WO2012036016A1 - Phosphor and light-emitting device - Google Patents

Abstract

Provided is a phosphor comprising a europium-activated sialon crystal indicated by formula (1), that emits a green light by being excited by ultraviolet light-blue light, and includes carbon at a ratio of 1-5,000 ppm. Formula (Sr_1-x, Eu_x)_αSi_βAl_γO_δN_ω (1) (wherein, x is 0<x<1, α is 0<α≦4, and β, γ, δ, and ω are numerals whose converted numerical values when α is 3 satisfy 9<β≦15, 1≦γ≦5, 0.5≦δ≦3, and 10≦ω≦25).

Description

Phosphor and light emitting device

Embodiments described herein relate generally to a phosphor and a light emitting device.

The phosphor powder is used, for example, in a light-emitting device such as a light-emitting diode (LED). The light emitting device includes, for example, a semiconductor light emitting element that is arranged on a substrate and emits light of a predetermined color, and a phosphor that emits visible light when excited by light such as ultraviolet light and blue light emitted from the semiconductor light emitting element. A light emitting part including powder in a transparent resin cured product which is a sealing resin.

As the semiconductor light emitting element of the light emitting device, for example, GaN, InGaN, AlGaN, InGaAlP or the like is used. Examples of the phosphor of the phosphor powder include a blue phosphor, a green phosphor, and a yellow phosphor that are excited by light emitted from the semiconductor light emitting element and emit blue light, green light, yellow light, and red light, respectively. A phosphor, a red phosphor or the like is used.

The light emitting device can adjust the color of the emitted light by including various phosphor powders such as a red phosphor in the sealing resin. That is, by using a combination of a semiconductor light emitting element and a phosphor powder that absorbs light emitted from the semiconductor light emitting element and emits light in a predetermined wavelength region, the light emitted from the semiconductor light emitting element and the phosphor powder are used. It becomes possible to emit light in the visible light region and white light by the action of the light emitted from.
Conventionally, a phosphor having a europium activated sialon (Si—Al—O—N) structure containing strontium is known as the phosphor.

International Publication No. 2007/105631

However, phosphors with a sialon (Si—Al—O—N) structure have a problem that when used in a high temperature region of about 100 ° C., the emission intensity is lower than when used in a normal temperature (25 ° C.) region. was there. Hereinafter, the fact that the emission intensity of the phosphor does not decrease or the degree of decrease when used in a high temperature region of about 100 ° C. compared to when used in a normal temperature region is referred to as good temperature characteristics. In addition, the fact that the emission intensity of the phosphor is greatly reduced when used in a high temperature region of about 100 ° C. compared to the case where it is used in a normal temperature region is referred to as poor temperature characteristics.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a phosphor and a light-emitting device having good temperature characteristics.

The phosphor and the light emitting device of the embodiment have been completed by finding that the temperature characteristics are improved by adding a specific amount of carbon to a phosphor having a specific composition.

The phosphor of the embodiment solves the above-mentioned problems, and the following general formula (1)

[Chemical 1]
General formula: (Sr _1-x , Eu _x ) _α Si _β Al _γ O _δ N _ω (1)
(Wherein x is 0 <x <1, α is 0 <α ≦ 4, and β, γ, δ and ω are values converted when α is 3, 9 <β ≦ 15, 1 ≦ γ ≦ 5, 0.5 ≦ δ ≦ 3, 10 ≦ ω ≦ 25)

Is a phosphor that emits green light when excited by ultraviolet light to blue light, and contains carbon at a ratio of 1 ppm to 5000 ppm.

In addition, the phosphor of the embodiment solves the above-mentioned problems, and the following general formula (2)

[Chemical 2]
General formula: (Sr _1-x , Eu _x ) _α Si _β Al _γ O _δ N _ω (2)
(Wherein x is 0 <x <1, α is 0 <α ≦ 3, and β, γ, δ and ω are values converted when α is 3, 5 ≦ β ≦ 9, 1 ≦ γ ≦ 5, 0.5 ≦ δ ≦ 2, 5 ≦ ω ≦ 15)

Is a phosphor that emits red light when excited by ultraviolet light to blue light, and contains carbon at a ratio of 1 ppm to 5000 ppm.

Furthermore, the light-emitting device of the embodiment solves the above-described problems. A substrate, a semiconductor light-emitting element that is arranged on the substrate and emits ultraviolet light to blue light, and a light-emitting surface of the semiconductor light-emitting element are provided. And a light emitting unit including a phosphor that emits visible light when excited by light emitted from the semiconductor light emitting element, and the phosphor includes the phosphor of the embodiment. .

An example of the emission spectrum of a light-emitting device. 6 shows another example of an emission spectrum of the light emitting device.

The phosphor and the light emitting device of the embodiment will be described. The phosphor of the embodiment includes a green phosphor that emits green light when excited by ultraviolet light to blue light, and a red phosphor that emits red light when excited by ultraviolet light to blue light.

