CN109494289B - Light emitting device using quantum dot color conversion and method of manufacturing the same - Google Patents

Light emitting device using quantum dot color conversion and method of manufacturing the same Download PDF

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CN109494289B
CN109494289B CN201710812987.0A CN201710812987A CN109494289B CN 109494289 B CN109494289 B CN 109494289B CN 201710812987 A CN201710812987 A CN 201710812987A CN 109494289 B CN109494289 B CN 109494289B
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light
layer
emitting device
photoluminescent
moisture barrier
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CN109494289A (en
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陈杰
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Maven Optronics Co Ltd
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Maven Optronics Co Ltd
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Priority to EP18192168.5A priority patent/EP3454384B1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/58—Optical field-shaping elements
    • H01L33/60—Reflective elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/50—Wavelength conversion elements
    • H01L33/501—Wavelength conversion elements characterised by the materials, e.g. binder
    • H01L33/502—Wavelength conversion materials
    • H01L33/504—Elements with two or more wavelength conversion materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/50—Wavelength conversion elements
    • H01L33/505—Wavelength conversion elements characterised by the shape, e.g. plate or foil
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/50—Wavelength conversion elements
    • H01L33/507—Wavelength conversion elements the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/52—Encapsulations
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
    • H01L2933/0008—Processes
    • H01L2933/0033—Processes relating to semiconductor body packages
    • H01L2933/0041—Processes relating to semiconductor body packages relating to wavelength conversion elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
    • H01L2933/0008—Processes
    • H01L2933/0033—Processes relating to semiconductor body packages
    • H01L2933/005—Processes relating to semiconductor body packages relating to encapsulations
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
    • H01L2933/0008—Processes
    • H01L2933/0033—Processes relating to semiconductor body packages
    • H01L2933/0058—Processes relating to semiconductor body packages relating to optical field-shaping elements

Abstract

The present invention provides a light emitting device, comprising: a flip chip LED chip; the photoluminescence structure is arranged on the LED chip; and the moisture barrier reflection structure covers the side surface of the photoluminescence structure and the vertical surface of the LED chip. The photoluminescence structure comprises a first photoluminescence layer, a light transparent isolation layer, a second photoluminescence layer and a light transparent moisture barrier layer which are sequentially stacked. In a preferred embodiment, the LED chip emits blue light, the first photoluminescent layer comprises a red fluorescent material, and the second photoluminescent layer comprises green quantum dots; therefore, the red fluorescent material of the first photoluminescence layer can firstly convert the blue light part with higher energy level into the red light with lower energy level, reduce the unconverted blue light intensity irradiating the green quantum dots, and effectively avoid the photooxidation of the quantum dots. The invention also provides a manufacturing method of the light-emitting device.

Description

Light emitting device using quantum dot color conversion and method of manufacturing the same
Technical Field
The invention relates to a chip-scale package light-emitting device and a manufacturing method thereof, in particular to a chip-scale package light-emitting device applying a green quantum dot material and red fluorescent powder and a manufacturing method thereof.
Background
Quantum Dot (QD) materials are semiconductor crystal materials with a size of nanometer grade, the particle size of which is usually between 1 nm and 50 nm, and after being irradiated by light of high energy level, the quantum dot materials can convert part of incident light into visible light of another lower energy level due to quantum confinement effect (quantum confinement effect), so the quantum dot materials can be used as a photoluminescence material. By changing the particle size, shape or material composition of the quantum dot material, the quantum dot material can emit visible light rays with different wavelengths, i.e., the emission spectrum (spectrum) of the quantum dot material is changed.
