TW201539802A - Wavelength conversion structure and lighting emitting device including the wavelength conversion structure - Google Patents

Abstract

A wavelength conversion structure includes a first phosphor layer and a second phosphor layer disposed on the first phosphor layer, wherein the first phosphor layer includes a plurality of first phosphor particles, and the second phosphor layer includes a plurality of second phosphor particles. The average particle size of the second phosphor particles is not equal to the average particle size of the first phosphor particles.

Description

Wavelength conversion structure and light emitting device including the same

The present invention relates to a wavelength conversion structure and a method of fabricating the same, and a light emitting device including the same, particularly a wavelength conversion structure having a high light extraction efficiency and a method of fabricating the same, and including the wavelength conversion Structure of the illuminating device.

In recent years, as energy issues have received increasing attention, many new types of energy-saving lighting tools have been developed. Among them, the Light Emitting Diode (LED) has the advantages of high luminous efficiency, low power consumption, no mercury and long service life, and has become a very popular next-generation lighting tool.

For white LEDs for illumination, LED chips are used in combination with phosphors to generate yellow light from YAG (Yttrium Aluminum Garnet, Y3Al5O12) yellow phosphors using blue light generated by blue LED chips, and then mixing the two. Forming white light.

Commonly used phosphor powder coating methods include Conformal Coating and Remote Phosphor. The coating layer applies the phosphor powder directly onto the LED wafer to form a phosphor powder layer. Since it is directly coated on the LED wafer, this method has the advantage of a relatively uniform thickness. However, since the LED chip and the carrier absorb the light emitted by the phosphor layer, the overall luminous efficiency is lowered. In addition, since the phosphor powder is in direct contact with the LED wafer, in the case where the LED wafer is operated at a high temperature of 100 ° C to 150 ° C, the phosphor powder layer is gradually deteriorated and deteriorates, thereby affecting the conversion efficiency.

The method of separating the fluorescent powder is to solve the problem of the above coating application. The phosphor layer of the LED light-emitting device of the separate phosphor is separated from the LED wafer, so that the light emitted by the phosphor layer can be prevented from being directly absorbed by the LED wafer. Also, since the phosphor layer is disposed away from the LED chip, the phosphor powder in the phosphor layer is less likely to be degraded by the high temperature during operation of the LED wafer.

After the phosphor particles receive light from the LED chip, they are excited and produce light of another color. However, the light generated by the phosphor particles is directed toward light in all directions, including inward, thus reducing luminous efficiency.

According to an embodiment of the invention, a wavelength conversion structure includes a first phosphor layer including a plurality of first phosphor particles; and a second phosphor layer on the first phosphor layer. And comprising a plurality of second phosphor particles, wherein the second phosphor particles have an average particle diameter that is different from an average particle diameter of the first phosphor particles.

According to an embodiment of the present invention, a method of fabricating a wavelength conversion structure includes

Forming a first phosphor layer, comprising a plurality of first phosphor particles; forming a second phosphor layer on the first phosphor layer, comprising a plurality of second phosphor particles, wherein the The average particle diameter of the second phosphor particles is not the same as the average particle diameter of the first phosphor particles.

According to an embodiment of the invention, a light-emitting device includes a carrier; a light-emitting element disposed on the carrier; a wavelength conversion structure is disposed on the light-emitting element, the wavelength conversion structure comprising: a first fluorescent light a powder layer comprising a plurality of first phosphor particles; and a second phosphor layer on the first phosphor layer, comprising a plurality of second phosphor particles, wherein the second phosphor particles The average particle diameter is not the same as the average particle diameter of the first phosphor particles.

Hereinafter, preferred embodiments of the present invention will be described in detail in conjunction with the drawings. The embodiments are set forth to enable those of ordinary skill in the art to recognize the invention. The invention is not limited to the embodiments listed, but other approaches may be used. In the drawings of the present specification, the width, length, thickness and other similar dimensions are enlarged as needed for convenience of explanation. In all the figures of the specification, the same element symbols represent the same elements.

It should be particularly noted herein that when an element or a layer of material is described or disposed on another element or layer of another material, it can be directly disposed or connected to another element or another Above the material layer, or indirectly on or connected to another element or layer of another material, that is to say, other elements or layers of material are interposed therebetween. Conversely, if the specification describes that an element or a layer of material is directly disposed or connected to another element or layer of another material, it means that no other element or layer of material is provided between the two.