[Green phosphor]
The green phosphor has the following general formula (1)

[Chemical formula 3]
General formula: (Sr _1-x , Eu _x ) _α Si _β Al _γ O _δ N _ω (1)
(Wherein x is 0 <x <1, α is 0 <α ≦ 4, and β, γ, δ and ω are values converted when α is 3, 9 <β ≦ 15, 1 ≦ γ ≦ 5, 0.5 ≦ δ ≦ 3, 10 ≦ ω ≦ 25)

Is a phosphor that emits green light when excited by ultraviolet to blue light. Hereinafter, the europium-activated sialon phosphor containing Sr is also referred to as “Sr sialon green phosphor”. The crystal system of Sr sialon green phosphor is orthorhombic.

In the general formula (1), x is a number that satisfies 0 <x <1, preferably 0.025 ≦ x ≦ 0.5, and more preferably 0.25 ≦ x ≦ 0.5.
When x is 0, the fired body obtained in the firing step is not a phosphor, and when x is 1, the luminous efficiency of the green phosphor powder is low.

Further, the smaller the x is in the range of 0 <x <1, the easier it is for the emission efficiency of the green phosphor to decrease. Furthermore, as x becomes larger in the range of 0 <x <1, the concentration quenching is more likely to occur due to the excessive Eu concentration.
For this reason, x is preferably a number satisfying 0.025 ≦ x ≦ 0.5, and more preferably a number satisfying 0.25 ≦ x ≦ 0.5, even if 0 <x <1.

In the general formula (1), the total subscript (1-x) α of Sr is a number satisfying 0 <(1-x) α <4. Further, the total subscript xα of Eu is a number satisfying 0 <xα <4. That is, in the general formula (1), the total subscripts of Sr and Eu are numbers exceeding 0 and less than 4, respectively.

In the general formula (1), β, γ, δ and ω are numerical values converted when α is 3.
In the general formula (1), β, which is a subscript of Si, is a number satisfying 9 <β ≦ 15 as a numerical value converted when α is 3.
In the general formula (1), γ, which is a subscript of Al, is a number satisfying 1 ≦ γ ≦ 5 as a numerical value converted when α is 3.
In the general formula (1), δ, which is a subscript of O, is a number satisfying 0.5 ≦ δ ≦ 3 when a value of α is 3.
In the general formula (1), ω, which is a subscript of N, is a number satisfying 10 ≦ ω ≦ 25 when the numerical value converted when α is 3.

In the general formula (1), when the subscripts β, γ, δ and ω are numbers outside the above ranges, the composition of the phosphor obtained by firing is an orthorhombic system represented by the general formula (1). The Sr sialon green phosphor may be different.
The Sr sialon green phosphor represented by the general formula (1) usually takes the form of a single crystal powder.

The Sr sialon green phosphor represented by the general formula (1) contains carbon in a proportion of 1 ppm to 5000 ppm, preferably 5 ppm to 1000 ppm, more preferably 50 ppm to 300 ppm.

Here, the carbon content is the ratio of the mass of carbon to the total mass of the green phosphor including carbon. The Sr sialon green phosphor usually takes the form of a single crystal powder, but a large amount of carbon exists in the vicinity of the surface of each particle constituting the phosphor powder.

When the carbon content is within the above range, the Sr sialon green phosphor is preferable because the luminance at room temperature (25 ° C.) is high and the decrease in luminance at a high temperature of about 150 ° C. is small.
If the carbon content is less than 1 ppm, the Sr sialon green phosphor may have a significant decrease in luminance at high temperatures.
If the carbon content exceeds 5000 ppm, the Sr sialon green phosphor may have low brightness at room temperature.

The Sr sialon green phosphor powder has an average particle size of preferably 1 μm to 100 μm, more preferably 5 μm to 20 μm, and even more preferably 10 μm to 20 μm. Here, the average particle diameter is a value measured by the Coulter counter method, it means the median D ₅₀ of the cumulative volume distribution.

When the average particle size of the Sr sialon green phosphor powder is less than 1 μm or more than 100 μm, the Sr sialon green phosphor powder or other color phosphor powders are dispersed in the cured transparent resin, and the semiconductor light emission When a light-emitting device having a structure in which green light or other color light is emitted by irradiation of ultraviolet light to blue light from the element, the light extraction efficiency from the light-emitting device may be reduced.
The Sr sialon green phosphor represented by the general formula (1) is excited when it receives ultraviolet light to blue light and emits green light.

Here, ultraviolet light to blue light means light having a peak wavelength in the wavelength range of ultraviolet light to blue light. The ultraviolet light to blue light is preferably light having a peak wavelength in the range of 370 nm to 470 nm.

