JP7067857B2 - A fluorescent substance, a method for producing the same, and a light emitting device using the fluorescent substance. - Google Patents

Description

The present invention relates to a fluorescent substance, a method for producing the same, and a light emitting device using the fluorescent substance.

A light-emitting diode (LED) light-emitting device is mainly composed of a combination of an LED chip as an excitation light source and a phosphor, and various colors of light-emitting colors can be realized by the combination.

A combination of an LED chip that emits light in a blue region and a phosphor is used in a white LED light emitting device that emits white light. For example, a combination of an LED chip that emits blue light and a phosphor mixture can be mentioned. As the phosphor, a yellow-emitting phosphor that emits yellow light, which is a complementary color of blue, is mainly used, and is used as a pseudo-white light LED light emitting device. In addition, LED chips that emit blue light, and three-wavelength white LEDs that use green to yellow emitting phosphors and red emitting phosphors have been developed. As one of the red light emitting phosphors used in such a light emitting device, K ₂ SiF ₆ : Mn phosphor is known.

When a conventionally known fluoride phosphor is continuously excited to emit light, the emission intensity after a lapse of time tends to decrease with respect to the initial emission intensity. When the phosphor is used in a light emitting device, it is desirable that the change in light emission intensity with the passage of time is small, that is, the light emission intensity maintenance rate is high. Therefore, it is desired to improve the emission intensity maintenance rate of the phosphor. In order to meet such needs, there is a report that the surface of a phosphor is treated with a treatment liquid containing a surface treatment agent such as an organic amine or an ammonium salt to improve durability in a high temperature and high humidity test. However, such a method requires a step of further treating the once synthesized fluorescent substance, and another method is desired in order to suppress the manufacturing cost of the fluorescent substance. Furthermore, conventionally known fluoride phosphors generally tend to have a reduced emission intensity when they come into contact with water, so it is not preferable to perform surface treatment with a treatment agent containing water as described above after synthesis. ..

Special Table 2009-528429 Gazette Japanese Unexamined Patent Publication No. 2014-141684

It is an object of the present invention to provide a fluorescent substance having an improved emission intensity retention rate of the fluorescent substance, and a light emitting device using such a fluorescent substance.

The main phase of the basic composition of the fluorescent substance according to the embodiment is the following general formula (A):
(K _{1-p / k} , M _{p / k} ) _a (Si _1-xy , Ti _x , Mn _y ) F _b (A)
(here,
M is at least one selected from the group consisting of Na and Ca.
k is a number indicating the valence of M, which is 1 or 2 and is
1.5 ≤ a ≤ 2.5,
5.0 ≤ b ≤ 6.5,
0 ≦ p / k ≦ 0.1,
0 ≦ x ≦ 0.3 and 0 <y ≦ 0.06
Is)
It is a fluorescent substance represented by
In the infrared absorption spectrum, the ratio of the maximum peak intensity I ₂ existing in the range of 3570 to 3610 cm ^-1 to the maximum peak intensity I ₁ existing in the range of 1200 to 1240 cm ^-1 is I _IR = I ₂ / I ₁ . Ratio I _XRD = I _{K' /} I of the peak intensity I K'existing at 27-29 ° to the peak intensity I _K present at 18-20 ° in the powder X-ray diffraction profile that is 0.01 or less. It is characterized in that _K is 1.00 or less.

In addition, the main phase of the basic composition of the fluorescent substance according to the embodiment is the following general formula (A) :.
(K _{1-p / k} , M _{p / k} ) _a (Si _1-xy , Ti _x , Mn _y ) F _b (A)
(here,
M is at least one selected from the group consisting of Na and Ca.
k is a number indicating the valence of M, which is 1 or 2 and is
1.5 ≤ a ≤ 2.5,
5.0 ≤ b ≤ 6.5,
0 ≦ p / k ≦ 0.1,
0 ≦ x ≦ 0.3 and 0 <y ≦ 0.06
Is)
It is a fluorescent substance represented by
In the infrared absorption spectrum, the ratio of the maximum peak intensity I ₂ existing in the range of 3570 to 3610 cm ^-1 to the maximum peak intensity I ₁ existing in the range of 1200 to 1240 cm ^-1 is I _IR = I ₂ / I ₁ . Between 0 and 0.01 and the absorption rates I ₅₂₀ , I ₅₆₀ and I ₆₀₀ at wavelengths 520 nm, 560 nm and 600 nm, respectively, and the average value I _ave between I ₅₂₀ and I ₆₀₀ in the visible absorption spectrum: connection of:
I _ave = (I ₅₂₀ + I ₆₀₀ ) / 2,
I ₅₆₀ -I _ave > 0
It is characterized by being.

Further, the light emitting device according to the embodiment is characterized by comprising a light emitting element that emits light having a peak in a wavelength region of 440 nm or more and 470 nm or less, and a phosphor layer containing the above-mentioned phosphor. It is something to do.