Figure 1 is a schematic diagram showing the wavelength conversion structure of a preferred embodiment of the present invention. The wavelength conversion structure 10 includes a conductive substrate 101, a first phosphor layer 102, a second phosphor layer 103, and a glue layer 104. The first phosphor layer 102 is formed on the conductive substrate 101 and is composed of first phosphor particles, and the first phosphor particles have a gap therebetween. The second phosphor layer 103 is formed on the first phosphor layer 102 and is composed of second phosphor particles having a gap between the second phosphor particles. The glue layer 104 is formed by filling the gaps of the phosphor powder particles of the first phosphor powder layer 102 and the second phosphor powder layer 103 with a glue material.

The conductive substrate 101 has a transparent conductive property, and its material may include, but is not limited to, a transparent conductive metal oxide (TCO). The first phosphor layer 102 is formed on the conductive substrate 101, and includes first phosphor particles, and the constituent materials thereof may include, but are not limited to, a yellow ceramic fluorescent material, and the particle size distribution is about 225-275 nm. There is a gap between the phosphor particles.

The first phosphor powder layer 102 has a thickness of about 1.5 to 4 times the average particle diameter of the first phosphor powder, and the first phosphor powder has an average particle diameter of 225 nm. The thickness of 102 is a minimum of about 337 nm. The second phosphor layer 103 is formed over the first phosphor layer 102, and the constituent materials may include, but are not limited to, yellow phosphor powder, such as a yellow ceramic phosphor material. The second phosphor layer 102 is composed of second phosphor particles, and the average particle size ratio of the second phosphor layer 102 and the first phosphor layer 102 is between about 3:1 and 5:1. The average particle diameter of the first phosphor particles is 225 nm, and the average particle diameter of the second phosphor particles is about 375 to 1125 nm, and the phosphor particles have voids.

The glue is filled into the gap between the first phosphor layer 102 and the second phosphor layer 103 to form a glue layer 104. The constituent materials of the rubber layer 104 include, but are not limited to, silicone rubber, which has a refractive index of about 1.45. The glue of this embodiment is silicone, but other materials may be used in other embodiments. For example, glass (refractive index of 1.5 to 1.9), resin (Resin, refractive index of 1.5 to 1.6), titanium dioxide (Titanium Oxide, TiO2, refractive index of 2.2 to 2.4), cerium oxide (Silicon Oxide, SiO2, refractive index is 1.5 to 1.7) or magnesium fluoride (Magnesium Fluoride, MgF, refractive index of 1.38).

In one embodiment, the thickness of the glue layer 104 is equal to the thickness of the first phosphor layer 102 plus the second phosphor layer 103. In another embodiment, the thickness of the glue layer 104 is greater than the thickness of the first phosphor layer 102 plus the second phosphor layer 103, and the top surface of the glue layer 106 is higher than the second phosphor layer 103. The top surface can make the surface of the wavelength conversion structure 10 flatter.

The rubber layer 104 is a rubber material having high transparency, and the material of the rubber material may also be a transparent metal oxide. Other materials may also be used in other embodiments. For example, glass (refractive index of 1.5 to 1.9), resin (Resin, refractive index of 1.5 to 1.6), titanium dioxide (Titanium Oxide, TiO2, refractive index of 2.2 to 2.4), cerium oxide (Silicon Oxide, SiO2, refractive index is 1.5 to 1.7) or magnesium fluoride (Magnesium Fluoride, MgF, refractive index of 1.38). The glue layer 104 may comprise an organic compound or an inorganic compound having a refractive index of about 1.3 to 2.4. Inorganic compounds, such as metal oxides, may be selected from metal oxides having a refractive index similar to that of the phosphor powder. Since the difference in refractive index is small, the loss of light due to total reflection can be effectively reduced. The refractive indices of the metal oxide and the phosphor particles are similar, and the scattering of light between the phosphor particles can also be reduced.

Hereinafter, a method of fabricating the wavelength conversion structure 10 of the present embodiment will be described. First, a conductive substrate 101 is placed in an electrophoresis device, and the conductive substrate 101 may be, for example, ITO glass. A plating layer of phosphor powder particles is deposited on the surface of the ITO by an electrophoresis technique to form a first phosphor layer 102 and a second phosphor layer 103. The phosphor layer 102, 103 of the present embodiment is a material having a wavelength for converting incident light, such as a phosphor material. The deposited phosphor layer 102, 103 is not limited to electrophoresis, and may include other methods of depositing a fluorescent material, such as gravity deposition. The transparent glue is then electroplated into the pores in the phosphor layers 102, 103. The material of the rubber material in this embodiment may be silicone rubber, and its refractive index is about 1.45. In another embodiment, the rubber material may also be a metal oxide such as ZnO, which has a refractive index of about 2. By filling in a transparent oxide having a refractive index close to that of the phosphor powder, it is possible to reduce the scattering loss of light and increase the light-emitting efficiency of white light. Furthermore, filling the metal oxide by electroplating can be used as a binder for the phosphor particles to increase the mechanical strength of the phosphor layer, as shown in the SEM photograph of FIG. The deposited metal oxide layer 103 is not limited to electroplating, and may include other methods of plating a metal oxide into the pores of the phosphor powder, such as a CVD method or a Sol-Gel method. The details of the sol-gel method have been used by those of ordinary skill in the art to which the present invention pertains and will not be further described herein. The wavelength conversion structure 10 generally has a uniform or non-uniform thickness.