Compared with conventional fluorescent materials, such as Yttrium Aluminum Garnet (YAG) phosphor, Nitride (Nitride) phosphor, Oxynitride (Oxynitride) phosphor, etc., the emission spectrum of the quantum dot material has a significantly narrower Full Width at half Maximum (FWHM), so that when the quantum dot material is used in combination with an LED chip to form an LED light emitting device as a backlight source of a display, the color purity of the display can be improved. Compared with the Color Gamut (Color Gamut) of 70% BT.2020 which can be achieved by an Organic Light Emitting Diode (OLED) display, the display applying the quantum dot material can have the Color Gamut of up to 90% BT.2020 in Color expression; in addition, compared with an OLED which belongs to an organic material, the service life of the OLED is shorter, and the service life of the quantum dot material which belongs to an inorganic material is relatively longer. On the other hand, the light emitting device using the quantum dot material can directly replace the backlight source of the existing liquid crystal display, and the color gamut range of the liquid crystal display can be obviously increased only through the change of the photoluminescence material.
Although the light emitting device with quantum dot material and LED chip has the advantages mentioned above, there are still some problems to be improved or overcome in practice. For example, quantum dot materials have poor thermal stability, and their performance is significantly degraded in high temperature environments (e.g., greater than 70 ℃). Therefore, the heat generated during the operation of the LED chip may significantly degrade the performance of the quantum dot material.
In addition, when the quantum dot material contacts moisture or oxygen in the air, the surface of the quantum dot material is easily oxidized to form oxide, so that the luminous intensity of the quantum dot material is reduced, and therefore, a light-emitting device using the quantum dot material needs to have good moisture barrier protection, so that external moisture and oxygen are not easy to permeate inwards to contact the quantum dot material, and the light-emitting device has a long service life.
Furthermore, in the presence of oxygen or moisture in the surroundings, when the quantum dot material is excited by light of higher energy level (such as ultraviolet light or blue light), photo-oxidation (photo-oxidation) is more likely to occur, resulting in a significant decrease in the luminous intensity (intensity) and a "blue shift" of the luminous spectrum. Specifically, when high-energy-level light is irradiated on a semiconductor material such as a quantum dot, the semiconductor material generates a large number of electrons and holes due to the action of a photoelectric effect (photoeffect), and the excited free electrons make the surface of the semiconductor material easily dissociate (disassociation) ambient oxygen molecules to form oxygen atoms and oxygen ions, so that the semiconductor material is more easily reacted with oxygen to form an oxide; numerous experimental verifications and descriptions of the photo-oxidation phenomenon of electron-activated (electron-active) semiconductor materials were made in the paper by school E.M. in Appl Phys A47: 259-69, 1988 and in the paper by school Sato S, equivalent to J Appl Phys 81:1518, 1997. Therefore, under the irradiation of high-energy-level light, the oxidation reaction of the quantum dot material is obviously accelerated.
Meanwhile, after the surface of the quantum dot is oxidized, the effective particle size of the quantum dot material is reduced, and the quantum dot photoluminescent material with smaller particle size can generate higher-energy-level converted light (i.e. shorter wavelength), so that the luminescent spectrum of the surface of the quantum dot material is shifted to a short wavelength after the surface of the quantum dot material is oxidized, and a so-called blue shifting phenomenon is generated. Moreover, the generation of the oxide will increase the structural defects (defects) of the quantum dot, and the structural defects will cause non-radiative electron-hole combination of electrons and holes during the photoelectric effect, and the non-radiative electron-hole combination will release energy in the form of thermal energy and will not be converted into photons of lower energy level, so the photo-oxidation phenomenon of the quantum dot material will also cause the light intensity to decrease, and finally the quantum dot will not emit light, i.e. the photo-bleaching phenomenon of the quantum dot. Therefore, when the quantum dot material is applied to an LED light-emitting device, the quantum dot material needs to be prevented from being irradiated by an excessively strong higher-energy-level light, so that light attenuation and blue shift of a light-emitting spectrum caused by a photo-oxidation phenomenon can be avoided.
