KR101078467B1 - Light emitting device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device, and more particularly, to a phosphor capable of high efficiency, high luminance white light emission, and a light emitting device using the same.

A light emitting device according to the present invention is a light emitting device comprising a light emitting element formed of a compound semiconductor and a phosphor for absorbing a part of light emitted from the light emitting element and emitting light having a wavelength different from the wavelength of the absorbed light. The light emitting device is formed of a gallium nitride compound semiconductor, and the phosphor is made of a polymer phosphor and an inorganic phosphor.

In addition, the light emitting device according to the present invention is a light emitting device consisting of a gallium nitride compound semiconductor disposed in the mount cup, and absorbs a part of the light emitted from the light emitting device and the light having a wavelength different from the wavelength of the absorbed light A light emitting device comprising a phosphor for emitting light, a coating portion coated with a polymer resin containing the phosphor in the mount cup, and a molding portion covering the coating portion, the light emitting element, and the mount cup, wherein the phosphor includes a polymer phosphor; It is characterized by consisting of an inorganic phosphor.

Light emitting device, phosphor

Description

Light emitting device {LIGHT EMITTING DEVICE}

1 is a representative structural diagram of a phosphor in a light emitting device according to the present invention;

2 is a representative structural diagram of a pendant type polymer phosphor applicable to a light emitting device according to the present invention;

3 is a structure diagram of a light emitting device capable of emitting blue or UV light and composed of a compound semiconductor formed on a substrate in a light emitting device according to the present invention, and a coating part provided on a surface thereof.

4 is a view for explaining an embodiment of the coating unit in the light emitting device according to the present invention.

5 is a view for explaining a light emitting device according to the present invention;

6 is another embodiment of a light emitting device according to the present invention;

7 is an example for explaining an emission spectrum of a light emitting device according to the present invention;

Description of the Related Art

10; Light emitting element 11; Coating part

12; Mount cup 20; Light emitting element

21; Coating part 22; Mount cup

24; Molding part 30; Light emitting element

31; Coating part 32; Mount cup

34; Molding part

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device, and more particularly, to a phosphor capable of high efficiency, high luminance white light emission, and a light emitting device using the same.

Light emitting diodes (LEDs) are compact and efficient, and can emit light with vivid colors, and because they are semiconductor devices, they are less susceptible to damage. They have excellent initial driving characteristics and shock resistance, and are used for repeated operation such as ON / OFF lighting. It has advantages with good characteristics. For this reason, light emitting diodes are widely used in various indicators and various light sources.

Recently, high brightness, high efficiency R, G, and B light emitting diodes have been developed, and large LED displays using the light emitting diodes have been commercialized. Such LED displays are expected to be used in the future because they can operate with low power consumption and have light and long lifespan.

In addition, various studies have been attempted to construct a white light emitting light source using a light emitting diode.

In order to use a light emitting diode and to obtain white light, since the light emitting diode has a monochromatic peak wavelength, three light emitting diodes of R, G, and B should be installed in close proximity to each other and diffused and mixed.

However, when white light is to be realized through such a configuration, there is a difficulty in obtaining desired white color due to irregular hue or luminance of the light emitting diode.

In addition, since each of the light emitting diodes is formed using a different material, the driving voltages of the light emitting diodes are different and it is necessary to apply different voltages.

In addition, since each light emitting diode is a semiconductor light emitting device, the temperature characteristics and changes with time vary, and the color tone varies according to the use environment, or it is difficult to uniformly mix the light generated by each light emitting diode, and there are many cases of staining. There are disadvantages.

In other words, it is true that the white light implementation through such tricolor mixing is not sufficient to obtain satisfactory results.

In order to solve this problem, a light emitting diode that emits light of a specific wavelength is used, and a phosphor that emits light having a wavelength different from that absorbed and absorbed by the light emitting element in a resin mold material covering the device portion of the light emitting diode. A method of realizing white light by containing is being studied.

For example, a resin containing a phosphor (eg, YAG: Ce ³⁺ ) that uses a light emitting device capable of emitting a blue wavelength region and absorbs light emitted from the light emitting element to emit light of a yellow wavelength region. It is a method of manufacturing a diode capable of emitting light of white light by mixing by molding.

