 3 that is a wavelength conversion member. The resin 6 is preferably a silicone resin composition, but an insulating resin composition having translucency such as an epoxy resin composition and an acrylic resin composition can also be used. When the lead frame electrode 4 a protruding from the resin 6 is electrically connected to a power source (not shown), light is emitted from the light emitting layer 8 contained in the layer of the light emitting element 2. The emission peak wavelength output from the light emitting layer 8 has an emission spectrum near 500 nm or less in the ultraviolet to blue region. Part of the emitted light excites the phosphor 3, and light having a wavelength different from the wavelength of the main light source from the light emitting layer 8 is obtained.

  The phosphor 3 is preferably mixed in the resin at a substantially uniform ratio. Thereby, light without color unevenness is obtained. However, it can also mix | blend so that the fluorescent substance 3 may be unevenly distributed partially. For example, it is possible to make the phosphor 3 unevenly distributed on the outer surface side of the resin 6 so that the heat generated in the light emitting element 2 is difficult to be transmitted to the phosphor 3, thereby suppressing deterioration of the phosphor 3. . Further, two or more kinds of phosphors may be contained in the resin 6. Thereby, the wavelength of the main light source output from the light emitting layer can be converted by the first phosphor, and light that has been wavelength-converted by the second phosphor can be obtained. By adjusting the combination of the plurality of phosphors, the main light source, the light wavelength-converted by the first phosphor, the light wavelength-converted by the second phosphor, and the main light source directly the second fluorescence Various colors can be expressed by combining light that has been wavelength-converted by the body.

(Example 10)
Next, FIG. 11 shows a light emitting device according to Example 10 of the present invention. In this light-emitting device, members that are the same as those in the light-emitting device according to Example 9 are given the same reference numerals, and descriptions thereof are omitted. In the light emitting device 20 of FIG. 4, the resin 6 including the phosphor 3 is filled only in the concave cup 10 molded by the lead frame 4. The phosphor 3 is not contained in the resin 6b filled in the outside of the cup 10 in the mold 11. The resin containing the phosphor 3 and the type of the resin not containing are preferably the same, but they may be different. In the case of different types of resins, the softness can be changed using the difference in temperature required for each resin to cure.

  In the light emitting device 20 of FIG. 11, since the light emitting element 2 is placed at the substantially central portion of the bottom surface forming the opening in the cup 10, the light emitting element 2 is embedded in the resin 6 including the phosphor 3. The In order for the light from the light emitting layer 8 to be wavelength-converted by the phosphor 3 without unevenness, the light from the light emitting element has only to pass through the phosphor-containing resin uniformly. That is, the phosphor-containing resin film through which light from the light emitting layer 8 passes may be made uniform. Therefore, the size of the cup 10 and the mounting position of the light emitting element 2 may be determined so that the distance from the periphery of the light emitting element 2 to the wall surface and upper part of the cup 10 is uniform. If it is the light-emitting device 20 of FIG. 11, it will become easy to adjust the film thickness of the resin 6 containing the fluorescent substance 3 uniformly.

(Example 11)
Furthermore, FIG. 12 shows a cap-type light-emitting device 30 as a light-emitting device according to Example 11 of the present invention. As the light emitting element 2, a light emitting element having an emission peak wavelength at about 400 nm is used. The light emitting device 30 is configured by covering a cap 31 made of a light transmissive resin in which the phosphor 3a is dispersed on the surface of the mold 11 of the light emitting device 20 of the tenth embodiment.