The Sr sialon green phosphor represented by the general formula (1) excited by receiving ultraviolet light to blue light emits green light having an emission peak wavelength in the range of 500 nm to 540 nm.

[Red phosphor]
The red phosphor has the following general formula (2)

[Chemical formula 4]
General formula: (Sr _1-x , Eu _x ) _α Si _β Al _γ O _δ N _ω (2)
(Wherein x is 0 <x <1, α is 0 <α ≦ 3, and β, γ, δ and ω are values converted when α is 3, 5 ≦ β ≦ 9, 1 ≦ γ ≦ 5, 0.5 ≦ δ ≦ 2, 5 ≦ ω ≦ 15)

Is a phosphor that emits red light when excited by ultraviolet to blue light. Hereinafter, the europium activated sialon phosphor containing Sr is also referred to as “Sr sialon red phosphor”. The crystal system of Sr sialon red phosphor is orthorhombic.

In the general formula (2), x is a number that satisfies 0 <x <1, preferably 0.025 ≦ x ≦ 0.5, and more preferably 0.25 ≦ x ≦ 0.5.
When x is 0, the fired body obtained in the firing step is not a phosphor, and when x is 1, the luminous efficiency of the red phosphor powder is low.

Also, the smaller the x is in the range of 0 <x <1, the easier it is for the luminous efficiency of the red phosphor to decrease. Furthermore, as x becomes larger in the range of 0 <x <1, the concentration quenching is more likely to occur due to the excessive Eu concentration.
For this reason, x is preferably a number satisfying 0.025 ≦ x ≦ 0.5, and more preferably a number satisfying 0.25 ≦ x ≦ 0.5, even if 0 <x <1.

In the general formula (2), the total subscript (1-x) α of Sr is a number satisfying 0 <(1-x) α <3. Further, the overall subscript xα of Eu is a number satisfying 0 <xα <3. That is, in the general formula (2), the total subscripts of Sr and Eu are numbers exceeding 0 and less than 3, respectively.

In the general formula (2), β, γ, δ, and ω are numerical values converted when α is 3.
In the general formula (2), β, which is a subscript of Si, is a number satisfying 5 ≦ β ≦ 9 when the numerical value converted when α is 3.
In the general formula (2), γ, which is a subscript of Al, is a number satisfying 1 ≦ γ ≦ 5 when the numerical value converted when α is 3.
In the general formula (2), δ, which is a subscript of O, is a number satisfying 0.5 ≦ δ ≦ 2 when the value α is 3.
In the general formula (2), ω, which is a subscript of N, is a number satisfying 5 ≦ ω ≦ 15 as a numerical value converted when α is 3.

In the general formula (2), when the subscripts β, γ, δ and ω are numbers outside the above ranges, the composition of the phosphor obtained by firing is an orthorhombic system represented by the general formula (2). The Sr sialon red phosphor may be different.
The Sr sialon red phosphor represented by the general formula (2) is usually in the form of a single crystal powder.

The Sr sialon red phosphor represented by the general formula (2) contains carbon in a proportion of 1 ppm to 5000 ppm, preferably 5 ppm to 1000 ppm, more preferably 50 ppm to 300 ppm.

Here, the carbon content is the ratio of the mass of carbon to the total mass of the red phosphor including carbon. The Sr sialon red phosphor usually takes the form of a single crystal powder, but a large amount of carbon exists in the vicinity of the surface of each particle constituting the phosphor powder.

When the carbon content is within the above range, the Sr sialon red phosphor is preferable because the luminance at room temperature (25 ° C.) is high and the decrease in luminance at a high temperature of about 150 ° C. is small.
If the carbon content is less than 1 ppm, the Sr sialon red phosphor may have a significant decrease in luminance at high temperatures.
If the carbon content exceeds 5000 ppm, the Sr sialon red phosphor may have low brightness at room temperature.

The Sr sialon red phosphor powder has an average particle size of preferably 1 μm to 100 μm, more preferably 5 μm to 20 μm, and even more preferably 10 μm to 20 μm. Here, the average particle diameter is a value measured by the Coulter counter method, it means the median D ₅₀ of the cumulative volume distribution.

When the average particle size of the Sr sialon red phosphor powder is less than 1 μm or more than 100 μm, the Sr sialon red phosphor powder or other color phosphor powders are dispersed in the cured transparent resin, and the semiconductor light emission When a light-emitting device having a structure in which red light or other color light is emitted by irradiation of ultraviolet light to blue light from the element, the light extraction efficiency from the light-emitting device may be reduced.
The Sr sialon red phosphor represented by the general formula (2) is excited when it receives ultraviolet light to blue light and emits red light.

Here, ultraviolet light to blue light means light having a peak wavelength in the wavelength range of ultraviolet light to blue light. The ultraviolet light to blue light is preferably light having a peak wavelength in the range of 370 nm to 470 nm.