However, when only inorganic yellow phosphors (YAG: Ce ³⁺ ) were used, the emission spectrum of the emitted light was observed due to the wavelength separation phenomenon caused by the narrow peak of the blue wavelength region and the broad peak of the yellow wavelength region. There is a disadvantage to be difficult to implement.

In addition, there is a method in which white light emission is possible by inducing luminescence in the visible light field by using UV light emitting diodes and blending R, G and B phosphors.

Most of these methods known to date apply a method using an inorganic phosphor.

In the case of such an inorganic phosphor, a polymer dispersion system is used, so that light emission loss due to scattering and absorption of molecular molecules due to dispersion of particles is inevitable.

In addition, there is a disadvantage that the surface treatment is required in order to prevent the aggregation phenomenon between the particles and deterioration of efficiency caused by the aggregation of the particles over time.

In addition, when the dispersion is not uniform, uniform light emission cannot be expected, and this phenomenon becomes a serious problem as the content of the phosphor is higher, causing color unevenness and ultimately reducing the efficiency of the device.

In order to compensate for this disadvantage, there is a disadvantage in that a certain amount of dispersant needs to be mixed.

An object of the present invention is to provide a phosphor capable of high efficiency and high luminance white light emission by easily dispersing and at the same time realizing the stability of the device and a light emitting diode using the same.

A light emitting device according to the present invention is a light emitting device comprising a light emitting element formed of a compound semiconductor and a phosphor for absorbing a part of light emitted from the light emitting element and emitting light having a wavelength different from the wavelength of the absorbed light. The light emitting device is formed of a gallium nitride compound semiconductor, and the phosphor is configured to include an organic phosphor and an inorganic phosphor.

Preferably, the organic fluorescent substance is characterized in that the polymeric fluorescent substance.

Preferably, the light emitting device is characterized in that the blue LED or UV LED.

Preferably, the inorganic phosphor is YAG: Ce ³⁺ -based phosphor or Sr ₂ SiO ₄ : Eu.

Preferably, the organic phosphor is characterized in that the green polymer phosphor.

Preferably, the organic phosphor and the inorganic phosphor absorb light of 350 to 500 nm wavelength and emit light of 450 to 650 nm wavelength.

Preferably, the organic fluorescent substance is characterized in that the polymeric fluorescent substance of the pendant type (pendant type) using one of polymethylmethacylate, polyurethane, polycarbonate.                     

Preferably, the phosphor further comprises a polymer resin for blending the organic phosphor and the inorganic phosphor.

The light emitting device according to the present invention includes a light emitting device comprising a gallium nitride compound semiconductor disposed in a mount cup, and absorbs part of the light emitted from the light emitting device and emits light having a wavelength different from that of the absorbed light. A light emitting device comprising a phosphor, a coating portion coated with a polymer resin containing the phosphor in the mount cup, and a molding portion covering the coating portion, the light emitting element, and the mount cup, wherein the phosphor includes an organic phosphor and an inorganic phosphor. Characterized in that comprises a.

Preferably, the phosphor absorbs a portion of the light emitted from the light emitting device so as to emit white light by emitting light having a different wavelength.

Preferably, the coating is characterized in that it comprises a photoluminescence phosphor and a small amount of light and oxidative stabilizer.

Preferably, the polymer resin is characterized by consisting of at least one of epoxy, urea, silicone.

Preferably, the molding part is characterized in that it comprises an organic phosphor and an inorganic phosphor.

Preferably, the organic fluorescent substance is characterized in that the polymeric fluorescent substance.

Preferably, the light emitting device is characterized in that the blue LED or UV LED.                     

Preferably, the inorganic phosphor is YAG: Ce ³⁺ -based phosphor or Sr ₂ SiO ₄ : Eu.

Preferably, the organic phosphor is characterized in that the green polymer phosphor.

Preferably, the organic phosphor and the inorganic phosphor absorb light of 350 to 500 nm wavelength and emit light of 450 to 650 nm wavelength.

Preferably, the organic fluorescent substance is characterized in that the polymeric fluorescent substance of the pendant type (pendant type) using one of polymethylmethacylate, polyurethane, polycarbonate.