  The cap 31 has the phosphor 3a uniformly dispersed in the light transmissive resin 6a. The resin 6 a containing the phosphor 3 a is molded into a shape that fits into the shape of the outer surface of the mold 11 of the light emitting device 30. Alternatively, a manufacturing method is also possible in which a light-transmitting resin 6a containing a predetermined in-frame phosphor is put, and then the light emitting device 30 is pushed into the mold and molded. As a specific material of the resin 6a of the cap 31, a transparent resin, silica gel, glass, an inorganic binder, etc. excellent in temperature characteristics and weather resistance, such as an epoxy resin, a urea resin, and a silicone resin, are used. In addition to the above, thermosetting resins such as melamine resins and phenol resins can be used. In addition, thermoplastic resins such as polyethylene, polypropylene, polyvinyl chloride, and polystyrene, thermoplastic rubbers such as styrene-butadiene block copolymer, segmented polyurethane, and the like can also be used. Moreover, you may contain diffusion presence, a barium titanate, a titanium oxide, aluminum oxide, etc. with a fluorescent substance. Moreover, you may contain a light stabilizer and a coloring agent. The phosphor 3a used for the cap 31 can be not only one type but also a mixture of a plurality of phosphors or a layered structure.

  In the light emitting device 20 of Example 10, the resin 6 containing the phosphor 3 is filled so as to cover the light emitting element 2 in the cup 10, but in the light emitting device 30 of Example 11, the cup 10 is fluorescent. It is not necessary to fill the body-containing resin. Thereby, the advantage that the phosphor is not directly affected by the heat generated from the light emitting element 2 is obtained. However, the cup 10 may be filled with the resin 6 containing one or a plurality of phosphors 3, and different phosphors 3 a may be used in the cap 31. Thereby, the light emitted from the light emitting element 2 excites the phosphor 3 and emits light from blue green to green and from yellow to red. A part of the light emitted from the phosphor 3 excites the phosphor 3a of the cap 31, and emits light from green to a yellow region. Due to the mixed color light of these phosphors, white light is emitted from the surface of the cap 31 to the outside. The material of the resin 6 filled in the cup 10 may be different from or the same as the material of the resin 6a filled in the cap 31.

(Example 12)
Furthermore, as a light emitting device according to Example 12 of the present invention, a surface mount type light emitting device 100 is shown in FIG. FIG. 13A is a plan view, and FIG. 13B is a cross-sectional view. As the light-emitting element 101, an ultraviolet-excited nitride semiconductor light-emitting element can be used. The light-emitting element 101 may be a blue-excited nitride semiconductor light-emitting element. Here, the light emitting element 101 excited by ultraviolet light will be described as an example. The light emitting element 101 uses a nitride semiconductor light emitting element having an InGaN semiconductor with an emission peak wavelength of about 370 nm as a light emitting layer. The light-emitting element 101 includes a p-type semiconductor layer and an n-type semiconductor layer (not shown), and the p-type semiconductor layer and the n-type semiconductor layer have a conductive wire 104 connected to the lead electrode 102. Is formed. An insulating sealing material 103 is formed so as to cover the outer periphery of the lead electrode 102 to prevent a short circuit. A light-transmitting window 107 extending from a Kovar lid 106 at the top of the package 105 is provided above the light emitting element 101. On the inner surface of the translucent window 107, a uniform mixture of the phosphors 3, 3a and the coating member 109 is applied to almost the entire surface.

  As a specific LED light emitting element 101 structure, an n-type GaN layer which is an undoped nitride semiconductor on a sapphire substrate, a GaN layer where an Si-doped n-type electrode is formed to become an n-type contact layer, an undoped nitride The single quantum well structure includes an n-type GaN layer that is a semiconductor, an n-type AlGaN layer that is a nitride semiconductor, and then an InGaN layer that constitutes a light-emitting layer. On the light emitting layer, an AlGaN layer as a p-type cladding layer doped with Mg and a GaN layer as a p-type contact layer doped with Mg are sequentially laminated. (The sapphire substrate is a buffer layer in which a GaN layer is formed at a low temperature. The p-type semiconductor is annealed at 400 ° C. or higher after film formation.) Nitriding on the sapphire substrate by etching The surface of each pn contact layer is exposed on the same side of the physical semiconductor. An n-electrode is formed in a strip shape on the exposed n-type contact layer, and a translucent p-electrode made of a metal thin film is formed on almost the entire surface of the p-type contact layer that remains without being cut. A pedestal electrode is formed on the p-electrode in parallel with the n-electrode using a sputtering method.

