KR20040080883A - Red phosphor comprising samarium for light emitted diode - Google Patents

Abstract

PURPOSE: A light emitting diode having an yttrium aluminate-based red fluorescent substance is provided, to improve emission luminance by using europium and samarium as a co-activator. CONSTITUTION: The light emitting diode comprises a UV LED chip which emits light in a wavelength range of 360-410 nm, is received in the cup located in the terminal of the frame of a cathode lead, and is connected with an anode lead and a cathode lead by a wire; and an epoxy mold layer which surrounds the UV LED chip in the cup, wherein the epoxy mold layer comprises a samarium-containing yttrium aluminate-based red fluorescent substance which comprises a yttrium aluminate-based matrix containing europium and samarium represented by (Y_1-a Eu_a)3Al5O12:Sm_b (0.05<=a<=0.3 and 0<b<=0.3).

Description

Red phosphor containing samarium for light emitted diode

The present invention relates to a light emitting diode, and more particularly, aluminum containing samarium having improved luminous brightness by adding europium oxide and samarium oxide as an active agent to yttrium aluminium (Y ₃ Al ₅ O ₁₂ ), which is a phosphor matrix. A light emitting diode having a yttrium-based red phosphor.

In order to manufacture LEDs such as red, green, and blue, it is necessary to manufacture different substrates such as GaAs, AlGaInP, InGaN, and GaN to utilize different semiconductor thin films, which causes high investment cost and high manufacturing cost in the LED manufacturing process. Have Therefore, if it is possible to manufacture LEDs emitting red, green, and blue light using the same semiconductor thin film, the process can be simplified, and manufacturing and investment costs can be drastically reduced.

In addition, the white LED, which is in the spotlight as a back light source for LCDs such as lighting, notebooks, and mobile phones, is currently manufactured by combining a YAG: Ce phosphor with a blue LED. White LEDs using blue LEDs have many problems with fluorescent materials suitable for the manufacture of white LEDs by mixing blue and yellow by exciting a yellow phosphor located in an upper layer by a blue light source having a wavelength of 450 to 470 nm. That is, with a blue LED having a wavelength of 450 ~ 470nm, it is difficult to implement only a white LED using YAG: Ce.

To solve these problems, efforts are being made to develop red, green, blue and white LEDs utilizing UV LEDs. That is, it is urgent to develop red, green, and blue fluorescent materials having excellent luminous efficiency from an excitation energy source between 350 and 410 nm.

On the other hand, a fluorescent material having excellent efficiency for long wavelength UV is also very important in the development of a fluorescent material for an active light emitting liquid crystal display device. In the active light emitting liquid crystal display, a light source irradiated from a back light source passes through a liquid crystal layer that prevents light from passing through the light by using an alignment property, and the back light passing through the liquid crystal layer excites a phosphor to realize a desired image. Is configured to. The active light emitting liquid crystal display device having such a structure needs to have excellent efficiency of the phosphor since the rear light source directly excites the phosphor coated on the front surface of the liquid crystal display device to emit light.

In active light emitting liquid crystal display device, long wavelength UV of 380 ~ 420nm wavelength should be used as a back light source for the protection of liquid crystal. The development of red fluorescent material with high efficiency in long wavelength UV is the same as the development of red and white LED. It is also very important in the development of liquid crystal display devices.

Inorganic fluorescent materials currently developed for long wavelength UV include K ₅ Eu (WO ₄ ) _6.25 , but have a very low luminous efficiency at excitation energy sources of 410 nm or more.

Accordingly, an object of the present invention is to use yttrium aluminum (Y ₃ Al ₅ O ₁₂ ) using yttrium oxide (Y ₂ O ₃ ) and aluminum oxide (Al ₂ O ₃ ) as the raw material of the phosphor as a parent and to study here By adding europium oxide (Eu ₂ O ₃ ) and samarium oxide (Sm ₂ O ₃ ) to provide a light emitting diode having a yttrium-aluminum-based red phosphor containing samarium excellent emission intensity by an excitation light source of 350 ~ 410nm have.