Hereinafter, a phosphor and a light emitting diode using the same according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a representative structural diagram of a phosphor in a light emitting device according to the present invention.

Phosphor according to the present invention can be used in the polymer compound having a variety of skeleton, as an example, in the case of the orange polymer phosphor PPV derivative, that is, poly (2-methoxy-5- (2-ethylhexyloxy) -1,4- phenylenevinylene series can be used, and in the case of green polymer phosphor, poly ((9,9-dioctyl-2,7-divinylenefluorenylene)-alt -co- (2-methoxy-5- ( 2-ethylhexyloxy) -1,4-phenylene)) series can be used.

In addition, poly in the case of yellow-based polymeric fluorescent substance ((9,9-dihexylfluorenyl-2,7- diyl ) - co - (1,4-benzo- (2,1 ', 3) -thiadiazole)) series can be used and, in the case of a blue-based fluorescent polymer is poly ((9,9-dioctylfluorenyl-2,7 -diyl) - co - (1,4- (2,5-dimethoxy) benzene) , and this series to be used, is red to step also as a PPV-based polymer poly ((9,9-di (2 -ethylhexyl) fluorenyl-2,7-diyl) - co - (N, N-diphenyl) -N, N'-di (p -butylphenyl) - The 1,4-diaminobenzene series can be used.

However, the above-mentioned phosphor is a preferred embodiment, and the present invention is not limited to the polymer phosphor.

In order to select the polymeric fluorescent substance, the absorption efficiency of the emission wavelength of the LED chip (465 nm) and the matching of the emission wavelength are important, and the stability against heat and light becomes an important factor.

Polymer phosphors, which have been recently developed, exhibit excellent thermal stability even at a high temperature of 200 ° C. or more, and by appropriately limiting the absorption wavelength, the polymer phosphor can be sufficiently equipped with reactivity to excitation light or resistance to aging.

Particularly, in the case of the polymeric fluorescent substance that does not require a binder, since the molecular itself forms a polymer skeleton, there is an advantage that a much more stable system configuration is possible than the type in which the organic fluorescent substance is blended into the polymer medium.

In addition, even when blending the polymeric fluorescent substance in the polymer medium to control the chromaticity, the chromaticity can be easily adjusted by controlling the amount of the polymeric fluorescent substance relative to the polymeric medium, and the blending is easily performed since the polymer medium has the same dispersion characteristics. There are possible advantages.                     

In addition, in the case of organic phosphors, unlike the inorganic phosphors, since the luminous efficiency theoretically shows 100%, there is an advantage that high luminous efficiency can be obtained compared to the inorganic phosphors. By appropriately adjusting the content ratio, it is possible to easily tune the desired color temperature and color rendering index.

2 is a representative structural diagram of a pendant type polymer phosphor applicable to a light emitting device according to the present invention.

Phosphors according to the present invention can be used in the polymer compound having a variety of skeleton, as a preferred embodiment shows a form in which the organic phosphor is coupled to the polymethylmethacrylate (PMMA) main chain.

As a green-yellow polymer phosphor, a PMMA polymer system in which a cumarine phosphor is introduced may be used. At this time, by controlling the substituents and ratio of the introduced cumarine molecules, there is an advantage that not only color tuning but also a separate dispersion medium is not required. In addition, there is an advantage that can be easily applied when using a copolymer system for proper tuning of the emission wavelength.

In particular, when light with longer wavelength than yellow is required, it is easy to synthesize polymer material of desired color by controlling the ratio of cumarine and DCM phosphor introduced by using pendant type copolymer system in which cumarine and DCM phosphor are introduced simultaneously as orange-red polymer phosphor. This is possible.

In addition, a variety of main chain polymer skeletons are available, and if the pendant type polymer phosphor is manufactured using a polymer skeleton having excellent light transmittance, heat resistance and light resistance, that is, polymethylmethacylate, polyurethane, polycarbonate, etc. There is an advantage that no polymer medium is required.

3 is a structural diagram of a light emitting device capable of emitting blue or UV light composed of a compound semiconductor formed on a substrate in a light emitting device according to the present invention, and a coating part provided on a surface thereof.