The figure which shows the infrared absorption spectrum of a fluorescent substance by an embodiment. An enlarged view of 800 to 1600 cm ^-1 of the infrared absorption spectrum of the phosphor according to the embodiment. Enlarged view of the infrared absorption spectrum (2500 to 4000 cm ^-1 ) of the phosphor according to the embodiment before and after the dehydration treatment. The figure which shows the change of the internal quantum efficiency of a fluorescent substance with respect to I _XRD . The figure which shows the visible absorption spectrum of a fluorescent substance before and after the dehydration treatment. Sectional drawing of the light emitting device by embodiment. Sectional drawing of the light emitting device by another embodiment. The figure which shows the infrared absorption spectrum of the fluorescent substance of Example 101, Comparative Example 101 and 102. The figure which shows the emission intensity maintenance rate of the phosphor of Example 101, Comparative Example 101 and 102. The figure which shows the infrared absorption spectrum of the fluorescent substance of Example 203 and Comparative Example 201. The figure which shows the visible absorption spectrum of Examples 201-203 and Comparative Example 201. The figure which shows the emission intensity maintenance rate of the fluorescent substance of Example 203 and Comparative Example 201.

Hereinafter, embodiments will be described in detail. The embodiments shown below show a phosphor and a light emitting device for embodying the technical idea of the present invention, and the present invention is not limited to the following examples.

As a result of diligent studies and studies on a fluorescent substance mainly composed of potassium silicate and activated with manganese, the present inventors have identified the fluorescent substance in the infrared absorption spectrum (hereinafter, may be referred to as IR spectrum). It was found that the peak intensity ratio of the above and the peak intensity of powder X-ray diffraction in the crystal phase present in the phosphor have a correlation with the luminous efficiency of the phosphor and the emission intensity retention rate of the phosphor.
The present inventors further describe the relationship between the average value of the absorption rates of the phosphors at two specific wavelengths and the absorption rates at the intermediate wavelengths of the two wavelengths, and the powder X due to the crystal phase present in the phosphor. It was also found that the peak intensity of linear diffraction correlates with the emission efficiency of the phosphor and the emission intensity maintenance rate of the phosphor.

In the embodiment, the preferred fluorophore has a main phase represented by the following general formula (A).
(K _{1-p / k} , M _{p / k} ) _a (Si _1-xy , Ti _x , Mn _y ) F _b (A)
(During the ceremony,
M is at least one selected from the group consisting of Na and Ca.
k is a number indicating the valence of M, which is 1 or 2 and is
1.5 ≤ a ≤ 2.5,
5.0 ≤ b ≤ 6.5,
0 ≦ p / k ≦ 0.1,
0 ≦ x ≦ 0.3 and 0 <y ≦ 0.06
Is)

The fluorophore according to the embodiment contains manganese as an activator. In order to make this fluorescent substance a red light emitting fluorescent substance, the valence of manganese is preferably +4. Manganese of other valences may be contained, but the proportion is preferably small, and most preferably all manganese is +4 valence.

When manganese is not contained (y = 0), emission cannot be confirmed even if excited by light having an emission peak in the ultraviolet to blue region. Therefore, x in the general formula (A) needs to be larger than 0. Further, the luminous efficiency tends to be improved as the manganese content increases, and y is preferably 0.005 or more.

However, if the manganese content is too high, a concentration quenching phenomenon occurs and the emission intensity of the phosphor tends to be weakened. In order to avoid such inconvenience, the manganese content ratio (y) is preferably 0.06 or less, and preferably 0.05 or less.

Further, as described above, the phosphor according to the embodiment may contain elements other than the main constituent elements K, Si, F, and Mn. As the contained element, for example, Na, Ca, Ti or the like may be contained in a small amount. Even when a small amount of these elements is contained, the phosphor exhibits an emission spectrum similar to that in the red region, and the desired effect can be achieved. However, from the viewpoint of the stability of the phosphor, the cost of synthesizing the reactive fluorescent substance at the time of synthesizing the phosphor, and the like, it is preferable that the content of these elements is small. In addition, elements other than those exemplified here may be contained as unavoidable components. Even in such a case, the effect of the embodiment is generally fully exhibited.

In order to analyze the content of each element in the whole phosphor, for example, the following methods can be mentioned. Metallic elements such as K, Na, Ca, Si, Ti, and Mn are obtained by alkali-melting the synthesized phosphor, for example, by an IRIS Advantage type ICP emission spectrophotometer (trade name, manufactured by Thermo Fisher Scientific Co., Ltd.). It can be analyzed by ICP emission spectroscopy. Further, the non-metal element F can be separated by thermal hydrolysis of the synthesized phosphor and analyzed by, for example, a DX-120 type ion chromatograph analyzer (trade name, manufactured by Nippon Dionex Corporation). Further, the analysis of F can be performed by an ion chromatograph method after being alkaline-melted in the same manner as the above-mentioned metal element.

The phosphor according to the embodiment does not contain oxygen stoichiometrically. However, oxygen may inevitably be mixed into the fluorescent substance during the process of synthesizing the fluorescent substance or due to decomposition of the surface of the fluorescent substance after the synthesis. It is desirable that the oxygen content in the phosphor is zero, but if the ratio of [oxygen content] / [(fluorine content) + (oxygen content)] is less than 0.05, it emits light. It is preferable because the efficiency is not significantly impaired.