The Sr sialon red phosphor represented by the general formula (2) excited by receiving ultraviolet light to blue light emits red light having an emission peak wavelength in the range of 550 nm to 650 nm.

[Method for producing green phosphor and red phosphor]
The Sr sialon green phosphor represented by the general formula (1) and the Sr sialon red phosphor represented by the general formula (2) are, for example, strontium carbonate SrCO ₃ , aluminum nitride AlN, silicon nitride Si ₃ N ₄ , Each phosphor raw material such as europium oxide Eu ₂ O ₃ and silicon carbide SiC can be dry-mixed to prepare a phosphor raw material mixture, and this phosphor raw material mixture can be produced by firing in a nitrogen atmosphere.

The Sr sialon green phosphor represented by the general formula (1) contains more nitrogen N than the Sr sialon red phosphor represented by the general formula (2). For this reason, the Sr sialon green phosphor represented by the general formula (1) and the Sr sialon red phosphor represented by the general formula (2) are SrCO ₃ , AlN, Si ₃ N in the phosphor raw material mixture. ₄ , Eu ₂ O ₃ , SiC, and other raw materials can be mixed, or the amount of nitrogen gas in the furnace during firing can be changed. For example, when the pressure of nitrogen gas in the furnace during firing is lowered to about 1 atm, the Sr sialon red phosphor represented by the general formula (2) can be easily obtained, and when the pressure is increased to about 7 atm, the general formula ( The Sr sialon green phosphor represented by 1) is easily obtained.
The phosphor raw material mixture may further contain strontium chloride SrCl ₂ as a reaction accelerator as a fluxing agent.
The phosphor raw material mixture is filled in a refractory crucible. As the refractory crucible, for example, a boron nitride crucible, a carbon crucible or the like is used.

The phosphor raw material mixture filled in the refractory crucible is fired. As the baking apparatus, an apparatus is used in which the composition and pressure of the internal baking atmosphere in which the refractory crucible is arranged, the baking temperature and the baking time are maintained under predetermined conditions. For example, an electric furnace is used as such a baking apparatus.
As the firing atmosphere, N ₂ -containing gas is used. As the N ₂ -containing gas, for example, N ₂ gas or a mixed gas of N ₂ and H ₂ is used.

In general, when a phosphor powder is fired from a phosphor raw material mixture, an appropriate amount of oxygen O disappears from the phosphor raw material mixture containing excessive oxygen O with respect to the phosphor powder. Obtain body powder.
N ₂ in the firing atmosphere has a function of eliminating an appropriate amount of oxygen O from the phosphor raw material mixture when the phosphor powder is fired from the phosphor raw material mixture.

Further, H ₂ in the firing atmosphere acts as a reducing agent when the phosphor powder is fired from the phosphor raw material mixture, and more oxygen O is lost from the phosphor raw material mixture than N ₂ .

Therefore, when the H ₂ contained in the N ₂ containing gas, as compared to the case where the N ₂ containing gas does not contain H _2, to shorten the baking time. However, if the content of H ₂ in the N ₂ -containing gas is too large, the composition of the obtained phosphor powder is represented by the Sr sialon green phosphor represented by the general formula (1) or the general formula (2). This is different from the Sr sialon red phosphor, and for this reason, the emission intensity of the phosphor powder may be weakened.

N ₂ containing gas, if a mixed gas of _{N 2} gas or _{N 2} and _{H 2,,} the molar ratio of _{N 2} and _{H 2} in _{N 2} containing gas _is, N 2: _{H 2} is usually 10 : 0 to 1: 9, preferably 8: 2 to 2: 8, more preferably 6: 4 to 4: 6.

When the molar ratio of N ₂ and H ₂ in the N ₂ -containing gas is within the above range, that is, usually 10: 0 to 1: 9, a high-quality unit with few defects in the crystal structure can be obtained in a short time. Crystalline phosphor powder can be obtained.

The molar ratio of N ₂ and H ₂ in N ₂ containing gas is a N ₂ and H ₂ which is continuously fed into the chamber of the calciner, N ₂ and the ratio of the flow rate the ratio of H ₂ The above ratio, that is, usually 10: 0 to 1: 9, can be obtained by continuously supplying the gas in the chamber and continuously discharging the mixed gas in the chamber.
It is preferable that the N ₂ -containing gas as the firing atmosphere be circulated in a chamber of the firing apparatus so as to form an air flow because firing is performed uniformly.
The pressure of the N ₂ -containing gas that is the firing atmosphere is usually 0.1 MPa (approximately 1 atm) to 1.0 MPa (approximately 10 atm).

When the pressure of the firing atmosphere is less than 0.1 MPa, the composition of the phosphor powder obtained after firing is represented by the general formula (1) as compared with the phosphor raw material mixture charged in the crucible before firing. This is likely to be different from the green phosphor or the Sr sialon red phosphor represented by the general formula (2), which may cause the emission intensity of the phosphor powder to be weak.

