KR101093575B1 - Nitride red phosphors and white light emitting diode using rare-earth-co-doped nitride red phosphors - Google Patents

Abstract

_X Re _x Al _y Si _{5 -} The invention of Ba ₂ nitride red phosphor, and relates to a white light emitting device using the same, in order to manufacture the white LED with high color rendering property and luminous efficiency that can be used for illumination, the new high-efficiency red phosphor _{- y} N ₈ It relates to a method for obtaining white light by using.

Description

RED PHOSPHORS AND WHITE LIGHT EMITTING DIODE USING RARE-EARTH-CO-DOPED NITRIDE RED PHOSPHORS

In the present invention, a nitride or oxynitride phosphor, which is a new nitride red phosphor suitable for 300 to 550 nm excitation light, is developed to obtain a white light source having high light efficiency, excellent thermal stability, and chemical stability suitable for blue and UV excitation light. It's about technology.

Efforts to apply light emitting diodes to lighting began in the late 1990s. In 2006, the global market for phosphors for lighting reached about $ 2 billion, and the LED lighting market is expected to grow by more than 20% annually, and the global market for 2012 is expected to grow to over $ 10 billion. Compared with the existing lighting fixtures, the light emitting diode has a long lifespan with high reliability, low maintenance costs, and low power consumption, which greatly contributes to energy saving. In addition, the design's low fluidity and heat generation make it suitable for use as lighting.

As a result of the technology of green and blue light emitting diodes, which are the first GaN-based light emitting diodes, all three primary colors of light, red, green and blue, can be obtained from light emitting diodes. Next, with continuous technology development, we produced white light emitting diodes using YAG-based phosphors for blue light emitting diodes, and technology development using red, green, and blue phosphors for ultraviolet light emitting diodes is in progress.

At present, the white light emitting diode is used as a backlight light source of a mobile phone display, a flash light source of a mobile phone equipped with a camera, and a backlight light source of an LCD monitor, and a new lighting fixture to replace conventional incandescent and fluorescent lamps due to a sharp rise in energy prices. Technology development is in progress.

In terms of efficiency, white light-emitting diodes are similar to incandescent lamps and fluorescent lamps, and their lifetimes are 10 times that of fluorescent lamps and 20 times more than incandescent lamps. As a next-generation lighting fixture, its position is firmly established. As the price is still high, it needs some time to spread, but in the current high oil price, the application of this technology can save enormous energy, and it is expected to spread to new lighting market in the near future.

Currently, a method of manufacturing a lamp using a semiconductor light source is a white light emitting diode using a YAG-based orange phosphor as a blue light emitting diode.

In addition, there is a white light emitting diode having a color rendering index improved by combining a red, green, blue phosphor or a yellow-red phosphor with a near ultraviolet or violet light emitting diode.

In addition, there are white light emitting diodes using a combination of red, green, and blue light emitting diodes.

However, a white light emitting diode using a YAG-based phosphor as a blue light emitting diode has a low color rendering property, and there is a side that is vulnerable to the limit of light efficiency and temperature effect due to Stokes shift, and there is a need for improvement thereof.

A white light emitting diode using a YAG-based phosphor for a blue light emitting diode has low color rendering because it uses two wavelengths, blue and yellow.

1 is a wavelength spectrum distribution diagram of a white light emitting diode according to the prior art.

1 shows a wavelength spectrum of a white light emitting diode manufactured from a blue light emitting diode and a YAG-based phosphor.

It can be seen that the color rendering index (Ra) is low because there is a region where the intensity of emission suddenly drops in the wavelength region between blue and green.

2 is a CIE chart of a white light emitting diode according to the prior art.

In FIG. 2, the B-LED represents a blue light emitting diode and the Y-phosphor represents yellow whose wavelength is partially converted by the YAG-based phosphor. White light moves along the connecting line between B-LED and Y-phosphor and is marked with W. It is composed of two wavelengths of blue and yellow, so the red color component is insufficient, so the color rendering property is about 60 to 75, which is not suitable for general indoor lighting.

As described above, a method of obtaining white light using a YAG phosphor, which is widely known as a method of fabricating a white light emitting diode, has low color rendering due to low efficiency and low red component of the phosphor, and uniform mixing ratio of epoxy and phosphor during fabrication. Difficulties arise in manufacturing techniques such as sex and reproducibility.