Fig. 3 is a schematic view showing a light-emitting device according to a preferred embodiment of the present invention. The light emitting device 20 includes a package substrate 111 and a light emitting diode 110, and the light emitting diode 110 is located on the package substrate 111. A light guiding layer 113 covers the package substrate 111 and the light emitting diode 110. The light-emitting device 20 includes the wavelength conversion structure 10 of the above embodiment, wherein the wavelength conversion structure 10 and the light-emitting diode 110 are separated by the bracket 112, and the phosphor powder is not directly in contact with the light-emitting diode 110, and can be avoided as much as possible. The light emitted by the phosphor layer is directly absorbed by the LED 110 wafer. Also, since the phosphor powder is disposed away from the wafer of the light-emitting diode 110, the phosphor powder in the phosphor powder layer is less likely to be degraded by the high temperature at the time of operation of the light-emitting diode 110 wafer.

In this embodiment, the light guiding layer 113 is a light passing layer, and may be a material layer having improved light extraction efficiency. In this embodiment, the light guiding layer 113 has a plurality of material layers and has a Gradient Refractive Index (GRIN). In this embodiment, the plurality of material layers of the light guiding layer 113 may be made of tantalum nitride (Silicon Nitride, Si3N4) having a refractive index of na = 1.95, aluminum oxide (Alluminum Oxide, Al2O3), and the refractive index thereof is Nb = 1.7, and Silicone, which has a refractive index of nc = 1.45. However, other combinations of materials may also be used in other embodiments. By using a gradient index layer formed by a small difference in refractive index between the layers and the layers, and gradually decreasing the refractive index of the light-emitting diode 110, the total reflection of the light can be effectively reduced. The material used may be: glass (refractive index) 1.5~1.9), resin (Resin, refractive index 1.5~1.6), diamond-like carbon film (Diamond Like Carbon (DLC), refractive index 2.0~2.4), titanium dioxide (Titanium Oxide, TiO2, refractive index 2.2~2.4) A combination of cerium oxide (Silicon Oxide, SiO2, refractive index: 1.5 to 1.7) or magnesium fluoride (Magnesium Fluoride, MgF, refractive index: 1.38). In the present embodiment, the light-emitting diode 110 can be selected from a GaN blue LED chip having a refractive index of 2.4. Therefore, by the gradient index of the stack, the difference in refractive index between the layers and the layers is small, and the total reflection of light can be effectively reduced.

In the light-emitting device 20 of the present embodiment, the wavelength conversion structure 10 as described in the above embodiment is disposed on the light guiding layer 113. After the light is emitted from the light-emitting diode 110, it passes through the light guiding layer 113 and enters the wavelength conversion structure 10, The plurality of material layers of the light guiding layer 113 have a small difference in refractive index between the material layers, which can effectively reduce the loss of light due to total reflection. When the light is incident on the wavelength conversion structure 10 through the light guiding layer 113, wherein the second phosphor powder layer 103 is closer to the light emitting diode 110, the light generated by the light emitting diode 110 is incident on the second phosphor powder layer 103. On the smooth side, the first phosphor layer 102 is a light-emitting surface. The light generated by the LED 110 excites the second phosphor particles of the second phosphor layer 103 to generate an excitation light, and the excitation light is incident on the first phosphor layer 102. The light powder particles have a larger specific surface area than the second phosphor powder particles, and the bulk density of the second phosphor powder particles is denser than the first phosphor powder particle density. When the excitation light is incident on the first phosphor layer 102, scattering phenomenon is caused to destroy the total reflection between the conductive substrate and the first phosphor layer 102. When at least a portion of the first phosphor particles contact the conductive substrate 101, as if the wavelength conversion structure is formed to form an interface roughening effect, the scattering phenomenon caused by the reflection of the interface between the conductive substrate 101 and the first phosphor layer 102 is increased. Light extraction efficiency.

The light-emitting device 20 of the present embodiment is a flat package structure. In other embodiments, the conductive substrate 101 of the wavelength conversion structure 10 is not limited to a flat plate, and may also be a convex lens, a concave lens or a triangular pyramid, that is, The surface of the conductive substrate 101 is a flat surface, a curved surface, or a meandering surface.

