KR100902416B1 - Strontium magnesium silicate based white phosphor and white led using the same - Google Patents

Abstract

A strontium magnesium silicate-based white phosphor is provided to ensure excellent light emitting property in a condition excluding a fluxing agent for lowering temperature and a poison component, and high efficiency. A method for manufacturing strontium magnesium silicate-based white phosphor comprises the steps of: mixing a strontium precursor, barium precursor, calcium precursor, magnesium precursor, silica precursor and europium precursor in the content represented by formula 1: (3-x-y)SrO.x(aBaO.bCaO).MgO.Si_zO_8 : yEu^(2+); drying the mixture at 100~150 °C to manufacture a phosphor precursor; and heat-treating the precursors in a mixed gas atmosphere of rogen and hydrogen at 800~1500 °C. In the chemical formula 1, 0 <= x <1, 0.005 <y <= 1, and 1.5 <= z <=1.9; a is a mole number of BaO and 0 <= a <=1; b is a mole number of CaO and 0 <= b <= 1.

Description

Strontium Magnesium Silicate based White Phosphor and White LED using the same

The present invention provides a novel strontium-magnesium-silicate-based white phosphor having a high absorption peak at 405 nm and good emission intensity and dominant wavelengths of 460 nm and 560 nm, which has excellent properties in realizing white color, and a white light emitting diode using the same. It is about.

In general, in order to manufacture light emitting diodes (LEDs) such as blue, green, and red, different substrates such as InGaN, GaN, GaAs, and ZnO series are used. It has a problem that the investment cost for the LED manufacturing process is high and the manufacturing cost is high. Therefore, if LEDs capable of emitting blue, red and green light emission using the same semiconductor thin film are possible, the manufacturing process is simplified, which can bring economic efficiency such as manufacturing cost and investment cost. .

Meanwhile, numerous studies have been conducted on display phosphors, which are core materials used to realize color in the display industry. These phosphors are selected to exhibit characteristics of excitation in the wavelength range of the incident light source, and it is required to have luminance, color purity, afterglow characteristics, current saturation characteristics, deterioration characteristics, and other physical properties suitable for various display methods.

In general, white LEDs, which are spotlighted as back light sources for light emitting liquid crystal displays (LCDs) such as lighting, notebooks, mobile phones, etc., are currently manufactured by combining YAG: Ce phosphors with blue LEDs [Korea Patent Publication No. 2000-49728]. . However, a white LED utilizing a blue LED has a wavelength of 450 nm as an excitation energy source, and thus has a limitation of using a suitable fluorescent material.

That is, using a blue LED having a wavelength of 450 nm is difficult to implement only a white LED using YAG: Ce. In order to solve these problems, efforts are being made to develop red, green, blue and white LEDs utilizing UV LEDs, and in the application of such UV LEDs, it is urgent to develop phosphors suitable for them. Therefore, the development of blue, green, and red phosphors having excellent luminous efficiency in the excitation energy source between 380 nm and 420 nm is a challenge, and such a phosphor having good efficiency in long-wavelength UV is also active in the development of an active light emitting liquid crystal display (LCD). Very important.

In active light emitting liquid crystal displays (LCDs), a long wavelength UV of 390 nm or more must be used as a back light source to protect the liquid crystal, and thus the phosphor itself needs to have long wavelength UV of 390 nm or more. As described above, the development of a white fluorescent material having good long wavelength UV is very important in the development of an active light emitting liquid crystal display (LCD) as in the development of a white light emitting diode (LED).

White phosphors developed for medium wavelength UV of 254 nm and 365 nm that are currently commercially available include Ca ₁₀ (PO ₄ ) ₆ FCl: Sb, Mn, but the emission intensity is deteriorated in long wavelength UV. Have.

Therefore, there is a big limitation in the development of white phosphors and white LEDs utilizing UV LEDs having an excitation wavelength between 380 nm and 420 nm and the development of active light emitting liquid crystal displays using white LEDs.

The present invention is excellent in luminescence and color purity in order to improve the problem that the conventional Ca ₁₀ (PO ₄ ) ₆ FCl: Sb, Mn-based white phosphor is rapidly lowered in the long wavelength, the luminescence intensity is maintained even in the medium wavelength A novel white phosphor and a white light emitting diode using the white phosphor are proposed.

In addition, the present invention heat-treat the phosphor mixture forming a certain component ratio as described above under a reaction gas in which nitrogen and hydrogen are mixed in a certain component ratio, it is possible to manufacture the phosphor in a low temperature range without using a separate flux for reducing the conventional firing temperature It is intended to provide a method of making a white phosphor, which is capable of eliminating the use of toxic components.