1 is a schematic configuration diagram and a partially enlarged cross-sectional view of a lead type light emitting diode using the fluorescent material of the present invention;

2 is a schematic configuration diagram and partly enlarged cross-sectional view of a lead type light emitting diode using the phosphor and the double mold of the present invention;

3 is a cross-sectional view of a surface mounted light emitting diode of a reflector injection structure type utilizing the phosphor of the present invention;

4 is a cross-sectional view of a surface mounted light emitting diode of a reflector injection structure type utilizing a phosphor and a double mold of the present invention;

5 is a cross-sectional view of a PCB-type surface mounted light emitting diode utilizing the phosphor of the present invention;

Figure 6 is a graph showing the absorption spectrum of the red phosphor added with samarium of the present invention,

7 is a graph showing a relative light emission spectrum of a red fluorescent substance without added samarium and a red fluorescent substance added with samarium of the present invention;

8 is a graph showing relative light emission intensity according to the amount of samarium added.

Explanation of symbols on the main parts of the drawings

3, 10, 20: LED chip

4, 11, 22: anode lead

5, 12, 21: cathode lead

6, 6 ', 13, 13', 23: epoxy mold layer

A light emitting diode having a yttrium-aluminum-based red phosphor containing samarium of the present invention for achieving the above object of the present invention is characterized by using a yttrium-aluminum-based red phosphor represented by the following formula (1).

(Y _1-a Eu _a ) ₃ Al ₅ O ₁₂ : Sm _{b [} Formula 1]

In said "formula 1", it is 0.05 <= a <= 0.3 and 0 <b <= 0.3.

Hereinafter, the preferred embodiment of the present invention will be described in detail.

1 is a schematic configuration diagram and a partially enlarged cross-sectional view of a lead type light emitting diode using the fluorescent material of the present invention. As shown in FIG. 1, the lead type white light emitting diode of the present invention is manufactured by filling a phosphor pigment in a container in which a reflector in a cup form is implemented as a conventional structure. That is, using the anode wire (anode wire 1) and the cathode wire (cathode wire 2) to connect the LED chip 3, the anode lead (anode lead) 4 and the cathode lead (cathode lead) 5, respectively, An epoxy mold layer 6 in which a phosphor and an epoxy are mixed is formed in the cup, and the epoxy mold layer 6 is formed, and the surrounding material 7 is molded by encapsulating a colorless or colored translucent resin and encapsulated therein. consist of. However, the epoxy mold layer 6 is characterized in that it contains a yttrium aluminum-based red phosphor containing samarium as a feature of the present invention.

2 is a schematic configuration diagram and a partially enlarged cross-sectional view of a lead type light emitting diode using the phosphor and the double mold of the present invention. 2 is different from that of forming a mold material having a two-layer structure inside the cup as compared to FIG. 1. That is, a silicon layer or a mold material 8 is formed by laminating a transparent material including silicon having transparent properties up to and including an area around the LED chip 3 bonded to the chip inside the cup. It is preferable to laminate | stack the said silicon layer or the mold material 8 by the height set in the range of 100 micrometers-200 micrometers in consideration that the depth inside a cup has a value within the range of 0.25 mm-0.55 mm. This is a height considering that the height of the LED chip 3 is about 100㎛ based on the bottom surface inside the cup. The epoxy mold layer 6 'having the yttrium-aluminum-based red phosphor containing samarium of the present invention is laminated on the silicon layer or the mold material 8 so as to have the same surface as the upper surface of the upper end of the cup.

3 is a cross-sectional view of a surface mounted light emitting diode of a reflector injection structure type utilizing the phosphor of the present invention. As shown in FIG. 3, an LED chip 10, a metal post (anode lead 11), a metal post (cathode lead 12), and an epoxy mold layer 13 including phosphors are formed. The LED chip 10 and the metal posts 11 and 12 are respectively connected to N-type electrodes and P-type electrodes by tax wires 14, respectively. The epoxy mold layer 13 is an epoxy mold layer 13 including a phosphor having a yttrium-aluminum-based red phosphor containing samarium of the present invention, and includes an upper portion of the LED chip 10 and stacked on the bottom of a cup. Let's do it. Then, a transparent silicon layer or a mold material is laminated on the epoxy mold layer 13 to have the same surface as the upper surface of the upper end of the cup.