White light emitting diodes using three red, green, and blue light emitting diodes exhibit the highest luminous efficiency due to no light loss, but precise control of the driving driver is required to achieve accurate white color. In addition, since the product is large and the temperature characteristics of the three light emitting diodes are different from each other, the optical properties and reliability of the product may be affected.

In the present invention, Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ using light emitted from the light emitting diode without using the YAG phosphor Since red light emitted after excitation of the phosphor is used, the composition of the phosphor amount can be easily controlled, and an object thereof is to improve uniformity and reproducibility.

In addition, the present invention is a new Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ The present invention relates to the fabrication of white light emitting diodes having good thermal stability and chemical resistance using phosphors, and uses a light emitting diode light source having an excitation wavelength band of 300 to 550 nm, and emits sulfur by mixing phosphor powder in an appropriate ratio with epoxy. To produce a white light emitting diode using red and green.

In addition, the white light emitting diode according to the present invention uses a light source with an excitation wavelength band of 300 to 550 nm, and Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ thereon. The phosphor powder is mixed with an epoxy resin or silicone resin, and then applied thinly. Alternatively, in the flip-chip form, the phosphor is manufactured in a thin plate shape, and then bonded onto a substrate and molded into an epoxy lens and surface-mounted. It is an object to produce a white light emitting diode lamp of the type.

The red nitride phosphor according to an embodiment of the present invention is represented by the following [Formula 1], and is activated by a rare earth element, and has an excitation wavelength of 300 to 550 nm and an emission wavelength of 520 to 700 nm.

[Formula 1]

Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈

(Wherein 0 <x ≦ 0.6 and 0 <y ≦ 5, Re is at least one rare earth element or transition metal selected from the group consisting of Ce, Pr, Eu, Tb, Yb, Er and Mn) Element.)

In addition, the white light emitting diode according to the embodiment of the present invention excites the above-mentioned nitride red phosphor Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ with a light emitting diode light source having a wavelength of 300 to 550 nm to 520 to 700 nm. It generates an emission wave of the band, characterized in that to form a white light using it.

(Wherein Re uses Eu and 0.01 ≦ x ≦ 0.4 and 0 <y ≦ 5).

Here, the main excitation wavelength of the light emitting diode light source is characterized in that 390 ~ 480 nm, the peak emission wavelength of red light emitted after exciting the red nitride phosphor is characterized in that the 610 ~ 670 nm.

The white light emitting diode of the present invention can be used for lighting applications requiring high color rendering properties and will contribute to the activation of related industries such as light emitting diode manufacturing technology and phosphor manufacturing technology.

1 is a wavelength spectrum distribution diagram of a white light emitting diode according to the prior art.
2 is a CIE chart of a white light emitting diode according to the prior art.
3 is a graph showing light emission characteristics when the excitation energy wavelength of the nitride red phosphor according to Examples 1 to 4 of the present invention is 460 nm.
4 is a graph showing light emission characteristics when the excitation energy wavelength of the nitride red phosphor according to Examples 5 to 10 of the present invention is set to 460 nm.
5 is a graph showing light emission characteristics of aluminum nitride concentrations when the excitation energy wavelength of the nitride red phosphor according to Examples 11 to 15 of the present invention is 460 nm.
6 is a graph showing light emission characteristics of aluminum nitride concentrations when the excitation energy wavelength of the nitride red phosphor according to Examples 11 to 15 of the present invention is 405 nm.
FIG. 7 is a graph showing light emission characteristics of Eu concentrations when the excitation energy wavelength of the nitride red phosphor according to Examples 16 to 20 of the present invention is 460 nm; FIG.
FIG. 8 is a graph showing luminescence properties by concentrations of Eu when the excitation energy wavelength of the nitride red phosphor according to Examples 16 to 20 of the present invention is 405 nm; FIG.
9 is a schematic view showing a shell-type white light emitting diode product using a red nitride phosphor according to the present invention.
10 is a schematic view showing a surface-mount white light emitting diode product using a blue light emitting diode according to the present invention.
11 is a schematic view showing an epoxy lenticular surface mount white light emitting diode product according to the present invention;
12 is a luminance comparison result of the blue light excitation nitride red phosphor and commercial YAG product (cmmercial YAG) and the European tungstate-based red phosphor product for LCD backlight (Eu ₂ W ₂ O ₉ : Eu ² ) according to the present invention Graph shown.

The nitride red phosphor according to the present invention is composed of oxides, sulfides, nitrides and the like to which transition metals or rare earth ions are added to activate light emission. To this, α-SiAlON ceramics can be added and used as new phosphors with better thermal stability and chemical resistance.