The present invention is characterized by the strontium-magnesium-silicate-based white phosphor represented by the following formula (1).

(3-xy) SrO · x (a BaO · b CaO) · MgO · Si z O 8: yEu 2+

In Formula 1, 0 ≦ x <1, 0.005 <y ≦ 1, 1.5 ≦ z ≦ 1.9, a represents the number of moles of BaO, 0 ≦ a ≦ 1, and b represents the number of moles of CaO. ≤ b ≤ 1.

In addition, the present invention is a step of mixing the strontium precursor, barium precursor, calcium precursor, magnesium precursor, silica precursor and europium precursor in the content shown in the formula (1); Drying the mixture at 100 to 150 ° C. to prepare a phosphor precursor; And it is another feature in the method for producing a strontium-magnesium-silicate-based white phosphor comprising the three steps of producing a phosphor by heat-treating the precursor at a temperature range of 800 ~ 1500 ℃ under a mixed gas atmosphere of hydrogen and nitrogen.

In addition, the present invention has another feature of the white light emitting diode comprising the strontium-magnesium-silicate-based white phosphor.

Since the strontium-magnesium-silicate-based phosphor according to the present invention has a high absorption peak at 405 nm and a good emission intensity, and dominant wavelengths are 460 nm and 560 nm, it shows excellent properties in realizing white color, so that color purity can be improved. It is expected that UV light emitting diodes and active light emitting liquid crystal displays will be applied to high-efficiency white fluorescent materials.

The present invention is a novel strontium-magnesium-silicate-based white phosphor in which alkaline earth metals such as strontium, barium or calcium, magnesium, silica, and europium are maintained at a specific component ratio, and the luminescence and color purity are controlled by controlling the content ratio of alkaline earth metals. Excellent and maintains luminous intensity at medium and long wavelengths.

Each component used in the present invention is commonly used as a component constituting the white phosphor, but the properties of the phosphor, that is, the physical properties of the phosphor, such as the expression color and luminescence intensity vary greatly depending on the component composition and content in the phosphor is simply known. The use of the components alone does not recognize the same phosphor.

In addition, the present invention enables the production of a white phosphor by using a reaction gas in which nitrogen and hydrogen are mixed in a predetermined component ratio during the heat treatment process, by reducing the europium ions of the activator from trivalent to divalent.

Looking at the method for producing a strontium-magnesium-silicate-based white phosphor according to the present invention in more detail.

Strontium precursor, barium precursor, calcium precursor, magnesium precursor, silica precursor and europium precursor are mixed in stoichiometric ratio as shown in the above formula (1).

Each of the strontium precursors, barium precursors, calcium precursors, magnesium precursors, silica precursors, and europium precursors is not particularly limited to compounds commonly used in the art, and specifically, oxides, carbonates, hydroxides, sulfates, fluorides, nitrates, acetates Preference is given to using compounds in the form of selenides, arsenates and tungstates.

The precursor of each component may be mixed and used in the range of the stoichiometric ratio shown in the formula (1), in the case of europium it is preferable to use 0.001 to 0.5 mol, preferably 0.01 to 0.3 mol relative to strontium for high luminous efficiency. . If the amount of use is less than 0.001 mole, the amount is not sufficient to function as an active agent, and if the amount is more than 0.5 mole, it is preferable to maintain the above range because luminance decreases due to concentration quenching.

Moreover, barium and calcium which are alkaline earth metal components can be used individually or in mixture, and when using them, it is good to use in the range of 0.005-0.5 mol of calcium with respect to 1 mol of barium. If the amount of calcium used is less than 0.005 mole, the second phase may be formed when the molar amount exceeds 0.5 mole, and the luminous efficiency may be reduced.

The mixing is not particularly limited to those commonly used in the art, but it is preferable to mix the mixture sufficiently so as to have a uniform composition by using a mixer such as ball milling or agate induction. At this time, it is preferable to use a small amount of a solvent such as alcohol and acetone to mix together for more effective mixing.

Next, the mixture is dried at 100 to 150 ° C. to prepare a phosphor precursor. At this time, if the drying temperature is less than 100 ℃ is a problem in the efficient reaction performance to increase the drying time, if it exceeds 150 ℃ it is preferable to maintain the above range because there is the possibility of self-reaction, and keep the drying time 1 to 24 hours Good to do. The drying is not particularly limited to the method generally performed in the art.