If the pressure of the firing atmosphere exceeds 1.0 MPa, the firing conditions are not particularly changed even when the pressure is 1.0 MPa or less, which is not preferable because energy is wasted.

In the case of producing the Sr sialon green phosphor represented by the general formula (1), the pressure of the N ₂ -containing gas that is the firing atmosphere is preferably 0.5 MPa to 0.8 MPa, more preferably 0.8 MPa. 6 MPa to 0.8 MPa.

Further, when the Sr sialon red phosphor represented by the general formula (2) is manufactured, the pressure of the N ₂ -containing gas that is the firing atmosphere is preferably 0.1 MPa to 0.4 MPa, more preferably 0. 1 MPa to 0.2 MPa.
The firing temperature is usually 1400 ° C. to 2000 ° C., preferably 1700 ° C. to 1900 ° C.
When the firing temperature is in the range of 1400 ° C. to 2000 ° C., a high-quality single crystal phosphor powder with few crystal structure defects can be obtained by firing in a short time.

If the calcination temperature is less than 1400 ° C., the resulting phosphor powder may be excited by ultraviolet to blue light and the emitted light may not have a desired color. That is, when it is desired to manufacture the Sr sialon green phosphor represented by the general formula (1), the color of light emitted by being excited by ultraviolet to blue light becomes a color other than green, or the general formula (2) When it is desired to produce the Sr sialon red phosphor represented, the color of the light that is excited and emitted by ultraviolet to blue light may be other than red.

When the firing temperature exceeds 2000 ° C., the composition of the phosphor powder obtained by increasing the degree of disappearance of N and O during firing is Sr sialon green phosphor represented by the general formula (1) or the general formula ( It is easy to differ from the Sr sialon red phosphor represented by 2), and for this reason, the emission intensity of the phosphor powder may be weakened.
The firing time is usually 0.5 hours to 20 hours, preferably 2 hours to 10 hours, more preferably 3 hours to 5 hours.

When the firing time is less than 0.5 hours or exceeds 20 hours, the composition of the obtained phosphor powder is represented by the Sr sialon green phosphor represented by the general formula (1) or the general formula (2). This is different from the Sr sialon red phosphor, and for this reason, the emission intensity of the phosphor powder may be weakened.

The firing time is preferably a short time within a range of 0.5 to 20 hours when the firing temperature is high, and a long time within a range of 0.5 to 20 hours when the firing temperature is low. It is preferable that

In the fire-resistant crucible after firing, a fired body made of phosphor powder is generated. The fired body is usually in the form of a weak and solid lump. When the fired body is lightly crushed using a pestle or the like, a phosphor powder is obtained. The phosphor powder obtained by crushing becomes a powder of Sr sialon green phosphor represented by general formula (1) or Sr sialon red phosphor represented by general formula (2).

According to the green phosphor and the red phosphor of the embodiment, a phosphor having good temperature characteristics can be obtained.

[Light emitting device]
The light emitting device is a light emitting device using the Sr sialon green phosphor represented by the general formula (1) or the Sr sialon red phosphor represented by the general formula (2).
Specifically, the light-emitting device is formed on the substrate, the semiconductor light-emitting element disposed on the substrate and emitting ultraviolet light to blue light, and the light-emitting surface of the semiconductor light-emitting element. A phosphor that emits visible light when excited by the emitted light, and the phosphor is a Sr sialon green phosphor represented by the general formula (1) or Sr represented by the general formula (2). A light emitting device including a sialon red phosphor.

The light emitting device emits green light from the emission surface of the light emitting device if the phosphor contained in the light emitting portion is only Sr sialon green phosphor, and the phosphor contained in the light emitting portion is only Sr sialon red phosphor. If there is, red light is emitted from the emission surface of the light emitting device.

In the light emitting device, the light emitting unit includes a phosphor such as a blue phosphor and a red phosphor in addition to the Sr sialon green phosphor, or a blue phosphor and a green phosphor in addition to the Sr sialon red phosphor. White light emitting device that emits white light from the emitting surface of the light emitting device by mixing the light of each color such as red light, blue light, and green light emitted from the phosphors of each color. It can also be.

Furthermore, the light emitting device may contain other green phosphors in addition to Sr sialon green phosphors, or may contain other red phosphors in addition to Sr sialon red phosphors.

Note that the light emitting device may include a Sr sialon green phosphor represented by the general formula (1) and a Sr sialon red phosphor represented by the general formula (2) as phosphors. When both the Sr sialon green phosphor and the Sr sialon red phosphor represented by the general formula (2) are included as the phosphor, a light emitting device with good temperature characteristics can be obtained.

(substrate)
As the substrate, for example, ceramics such as alumina and aluminum nitride (AlN), glass epoxy resin, and the like are used. It is preferable that the substrate is an alumina plate or an aluminum nitride plate because the thermal conductivity is high and the temperature rise of the LED light source can be suppressed.

