KR102637411B1 - Phosphor emitting red light and light emitting device using the same - Google Patents

Abstract

The present invention relates to phosphors, and particularly to red light-emitting phosphors and light-emitting devices using the same. The present invention is characterized in that the red light-emitting phosphor emits light having a main absorption band in the blue wavelength band and a main peak in the red wavelength band, and is represented by the following formula (1).
<Formula 1> Li _{1 .5+ x} Sr _{1 - y} Al _{0 .5+ z} Si _{1 - z} O _{3 + z} N _{1 -z} :Eu _y

Description

Red light emitting phosphor and light emitting device using the same {Phosphor emitting red light and light emitting device using the same}

The present invention relates to phosphors, and particularly to red light-emitting phosphors and light-emitting devices using the same.

Light emitting diode (LED) or laser diode (LD) is one of the candidates for next-generation light emitting devices that are replacing fluorescent lamps, which are the most representative type of general lighting.

Semiconductor light-emitting devices, such as LED or LD, consume less power than existing light sources and, unlike fluorescent lamps, do not contain mercury, so they can be said to be environmentally friendly. Additionally, compared to existing light sources, it has the advantage of long lifespan and fast response speed.

These LEDs can be used with phosphors that absorb light emitted from the LEDs and emit light of various colors. Such phosphors can usually emit yellow, green, and red light.

White LEDs are currently manufactured by consisting of a blue light-emitting LED and a phosphor that converts the emission wavelength of the light emitted from the LED. As the range of use of these white LEDs increases, more efficient LEDs are required, and for this, improvement in the luminous efficiency of the phosphor is required. Additionally, the demand for more reliable LEDs is increasing.

Usually, such white LEDs are composed of blue-emitting LEDs and phosphors that change wavelength. As the range of use of white LEDs increases, white LEDs with excellent color rendering are required, and for this purpose, there is a need for phosphors with various emission wavelengths. It's getting higher.

Conventional white LEDs are a combination of blue LEDs and yellow phosphors, and have the disadvantage of low color rendering due to the lack of green and red components.

Additionally, attempts are being made to improve color rendering by adding red phosphors to blue LEDs.

However, the light conversion efficiency of these red phosphors is not high, and therefore, there is a need to develop red phosphors with high light conversion efficiency.

The present invention aims to provide a red light-emitting phosphor with high light conversion efficiency.

Additionally, the present invention aims to provide a light-emitting device with excellent color rendering and high luminescence intensity using a red light-emitting phosphor with high light conversion efficiency.

As a first aspect for achieving the above technical problem, the present invention relates to a red light-emitting phosphor, which emits light having a main absorption band in the blue wavelength band and a main peak in the red wavelength band, expressed by the following formula (1) It is characterized by being

<Formula 1> Li _{1 .5+ x} Sr _{1 - y} Al _{0 .5+ z} Si _{1 - z} O _{3 + z} N _{1 -z} :Eu _y

This red light-emitting phosphor is a new, hitherto unknown phosphor, and can have high light conversion efficiency.

Additionally, x, y and z may satisfy at least one of the following conditions: -1.5 < x < 2, 0.0001 < y < 0.2, and -0.5 < z <1.

Additionally, the red light-emitting phosphor may have a monoclinic crystal structure.

At this time, the lattice constant of the crystal structure may satisfy a = 5.1777 Å, b = 14.828 Å, and c = 5.4244 Å.

Additionally, the red light-emitting phosphor may have an excitation light wavelength band of 300 to 500 nm.

As a second aspect for achieving the above technical problem, the present invention provides a light-emitting device, comprising: a light-emitting element; and a first phosphor that is excited by light emitted from the light emitting device and emits red light, and is represented by the following formula (1).

<Formula 1> Li _{1 .5+ x} Sr _{1 - y} Al _{0 .5+ z} Si _{1 - z} O _{3 + z} N _{1 -z} :Eu _y

Additionally, x, y and z may satisfy at least one of the following conditions: -1.5 < x < 2, 0.0001 < y < 0.2, and -0.5 < z <1.