Conventionally, a fluoride phosphor having a basic structure containing potassium, silicon, and fluorine and activated by manganese emits light when used as a light emitting device and when the light emitting device is continuously operated. In general, the intensity decreases with time, causing color shift of light emission. Various methods for solving such problems have been studied, but all of them have room for improvement. On the other hand, the present inventors have found that among such phosphors, those exhibiting a specific IR spectrum exhibit excellent characteristics. Specifically, in the IR spectrum, the intensity of the maximum peak existing at 3570 to 3610 cm ^-1 (hereinafter referred to as I ₂ ) with respect to the intensity of the maximum peak existing at 1200 to 1240 cm ^-1 (hereinafter referred to as I ₁ ). Fluorescent materials with a ratio of I _IR (I ₂ / I ₁ ) of 0.01 or less show excellent properties.

It is considered that the intensity ratio of such an IR spectrum corresponds to the content of various OH groups present in the phosphor. That is, as will be described later, the peak existing at 3570 to 3610 cm ^-1 corresponds to the natural vibration of the OH bond of the isolated OH group, and the vicinity of 3200 cm ^-1 is the OH bond contained in the water molecule contained around the phosphor. It is presumed to correspond to the natural vibration. Then, it is considered that excellent characteristics are exhibited when the intensity ratio in the IR spectrum of the phosphor is in a specific range, that is, when the OH bond contained in the phosphor is small.

The method for measuring the IR spectrum is not particularly limited, but the IR spectrum can be measured by, for example, an infrared spectroscope such as a VERTEX70V FT-IR spectrometer (trade name, manufactured by Bruker Optics Co., Ltd.). The measurement conditions can be, for example, as follows.
Wavenumber resolution: 4 cm ^-1
Number of sample scans: 100 times Measurement wave number range: 350-4000 cm ^-1
Measurement atmosphere: Vacuum detector: TGS (DTGS) detector

There are a transmission method, a reflection method, an ATR method and the like as a method for measuring an IR spectrum, but the phosphor according to this embodiment is generally a powder having a particle size of several μm to 60 μm, and sample preparation is easy. It is preferably carried out by a diffuse reflection method capable of measurement. In addition, the diffuse reflection method is generally measured by diluting it to an appropriate concentration (about 1 to 10%) with a light-transmitting diluent such as KBr or KCl in the infrared region. In the IR spectrum of the phosphor in the above, since the peak intensities around 3590 cm ^-1 and around 3220 cm ^-1 are small, it is preferable to perform the measurement without using the above-mentioned diluent. However, in the background measurement, it is preferable to perform the measurement using the above-mentioned diluent.

FIG. 1 shows an example of the IR spectrum of the phosphor according to the present embodiment. FIG. 2 is an enlarged view of the IR spectrum of FIG. 1 from 800 to 1600 cm ^-1 . In addition, FIG. 2 also shows the IR spectrum of K ₂ SiF ₆ powder (for example, a commercially available Kanto Chemical deer special grade reagent) in which Mn is not activated. From FIG. 2, it can be seen that the peak of 800 to 1600 cm ^-1 is observed at almost the same position in the Mn-activated phosphor and the K ₂ SiF ₆ powder not activated by Mn. Understand. From this, it is considered that the peak around 800 to 1600 cm ^-1 in the Mn-activated fluorescent material corresponds to the vibration mode peculiar to the parent _{K2 SiF 6 crystal} .

FIG. 3 is an enlarged view of the IR spectrum of FIG. 1 from 3000 to 4000 cm ^-1 . From FIG. 3, it can be seen that in the phosphor of the embodiment, almost no peak is detected in this range. On the other hand, in a conventional silicon fluorofluoride phosphor that has not been subjected to internal dehydration treatment of particles, it is common that a vibration peak exists in such a range. That is, in the case of producing a fluorescent substance according to an embodiment, it is preferable to form a fluorescent substance crystal in an aqueous medium and then dehydrate the inside of specific fluorescent substance particles (details will be described later). A sharp vibration peak can be confirmed in the vicinity of 3720, 3630, and 3590 cm ^-1 in the fluorescent material before the dehydration treatment inside the fluorescent material particles. Furthermore, a broad vibration peak is confirmed at 2500 to 3500 cm ^-1 . The former vibration peak is considered to be a peak peculiar to the isolated OH group present in the phosphor. Further, the latter broad vibration peak is considered to be a peak attributed to an OH bond contained in a water molecule that is adsorbed on a phosphor crystal or has a hydrogen bond or a coordination bond. This embodiment has been completed based on the finding that there is a correlation between the sharp maximum peak intensity (I ₂ ) existing in the above 3570 to 3610 cm ^-1 and the characteristics of the phosphor.

However, since IR measurement is generally used for qualitative evaluation, it is difficult to quantitatively evaluate the sharp maximum peak existing in 3570 to 3610 cm ^-1 , and its peak intensity and phosphor. It is difficult to clarify the correlation with the characteristics of. Therefore, in the embodiment, the maximum peak existing in 1200 to 1240 cm ^-1 _{which is considered to be attributed to the natural vibration mode of the K2 SiF 6 crystal} in the obtained IR spectrum is used as a reference, and 3570 to 3610 cm with respect to the maximum peak. The relative intensity of the maximum peak present at ^-1 (I _IR = I ₂ / I ₁ ) was used as an index.