(Semiconductor light emitting device)
The semiconductor light emitting element is disposed on the substrate.
As the semiconductor light emitting element, a semiconductor light emitting element that emits ultraviolet light to blue light is used. Here, ultraviolet light to blue light means light having a peak wavelength in the wavelength range of ultraviolet light to blue light. The ultraviolet light to blue light is preferably light having a peak wavelength in the range of 370 nm to 470 nm.

Examples of semiconductor light emitting devices that emit ultraviolet light to blue light include ultraviolet light emitting diodes, purple light emitting diodes, blue light emitting diodes, ultraviolet laser diodes, purple laser diodes, and blue laser diodes. When the semiconductor light emitting element is a laser diode, the peak wavelength means a peak oscillation wavelength.

(Light emitting part)
The light emitting section includes a phosphor that is excited by ultraviolet light to blue light, which is emitted light from the semiconductor light emitting element, and emits visible light in the transparent resin cured product, and covers the light emitting surface of the semiconductor light emitting element. Formed as follows.

The phosphor used in the light emitting unit includes at least the above-described Sr sialon green phosphor or Sr sialon red phosphor. The phosphor may include both Sr sialon green phosphor and Sr sialon red phosphor.

Moreover, the phosphor used in the light emitting unit may include a Sr sialon green phosphor or a Sr sialon red phosphor and a phosphor other than the Sr sialon green phosphor or the Sr sialon red phosphor. As a phosphor other than the Sr sialon green phosphor or the Sr sialon red phosphor, for example, a red phosphor, a blue phosphor, a green phosphor, a yellow phosphor, a purple phosphor, an orange phosphor and the like can be used. As the phosphor, a powdery one is usually used.
In the light emitting part, the phosphor is contained in the cured transparent resin. Usually, the phosphor is dispersed in a cured transparent resin.

The transparent resin cured product used for the light emitting part is obtained by curing a transparent resin, that is, a highly transparent resin. As the transparent resin, for example, a silicone resin or an epoxy resin is used. Silicone resins are preferred because they have higher UV resistance than epoxy resins. Among silicone resins, dimethyl silicone resin is more preferable because of its high UV resistance.

The light emitting part is preferably composed of 20 to 1000 parts by mass of the transparent resin cured product with respect to 100 parts by mass of the phosphor. When the ratio of the transparent resin cured product to the phosphor is within this range, the light emission intensity of the light emitting part is high.

The film thickness of the light emitting part is usually 80 μm or more and 800 μm or less, preferably 150 μm or more and 600 μm or less. When the film thickness of the light emitting portion is 80 μm or more and 800 μm or less, practical brightness can be ensured with a small amount of leakage of ultraviolet light to blue light emitted from the semiconductor light emitting element. When the film thickness of the light emitting part is 150 μm or more and 600 μm or less, light emitted from the light emitting part can be brightened.

For example, the light emitting unit first mixes a transparent resin and a phosphor to prepare a phosphor slurry in which the phosphor is dispersed in the transparent resin, and then applies the phosphor slurry to the semiconductor light emitting device and the inner surface of the globe. It is obtained by curing.

When the phosphor slurry is applied to the semiconductor light emitting element, the light emitting portion is in contact with and covered with the semiconductor light emitting element. Further, when the phosphor slurry is applied to the inner surface of the globe, the light emitting portion is formed on the inner surface of the globe while being separated from the semiconductor light emitting element. A light emitting device in which the light emitting portion is formed on the inner surface of the globe is referred to as a remote phosphor type LED light emitting device.
The phosphor slurry can be cured by heating to 100 ° C. to 160 ° C., for example.

FIG. 1 is an example of an emission spectrum of the light emitting device.
Specifically, a violet LED that emits violet light having a peak wavelength of 400 nm is used as a semiconductor light emitting element, and Sr sialon represented by Sr _2.7 Eu _0.3 Si ₁₃ Al ₃ O ₂ N ₂₁ as a phosphor. It is an emission spectrum of a green light emitting device at 25 ° C. using only a green phosphor.
The purple LED has a forward voltage drop Vf of 3.195 V and a forward current If of 20 mA.

As shown in FIG. 1, the green light emitting device using the Sr sialon green phosphor represented by the general formula (1) as the phosphor has a high emission intensity even when excitation light having a short wavelength such as violet light is used. .
FIG. 2 is another example of an emission spectrum of the light emitting device.

Specifically, a violet LED that emits violet light having a peak wavelength of 400 nm is used as a semiconductor light emitting device, and Sr sialon red fluorescence represented by Sr _1.6 Eu _0.4 Si ₇ Al ₃ ON ₁₃ as a phosphor. It is an emission spectrum of a red light emitting device at 25 ° C. using only the body.
The purple LED has a forward voltage drop Vf of 3.190 V and a forward current If of 20 mA.