  Next, each electrode of the die-bonded light emitting element 101 and each lead electrode 102 exposed from the bottom of the package recess are electrically connected by a conductive wire 104 such as an Ag wire. After sufficiently removing moisture in the recess of the package, sealing is performed with a Kovar lid 106 having a glass window 107 at the center, and seam welding is performed. The glass window portion contains oxynitride phosphors 3 and 3a which are wavelength conversion members with respect to a slurry made of 90 wt% nitrocellulose and 10 wt% γ-alumina in advance, and the translucent window portion 107 of the lid 106. The color conversion member is configured by applying to the back surface of the film and curing by heating at 220 ° C. for 30 minutes. The light output from the light-emitting element 101 of the light-emitting device 100 thus formed excites the phosphors 3 and 3a, and a light-emitting device capable of emitting a desired color with high luminance can be obtained. As a result, it is possible to obtain a light emitting device that is extremely easy to adjust the chromaticity and has excellent mass productivity and reliability.

  The rare earth oxynitride phosphor of the present invention and a light-emitting device using the same emit light using a fluorescent display tube, display, PDP, CRT, FL, FED, projection tube, etc., particularly a blue light emitting diode or an ultraviolet light emitting diode as a light source. It can be suitably used for a white illumination light source, an LED display, a backlight light source, a traffic light, an illumination switch, various sensors, various indicators, and the like that have extremely excellent characteristics.

The emission spectra when the rare earth oxynitride phosphors of Comparative Example 1 and Examples 1 to 4 are excited at 253.7 nm are shown. The emission spectra when the rare earth oxynitride phosphors of Comparative Example 1 and Examples 1 to 4 are excited at 365 nm are shown. The emission spectrum when the rare earth oxynitride phosphor of Comparative Example 1 is excited at 365 nm is shown. The emission spectrum when the rare earth oxynitride phosphor of Example 1 is excited at 365 nm is shown. 2 shows an emission spectrum when the rare earth oxynitride phosphor of Example 2 is excited at 365 nm. The emission spectrum when the rare earth oxynitride phosphor of Example 3 is excited at 365 nm is shown. The emission spectrum when the rare earth oxynitride phosphor of Example 4 is excited at 365 nm is shown. The emission spectra when the rare earth oxynitride phosphors of Comparative Example 1 and Examples 1 to 4 are excited at 400 nm are shown. The emission spectrum when the rare earth oxynitride phosphor of Comparative Example 1 is excited at 400 nm is shown. The emission spectrum when the rare earth oxynitride phosphor of Example 1 is excited at 400 nm is shown. 2 shows an emission spectrum when the rare earth oxynitride phosphor of Example 2 is excited at 400 nm. 2 shows an emission spectrum when the rare earth oxynitride phosphor of Example 3 is excited at 400 nm. 2 shows an emission spectrum when the rare earth oxynitride phosphor of Example 4 is excited at 400 nm. It is a graph which shows the excitation spectrum of the rare earth oxynitride type | system | group fluorescent substance of the comparative example 1 and Examples 1-4. (A) is a 1000 times magnified photograph of the rare earth oxynitride phosphor of Example 1, and (b) is a 5000 times magnified photograph of the rare earth oxynitride phosphor of Example 1. The emission spectrum when the rare earth oxynitride phosphors of Examples 5 to 8 are excited at 253.7 nm is shown. The emission spectrum when the rare earth oxynitride phosphor of Example 5 is excited at 253.7 nm is shown. The emission spectrum when the rare earth oxynitride phosphor of Example 6 is excited at 253.7 nm is shown. The emission spectrum when the rare earth oxynitride phosphor of Example 7 is excited at 253.7 nm is shown. The emission spectrum when the rare earth oxynitride phosphor of Example 8 is excited at 253.7 nm is shown. The emission spectrum when the rare earth oxynitride phosphors of Examples 5 to 8 are excited at 365 nm is shown. The emission spectrum when the rare earth oxynitride phosphor of Example 5 is excited at 365 nm is shown. The emission spectrum when the rare earth oxynitride phosphor of Example 6 is excited at 365 nm is shown. The emission spectrum when the rare earth oxynitride phosphor of Example 7 is excited at 365 nm is shown. The emission spectrum when the rare earth oxynitride phosphor of Example 8 is excited at 365 nm is shown. The emission spectrum when the rare earth oxynitride phosphors of Examples 5 to 8 are excited at 400 nm is shown. The emission spectrum when the rare earth oxynitride phosphor of Example 5 is excited at 400 nm is shown. The emission spectrum when the rare earth oxynitride phosphor of Example 6 is excited at 400 nm is shown. The emission spectrum when the rare earth oxynitride phosphor of Example 7 is excited at 400 nm is shown. The emission spectrum when the rare earth oxynitride phosphor of Example 8 is excited at 400 nm is shown. The excitation spectrum of the rare earth oxynitride type | system | group fluorescent substance of Examples 5-8 is shown. The excitation spectrum of the rare earth oxynitride phosphor of Example 5 is shown. The excitation spectrum of the rare earth oxynitride phosphor of Example 6 is shown. The excitation spectrum of the rare earth oxynitride phosphor of Example 7 is shown. The excitation spectrum of the rare earth oxynitride phosphor of Example 8 is shown. It is sectional drawing which shows the bullet-type light-emitting device based on Example 9 of this invention. It is sectional drawing which shows the bullet-type light-emitting device based on Example 10 of this invention. It is sectional drawing which shows the bullet-type light-emitting device based on Example 11 of this invention. (A) is a top view which shows the surface mount type light-emitting device based on Example 12, (b) is sectional drawing which shows the light-emitting device of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light-emitting device 2 ... Light-emitting element 3 ... Rare earth oxynitride type phosphor 3a ... Phosphor 4 ... Lead frame 4a ... Lead frame electrode 5 ... Bonding wire 6, 6a, 6b ... Resin 8 ... Light emitting layer 9 ... Electrode 10 ... Cup 11 ... Mold 20 ... Light emitting device 30 ... Light emitting device 31 ... Cap 100 ... Light emitting device 101 ... Light emitting element 102 ... Lead electrode 103 ... Insulating encapsulant 104 ... Conductive wire 105 ... Package 106 ... Kovar lid 107 ... Translucent Sex window (glass window)
109 ... Coating member