The above-mentioned maximum peak position (wave number) in the IR spectrum may change depending on the composition of the phosphor and the synthesis conditions of the phosphor. In the present embodiment, the peak position near 1220 cm ^-1 is an important factor, but this peak position may fluctuate by about ± 15 cm ^-1 under favorable conditions and about ± 5 cm ^-1 under more preferable conditions. be.
In addition, in order to perform measurement in a wide wave number range, it is preferable to use a TGS (DTGS) detector having high response linearity.

In the present embodiment, when the relative intensity _IIR value is 0.01 or less, when the phosphor is used in the light emitting device, the change in the light emitting intensity with the passage of time during continuous operation is small, that is, the light emitting intensity. It was found that the maintenance rate was high. In this embodiment, the detailed reason why the fluorophore exhibits excellent properties when the relative intensity _IIR value is in the above range has not been fully elucidated. However, it is estimated as follows. When a general fluoride-based fluorescent substance is incorporated into a light emitting device and operated, the temperature of the fluorescent substance becomes high due to the operation, and as a result, hydrolysis involving isolated OH groups contained in the fluorescent substance occurs, so that light emission occurs. It is presumed that a decrease in strength will occur. On the other hand, it is presumed that the phosphor according to the embodiment has a small content of isolated OH groups, so that hydrolysis does not occur and the decrease in emission intensity is small.

The relative strength _IIR is preferably 0.01 or less, more preferably 0.005 or less, still more preferably 0.002 or less. Most preferably, there are no peaks in the range of 3570 to 3610 cm ^-1 , i.e. I ₂ = I _IR = 0.

The fluorescent substance according to the embodiment can be produced by any method, and can be produced, for example, by the method described below.

The phosphor having a composition represented by the general formula (A) is obtained by dissolving a mixture of hexafluorosilicic acid (H ₂ SiF ₆ ), potassium hexafluorosilicate (K ₂ MnF ₆ ), sodium hexafluoromanganate and the like. It can be produced by a method such as a co-precipitation method in which a potassium-containing raw material is added to an aqueous solution of chlorofluorosilic acid and reacted. In addition, a method of reacting a Si source or Ti source with potassium permanganate in an aqueous solution of hydrofluoric acid, or potassium in a solution in which hexafluorosilicic _acid and potassium hexafluoromanganate (K2 MnF ₆ ) are dissolved. It can be synthesized by a method of adding a source and reacting, a method of precipitating a poor solvent, or the like. In any of the production methods, the basic fluorescent substance can be obtained by synthesizing it in an aqueous solution using hydrofluoric acid and then subjecting it to a drying treatment such as suction filtration.

According to the studies by the present inventors, even in the case of a fluorescent substance that has been dried by suction filtration or the like, water molecules adsorbed on isolated OH groups or the surface of the fluorescent substance are inevitable in the fluorescent material. It turned out that it was included. Although it is possible to reduce the content of water contained in isolated OH groups and phosphors to some extent by selecting a synthesis method and optimizing synthesis parameters, it is possible to completely eliminate isolated OH groups and water molecules only by examining the synthesis method. It is not easy to remove. Therefore, in order to remove the above-mentioned isolated OH groups and water molecules, after the above-mentioned basic phosphor is synthesized, if necessary, a drying treatment is performed, and then a dehydration treatment inside the phosphor particles is performed to isolate the fluorophore particles. OH groups and water molecules can be removed. The dehydration treatment inside the phosphor particles is preferably carried out in a temperature range of 200 ° C. or higher and 800 ° C. or lower, a pressure range of 0.0003 atm or higher and 8 atm or lower, and a treatment time of 1 minute or longer and 24 hours or shorter. More preferably, it is 200 ° C. or higher and 750 ° C. or lower, 0.01 atm or more and 6 atm or less, 5 minutes or more and 10 hours or less. Further, the atmosphere for dehydrating the inside of the phosphor particles can be a nitrogen, argon, or helium atmosphere .

However, if excessive dehydration treatment inside the fluorescent substance particles is performed in order to remove isolated OH groups and water molecules and lower the _IR value, it is considered that a part of the fluorescent substance is denatured or oxidized. In the past, for the reason of avoiding denaturation or oxidation, it was common that the fluorescent material formed in the aqueous medium was not actively heated or depressurized to dehydrate the inside of the particles. In the embodiment, in order to avoid such denaturation or oxidation of the fluorescent substance, it can be controlled by adjusting the temperature, pressure and atmosphere in the dehydration step inside the fluorescent substance particles after synthesis.

FIG. 4 shows the relationship between the internal quantum efficiency of the phosphor and the intensity of the powder X-ray diffraction peak. The horizontal axis of FIG. 4 belongs to (111), which is the strongest line of K2 SiF ₆ (PDF # _01-075-0694 ) in powder X-ray diffraction (X-ray diffraction: hereinafter, may be referred to as XRD) measurement. The intensity ratio ( _IXRD = I _K' / I _K ) of the diffraction line intensity (I _K' ) around 28.063 ° to the diffraction line intensity (I _K ) near 18.881 ° is plotted. .. In the embodiment, the peaks of _IK and _IK'may change depending on the synthesis conditions of the phosphor. However, even in such a case, since these peaks are in the range of the diffraction angles of 18 to 20 ° and 27 to 29 °, respectively, in the embodiment, the intensity of the peak corresponding to the maximum peak in the range is reached. Let be I _K and I _K' , respectively.