As shown in FIG. 2, the red light emitting device using the Sr sialon red phosphor represented by the general formula (2) as the phosphor has a high emission intensity even when excitation light having a short wavelength such as violet light is used. .

According to the light emitting device of the embodiment, a light emitting device with good temperature characteristics can be obtained.

Examples are shown below, but the present invention is not limited to these examples.

[Example 1]
(Production of phosphor)
First, 337 g of SrCO ₃ , 104 g of AlN, 514 g of Si ₃ N ₄ , 45 g of Eu ₂ O ₃ , and 0.003 g of SiC are weighed, and an appropriate amount of a flux agent is added thereto, followed by dry mixing to obtain a phosphor raw material mixture Was prepared. Thereafter, the phosphor raw material mixture was filled in a boron nitride crucible. Table 1 shows the blending amounts of raw materials such as SrCO ₃ .
When a boron nitride crucible filled with the phosphor raw material mixture is baked in an electric furnace at 1800 ° C. for 4 hours in a nitrogen atmosphere of 0.7 MPa (approximately 7 atm), a lump of baked powder is obtained in the crucible. It was.
After crushing this lump, pure water of 10 times the mass of the calcined powder was added to the calcined powder, stirred for 10 minutes, and filtered to obtain a calcined powder. This baked powder washing operation was further repeated twice to wash a total of three times. The baked powder after washing was filtered and dried, and then sieved with a nylon mesh having an opening of 75 microns to obtain a baked powder.
When the calcined powder was analyzed, it was a single crystal Sr sialon green light emitting phosphor having the composition shown in Table 2. The calcined powder contained the amount of carbon shown in Table 2. The carbon content is the ratio of the mass of carbon to the total mass of the calcined powder including carbon. A large amount of carbon was present in the vicinity of the surface of each particle constituting the phosphor powder (fired powder).

(Phosphor analysis)
The obtained Sr sialon green light emitting phosphor was examined for average particle diameter, emission peak wavelength and luminance.
The average particle diameter is a value measured by the Coulter counter method, the value of the median D ₅₀ of the cumulative volume distribution.
The luminance was measured at room temperature (25 ° C.) and 150 ° C. The luminance at room temperature is shown as a relative value (%) (hereinafter referred to as relative luminance) where the luminance at room temperature of Example 1 is 100.
In the examples and comparative examples described below, the luminance at room temperature is shown as a relative value (%) (relative luminance) where the luminance at room temperature in Example 1 is 100.
Also, the luminance measured at 150 ° C. is converted into the relative luminance at 150 ° C., and then the relative luminance at room temperature is calculated from the formula (relative luminance at room temperature−relative luminance at 150 ° C.) / (Relative luminance at room temperature). The luminance reduction rate (%) at 150 ° C. was calculated. The table shows the luminance reduction rate (%) at 150 ° C.
The measurement results are shown in Table 2 and Table 3.

[Examples 2 to 9, Comparative Examples 1 to 6]
(Production of phosphor)
In order to obtain Sr sialon green light-emitting phosphors having the composition and carbon content shown in Table 2, the blending amounts of SrCO ₃ , AlN, Si ₃ N ₄ , Eu ₂ O ₃ and SiC in the phosphor raw material mixture are shown in Table 1. A calcined powder was obtained in the same manner as in Example 1 except for changing as shown in Examples 2 to 9 and Comparative Examples 1 to 6.
When each fired powder was analyzed, it was a single crystal Sr sialon green light emitting phosphor having the composition shown in Table 2. The calcined powder contained the amount of carbon shown in Table 2. When the phosphor powder contains carbon, a large amount of carbon is present in the vicinity of the surface of each particle constituting the phosphor powder (fired powder).

(Phosphor analysis)
The obtained Sr sialon green light emitting phosphor was examined in the same manner as in Example 1 for the average particle size, emission peak wavelength, and luminance.
The brightness of some examples (Examples 2 to 7) and comparative examples (Comparative Examples 1 to 3) were measured at room temperature (25 ° C.) and 150 ° C. as in Example 1. The luminances of Examples 8 and 9 and Comparative Examples (Comparative Examples 4 to 6) were measured at room temperature (25 ° C.) and 100 ° C.
The luminance measured at 100 ° C. is converted to the relative luminance at 100 ° C., and then calculated from the formula of (relative luminance at room temperature−relative luminance at 100 ° C.) / (Relative luminance at room temperature) to 100 ° C. relative to the luminance at room temperature. The reduction rate (%) of the luminance was calculated. The table shows the luminance reduction rate (%) at 100 ° C.
The measurement results are shown in Table 2 and Table 3.