Additionally, the light emitting device may further include a second phosphor that is excited by light emitted from the light emitting device and emits yellow light.

Additionally, the light emitting device may further include a third phosphor that is excited by light emitted from the light emitting device and emits green light.

At this time, the first phosphor, the second phosphor, and the third phosphor form a mixture, and the mixture may be excited by light emitted from the light emitting device to emit yellow light.

According to the present invention, the following effects are achieved.

First, according to the present invention, a red light-emitting phosphor with high light conversion efficiency can be provided.

In addition, according to the present invention, it is possible to provide a light-emitting device with excellent color rendering and high luminescence intensity by using a red light-emitting phosphor with high light conversion efficiency.

Figure 1 is an XRD spectrum according to an embodiment of the present invention.
Figure 2 is a diagram showing a crystal structure according to an embodiment of the present invention.
Figure 3 is an absorption spectrum of a red light-emitting phosphor according to an embodiment of the present invention.
Figure 4 is an emission spectrum of a red light-emitting phosphor according to an embodiment of the present invention.
Figure 5 is an emission spectrum of a red light-emitting phosphor according to each example of the present invention.
Figure 6 is a cross-sectional view showing an example of a light-emitting device using the red light-emitting phosphor of the present invention.
FIG. 7 is a partially enlarged view of FIG. 6 to explain the optical conversion process.
Figure 8 is an emission spectrum of a light-emitting device to which a red light-emitting phosphor is applied according to an embodiment of the present invention.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the attached drawings.

While the invention is susceptible to various modifications and variations, specific embodiments thereof are illustrated in the drawings and will be described in detail below. However, it is not intended to limit the invention to the particular form disclosed, but rather, the invention is intended to cover all modifications, equivalents and substitutions consistent with the spirit of the invention as defined by the claims.

It will be understood that when an element such as a layer, region or substrate is referred to as being “on” another element, it may be present directly on the other element or there may be intermediate elements in between. .

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers and/or regions, these elements, components, regions, layers and/or regions are It will be understood that we should not be limited by these terms.

In the detailed description, “and/or” may mean at least one or more of the two components.

First, the red light-emitting phosphor according to the present invention will be described.

The present invention is characterized in that the red light-emitting phosphor emits light having a main absorption band in the blue wavelength band and a main peak in the red wavelength band, and is represented by the following formula (1).

This red light-emitting phosphor is a new, hitherto unknown phosphor, and can have high light conversion efficiency.

In Formula 1, Li is lithium, Sr is strontium, Al is aluminum, Si is silicon, O is oxygen, N is nitrogen, and Eu is europium. Hereinafter, the present invention will be described using the corresponding chemical symbols. Here, Eu can act as an activator in the phosphor matrix made of LiSrAlSiON.

In Formula 1, x, y and z may satisfy at least one of the following conditions: -1.5 < x < 2, 0.0001 < y < 0.2, and -0.5 < z <1.

The red light-emitting phosphor represented by Formula 1 may have a monoclinic crystal structure.

The lattice constants of this monoclinic crystal structure can satisfy a=5.1777Å, b=14.828Å, and c=5.4244Å.

Additionally, the red light-emitting phosphor represented by Formula 1 may have an excitation light wavelength band of 300 to 500 nm.

Hereinafter, the red light-emitting phosphor represented by Chemical Formula 1 will be described in detail with reference to the drawings and tables.

The red light-emitting phosphor according to the present invention relates to a phosphor material of a new composition that causes photoconversion using near-ultraviolet rays and/or blue light.

Additionally, a light-emitting device can be implemented using this red light-emitting phosphor. This light emitting device may use a light emitting diode (LED), but a laser diode may also be used. These light-emitting devices can be used for various lighting purposes.

Among these, LED lighting using LEDs may include phosphors that can cause light conversion using near-ultraviolet rays and/or blue light as excitation light along with LEDs. These LED lights may be called phosphor converted LEDs, white LEDs, etc.