The XRD measurement of the phosphor can be measured by SmartLab (trade name, manufactured by Rigaku) or the like. The measurement conditions may vary depending on the type of the phosphor to be measured, the particle shape, and the like, but for example, the measurement can be performed under the following conditions.
X-ray source CuKα
Measured voltage / current 45kV, 200mA
Step width 0.01 °
Measurement speed 20 ° / min.

式中
Ｅ（λ）：蛍光体へ照射した励起光源の全スペクトル（フォトン数換算）
Ｒ（λ）：蛍光体の励起光源反射光スペクトル（フォトン数換算）
Ｐ（λ）：蛍光体の発光スペクトル（フォトン数換算）
である。 The absorption rate of the phosphor and the internal quantum efficiency η'are calculated by the following equations.

E (λ) in the formula: The entire spectrum of the excitation light source irradiated to the phosphor (converted to the number of photons)
R (λ): Excitation light source reflected light spectrum of phosphor (converted to photon number)
P (λ): Emission spectrum of phosphor (converted to the number of photons)
Is.

The absorption rate and internal quantum efficiency of the phosphor can be measured by, for example, a C9920-02G type absolute PL quantum yield measuring device (trade name, manufactured by Hamamatsu Photonics Co., Ltd.). As the excitation light for measuring the base color, a peak wavelength of around 650 nm and a half width of 5 to 10 nm can be used. Further, as the excitation light for measuring the internal quantum efficiency, blue light having a peak wavelength of around 440 to 470 nm and a half width of 5 to 15 nm can be used.

FIG. 5 shows a visible absorption spectrum of a phosphor that has not been internally dehydrated of particles and a visible absorption spectrum of a phosphor that has been internally dehydrated of particles. This visible absorption spectrum can be obtained by measuring the absorption rate in the visible region, for example, in the wavelength range of 400 to 750 nm by changing the wavelength of the incident light (half width of 5 to 15 nm). This absorption rate can be measured, for example, by using the above-mentioned C9920-02G type absolute PL quantum yield measuring device (trade name, manufactured by Hamamatsu Photonics Co., Ltd.). The peak near 450 nm indicates the absorption band of Mn, which is the center of emission, and it is considered that the peak at about 520 nm or more indicates absorption due to maternal coloring.

From FIG. 5, in the phosphor according to the embodiment, the following relationships are established between the absorptivity I ₅₂₀ , I ₅₆₀ and I ₆₀₀ , and the average value I _ave of I ₅₂₀ and I ₆₀₀ at wavelengths of 520 nm, 560 nm and 600 nm, respectively. do.
I _ave = (I ₅₂₀ + I ₆₀₀ ) / 2,
I ₅₆₀ -I _ave > 0
On the other hand, in the case of a silicon fluorofluoride phosphor that has not been subjected to internal dehydration treatment, the following relationship is obtained.
I ₅₆₀ -I _ave ≤ 0
It is considered that the reason why the phosphor according to the embodiment shows such a visible absorption spectrum is that a crystal phase that absorbs visible light having a wavelength of around 560 nm exists, and the presence of the crystal phase improves the retention rate. ..

In the visible absorption spectrum of FIG. 5, when the matrix coloring becomes large, the coloring at the excitation wavelength leads to a decrease in R (λ) of the equation 2, and the phosphor absorbs light in the emission wavelength region, that is, a phosphor. When there is coloring, P (λ) in Equation 2 tends to decrease, and the internal quantum efficiency tends to decrease. Therefore, in order to achieve an internal quantum efficiency of 70% or more, it is preferable that the absorption rate at 650 nm near the emission wavelength of the phosphor is low, specifically 0.1 or less, preferably closer to 0. good.

In the present specification, the fluorescent substance whose main phase is represented by the general formula (A) means that a crystal phase other than the general formula (A) is slightly contained. This is clear from the fact that diffraction lines other than the general formula (A) are confirmed by XRD measurement as described above, or from the fact that there is a component that absorbs light in a specific wavelength region by the visible absorption spectrum. be. In the phosphor according to the first embodiment, the peak intensity of powder X-ray diffraction by the crystal phase of the general formula (A) is relatively larger than that of the phosphor whose main phase is represented by the general formula (A). That means that the I _XRD is small. When the I _XRD becomes excessively large, the emission of the phosphor is hardly detected.
Specifically, the _IXRD of the phosphor according to the embodiment is preferably 1.00 or less, and more preferably 0.16 or less. On the other hand, since the lower limit of quantification in the XRD apparatus is about 1% by weight, the peak intensity ratio I _XRD of powder X-ray diffraction is 0.002 or more. In addition, the phosphor according to the second embodiment has an _Ave larger than that of I ₅₆₀ . Specifically, I _ave -I ₅₆₀ > 0, but it is preferable that I _ave -I ₅₆₀ > 0.001.

Further, in order to use the phosphor according to the embodiment for a light emitting device or the like, the internal quantum efficiency is preferably 70% or more. From FIG. 4, it can be seen that the internal quantum efficiency decreases as the _IXRD increases. It can be seen that the intensity ratio ( _IXRD ) is preferably 0.16 or less in order to achieve the internal quantum efficiency of 70% or more. Further, from FIG. 4, the quantum efficiency is higher when the modification or oxidation when removing the isolated OH group or the water molecule of the phosphor represented by the general formula (A) in the phosphor is suppressed. The dehydration conditions inside the fluorophore particles should be optimized.