Next, the precursor is heat-treated under a mixed gas atmosphere of hydrogen and nitrogen to prepare a phosphor. The mixed gas is introduced in order to reduce the activator by reacting with the precursor and hydrogen gas, and to change the crystal lattice to play a role of obtaining an appropriate luminous efficiency. The volume ratio of nitrogen and hydrogen is 75 to 98: 2 to 25 It is good to maintain the volume ratio. If the volume of the nitrogen exceeds the range of the active agent is not reduced well because the light of the desired color is not good, if the volume of the hydrogen exceeds the range, the hydrogen gas reacts with the external oxygen to explode Therefore, it is preferable to maintain the above range.

The temperature during the heat treatment is preferably maintained at a temperature range of 800 ~ 1500 ℃, preferably 1000 ~ 1400 ℃. As a result of measuring the photoluminescence (PL) of the phosphor powder thus prepared with an excitation wavelength of 405 nm, it can be seen that a white spectrum having a main peak at 455 nm and 560 nm was produced.

The strontium magnesium silicate-based white phosphor prepared as described above has an excellent luminescence and color purity by adding alkaline earth metal in the composition of the component, thereby maintaining the luminescent intensity in the medium-wavelength.

In addition, by heat treatment under a reaction gas mixed with nitrogen and hydrogen, it is possible to produce a phosphor having excellent luminescence properties under conditions that eliminate the use of flux and toxic components for reducing the conventional firing temperature.

The present invention also provides a UV LED and an active light-emitting liquid crystal display using the strontium-magnesium-silicate-based white phosphor, wherein the white phosphor of the present invention based on strontium magnesium silicate and doped with a euro component is used as a UV LED and When applied to an active light emitting liquid crystal display has a high luminous efficiency.

Although this invention is demonstrated in detail based on an Example, this invention is not limited to an Example.

Example 1: 2.97 SrO-MgO - Si _z O ₈ : 0.03Eu ²⁺ (1.5 ≦ _z ≦ 1.9) phosphor

2.97 mol of strontium precursor (SrCO ₃ ), 1 mol of magnesium precursor (MgO), 1.5 mol to 1.9 mol (1.5 mol, 1.6 mol, 1.7 mol, 1.8 mol and 1.9 mol) of silica precursor (SiO ₂ ), europium precursor (Eu ₂ O ₃ ) 0.03 moles were mixed in a stoichiometric ratio, and mixed sufficiently to achieve a uniform composition by ball milling under 5 mL of acetone solvent for effective mixing. The mixture was then placed in an oven and dried at 120 ° C. for 24 hours. The dry mixture was placed in a high purity alumina boat and heat treated at 1250 ° C. under a mixed gas having a ratio of hydrogen and nitrogen in a volume ratio of 20:80 for 24 hours using an electric furnace to prepare a strontium-magnesium-silicate-based white phosphor.

The emission spectrum of the strontium-magnesium-silicate-based white phosphor prepared above was measured and the results are shown in FIG. 2.

As shown in FIG. 2, as the content of the silica precursor (SiO ₂ ) was increased, 460 nm increased and 520 nm decreased. At this time, the color temperature can be determined according to the two wavelengths.

Example 2 (2.97-x) SrOxBaOMgOSi _1.7 O ₈ : 0.03Eu ²⁺  (0≤x≤0.5) white phosphor

In the same manner as in Example 1, except that the strontium precursor (SrCO ₃ ) (2.97-x) mol, the barium precursor (BaCO ₃ ) 0 mol ~ 0.5 mol (0 mol, 0.05 mol, 0.1 mol, 0.2 mol, 0.3 mol, 0.4 mole, and 0.5 mole), 1 mole of magnesium precursor (MgO), 1.7 mole of silica precursor (SiO ₂ ), 0.03 mole of europium precursor (Eu ₂ O ₃ ) are mixed in stoichiometric ratios of strontium-magnesium-silicate-based white phosphors Was prepared.

The emission spectrum of the strontium-magnesium-silicate-based white phosphor prepared above was measured and the results are shown in FIG. 3.

As shown in FIG. 3, the silica precursor (SiO ₂ ) was fixed at 1.7 mol, and when the content of the barium precursor (BaCO ₃ ) was increased, the wavelength changed from 520 nm to 550 nm, and the 460 nm wavelength decreased. Could.

Example 3: (2.97-x) SrO.xBaO.MgO.Si _1.8 O ₈  : 0.03Eu ²⁺ (0≤x≤0.7) white phosphor

In the same manner as in Example 1, except that the strontium precursor (SrCO ₃ ) (2.97-x) mol, the barium precursor (BaCO ₃ ) 0 mol ~ 0.5 mol (0 mol, 0.05 mol, 0.1 mol, 0.2 mol, 0.3 mol, 0.4 mol, and 0.5 mol), 1 mol of magnesium precursor (MgO), silica precursor 1.8 Moles and 0.03 moles of europium precursor were mixed in a stoichiometric ratio to prepare a strontium-magnesium-silicate-based white phosphor.