White LEDs usually consist of a blue LED chip and a phosphor that converts the blue light emitted by the blue LED chip.

As the range of use of these white LEDs increases, excellent color rendering index (CRI) characteristics are required, and for this purpose, the demand for phosphors with various emission wavelengths is increasing.

A typical white LED is implemented by combining a blue LED chip and a yellow phosphor, and usually has a disadvantage of low color rendering because it may lack green and red components.

In an effort to improve color rendering, green or yellow phosphors and red phosphors can be combined in blue LED chips.

According to the present invention, while realizing excellent red light emission, it is possible to implement a white LED with excellent color rendering properties when used in a white LED.

Figure 1 is an XRD spectrum according to an embodiment of the present invention.

Referring to Figure 1, it shows the X-ray diffraction (XRD) spectrum of the new phosphor provided by the present invention.

Figure 2 is a diagram showing a crystal structure according to an embodiment of the present invention.

Referring to FIG. 2, in the red light-emitting phosphor according to an embodiment of the present invention, (Si-Al)-(O/N) and Si(O/N) form a polyhedra structure, and these polyhedral structures are It can be seen that it has a connected structure.

These polyhedral structures form a regular tetrahedral structure, and Sr and Li are bonded around these polyhedral structures.

It can be seen that the overall crystal system of the red light-emitting phosphor according to an embodiment of the present invention has a monoclinic crystal structure.

The lattice constants of this monoclinic crystal structure are a=5.1777Å, b=14.828Å, and c=5.4244Å.

Table 1 below summarizes the crystal system and lattice characteristics of the matrix of the red light-emitting phosphor according to the present invention.

In Table 1, the activator (Eu) is not included, and compared to Formula 1, it shows the parent data corresponding to x = 0 and z = 0. Here, it can be seen that the activator (Eu) is substituted with Sr.

Figure 3 is an absorption spectrum of a red light-emitting phosphor according to an embodiment of the present invention. Additionally, Figure 4 is an emission spectrum of a red light-emitting phosphor according to an embodiment of the present invention.

Referring to Figure 3, the red light-emitting phosphor according to an embodiment of the present invention absorbs light in the 250 to 550 nm wavelength band. Additionally, it can be seen that maximum absorption is observed at a wavelength of 400 nm.

Referring to this absorption spectrum, it can be seen that light absorption increases up to the 350 nm wavelength band, the increase rate becomes gradual at around 350 nm, and the absorption rate slightly increases in the portion marked 'a'.

In addition, it can be seen that a gentle peak area is shown in the area indicated by 'a' to 'b'. The region indicated by 'a' to 'b' may correspond to the 370 to 410 nm wavelength band.

Referring to Figure 4, the red light-emitting phosphor has a wide emission spectrum ranging from 470 to 800 nm wavelength, and has a peak wavelength at 600 nm wavelength.

At this time, it can be seen that the half width of the emission spectrum corresponds to the wavelength band indicated by 'c' to 'd' and is approximately 540 to 670 nm.

<Example>

Table 2 below shows the amount of raw materials used in each example. Here, the amount of raw materials refers to mass (g).

In each example, phosphors were synthesized by mixing the corresponding amounts of raw materials.

First, each raw material is made into powder form, the corresponding mass is added and mixed, and then the temperature is raised in a high-temperature nitrogen atmosphere to synthesize the phosphor.

Figure 5 is an emission spectrum of a red light-emitting phosphor according to each example of the present invention. That is, Figure 5 shows the emission spectrum of the phosphor produced in each example corresponding to Table 2.

Referring to FIG. 5, the emission spectrum shown in FIG. 4 may correspond to the second embodiment (Example 2).

Compared to the second embodiment, it can be seen that the emission peak wavelength of the fourth embodiment moved from the 600 nm wavelength toward a shorter wavelength, and the seventh and third embodiments each moved toward a shorter wavelength than the fourth embodiment. You can see that

On the other hand, it can be seen that the peak emission wavelength of the first example shifted from 600 nm to a longer wavelength compared to the second example. In addition, it can be seen that the fifth and sixth embodiments each moved to a longer wavelength compared to the first embodiment.