Referring to FIG. 3, the light emitting device 10 in which a gallium nitride compound semiconductor device is formed on a sapphire substrate to enable blue light emission or UV light emission is mounted on an area of a mount cup 12 in which a reflective film is formed. On top of that, the transparent polymer resin and the organic / inorganic phosphors are mixed and coated to have a structure in which the coating part 11 is coated.

In this case, the coating part 11 includes a photoluminescence phosphor that absorbs at least a portion of the light emitted from the light emitting device 10 and converts the wavelength to emit fluorescence. Included is a light emitting diode capable of emitting white light.

In addition, the polymer resin that can be used may use a transparent material that does not yellow for a long time even at high temperature, that is, UV or thermosetting resin having excellent heat resistance, light resistance, weather resistance, such as epoxy, urea, and silicone.

In addition, it is possible to control the ratio of the organic resin / inorganic phosphor to the amount of the polymer resin, and the coating is possible in a way that can be easily color tuning has the advantage that low-cost process is possible.

In addition, as shown in FIG. 4, a method of applying a coating agent to the mount cup 12 area can be adjusted in a desired shape. The convex lens type, the flat type, and the concave lens type can adjust the distance between the actual light emitting LED chips. In order to achieve maximum luminous efficiency, it can be applied in an optimal shape. To this end, by adjusting variables such as solvent amount and curing conditions, the resin can obtain the desired shape by using the molecular movement difference between the cup surface and the central region.

5 is a view for explaining a light emitting device in the present invention.

The present invention includes a light emitting device 20 capable of emitting blue or UV light composed of a compound semiconductor, and a molding part 24 including a coating part 21 formed on a surface thereof.

In other words, the semiconductor light emitting device 20 is mounted on the mount cup 22 where the reflective film is formed, and the coating is formed by coating a coating material mixed with a transparent polymer resin and an organic / inorganic phosphor thereon. The part 21 has a structure in which a molding part 24 in the form of a convex lens or a concave lens is formed.

In this case, the molding material that can be used may be a transparent material that does not yellow for a long time even at a high temperature, that is, a resin such as epoxy, urea, silicone, or the like. If necessary, light stabilizers, antioxidants, or heat stabilizers such as barium zinc, calcium-zinc, and antioxidants such as phenol, thio, phosphorus, etc. It can also be mixed.                     

Plastic additives should have the main effect of using, and in addition, the following characteristics are required in practical terms. It is excellent in compatibility with plastics, and should not leach into the surface to reduce its appearance or function, to withstand processing temperatures of plastics, and not to disintegrate or volatilize.

In addition, they must not react with the combined formulations to reduce the effects of each other and must not be colored. There is a need for properties that should not discolor over time and non-toxic. In order to obtain the required properties of plastics, additives are rarely used alone, and many additives are used simultaneously.

6 is another embodiment of a light emitting device according to the present invention.

Referring to FIG. 6, there is provided a light emitting device 30 capable of emitting blue or UV light including a compound semiconductor formed on a substrate, and a molding part 34 including a coating part 31 provided on a surface thereof. The semiconductor light emitting device 30 is mounted on the formed mount cup 32, and a molding part having a convex lens or a concave lens is formed on a structure in which a coating material is coated by mixing a transparent polymer resin and an organic / inorganic phosphor. 34) has a structure formed.

At this time, one difference is that the molding part 34 contains an organic / inorganic phosphor at the same time to maximize the luminous efficiency. Therefore, by simultaneously incorporating organic / inorganic phosphors into the molding unit 34 as well as the coating unit 31, the color temperature and color rendering index can be easily adjusted by appropriately controlling the organic phosphor contained in the molding unit 34. You will have the advantage.

<Example>

As a specific example of the present invention, a blue LED having a wavelength of 465 nm was used as a light source, a YAG: Ce ³⁺ based phosphor as an inorganic phosphor, and a green polymer as an organic phosphor. Mixing by weight ratio was applied and cured on the light source in the same manner as in FIG.

In addition to the above embodiment, it is possible to use a UV-LED semiconductor element as a light source, and Sr ₂ SiO ₄ : Eu in the form of a non-YAG type as an inorganic light emitter, that is, a mixture of strontium-silicon oxide and europium (Eu) as an activator. The same phosphor may be used.