Further, the phosphor according to the embodiment can be classified according to the application method to the light emitting device to be used. In a normal white LED or the like using excitation light having an emission peak in the blue region, it is generally preferable to use phosphor particles classified into 1 to 50 μm. If the particle size of the phosphor after classification is excessively small, the emission intensity may decrease. Further, if the particle size is excessively large, when the LED is coated, the phosphor may be clogged in the phosphor layer coating device, which may cause a decrease in work efficiency and yield, and color unevenness of the completed light emitting device.

The phosphor according to the embodiment can be excited by an excitation light source having an emission peak in the ultraviolet to blue region. When this phosphor is used in a light emitting device, it is desirable to use a light emitting element having a light emitting peak in a wavelength region of 440 nm or more and 470 nm or less as an excitation light source from the excitation spectrum of the phosphor. It is not preferable to use a light emitting device having a light emitting peak outside the above wavelength range from the viewpoint of light emitting efficiency. As the light emitting element, a solid-state light source element such as an LED chip or a laser diode can be used.

The fluorophore according to the embodiment is a fluorophore that emits red light. Therefore, when blue light is used as the excitation light source, a white light emitting device can be obtained by using it in combination with a green light emitting phosphor and a yellow light emitting phosphor. When ultraviolet light is used as the excitation light source, a white light emitting device can be obtained by using the blue light emitting phosphor in combination with the green light emitting phosphor and the yellow light emitting phosphor. The type of phosphor to be used can be arbitrarily selected according to the purpose of the light emitting device. For example, when providing a white light emitting device for lighting with a low color temperature, it is possible to provide a light emitting device having both efficiency and color rendering properties by combining the phosphor according to the embodiment and the yellow light emitting phosphor.

It can be said that the green light emitting phosphor and the yellow light emitting phosphor have a main emission peak in the wavelength region of 520 nm or more and 570 nm or less. Examples of such a fluorescent substance include (Sr, Ca, Ba) ₂ SiO ₄ : Eu, Ca ₃ (Sc, Mg) ₂ Si ₃ O ₁₂ : Ce and other silicate phosphors, (Y, Gd). ₃ (Al, Ga) ₅ O ₁₂ : an aluminate phosphor such as Ce, (Ca, Sr, Ba) Ga ₂ S ₄ : a sulfide phosphor such as Eu, (Ca, Sr, Ba) Si ₂ O ₂ N ₂ : Examples thereof include alkaline earth acid nitride phosphors such as (Ca, Sr) -αSiAlON and βSiAlON activated with Eu and Eu. The main emission peak is a wavelength at which the peak intensity of the emission spectrum is the largest, and the emission peaks of the exemplified phosphors have been reported in the literature and the like. A change in the emission peak of about 10 nm may be observed due to the addition of a small amount of elements or a slight change in composition during the production of the fluorescent substance, and such a fluorescent substance is also included in the above-exemplified fluorescent substance. It shall be.

The blue light emitting phosphor can be said to be a fluorescent material having a main light emitting peak in a wavelength region of 440 nm or more and 500 nm or less. For example, a halophosphate phosphor such as (Sr, Ca, Ba, Mg) ₅ (PO ₄ ) ₃ (Cl, Br): Eu, (Sr, Ca, Ba, Mg) ₅ (PO ₄ ) ₃ Cl: Eu. , 2SrO · 0.84P ₂ O ₅ · 0.16B ₂ O ₃ : Phosphate phosphors such as Eu, and alkaline earth metal aluminate phosphors such as BaMgAl ₁₀ O ₁₇ : Eu.

Further, in the light emitting device using the phosphor according to the embodiment, an orange light emitting phosphor and a red light emitting phosphor other than the above can also be used depending on the application.
As orange-emitting phosphors and red-emitting phosphors, (Sr, Ca, Ba) ₂ SiO ₄ : silicate fluorescent substances such as Eu, tungstate phosphors such as Li (Eu, Sm) W ₂ O ₈ ; La, Gd, Y) ₂ O ₂ S: Acid sulfide phosphors such as Eu, (Ca, Sr, Ba) S: Sulfuric acid phosphors such as Eu, (Sr, Ba, Ca) ₂ Si ₅ N ₈ :. Eu, (Sr, Ca) AlSiN ₃ : Nitride phosphors such as Eu and the like can be mentioned. By further using these phosphors in combination with the phosphors according to the embodiment, not only the efficiency but also the color rendering property in the lighting application and the color gamut in the backlight application can be further improved. However, if the number of phosphors used is too large, a reabsorption / emission phenomenon or a scattering phenomenon occurs in which the phosphors absorb and emit light, and the luminous efficiency of the light emitting device is lowered.
FIG. 6 shows a cross section of the light emitting device according to the embodiment.

In the illustrated light emitting device, the light emitting device includes a lead 100, a lead 101, a stem 102, a semiconductor light emitting device 103, a reflecting surface 104, and a phosphor layer 105. A semiconductor light emitting element 103 is mounted on the center of the bottom surface by Ag paste or the like. As the semiconductor light emitting device 103, one that emits ultraviolet light or one that emits light in the visible region can be used. For example, it is possible to use semiconductor light emitting diodes such as GaAs-based and GaN-based. The arrangement of the leads 100 and the leads 101 can be changed as appropriate. The phosphor layer 105 is arranged in the recess of the light emitting device. The fluorescent material layer 105 can be formed by dispersing the fluorescent material according to the embodiment in a resin layer made of, for example, a silicone resin at a ratio of 5 wt% or more and 80 wt% or less.