In addition, the light emitting device using the quantum dot color conversion generally needs to uniformly disperse the quantum dot material in the binder (binder) to obtain good light emitting efficiency. However, the quantum dot material is not compatible with all kinds of glue materials, and usually the quantum dot material needs to be surface modified, such as forming Ligand (Ligand), to uniformly disperse the quantum dots in a specific glue material; therefore, surface modification, selection of specific glue materials and process compatibility between different glue materials also become important technical challenges for realizing application of quantum dot materials to LED light emitting devices.
In summary, it is an objective of the LED industry to better solve or overcome any of the above problems to apply quantum dot materials to LED light emitting devices.
Disclosure of Invention
An object of the present invention is to provide a light emitting device using quantum dot color conversion and a method for manufacturing the same, wherein the light emitting device is a chip scale package light emitting device, a flip chip LED chip is used, and a heat dissipation path with low thermal resistance is provided to reduce Junction Temperature (Junction Temperature) of the LED chip, so that a thermal decay phenomenon of a quantum dot material can be effectively improved, and a Temperature borne by the quantum dot material can be reduced.
An object of the present invention is to provide a light emitting device using quantum dot color conversion and a method for manufacturing the same, wherein the light emitting device has good moisture barrier hermeticity (hermeticity) to reduce or prevent moisture and oxygen in the outside air from contacting the quantum dot material, thereby effectively improving the oxidation phenomenon of the quantum dot material.
One objective of the present invention is to provide a light emitting device using quantum dot color conversion and a method for manufacturing the same, in which a fluorescent material that is not easily photo-oxidized is disposed between a quantum dot material that is easily photo-oxidized and an LED chip, so as to effectively reduce the intensity of high-energy-level light incident on the quantum dot material, and make the light not exceed the light that can be borne by the quantum dot material, thereby improving the photo-oxidation phenomenon of the quantum dot material.
The invention provides a light-emitting device applying quantum dot color conversion and a manufacturing method thereof, wherein an adhesive material required for fixing a fluorescent material and an adhesive material required for fixing a quantum dot material have different characteristics, and the adhesive material curing process is incompatible, so that the light-emitting device can effectively block a high polymer material for fixing the quantum dot material and a high polymer material for fixing the fluorescent material, and the problem of incompatibility of the processes or material characteristics is avoided.
To achieve the above object, a light emitting device is provided, which includes: the flip chip type LED chip is used for providing a first light ray, and the first light ray is a blue light ray, a deep blue light ray, a purple light ray or an ultraviolet light ray; a photoluminescent structure disposed on an upper surface of the flip-chip LED chip and including a first photoluminescent layer, a light-transparent isolation layer, a second photoluminescent layer, and a light-transparent moisture barrier layer, the light-transparent isolation layer being disposed on the first photoluminescent layer, the second photoluminescent layer being disposed on the light-transparent isolation layer, and the light-transparent moisture barrier layer being disposed on the second photoluminescent layer, wherein the first photoluminescent layer includes a first polymer material and a fluorescent material (e.g., red fluorescent material) with a lower excitation energy level mixed in the first polymer material, and the second photoluminescent layer includes a second polymer material and a quantum dot material (e.g., green quantum dot material) with a higher excitation energy level mixed in the second polymer material; the moisture barrier reflection structure covers one side surface of the photoluminescence structure and one vertical surface of the crystal-coated LED chip and is not lower than one electrode surface of the crystal-coated LED chip; the fluorescent material with lower excitation energy level of the first photoluminescent layer is used to convert a part of the first light (e.g. blue light) into visible light (e.g. red light) with longer wavelength, so that the light intensity of the unconverted first light (e.g. blue light) is reduced to be not more than the light intensity that can be borne by the quantum dot material with higher excitation energy level (e.g. green quantum dot material). The method for manufacturing the light-emitting device disclosed by the invention comprises the following steps: attaching a photoluminescence structure to a flip-chip LED chip; and forming a moisture barrier reflection structure to cover one side surface of the photoluminescence structure and one vertical surface of the flip chip type LED chip.