<Light-emitting device>

Figure 6 is a cross-sectional view showing an example of a light-emitting device using the red light-emitting phosphor of the present invention. Figure 6 shows an example of a lamp-type light emitting device package 100 according to an embodiment of the light emitting device of the present invention.

The light-emitting device according to the present invention may include a light-emitting device 130 and a phosphor 170 that is excited by light emitted from the light-emitting device 130 and emits red light, and is represented by Formula 1.

This lamp-type white light emitting device package 100 includes a pair of lead frames 110 and 120 and a light emitting device 130 that generates light according to the application of voltage.

The light-emitting device 130 is electrically connected to the lead frames 110 and 120 and a wire 140, and a light-transmitting resin 150 is molded on the light-emitting device 130. This light-emitting device 130 may emit near-ultraviolet or blue light.

In addition, instead of a near-ultraviolet light-emitting device, a light-emitting device having a main emission peak in the same wavelength range may be used, such as a laser diode, surface-emitting laser diode, inorganic electroluminescent device, or organic electroluminescent device.

The present invention shows an example in which a nitride semiconductor light emitting diode is used as a preferred application example. In FIG. 6, the light emitting device 130 is schematically represented, and either horizontal or vertical nitride semiconductor light emitting diodes can be used.

The light-transmitting resin 150 may be provided with dispersed phosphors 170 and 171 (see FIG. 7), and an exterior material 160 that closes the external space of the entire device may be provided on the light-transmitting resin 150. .

The phosphors 170 and 171 used here may include a red light-emitting phosphor 170 and a yellow phosphor 171 according to the present invention. Additionally, phosphors that emit light of different colors may be further included. For example, a green light-emitting phosphor 172 may be further provided.

At this time, the yellow phosphor may be any one of YAG, La ₃ Si ₆ N ₁₁ , LuAG (Al ₅ Lu ₃ O ₁₂ ), and Silicate. At this time, the yellow phosphor may have an emission wavelength band of 520 to 570 nm.

Additionally, the green phosphor may be any one of β-SiAlON, silicate, BaSi ₂ O ₂ N ₂ , and SrSi ₂ O ₂ N ₂ .

Meanwhile, in some cases, in addition to the red light-emitting phosphor according to the present invention, any one of CASN, SCASN, (Sr, Ca, Ba) ₂ Si ₅ N ₈ , and K ₂ SiF ₆ may be further used.

The light-transmitting resin 150 used as a molding member may be a light-transmitting epoxy resin, silicone resin, polyimide resin, urea resin, or acrylic resin. Preferably, a light-transmitting epoxy resin or a light-transmitting silicone resin may be used.

This light-transmitting resin 150 can be molded entirely around the light-emitting device 130, but it can also be partially molded on the light-emitting area if necessary.

That is, in the case of a high-output light-emitting device, if the light-emitting device 130 is enlarged and molded as a whole, uniform dispersion of the phosphors 170 and 171 dispersed in the light-transmitting resin 150 may be disadvantageous. In this case, it may be advantageous to partially mold the light emitting area.

FIG. 7 is an enlarged view of a portion of FIG. 6 for explaining the light conversion process. Referring to FIG. 6 as well, the process of implementing white light is explained as follows.

Blue light in the 400 to 480 nm wavelength range corresponding to near ultraviolet rays or blue light emitted from the light emitting device 130 passes through the phosphors 170 and 171. Here, some of the light excites the phosphors 170 and 171 to generate light with a main peak in the 500 to 600 nm range at the center of the emission wavelength as shown in FIG. 7, and the remaining light (a) remains as blue light. Permeate.

In addition, as described above, a portion of the blue light in the 400 to 480 nm wavelength range corresponding to the near-ultraviolet or blue light emitted from the light-emitting device 130 or the light converted from the phosphors 170 and 171 is absorbed and undergoes photoconversion. This phosphor 172 may further be included.