As the semiconductor light emitting device 103, a flip-chip type device having an n-type electrode and a p-type electrode on the same surface can also be used. In this case, problems caused by the wire such as disconnection and peeling of the wire and light absorption by the wire can be solved, and a highly reliable and high-brightness semiconductor light emitting device can be obtained. Further, an n-type substrate may be used for the semiconductor light emitting device 103 to have the following configuration. Specifically, an n-type electrode is formed on the back surface of the n-type substrate, a p-type electrode is formed on the upper surface of the semiconductor layer on the substrate, and the n-type electrode or the p-type electrode is mounted on a lead. The p-type or n-type electrode can be connected to the other lead by a wire. The size of the semiconductor light emitting device 103, the size and shape of the recess can be changed as appropriate.

FIG. 7 shows an example of a bullet-shaped light emitting device. The semiconductor light emitting device 201 is mounted on the lead 200'via the mounting material 202 and is covered with the predip material 204. The lead 200 is connected to the semiconductor light emitting device 201 by the bonding wire 203 and is sealed with the casting material 205. The fluorescent material according to the embodiment is contained in the predip material 204.
As described above, the light emitting device according to the embodiment, for example, a white LED, is most suitable not only as a general lighting or the like, but also as a light emitting device used in combination with a color filter or the like, for example, a light source for a liquid crystal backlight. Specifically, it can also be used as a red light emitting material of an inorganic electroluminescence apparatus using a liquid crystal backlight light source or a blue light emitting layer.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples as long as the gist of the present invention is not exceeded.

[Example 101, Comparative Examples 101 and 102]
After dissolving the KMnO ₄ powder and the KF powder in the HF aqueous solution, the H2 O ₂ aqueous solution was gradually _added dropwise, and the reaction was sufficiently carried out in the HF aqueous solution to synthesize K2 _{MnF 6 .} The synthesized K ₂ MnF ₆ was suction filtered to obtain K ₂ MnF ₆ powder. Further, the SiO ₂ powder was dissolved in the HF aqueous solution to prepare the H ₂ SiF ₆ solution. Further, the KF powder was dissolved in the HF aqueous solution to prepare the KF aqueous solution. The synthesized K2 MnF ₆ powder was dissolved in the prepared H ₂ SiF ₆ solution to _prepare a reaction solution. K2 SiF ₆ : Mn was synthesized by _adding a pre-prepared KF aqueous solution to the prepared reaction solution and allowing the reaction to be sufficiently carried out in the reaction solution. The synthesized K ₂ SiF ₆ : Mn was suction-filtered to obtain a phosphor powder (Comparative Example 101). When the composition of the synthesized fluorescent substance was analyzed, it was K _2.03 (Si _0.98 , Mn _0.02 ) _F6 . In addition, it was confirmed by XRD measurement that I _K'was below the detection limit and the phosphor was only the K ₂ SiF ₆ crystal phase. The synthesized fluorescent material was dried so as not to completely remove isolated OH groups and water molecules (Comparative Example 102). Further, in order to completely remove isolated OH groups and water molecules from the synthesized fluorescent substance, the inside of the fluorescent substance particles was dehydrated (Example 101).

When the IR spectra of Example 101, Comparative Examples 101 and 102 were measured, the results were as shown in FIG. Intensity of the maximum peak in the range of 3570 to 3610 cm ^-1 with respect to the intensity of the maximum peak in the range of 1200 to 1240 cm ^-1 in the infrared absorption spectra of Examples 1 and 2 _IR , internal quantum efficiency. And, in the powder X-ray diffraction profile, the intensity I K'ratio I _XRD = I _{K' /} I _K of the peak present at 27-29 ° to the intensity I _K of the peak present at 18-20 ° is shown in Table 1. It was as shown.
A VERTEX70V FT-IR spectrometer (trade name, manufactured by Bruker Optics Co., Ltd.) was used for IR spectrum measurement. The detection limit of _IR by this device is 0.001, and when it is below the detection limit, it is described as 0.001 or less in Table 1. In addition, SmartLab (trade name, manufactured by Rigaku) is used for powder X-ray diffraction measurement, and the detection limit of _IK'by this device is 0.002. If it is below the detection limit, Table 1 shows. Was described as 0.002 or less.

[Examples 102, 103, and Comparative Example 103]
The phosphors of Example 101, Comparative Examples 101 and 102 were mixed with a resin and sealed on a GaN-based LED light emitting device to form a light emitting device. For each light emitting device, a current was injected into each LED to continuously light the light emitting device. When the behavior of the emission intensity of the phosphors of Examples 1 and Comparative Examples 1 and 2 was observed, it was as shown in FIG. The vertical axis of FIG. 9 is the emission intensity maintenance rate, which is the ratio ( _Ip / _{IL) of the intensity (Ip )} of red emission emitted from the phosphor to the emission intensity ( _IL ) of the LED. The emission intensity retention rates after 500 hours and 1000 hours were as shown in Table 1. From the results of FIG. 9, it can be understood that the phosphor according to the embodiment suppresses the decrease in emission intensity when the light emitting device is used.