Preparation materials according to the present invention include Si ₃ N ₄ , Mg ₃ N ₂ , MgO, MgCO ₃ , Ba ₃ N ₂ , BaCl ₂ , Ba (OH) ₂ , BaCO ₃ , CaO, Ca ₃ N ₂ , CaCl ₂ , Ca (OH) ₂ , CaCO ₃ , CaO, Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ by solid state reaction at atmospheric pressure using EuN, Eu (OH) ₃ , Eu ₂ O ₃ Phosphors were prepared, and the light emission characteristics of the concentrations of the elements included in the phosphors were measured. At this time, 0 <x <0.6 is preferable, and more preferably 0.01 <x <0.4.

To this end, the above-mentioned materials were first ground and mixed in a grove box filled with high purity nitrogen or argon gas, and then vacuum dried.

Next, the dried material was subjected to a first heat treatment in an N ₂ atmosphere at 600 to 900 ° C., and then subjected to secondary sintering in an N ₂ atmosphere containing at least 5% hydrogen at 1300 to 1800 ° C. FIG.

3 is a graph showing light emission characteristics when the excitation energy wavelength of the nitride red phosphor according to Examples 1 to 4 of the present invention is set to 460 nm.

FIG. 3 shows Re used as Eu in the nitride red phosphor Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ , fixing the value of x to 0.2, and changing the composition of the y value from 0.5 to 3.0 1300 to 1800 Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ calcined at It is a graph for examining the excitation and emission characteristics of the phosphor.

As a measuring method, a PL measuring instrument (Perkin Elmer LS 55) was used. As a result of spectrum measurement, the wavelength of the portion having the highest intensity was measured to show excitation and emission characteristics.

When the excitation wavelength is 460 nm (ex 460 nm), the emission wavelength is 622 nm (em622) for Example 1 (y = 0.5 mol), and 619 nm (em 619) for Example 2 (y = 1.0 mol). In Example 3 (y = 2.0 mol), 625 nm (em 625) and in Example 4 (y = 3.0 mol), 632 nm (em 632).

Thus, combining the above results, it can be seen that the composition of most nitride red phosphors according to the present invention has an emission wavelength of approximately 630 nm from an excitation wavelength of 460 nm to 619 to 632 nm.

4 is a graph showing light emission characteristics when the excitation energy wavelength of the nitride red phosphor according to Examples 5 to 10 of the present invention is set to 460 nm.

FIG. 4 shows Re using Eu as the nitride red phosphor Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ , fixing the value of x to 0.1, and changing the composition of the y value from 0.5 to 5.0 1300 to 1800. Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ calcined at It is a graph for examining the excitation and emission characteristics of the phosphor.

As a measuring method, a PL measuring instrument (Perkin Elmer LS 55) was used. As a result of spectrum measurement, the wavelength of the portion having the highest intensity was measured to show excitation and emission characteristics.

When the excitation wavelength is 460 nm (ex 460 nm), in Example 5 (y = 0.5 mol), the emission wavelength is 600 nm (em 600), and in Example 6 (y = 1.0 mol), it is 607 nm (em 607). In the case of Example 7 (y = 2.0 mol), 615 nm (em 615) and in Example 8 (y = 3.0 mol), 617 nm (em 617), and Example 9 (y = 4.0 mol). In the case of 619 nm (em 619), and in Example 10 (y = 5.0 mol) it is shown as 630 nm (em 630).

Accordingly, it can be seen from the above results that the composition of most nitride red phosphors according to the present invention has an emission wavelength of approximately 630 nm from an excitation wavelength of 460 nm to 600 to 630 nm.

In addition, referring to FIGS. 3 and 4, the y-value of the nitride red phosphor Ba _2-x Re _x Al _y Si _5-y N ₈ according to the present invention, that is, the emission of Al is increased from 0.5 to 5 mol. It can be seen that the spectrum shows the maximum value towards the longer wavelength. In addition, when comparing the content of Eu in Figures 3 and 4, it can be seen that as the content of Eu increases, the band narrows and the maximum value of the spectrum appears on the long wavelength side.

The nitride red phosphor of the present invention described above has a (Si, Al) (O, N) ₄ network structure based on a ring structure of [Al-N] and [Si-N], and these host lattice materials In the central part of the basic skeletal structure formed by the superposition of the atoms, the atoms with large ionic radius are placed on stoichiometry, and the rare earth metals such as Ce, Tb, Eu, and Y are located due to charge imbalance.