Therefore, the light-emitting device provided by the invention can at least provide the following beneficial technical effects:
1. compared with the position of the flip-chip LED chip, the second photoluminescent layer is arranged above the first photoluminescent layer, so that part of first light emitted by the flip-chip LED chip is converted by the first photoluminescent layer, and the dosage of the quantum dot material (such as green quantum dot material) with higher excitation energy level, which is irradiated by the first light, in the second photoluminescent layer is reduced. Therefore, the light intensity of the first light irradiated to the quantum dot material with the higher excitation energy level is not greater than the light intensity which can be borne by the first light, and the photo-oxidation phenomenon of the quantum dot material with the higher excitation energy level can be effectively inhibited or avoided.
2. The light-emitting device does not need a packaging support, so that the light-emitting device has a larger light-emitting area under the same packaging volume, and the unit area intensity of blue light irradiated on the quantum dot material can be effectively reduced, so that the photooxidation of the quantum dot material is reduced.
3. The light transparent moisture barrier layer and the moisture barrier reflection structure both have lower water vapor permeability, so that external water vapor and oxygen can not easily penetrate through the light transparent moisture barrier layer and the moisture barrier reflection structure to contact the quantum dot material in the second photoluminescence layer, and the oxidation phenomenon of the quantum dot material can be effectively avoided or reduced.
4. The second photoluminescent layer and the first photoluminescent layer are separated by the optically transparent isolation layer and are not in contact with each other, in other words, the second polymer material for gluing the quantum dot material with a higher excitation energy level and the first polymer material for gluing the fluorescent material with a lower excitation energy level (for example, a red fluorescent material) are not in contact with each other, and therefore, the material characteristics or the process characteristics (for example, a curing mechanism) of the other party are not influenced.
5. Compared with a light-emitting device adopting a packaging support or a packaging substrate, the chip-scale packaging light-emitting device adopting the flip-chip LED chip has lower thermal resistance, can effectively reduce the junction temperature of the LED chip, and the second photoluminescent layer is far away from the flip-chip LED chip, so that the influence of heat energy generated by the flip-chip LED chip on the quantum dot material is smaller, the temperature born by the quantum dot material can be reduced, such as the temperature lower than 50 ℃, 40 ℃ or 30 ℃, and the thermal attenuation phenomenon of the quantum dot material is effectively improved.
6. When the fluorescent material with a lower excitation energy level adopted by the first photoluminescent layer is a fluoride fluorescent material (i.e., KSF or MGF), since KSF and MGF are not excited by green light, light with a higher energy level (e.g., green light) emitted by the quantum dot material with a higher excitation energy level can be effectively scattered outwards, and thus the overall light extraction efficiency of the light-emitting device can be increased.
Drawings
In order to make the aforementioned objects, features and advantages more comprehensible, preferred embodiments accompanied with figures are described in detail below.
Fig. 1A and 1B are two schematic cross-sectional views of a light emitting device according to a first preferred embodiment of the invention 1;
fig. 1C is a schematic cross-sectional view of another aspect of a light-emitting device according to embodiment 1 of the invention;
fig. 2A and 2C are two cross-sectional views of a light emitting device according to a first preferred embodiment of the invention 1, showing light conversion and transmission;
FIG. 2B is a measurement result of an emission spectrum of the light-emitting device according to embodiment 1 of the present invention;
fig. 3 is a schematic cross-sectional view of a light-emitting device according to embodiment 2 of the invention;
fig. 4A is a schematic cross-sectional view of a light-emitting device according to a 3 rd preferred embodiment of the invention;
fig. 4B is a schematic cross-sectional view of another aspect of a light-emitting device according to embodiment 3 of the invention;
fig. 5A to 5I are schematic diagrams illustrating steps of a method for manufacturing a light emitting device according to a preferred embodiment of the invention; and
fig. 6A to 6D are schematic diagrams illustrating steps of a method for manufacturing a light emitting device according to a preferred embodiment of the invention.