Next, the fluorescent material was synthesized by the same method as in Comparative Example 101, and the fluorescent materials of Comparative Example 103 and Examples 102 and 103 in which the drying conditions were changed were synthesized. The I _IR , I _XRD , and internal quantum efficiencies in the fluorophore are as shown in Table 1. Table 1 shows the emission intensity maintenance rate of the light emitting device in which the phosphors of Examples 102 and 103 were mixed together with the resin and sealed on the GaN-based LED light emitting element.

これらの結果より、Ｉ_ＩＲが０．０１以下であり、かつＩ_ＸＲＤが１．００以下である場合には、内部量子効率が実用上十分に高く、同時に発光強度維持率も高いことがわかる。

From these results, it can be seen that when the I _IR is 0.01 or less and the I _XRD is 1.00 or less, the internal quantum efficiency is practically sufficiently high and at the same time the emission intensity maintenance rate is also high.

[Examples 201 to 204 and Comparative Example 201]
Fluorescent materials were synthesized in the same manner as in Comparative Example 101, and the fluorescent materials of Examples 201 to 204 and Comparative Example 201 were synthesized by changing the drying conditions. When the IR spectra of Example 203 and Comparative Example 201 were measured, the results were as shown in FIG. The visible absorption spectra of Examples 201 to 204 and Comparative Example 201 were as shown in FIG. Further, under the acceleration conditions in which the phosphors of Example 203 and Comparative Example 201 were mixed together with the resin and the light density and temperature were increased, the intensity of red emission from the phosphor to the emission intensity ( _IL ) of the blue LED (I). When the ratio of _P ) ( _IP / _IL ) was observed, it was as shown in FIG. It should be noted that the emission intensity maintenance rate under these acceleration conditions cannot be compared with the evaluation results shown in Table 1 because the driving conditions and the LED package used are different.

For the phosphors of Examples 201 to 204 and Comparative Example 201, the relationship between I _IR , I ₅₆₀ and _Iave , the internal quantum efficiency, and the emission intensity retention rate (converted value) are as shown in Table 2.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

100 and 101 ... leads, 102 ... stems, 103 ... semiconductor light emitting devices, 104 ... reflective surfaces, 105 ... phosphor layers, 200 and 200'... leads, 201 ... semiconductor light emitting devices, 202 ... mount materials, 203 ... bonding wires, 204 ... Predip material, 205 ... Casting material

Claims (8)

The prime minister is the following general formula (A):
K _a (Si _1-y , Mn _y ) F _b (A) (Here,
1.5 ≤ a ≤ 2.5,
b = 6 and 0 <y ≦ 0.06
Is)
It is a fluorescent substance represented by
In the infrared absorption spectrum, the ratio of the maximum peak intensity I ₂ existing in the range of 3570 to 3610 cm ^-1 to the maximum peak intensity I ₁ existing in the range of 1200 to 1240 cm ^-1 is I _IR = I ₂ / I ₁ . The ratio of the peak intensity I _K'existing at 27 to 29 ° to the intensity I _K of the peak existing at 18 to 20 ° in the powder X-ray diffraction profile, which is 0 or more and 0.01 or less, I _XRD = _IKE . _' / A phosphor having an _IK of 0.002 or more and 1.00 or less. The fluorescent substance according to claim 1, wherein the _IXRD is 0.002 or more and 0.16 or less. The prime minister is the following general formula (A):
K _a (Si _1-y , Mn _y ) F _b (A) (Here,
1.5 ≤ a ≤ 2.5,
b = 6 and 0 <y ≦ 0.06
Is)
It is a fluorescent substance represented by
In the infrared absorption spectrum, the ratio of the maximum peak intensity I ₂ existing in the range of 3570 to 3610 cm ^-1 to the maximum peak intensity I ₁ existing in the range of 1200 to 1240 cm ^-1 is I _IR = I ₂ / I ₁ . Between 0 and 0.01 and the absorption rates I ₅₂₀ , I ₅₆₀ and I ₆₀₀ at wavelengths 520 nm, 560 nm and 600 nm, respectively, and the average value I _ave between I ₅₂₀ and I ₆₀₀ in the visible absorption spectrum: connection of:
I _ave = (I ₅₂₀ + I ₆₀₀ ) / 2,
I ₅₆₀ -I _ave > 0
A fluorescent substance characterized by being. The fluorescent substance according to any one of claims 1 to 3, wherein the I _IR is 0 or more and 0.005 or less. The fluorescent substance according to any one of claims 1 to 4, wherein the internal quantum efficiency η'of the fluorescent substance is 70% or more. The fluorescence according to any one of claims 1 to 5, wherein the ratio of [oxygen content] / [(fluorine content) + (oxygen content)] in the fluorescent substance is 0 or more and less than 0.05. body. A light emitting device comprising a light emitting device that emits light having a peak in a wavelength region of 440 nm or more and 470 nm or less, and a phosphor layer containing the phosphor according to any one of claims 1 to 6. Device. The apparatus according to claim 7, wherein the fluorescent substance layer further includes a fluorescent substance having an emission peak in a wavelength region of 520 nm or more and 570 nm or less.

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