Therefore, the nitride red phosphor developed in the present invention is a Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ as a stoichiometric compound. The optical properties vary depending on the type of Re (Ce, Pr, Eu, Tb, Yb, Er) in the substrate. That is, Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ 1 to 2 or more of the Re elements stoichiometrically at the position of Ba in the solution form an interstitial or substitutional solid solution, which is structurally stable in a wide wavelength range and maximizes photon absorption. You will get the optimal structure.

FIG. 5 is a graph showing light emission characteristics according to aluminum nitride concentration when the excitation energy wavelength of the nitride red phosphor according to Examples 11 to 15 of the present invention is 460 nm, and FIG. 6 is Examples 11 to 15 of the present invention. It is a graph which shows the light emission characteristic by aluminum nitride density | concentration when the excitation energy wavelength of the nitride red fluorescent substance which concerns on 15 is set to 405 nm.

Examples 11 to 15 used in FIGS. 5 and 6 include Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ . The case where Re is used as Eu and Eu addition ratio is set to 0.01 mol, 0.05 mol, 0.1 mol, 0.2 mol and 0.4 mol respectively is shown.

Here, the intensity of each emission wavelength was measured when the excitation wavelength was 460 nm or 405 nm while varying the content (mol) of AlN according to each example.

As the content of AlN increases, the intensity of the emission wavelength decreases. On the contrary, as the content of Eu increases, the intensity of the emission wavelength increases.

7 is a graph showing luminescence properties by Eu concentration when the excitation energy wavelength of the nitride red phosphor according to Examples 16 to 20 of the present invention is 460 nm, and FIG. 8 is Examples 16 to 20 of the present invention. Is a graph showing the luminescence properties for each Eu concentration when the excitation energy wavelength of the nitride red phosphor is set to 405 nm.

Examples 16 to 21 used in FIGS. 7 and 8 include Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ . The case where Re is used as Eu and y is set to 0.5 mol, 1.0 mol, 2.0 mol, 3.0 mol, 4.0 mol and 5.0 mol, respectively.

Here, the intensity of each emission wavelength at the time of setting 460 nm and 405 nm as an excitation wavelength was measured, changing the addition ratio of Eu to 0.001-0.4 mol, respectively.

As the content of Eu increases, the intensity of the emission wavelength decreases, and as the content of Al increases, the intensity of the emission wavelength decreases.

In the above description, Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ medium Examples of using Eu as a material that can represent Re, but is not limited thereto.

Such a nitride red phosphor according to the present invention has an orthorhombic, and when the structure is analyzed by X-ray diffraction pattern measurement, it appears as a structure having a maximum peak at 35.18 °.

This structure is completely different from CaAlSiN ₃ , M ₂ Si ₅ N ₈ (M = Ca, Sr, Ba) nitrides, and MSi ₂ O ₂ N ₂ (M = Ca, Sr, Ba) oxynitrides. It has a crystal structure.

In addition, the particles of the nitride red phosphor according to the present invention was composed of fine particles having a length of about 3 ~ 4㎛, it can be seen that particles of 2㎛ or less are formed. Such a phosphor particle size is easy to mix with an epoxy or the like and is suitable for application of a white light emitting diode device. Generally, it is known that the average particle diameter of the phosphor for LED excitation is suitably 10 μm or less.

Therefore, in the present invention, Ba _{2 - x} Re _x Al _y Si _{5 - y} N _{8 which is} excited by light emitting diode having a wavelength of 300 to 550 nm and emits red light as described above. The phosphor may be mixed in an appropriate ratio to produce a white light emitting diode or a white light emitting diode lamp.

The white light emitting diode or the white light emitting diode lamp according to the present invention includes a mixed region such as epoxy or silicone resin and a lead frame or electrode wiring for connecting the epoxy lens and the electrode to the outside.

9 is a schematic view showing a shell-type white light emitting diode product using a nitride red phosphor according to the present invention.

Referring to FIG. 9, the blue light emitting diode 110 may be an (Al) InGaN active layer, and the substrate may be a sapphire substrate or a silicon carbide (SiC) substrate. After the die bonding of the blue light emitting diode 110 to the lead frame 150, gold wire bonding 140 is performed to connect the electrodes to the outside. Gold wire bonding 140, when using a sapphire substrate, there is a p-type and n-type electrode on the upper part of the device must be gold wire bonding 140, respectively, and when using a SiC conductive substrate, one gold wire bonding (140) )can do. After gold wire bonding 140, a region 120 in which epoxy and phosphors are mixed for white light emission is applied using a dispenser or a suitable coating method.