4 is a cross-sectional view of a surface mounted light emitting diode of a reflector injection structure type utilizing a phosphor and a double mold of the present invention. 4 differs from that in which the mold material of the two-layer structure of FIG. 3 was formed, compared with what formed the mold material of the three-layer structure. That is, first, the transparent silicon layer or the mold material 15 is first stacked on the inner bottom of the cup including the upper portion of the LED chip 10, and then the samarium of the present invention is placed on the transparent silicon layer or the mold material 15. Forming an epoxy mold layer (13 ') comprising a phosphor having a yttrium-aluminum-based red phosphor comprising a transparent silicon layer or a mold material having the same surface as the upper surface of the top of the cup on the epoxy mold layer (13') Laminated.

5 is a cross-sectional view of a PCB-type surface mounted light emitting diode utilizing the phosphor of the present invention. As shown in FIG. 5, an LED chip 20, a metal post (anode lead 22), a metal post (cathode lead 21), and an epoxy mold layer 23 including phosphors are formed. The LED chip 20 and the metal posts 21 and 22 are respectively connected with N-type electrodes and P-type electrodes by tax lines. The epoxy mold layer 23 is an epoxy mold layer 23 including a phosphor having a yttrium-aluminum-based red phosphor containing samarium of the present invention, and is laminated at a predetermined height including an upper portion of the LED chip 20. . Then, a transparent silicon layer or a mold material is laminated on the epoxy mold layer.

The light emitting diodes shown in FIGS. 2 and 4 form shrinkage-expansion of the epoxy mold layers 6 'and 13' by forming transparent silicon layers or mold materials 8 and 15 on top of the LED chips 3 and 10. In addition to preventing the stress of the LED chips 3 and 10 applied by the light path, the light path difference of the light is reduced by the transparent silicon layer or the mold materials 8 and 15 during light emission, thereby improving the brightness.

A yttrium-aluminum-based red phosphor containing samarium applied to the light emitting diodes will be described.

In the present invention, the result of excellent red light emission luminance is obtained by adding europium oxide (Eu ₂ O ₃ ) and samarium oxide (Sm ₂ O ₃ ) to yttrium aluminium (Y ₃ Al ₅ O ₁₂ ) as a activator. In particular, the yttrium-based red phosphor is sufficiently excited by a light source generated from 350 to 410 nm UV LED to emit red light, which is excellent in luminescence intensity and is suitable for UV LEDs and active light emitting liquid crystal display devices.

Such a yttrium aluminum (Y ₃ Al ₅ O ₁₂ ) -based red phosphor used in the present invention will be described in more detail based on the manufacturing method as follows.

First, yttrium oxide (E ₂ O ₃ ) and samarium oxide (Sm ₂ O ₃ ) are added and mixed as yttria (Y ₂ O ₃ ) and aluminum oxide (Al ₂ O ₃ ) as a activator. At this time, yttrium oxide used as a study aid is added to 0.1 mol known and samarium oxide to 0.01 to 0.3 mol, preferably 0.01 to 0.05 mol, if the amount is less than 0.01 mol to function as a study aid If the amount is not sufficient, and if it exceeds 0.05 mol, there may be a problem in that the luminance decreases due to the concentration?

Mixing the phosphor raw material and the study agent as described above in a predetermined ratio according to the desired composition is sufficiently mixed so as to have a uniform composition by using a mixer such as ball milling or agate induction under acetone solvent for a more efficient mixing. do. Thereafter, the mixture is placed in an oven and dried at 100 to 150 ° C. for 1 to 2 hours. The dry mixture is placed in a high purity alumina boat, heat treated at an temperature of 1,200 ° C. to 1,700 ° C. for 3 to 6 hours using an electric furnace, and then sufficiently ground.

As a result of measuring the light emission intensity (Photoluminescence, PL) with respect to these powders, a red phosphor represented by the above-mentioned "Formula 1" exhibiting a strong emission spectrum in the region of 590 to 700 nm under 390 nm excitation and having excellent emission luminance was obtained. do.

As described above, the yttrium-aluminum-based red phosphor manufactured in the present invention emits red light having excellent light emission luminance under the ultraviolet long wavelength region, and thus has very high luminous efficiency when applied to UV LEDs and active light emitting liquid crystal display devices.

Hereinafter, the characteristics of the yttrium-aluminum-based red phosphor containing samarium through a comparative example through a graph.