Claims (6)

The general formula is Y ₄ Si ₂ O ₇ N ₂ : Ce, Tb,
A rare earth oxynitride phosphor that is co-activated with cerium and terbium and absorbs ultraviolet or blue light to emit green light. The rare earth oxynitride phosphor according to claim 1 ,
Excited by excitation light from an excitation light source having an emission peak wavelength of 460 nm or less,
A rare earth oxynitride phosphor which emits fluorescence having a peak wavelength in a wavelength range of 530 nm to 570 nm. The general formula is Y ₄ Si _2-m Al _m O _{7 + m} N _2-m : Ce, Tb,
The range of m is 0 <m ≦ 0.2,
A rare earth oxynitride phosphor that is co-activated with cerium and terbium and absorbs ultraviolet or blue light to emit green light. The rare earth oxynitride phosphor according to claim 3 ,
Excited by excitation light from an excitation light source having an emission peak wavelength of 460 nm or less,
A rare earth oxynitride phosphor which emits fluorescence having a peak wavelength in a wavelength range of 530 nm to 570 nm. The rare earth oxynitride phosphor according to any one of claims 1 to 4 ,
A rare earth oxynitride phosphor, wherein the phosphor has an average particle size of 2 μm or more and 20 μm or less. An excitation light source having a first emission spectrum emitting a wavelength of 460 nm or less;
One or more wavelength conversion members that absorb at least a portion of the first emission spectrum and emit the second emission spectrum;
A light emitting device comprising:
The light emitting device, wherein the wavelength conversion member includes the rare earth oxynitride phosphor according to any one of claims 1 to 5 .