Description of the symbols:
1 to 3 light emitting devices
10 flip chip type LED chip and LED chip
101 upper surface
102 electrode surface and lower surface
103 vertical surface
104 electrode group
20 photoluminescent Structure, PL Structure
201 top surface
202 bottom surface
203 side surface
21 first photoluminescent layer, first PL layer
211 first polymer material
212 fluorescent material with lower excitation energy level and red fluorescent material
22 light transparent barrier layer
23 second photoluminescent layer, second PL layer
231 second polymeric material
232 quantum dot material, green quantum dot material and green QD material with higher excitation energy level
233 light scattering fine particles
234 blue quantum dot material
24 light transparent moisture barrier
25 light transparent heat conducting layer
26 optically transparent spacer layer
30 moisture barrier reflective structure, reflective structure
301 top surface
302 bottom surface
31 third high molecular material
32 light scattering particles
40 light guide structure
401 top surface
402 inclined side
900-release material
B blue light, blue light spectrum
G. G1, G2 green, green spectrums
R red, red spectrum
Detailed Description
Please refer to fig. 1A and 1B, which are schematic diagrams of a light emitting device 1 according to a first preferred embodiment of the invention. The light-emitting device 1 may include a flip-chip LED chip 10, a photoluminescent structure 20, and a moisture-blocking reflective structure 30, the technical contents of each of which will be described in sequence below.
The flip chip LED chip (hereinafter referred to as LED chip) 10 is used to provide a first light (or called principal light), which may be a light with a higher energy level such as a blue light, a deep blue light, a violet light, or an ultraviolet light; taking a blue LED chip as an example, the first light provided by the LED chip 10 is blue light. The chip 10 may include an upper surface 101, a lower surface 102, a vertical surface 103 and an electrode assembly 104, wherein the upper surface 101 and the lower surface 102 are disposed opposite and opposite to each other, the vertical surface 103 is formed between the upper surface 101 and the lower surface 102 and connects the upper surface 101 and the lower surface 102, in other words, the vertical surface 103 is formed along the edge of the upper surface 101 and the edge of the lower surface 102, so that the vertical surface 103 is annular (e.g., rectangular ring) with respect to the upper surface 101 and the lower surface 102.
The electrode assembly 104 is disposed on the lower surface 102 and may have more than two electrodes. Since the electrode assembly 104 is disposed thereon, the lower surface 102 is also referred to as the electrode surface 102; in other words, the electrode surface 102 does not refer to the lower surface of the electrode 104. The LED chip 10 can convert the electric energy (not shown) through the electrode assembly 104 to emit light in a wavelength range corresponding to the first light (blue light); the light can be emitted mostly from the top surface 101 and the facade 103.
On the other hand, compared with the light emitting device using a bracket or a substrate, the light emitting device 1 disclosed by the present invention is a chip scale package light emitting device, and one technical feature is that the LED chip 10 is a flip chip type chip and can be directly bonded to a printed circuit board or other application substrates, and since the light emitting device does not include a bracket, the heat resistance is low, and the heat generated during the operation can be directly dissipated through the electrode assembly 104, thereby reducing the influence of the heat on other structures.
The Photo Luminescent (PL) structure 20 may absorb a portion of the first light to convert into light of a lower energy level (e.g., red light and green light) after being excited by the first light emitted from the LED chip 10, and then a portion of the unconverted first light (e.g., blue light) is mixed with the red light and the green light to form light of a desired color (e.g., white light).
In appearance, the photoluminescent structure (PL structure) 20 may include a top surface 201, a bottom surface 202, and a side surface 203, where the top surface 201 is opposite and opposite to the bottom surface 202, and the side surface 203 is formed between the top surface 201 and the bottom surface 202, and connects the top surface 201 and the bottom surface 202, in other words, the side surface 203 is annular (e.g., rectangular ring) with respect to the top surface 201 and the bottom surface 202.