The emission spectrum of the strontium-magnesium-silicate-based white phosphor prepared above was measured and the results are shown in FIG. 4.

As shown in FIG. 3, the silica precursor (SiO ₂ ) was fixed at 1.8 mol, and when the content of the barium precursor (BaCO ₃ ) was increased, the wavelength was changed from 520 nm to 540 nm, and the 460 nm wavelength was decreased. Could.

Example 4: (2.97-x) SrO.xCaO.MgO.Si _1.7 O ₈ : 0.03Eu ²⁺  (0≤x≤0.8) white phosphor

In the same manner as in Example 1, strontium precursor (SrCO ₃ ) (2.97-x) mol, calcium precursor (CaCO ₃ ) 0 mol ~ 0.8 mol (0 mol, 0.1 mol, 0.2 mol, 0.3 mol, 0.4 mol, 0.5 mole, 0.6 mole, 0.7 mole, 0.8 mole), 1 mole of magnesium precursor (MgO), 1.7 mole of silica precursor (SiO ₂ ), 0.03 mole of europium precursor (Eu ₂ O ₃ ) are mixed in stoichiometric ratios of strontium-magnesium Silicate-based white phosphors were prepared.

The emission spectrum of the strontium-magnesium-silicate-based white phosphor prepared above was measured and the results are shown in FIG. 5.

As shown in FIG. 3, the silica precursor (SiO ₂ ) was fixed at 1.7 mol, and when the content of the calcium precursor (CaCO ₃ ) was increased, the wavelength of 560 nm increased and the wavelength of 460 nm decreased.

Example 5 (2.97-x) SrOx (CaOBaO) MgOSi _1.7 O ₈ : 0.03Eu ²⁺  (0.1≤x≤0.6) white phosphor

In the same manner as in Example 1, but the strontium precursor (SrCO ₃ ) (2.97-x) mol, calcium precursor (CaCO ₃ ) and barium precursor (BaCO ₃ ) 0.1 mol to 0.6 mol (0.1 mol, 0.2 mol, 0.3 mol , 0.4 mole, 0.5 mole, and 0.6 mole), 1 mole of magnesium precursor (MgO), 1.7 mole of silica precursor (SiO ₂ ), 0.03 mole of europium precursor (Eu ₂ O ₃ ) are mixed in stoichiometric ratios of strontium-magnesium- A silicate white phosphor was prepared.

The emission spectrum of the strontium-magnesium-silicate-based white phosphor prepared above was measured and the results are shown in FIG. 6.

As shown in FIG. 6, the silica precursor (SiO ₂ ) was fixed at 1.7 mol, and when the contents of the calcium precursor (CaCO ₃ ) and the barium precursor (BaCO ₃ ) were increased, the wavelength of 550 nm was confirmed to increase. .

Experimental Example 1: (2.97-x) SrO-xBaO-MgO-Si _1.7 O ₈ : 0.03Eu ²⁺ (0≤x≤0.4) Fabrication of White Light Emitting Diodes (LEDs) Using White Phosphors

Next, a white light emitting diode was manufactured by introducing the strontium magnesium silicate-based white phosphors prepared in Examples 1 and 2 using the long wavelength ultraviolet light emitting diode chip shown in FIG. 1.

The long wavelength ultraviolet light emitting diode chip (InGaN) emission spectrum using the strontium magnesium silicate-based white phosphors obtained in Examples 1 and 2 was measured, and the results are shown in FIG. 7.

The following Table 1 shows the physical properties such as color temperature, color rendering index and efficiency according to the type of phosphor, wherein the physical properties are 6 inch integrated using the LED Test System [Optronic Laoratories, OL770 model] possessed by the Korea Institute of Optical Technology. The measurements were taken at 20 mA using the sphere.

Type of phosphor Color temperature (K) Color rendering index (R) Efficiency (lm / W) Si 1.8 6400 67.9 15.7 Si 1.7 6100 68.9 15.7 Si 1.7-Ba 0.1 4900 75.6 14.3 Si 1.7-Ba 0.2 5100 72.4 13.6 Si 1.7-Ba 0.3 5100 67.3 14.6 Si 1.7-Ba 0.4 5300 63.6 14.9

As shown in FIG. 7, the strontium magnesium silicate-based white phosphor of the present invention absorbs the energy of the 405 nm chip and shows two wavelengths of 460 nm and 560 nm depending on the content of the phosphor. Accordingly, the color rendering index is good when the content of silicate is 1.7 mol, and the color rendering index is the best when the content of barium is 0.1 mol.