Comparative Example 1: Preparation of (Y _0.9 Eu _0.1 ) ₃ Al ₅ O ₁₂ phosphor

It is weighed at a ratio of 0.9 mol of yttrium oxide, 1 mol of aluminum oxide, and 0.1 mol of europium oxide, which is mixed evenly in acetone using agate induction. The mixed sample is dried at 130 ° C. for 1 hour using an oven. The obtained mixture was placed in a high purity alumina boat and heat-treated in an atmosphere using an electric furnace at a temperature between 1,200 ° C. and 1,700 ° C. for 3 to 6 hours, and then sufficiently pulverized to be represented as (Y _0.9 Eu _0.1 ) ₃ Al ₅ O ₁₂ . Obtain a red phosphor.

Example 1: Preparation of (Y _0.9 Eu _0.1 ) ₃ Al ₅ O ₁₂ : Sm _x Phosphor

The production conditions were similar to those of Comparative Example 1 and only the samarium oxide (Sm ₂ O ₃ ) was changed from 0.005 to 0.3. The absorption spectrum of the prepared fluorescent material was observed between 350 nm and 500 nm, and the luminescence properties when 390 nm UV was used as the excitation energy source were observed.

Figure 6 shows the absorption spectrum of the prepared fluorescent material. Absorption spectra show high absorption peaks at 361, 380, 392, and 458 nm, which are red phosphors for UV LEDs, active light-emitting liquid crystal display devices, pink LED implementations, and UV-based applications. It can be seen that this is suitable.

FIG. 7 shows the red light emission spectrum with and without samarium. It can be seen that the fluorescent material to which 0.02 mol of samarium is added is superior in luminescence intensity to the fluorescent material to which samarium is not added in Comparative Example 1.

FIG. 8 shows the relative luminescence intensity of the fluorescent material according to the amount of samarium added. When the amount of samarium added is more than 0.02 mol, concentration quenching effect occurs to reduce luminescence brightness. Therefore, it can be seen that the concentration of samarium, which can exhibit particularly excellent luminescence brightness, is 0.02 mol.

As described above, the light emitting diode having the yttrium-aluminum-based red phosphor containing samarium according to the present invention is excited by adding europium and samarium as an active agent to the yttrium-aluminum-based phosphor, and thus a long-wavelength UV region of 380 to 410 nm excitation. Since it shows very excellent red light emission with high brightness under the following conditions, it can be applied to applications such as UV LED, active light emitting liquid crystal display device and long wavelength UV as energy source. The present invention is not limited to the above-described embodiment, and it will be apparent that many modifications are possible by those skilled in the art within the technical spirit of the present invention.

Claims (3)

In the cup provided at the tip of the cathode frame forming the cathode, UV LED chips having light emission characteristics in the range of 360 nm to 410 nm, which are UV regions of the InGaN series, are stored and bonded, and the LED chips, anodes and cathodes are bonded. In the light emitting diodes each connected by a wire, including an epoxy mold layer containing a phosphor inside the cup including the surrounding the LED chip, The epoxy mold layer is a light emitting diode having a yttrium-aluminum-based red phosphor containing samarium, characterized in that the yttrium aluminum-based system represented by the following "Formula 1" as a matrix, and europium and samarium are added. (Y _1-a Eu _a ) ₃ Al ₅ O ₁₂ : Sm _{b [} Formula 1] (Where 0.05 ≦ a ≦ 0.3, 0 <b ≦ 0.3) The LED chip is installed in the frame recess, and the epoxy mold layer including a predetermined phosphor is filled in the frame recess. The LED chip is connected to the terminal and the anode and the cathode surrounding the PCB by wires, respectively. In the surface-mounted light emitting diode made of, The epoxy mold layer is a light emitting diode having a yttrium-aluminum-based red phosphor comprising samarium, characterized in that the yttrium-aluminum system represented by the following "Formula 2" as a mother, and europium and samarium are added. (Y _1-a Eu _a ) ₃ Al ₅ O ₁₂ : Sm _{b [} Formula 2] (Where 0.05 ≦ a ≦ 0.3, 0 <b ≦ 0.3) The method of claim 1 or claim 2, wherein between the epoxy mold layer and the LED chip containing samarium, characterized in that formed by further forming a transparent silicon layer or mold material for preventing the stress of the LED chip and reducing the optical path difference A light emitting diode having a yttrium aluminum-based red phosphor.