Table 1 shows a test light intensity comparison table of the light-emitting device 20 of the embodiment of the present invention having a wavelength conversion structure 10, wherein the comparison wavelength conversion structure 10 has (a) mixing the first phosphor powder particles and the second phosphor powder particles. a stacked structure deposited on the conductive substrate 101, (2) a second phosphor layer 103 / a stack structure of the first phosphor layer 102 / the conductive substrate 101, and (3) a second phosphor powder / a conductive substrate 101 A stacking structure, and (b) an optical efficiency comparison table of the stack structure of the first phosphor layer 102 / the second phosphor layer 103 / the conductive substrate 101. The stack structure of the (2) second phosphor layer 103 / the first phosphor layer 102 / the conductive substrate 101 has a luminous flux of 173 lumens, and the luminous flux thereof increases by about 3-4% compared with other stacked structures. The results are shown in Table 1.

The preferred embodiments of the illuminating device of the present invention have been described as before, but are not limited to the above-described methods, and those skilled in the art to which the present invention pertains can achieve equivalents without departing from the spirit and scope of the present invention. Alterations or modifications are intended to be included within the scope of the invention.

10‧‧‧wavelength conversion structure
101‧‧‧Electrical substrate
102‧‧‧First phosphor layer
103‧‧‧Second phosphor layer
104‧‧‧Material layer
110‧‧‧Lighting diode
111‧‧‧Package substrate
112‧‧‧ bracket
113‧‧‧Light guide layer
20‧‧‧Lighting device

1 is a schematic diagram of a wavelength conversion structure according to a first embodiment of the present invention;

Figure 2 is an electron micrograph of the wavelength conversion structure;

Figure 3 is a schematic view of a light-emitting device of the present invention.

no

no

10‧‧‧wavelength conversion structure

101‧‧‧Electrical substrate

102‧‧‧First phosphor layer

103‧‧‧Second phosphor layer

104‧‧‧Material layer

Claims (10)

A light-emitting device comprising: a light-emitting diode; and a wavelength conversion structure comprising: a plurality of first phosphor particles; a plurality of second phosphor particles, and an average particle diameter of the second phosphor particles An average particle diameter larger than the first phosphor particles; and a rubber material having a thickness filled in the gap between the first phosphor particles and the gap between the second phosphor particles. The thickness of the glue is greater than the sum of the thicknesses of the first phosphor particles and the second phosphor particles. The illuminating device of claim 1, further comprising a conductive substrate on one side of the first phosphor particles. The illuminating device of claim 1, wherein the ratio of the average particle diameter of the second phosphor particles to the average particle diameter of the first phosphor particles is 3:1 to 5:1. The first phosphor particles have a particle size distribution ranging from 225 to 275 nm, and/or the second phosphor particles have a particle size distribution ranging from 740 to 910 nm. The illuminating device according to any one of the preceding claims, wherein the distance between the first phosphor particles and the illuminating diode is greater than the second phosphor particles and the illuminating diode the distance. The light-emitting device according to any one of claims 1 to 3, wherein the rubber material comprises an organic compound or an inorganic compound, wherein the organic compound or the inorganic compound has a refractive index of about 1.45 to 2. A light-emitting device comprising: a carrier; a light-emitting diode disposed on the carrier; a light guiding layer covering the carrier and the LED; a wavelength conversion structure on the light guiding layer And not directly contacting the light emitting diode, the wavelength conversion structure comprises: a plurality of first phosphor particles; and a plurality of second phosphor particles, wherein the second phosphor particles have an average particle diameter larger than the The average particle diameter of the first phosphor particles, wherein the distance between the first phosphor particles and the LED is greater than the distance between the second phosphor particles and the LED. The illuminating device of claim 6, further comprising a conductive substrate located on one side of the first phosphor particles. The illuminating device of claim 6, wherein the ratio of the average particle diameter of the second phosphor particles to the average particle diameter of the first phosphor particles is 3:1 to 5:1. The first phosphor particles have a particle size distribution ranging from 225 to 275 nm, and/or the second phosphor particles have a particle size distribution ranging from 740 to 910 nm. The illuminating device of any one of the preceding claims, further comprising a rubber material having a thickness and filling between the gaps between the first phosphor particles and the second phosphor particles a gap, wherein the first thickness of the glue is greater than a sum of thicknesses of the first phosphor particles and the second phosphor particles. The illuminating device of claim 6, further comprising a bracket disposed between the wavelength conversion structure and the carrier.