[Example 10]
(Production of phosphor)
In order to obtain Sr sialon red light emitting phosphors having the composition and carbon content shown in Table 5, the blending amounts of SrCO ₃ , AlN, Si ₃ N ₄ , Eu ₂ O ₃ , and SiC in the phosphor raw material mixture are shown in Table 4. A red powder was obtained in the same manner as in Example 1 except that the changes were made.
When the red powder was analyzed, it was a single crystal Sr sialon red light emitting phosphor having the composition shown in Table 5. The red powder contained carbon in the amount shown in Table 5. A large amount of carbon was present in the vicinity of the surface of each particle constituting the phosphor powder (red powder).

(Phosphor analysis)
About the obtained Sr sialon red light-emitting phosphor, the average particle diameter, the emission peak wavelength and the luminance were examined in the same manner as in Example 1.
The measurement results are shown in Table 5 and Table 6.

[Examples 11 to 18, Comparative Examples 7 to 10]
(Production of phosphor)
In order to obtain Sr sialon red light emitting phosphors having the composition and carbon content shown in Table 5, the blending amounts of SrCO ₃ , AlN, Si ₃ N ₄ , Eu ₂ O ₃ , and SiC in the phosphor raw material mixture are shown in Table 4. A red powder was obtained in the same manner as in Example 1 except that the conditions were changed as shown in Examples 11 to 16 and Comparative Examples 7 to 10.
When the red powder was analyzed, it was a single crystal Sr sialon red light emitting phosphor having the composition shown in Table 5. The red powder contained carbon in the amount shown in Table 5. When the phosphor powder contains carbon, a large amount of carbon is present in the vicinity of the surface of each particle constituting the phosphor powder (red powder).

(Phosphor analysis)
About the obtained Sr sialon red light-emitting phosphor, the average particle diameter, the emission peak wavelength and the luminance were examined in the same manner as in Example 1.
The brightness of some Examples (Examples 11 to 16) and Comparative Example (Comparative Example 7) were measured at room temperature (25 ° C.) and 150 ° C. as in Example 1. The luminances of Examples 17 and 18) and Comparative Examples (Comparative Examples 8 to 10) were measured at room temperature (25 ° C.) and 100 ° C. in the same manner as Comparative Example 1.
The measurement results are shown in Table 5 and Table 6.

From Tables 1 to 6, it can be seen that when the carbon content is 0 ppm, the brightness is greatly reduced at high temperatures, and when the carbon content is 5000 ppm or more, the brightness at room temperature is low.

In addition, although several embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

According to the embodiment described above, a phosphor and a light emitting device having good temperature characteristics can be obtained.

Claims (7)

The following general formula (1)
[Chemical 1]
General formula: (Sr _1-x , Eu _x ) _α Si _β Al _γ O _δ N _ω (1)
(Wherein x is 0 <x <1, α is 0 <α ≦ 4, and β, γ, δ and ω are values converted when α is 3, 9 <β ≦ 15, 1 ≦ γ ≦ 5, 0.5 ≦ δ ≦ 3, 10 ≦ ω ≦ 25)
Is a phosphor that emits green light when excited by ultraviolet to blue light.
A phosphor containing carbon in a ratio of 1 ppm to 5000 ppm. The following general formula (2)
[Chemical 2]
General formula: (Sr _1-x , Eu _x ) _α Si _β Al _γ O _δ N _ω (2)
(Wherein x is 0 <x <1, α is 0 <α ≦ 3, and β, γ, δ and ω are values converted when α is 3, 5 ≦ β ≦ 9, 1 ≦ γ ≦ 5, 0.5 ≦ δ ≦ 2, 5 ≦ ω ≦ 15)
Is a phosphor that emits red light when excited by ultraviolet to blue light.
A phosphor containing carbon in a ratio of 1 ppm to 5000 ppm. 3. The phosphor according to claim 1, wherein an average particle diameter is 1 μm or more and 100 μm or less. 2. The fluorescence according to claim 1, which emits green light having an emission peak wavelength of 500 nm or more and 540 nm or less by being excited by ultraviolet light or blue light having a peak wavelength in a range of 370 nm or more and 470 nm or less. body. 3. The fluorescence according to claim 2, wherein red light having an emission peak wavelength of 550 nm or more and 650 nm or less is emitted by being excited by ultraviolet light to blue light having a peak wavelength in a range of 370 nm to 470 nm. body. A substrate,
A semiconductor light emitting device disposed on the substrate and emitting ultraviolet light to blue light;
A light-emitting unit that is formed so as to cover the light-emitting surface of the semiconductor light-emitting element and includes a phosphor that emits visible light when excited by light emitted from the semiconductor light-emitting element;
6. A light-emitting device, wherein the phosphor includes the phosphor according to claim 1. The light emitting device according to claim 6, wherein the semiconductor light emitting element is a light emitting diode or a laser diode that emits light having a peak wavelength in a range of 370 nm to 470 nm.

Images