According to the present embodiment, the organic / inorganic phosphor absorbs light of 350 to 500 nm wavelength and emits light of 450 to 650 nm wavelength.

In the case of (a) of FIG. 7, the coating agent is applied thinly according to the same content ratio, and in the case of (b), the coating agent is thickly applied. It can be seen that. When a current of 1 mA was applied to the device, a spectrum (SPECTRUM) as shown in FIG. 7 was obtained.

As described above, the present invention provides a method capable of fabricating a white light emitting device having high brightness and high efficiency by using a semiconductor LED device and organic / inorganic phosphors of appropriately designed blue and UV bands.

In addition, the design of various organic phosphor structures and content ratios makes it easier to adjust the color temperature and color rendering index.

In addition, since it is easily blended (blending) to the polymer medium, unlike the dispersion of particles, there is an advantage in that there is no loss of light due to scattering and it is easy to secure uniformity of emission color. According to these advantages, it is possible to supply low-cost devices by simplifying the process without requiring expensive equipment.

By using this advantage, the present invention can obtain excellent efficiency in providing a method capable of supplying a large amount of low-cost white light source devices having various applications as a light source or a display light source for a key pad used in a mobile phone or a mobile device.

The present invention has an advantage of providing a phosphor capable of high-efficiency, high luminance white light emission and a light emitting diode using the same.

Claims (19)

A light emitting device comprising a light emitting element formed of a compound semiconductor and a phosphor for absorbing a part of the light emitted from the light emitting element and emitting light having a wavelength different from the wavelength of the absorbed light. The light emitting device is formed of a gallium nitride compound semiconductor, and the phosphor is a light emitting device comprising a polymer phosphor and an inorganic phosphor. delete The method of claim 1, The light emitting device is a light emitting device, characterized in that the blue LED or UV LED. The method of claim 1, The inorganic phosphor is a YAG: Ce ³⁺ -based phosphor or Sr ₂ SiO ₄ : Eu characterized in that the light emitting device. The method of claim 1, The polymer phosphor is a light emitting device, characterized in that the green polymer phosphor. The method of claim 1, The polymer phosphor and the inorganic phosphor absorb light having a wavelength of 350 to 500 nm to emit light having a wavelength of 450 to 650 nm. The method of claim 1, The polymer fluorescent substance is a light emitting device, characterized in that the polymeric fluorescent substance of the pendant type (pendant type) using one of polymethylmethacylate, polyurethane, polycarbonate. The method of claim 1, The phosphor further includes a polymer resin for blending the polymer phosphor and the inorganic phosphor. A light emitting element comprising a gallium nitride compound semiconductor disposed in the mount cup, a phosphor for absorbing a part of the light emitted from the light emitting element and emitting light having a wavelength different from the wavelength of the absorbed light; A light emitting device including a coating part coated with a polymer resin containing the phosphor, and a molding part covering the coating part, the light emitting element, and the mount cup. The phosphor is a light emitting device characterized in that it comprises a polymer phosphor and an inorganic phosphor. The method of claim 9, Wherein the phosphor absorbs a portion of the light emitted from the light emitting element and emits light having a different wavelength to emit white light. The method of claim 9, The coating unit includes a photoluminescent phosphor and a light emitting device, characterized in that it contains a small amount of light and oxidative stabilizer. The method of claim 9, The polymer resin is a light emitting device, characterized in that made of at least one of epoxy, urea, silicon. The method of claim 9, The molding unit includes a polymer phosphor and an inorganic phosphor. delete The method of claim 9, The light emitting device is a light emitting device, characterized in that the blue LED or UV LED. The method of claim 9, The inorganic phosphor is a YAG: Ce ³⁺ -based phosphor or Sr ₂ SiO ₄ : Eu characterized in that the light emitting device. The method of claim 9, The polymer phosphor is a light emitting device, characterized in that the green polymer phosphor. The method of claim 9, The polymer phosphor and the inorganic phosphor absorb light having a wavelength of 350 to 500 nm to emit light having a wavelength of 450 to 650 nm. The method of claim 9, The polymer fluorescent substance is a light emitting device, characterized in that the polymeric fluorescent substance of the pendant type (pendant type) using one of polymethylmethacylate, polyurethane, polycarbonate.

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