Next, after application, the resultant is cured at a constant temperature so as not to flow down. Thereafter, the epoxy lens 130 is formed by using a mold having a desired shape, and the shell type white light emitting diode lamp 100 is manufactured by trimming and cutting the lead frame 150.

Here, in order to further embody the present invention, epoxy and Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ By varying the proportion of the phosphor, a shell-type lamp was fabricated to measure the color rendering, color temperature and spectrum. For example, epoxy and phosphor mixture are applied by a dispensing method by adding 0.1 g, 0.2 g, 0.3 g, 0.4 g, and 0.5 g of phosphors based on 100 µl of transparent epoxy to prepare a transparent epoxy lamp.

In addition, other types of package types may be manufactured, and in particular, the surface mount type (SMD, SMT) can be manufactured, which are shown in the following simple drawings in FIGS. 10 and 11.

10 is a schematic view showing a surface mounted white light emitting diode product using a blue light emitting diode according to the present invention.

Referring to FIG. 10, the blue light emitting diode 210 is die bonded on the metal line 270 of the PCB substrate 260, and the p and n electrodes of the light emitting diode are bonded 240 to the metal line 270 with gold wires. To be in electrical communication with the outside. Then in a suitable amount of epoxy (220) Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ The phosphors 220a and 220b are mixed and placed on the blue light emitting diode 210. Next, the epoxy mixed with the phosphor may be molded in a dispenser type, and another method may be solidified to complete the surface mounted white light emitting diode lamp 200 manufactured in a transfer mold type.

11 is a schematic view showing an epoxy lens-type surface mounted white light emitting diode product according to the present invention.

Referring to FIG. 11, the package is a PCB substrate or a ceramic substrate 360, and a metal wire 370 is attached to a portion to be an anode and a cathode, and the substrate 360 is separated by an insulator 390 or the like. It is. The interior of the epoxy confinement region 380 is composed of a reflective film coated with aluminum or silver, which serves to reflect upward the light emitted from the diode and to confine an appropriate amount of epoxy. The epoxy light emitting diode 310 is die-bonded in the form of a flip chip with a bonding material 340 such as a gold bumper or Au-Sn, and an epoxy or silicone resin 320 mixed with green and red phosphors at a proper mixing ratio is used. Dispensing. Here, the silicone resin 320 may be used for a high power light emitting diode package. The silicone resin 320 may prevent thermal stress from being directly transmitted to the chip, adversely affecting reliability or short-circuit of the gold wire due to heat shrinkage or expansion. In addition, by using the silicone resin 320 having a higher refractive index than the epoxy, it is possible to improve the luminance by reducing the reflection at the interface of the light emitted from the diode.

As described above, after the epoxy or silicone resin 320 having the phosphor mixed thereon, an epoxy lens 330 is formed thereon. At this time, the epoxy lens 330 may be changed in shape depending on the desired orientation angle.

When evaluating the optical properties of the products according to the invention formed as described above are as follows.

12 is a luminance comparison result of the blue light excitation nitride red phosphor and commercial YAG product (cmmercial YAG) and the European tungstate-based red phosphor product for LCD backlight (Eu ₂ W ₂ O ₉ : Eu ² ) according to the present invention The graph shown.

Referring to FIG. 12, in the region where the emission wavelength by the blue light source excitation light according to the present invention is 610 nm or more, existing commercial YAG products (cmmercial YAG) and European tungstate-based red phosphor products for LCD backlights (Eu ₂ W ₂ O ₉ Compared with: Eu ² ), it has better performance.

As described above, the present invention is Ba _{2 - x} Re _x Al _y Si _{5 - y} N ₈ By exciting the phosphor at a wavelength of 460nm, it is possible to improve the efficiency and high color rendering of the white diode using the blue and ultraviolet light-based light emitting diodes, thereby enabling a variety of colors.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above embodiments, but may be modified in various forms, and having ordinary skill in the art to which the present invention pertains. It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (4)

A red nitride phosphor, represented by the following [Formula 1], having an excitation wavelength of 405 to 460 nm and an emission wavelength of 600 to 630 nm.
[Formula 1]
Ba _2-x Re _x Al _y Si _5-y N ₈
(Wherein values of 0.1 ≦ x ≦ 0.2 and 0.5 ≦ y ≦ 5, Re is at least one rare earth element selected from the group consisting of Ce, Pr, Eu, Tb, Yb and Er.) delete delete delete

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