Experimental Example 2: (2.97-x) SrO-xBaO-MgO-Si _1.7 O ₈ : 0.03Eu ²⁺  (0≤x≤0.4) Variation of Color Coordinates According to Barium Content of White Phosphor

8 shows changes in color coordinates of the strontium magnesium silicate-based white phosphor obtained in Experimental Example 1 according to the change in the amount of barium added to the long wavelength ultraviolet light emitting diode chip (InGaN).

As shown in FIG. 8, the strontium magnesium silicate-based white phosphor of the present invention absorbed the energy of the 405 nm chip, and thus the CIE X and CIE Y values increased according to the phosphor content.

FIG. 1 (a) shows a white light emitting diode in package form and FIG. 1 (b) shows a top view of a top light emitting diode.

 [Explanation of symbols for the main parts of the flowchart of FIG. 1]

1: ultraviolet light emitting chip 2: Ag paste

3: white fluorescent substance 4: Au wire

5: epoxy 6: lead frame

Figure 2 shows the emission spectrum of 2.97SrO.MgO.Si _z O ₈ : 0.032Eu ⁺ (1.5≤z≤1.9) white phosphor prepared in Example 1 according to the present invention.

Figure 3 shows the emission spectrum of the (2.97-x) SrO.Ba0.MgO.Si _1.7 O ₈ : 0.032Eu ⁺ (0≤x≤0.5) phosphor prepared in Example 2 according to the present invention.

Figure 4 shows the emission spectrum of the (2.97-x) SrO.Ba0.MgO.Si _1.8 O ₈ : 0.032Eu ⁺ (0≤x≤0.7) phosphor prepared in Example 3 according to the present invention.

Figure 5 shows the emission spectrum of the (2.97-x) SrO.Ca0.MgO.Si _1.7 O ₈ : 0.032Eu ⁺ (0≤x≤0.8) phosphor prepared in Example 4 according to the present invention.

6 shows the emission spectrum of (2.97-x) SrO.x (BaO.Ca0) .MgO.Si _1.7 O ₈ : 0.032Eu ⁺ (0.1≤x≤0.6) phosphor prepared in Example 5 according to the present invention. will be.

7 is a white film according to a change in barium content using (2.97-x) SrO.Ba0.MgO.Si _1.7 O ₈ : 0.032Eu ⁺ (0≤x≤0.4) phosphor prepared according to the present invention. The emission spectrum of the LED lamp is shown.

8 is a (2.97-x) SrO.Ba0.MgO.Si _1.7 O ₈ : 0.032Eu ⁺ (0≤x≤0.4) phosphor prepared in Example 2 according to the present invention. It is shown.

Claims (4)

Strontium-magnesium-silicate-based white phosphor, characterized in that represented by the formula (1); [Formula 1] (3-xy) SrO · x (a BaO · b CaO) · MgO · Si z O 8: yEu 2+ In Formula 1, 0 ≦ x <1, 0.005 <y ≦ 1, 1.5 ≦ z ≦ 1.9, a represents the number of moles of BaO, 0 ≦ a ≦ 1, and b represents the number of moles of CaO. ≤ b ≤ 1. 1 step of mixing the strontium precursor, barium precursor, calcium precursor, magnesium precursor, silica precursor and europium precursor to the content shown in the following formula (1); Drying the mixture at 100 to 150 ° C. to prepare a phosphor precursor; And Three steps of producing a phosphor by heat-treating the precursor at a temperature range of 800 ~ 1500 ℃ under a mixed gas atmosphere of hydrogen and nitrogen Method for producing a strontium-magnesium-silicate-based white phosphor, characterized in that consisting of: [Formula 1] (3-xy) SrO · x (a BaO · b CaO) · MgO · Si z O 8: yEu 2+ In Formula 1, 0 ≦ x <1, 0.005 <y ≦ 1, 1.5 ≦ z ≦ 1.9, a represents the number of moles of BaO, 0 ≦ a ≦ 1, and b represents the number of moles of CaO. ≤ b ≤ 1. The method according to claim 2, wherein the nitrogen and hydrogen are mixed and used in a volume ratio of 75 to 98: 2 to 25. A white light emitting diode comprising the strontium-magnesium-silicate-based white phosphor of claim 1.

Images