As a result, white light with a wide wavelength spectrum of 400 to 700 nm is emitted.

Figure 8 is an emission spectrum of a light-emitting device to which a red light-emitting phosphor is applied according to an embodiment of the present invention.

FIG. 8 shows the light emission spectrum when the red light-emitting phosphor 170 and the green phosphor 171 are mixed on the light-emitting device 130 to create a white light-emitting device (white LED).

On the other hand, in Figure 8, the white LED of the prior art shows the spectrum when using a light emitting element that emits blue light and yellow phosphor (YAG).

As shown in Figure 8, it can be seen that the color rendering index (CRI) of the light emitting device according to the present invention is improved compared to the white LED of the prior art.

Table 3 below shows the relative luminous flux and color rendering index of the light emitting device corresponding to FIG. 8.

In general, the luminous flux and color rendering index (CRI) of a light emitting device have a complementary relationship, so if the relative luminous flux is increased under the same conditions, the CRI can be reduced.

However, looking at Table 3 below, it can be seen that the white LED to which the phosphor of the present invention is applied has improved both relative luminous flux and CRI.

Here, the phosphor of the present invention represents the phosphor of the second embodiment used.

Table 4 below shows the relative luminance (relative luminous flux), CRI, and center wavelength when the phosphor of each example described above was used.

In this way, according to the present invention, a red light-emitting phosphor with high light conversion efficiency can be provided.

In addition, according to the present invention, it is possible to provide a light-emitting device with excellent color rendering and high luminescence intensity by using a red light-emitting phosphor with high light conversion efficiency.

Meanwhile, the embodiments of the present invention disclosed in the specification and drawings are merely provided as specific examples to aid understanding, and are not intended to limit the scope of the present invention. It is obvious to those skilled in the art that in addition to the embodiments disclosed herein, other modifications based on the technical idea of the present invention can be implemented.

100: light emitting device package 110, 120: lead frame
130: light emitting element 140: wire
150: Light-transmitting resin 160: Exterior material
170, 171, 172: Phosphor

Claims (10)

In the red light-emitting phosphor,
The maximum absorption band is included in the 250 to 550 nm wavelength band, and the maximum emission wavelength band appears in the 470 to 800 nm wavelength band, and is represented by the following formula (1),
Formula 1:

The x, y and z satisfy the conditions of -1.5 < x < 2, 0.0001 < y < 0.2, -0.5 < z <1,
A red light-emitting phosphor characterized by having a monoclinic crystal structure. delete delete The red light-emitting phosphor according to claim 1, wherein the lattice constant of the crystal structure satisfies a=5.1777Å, b=14.828Å, and c=5.4244Å. The red light-emitting phosphor according to claim 1, wherein the red light-emitting phosphor has an excitation light wavelength band of 300 to 500 nm. In the light emitting device,
light emitting device;
It is excited by light emitted from the light emitting device and emits red light, and includes a first phosphor represented by the following formula (1),
Formula 1:

The x, y and z satisfy the conditions of -1.5 < x < 2, 0.0001 < y < 0.2, -0.5 < z <1,
A light emitting device characterized in that the first phosphor has a monoclinic crystal structure. delete The light emitting device of claim 6, further comprising a second phosphor that is excited by light emitted from the light emitting device and emits yellow light in an emission wavelength range of 520 to 570 nm. The method of claim 8, further comprising a third phosphor including any one of β-SiAlON, silicate, BaSi ₂ O ₂ N ₂ , and SrSi ₂ O ₂ N ₂ excited by light emitted from the light emitting device. Characterized by a light emitting device. The method of claim 9, wherein the first phosphor, the second phosphor, and the third phosphor form a mixture, and the mixture is excited by light emitted from the light-emitting device to emit yellow light in an emission wavelength range of 520 to 570 nm. A light-emitting device characterized in that it emits light.

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