In position, the PL structure 20 is disposed on the LED chip 10, the bottom surface 202 of the PL structure 20 is located on the upper surface 101 of the LED chip 10, and the bottom surface 202 can directly cover the upper surface 101, but there is no vertical surface 103 covering the LED chip; however, implementations in which the bottom surface 202 is spaced from the top surface 101 are not excluded, meaning that other structures or materials (not shown) may be disposed between the PL structure 20 and the LED chip 10. In addition, the bottom surface 202 may be slightly larger than the upper surface 101, but not limited thereto.
Structurally, the PL structure 20 includes a first photoluminescent layer (hereinafter referred to as a first PL layer) 21, an optically transparent isolation layer 22, a second photoluminescent layer (hereinafter referred to as a second PL layer) 23, and an optically transparent moisture barrier layer 24, which are sequentially stacked along a normal direction of the upper surface 101 of the LED chip 10, that is, the first PL layer 21 is disposed on the upper surface 101 of the LED chip 10, the optically transparent isolation layer 22 is disposed on the first PL layer 21, the second PL layer 23 is disposed on the optically transparent isolation layer 22, and the optically transparent moisture barrier layer 24 is disposed on the second PL layer 23.
The first PL layer 21 can generate a light of a lower energy level (e.g., red light) when excited by the first light, which can include a first polymer material 211 and a fluorescent material of a lower excitation energy level (e.g., red fluorescent material) 212. for simplicity, the red fluorescent material 212 and the emitted red light will be described below as an example. The red fluorescent material 212 can be uniformly mixed and glued (fixed) in the first polymer material 211. The red phosphor material 212, when excited by the first light of higher energy level, can partially convert the first light into red light; in other words, after the first light passes through the first PL layer 21, since a portion of the first light is converted into red light, the light intensity of the portion of the unconverted first light is reduced; this aspect of the technology will be further explained with reference to fig. 2A. In addition, the phosphor material (e.g., red phosphor material) 212 may withstand higher temperatures than the later-described quantum dot material (e.g., green quantum dot material) 232 and thus may be closer to or in contact with the LED chip 10.
The red fluorescent material 212 may include, for example, but is not limited to: a fluoride fluorescent material or a nitride fluorescent material, etc. capable of generating red light; the fluoride fluorescent material may be, for example, a KSF fluorescent material, which may include at least one of the following: (A) a. the2[MF6]:Mn4+Wherein A is selected from Li, Na, K, Rb, Cs and NH4And combinations thereof, M is selected from Ge, Si, Sn, Ti, Zr, and combinations thereof; (B) e2[MF6]:Mn4+Wherein E is selected from the group consisting of Mg, Ca, Sr, Ba, Zn, and combinations thereof, and M is selected from the group consisting of Ge, Si, Sn, Ti, Zr, and combinations thereof; (C) ba0.65Zr0.35F2.70:Mn4+(ii) a Or (D) A3[ZrF7]:Mn4+Wherein A is selected from Li, Na, K, Rb, Cs and NH4And combinations thereof. The other fluoride fluorescent material may be, for example, MGF fluorescent material, which may include at least one of the following: (x-a) MgO (a/2) Sc2O3.yMgF2.cCaF2.(1-b)GeO2.(b/2)Mt2O3:zMn4+(ii) a Wherein x is more than or equal to 2.0 and less than or equal to 4.0 and 0<y<1.5、0<z<0.05、0≤a<0.5、0<b<0.5、0≤c<1.5、y+c<1.5, and Mt is selected from at least 1 of Al, Ga and In.
The Light generated by the above kind of fluoride fluorescent material has a narrow half-wave width, and the wavelength of the Light source that can be excited is less than 500nm, so that the Light is not excited by the green Light generated by the second PL layer 23, and the total Light Extraction Efficiency (Light Extraction Efficiency) of the Light emitting device 1 can be increased; the technical content of this aspect will be further explained with reference to fig. 2C.
The first polymer material 211 may include, but is not limited to: a resin material or a silicone material. Since the first PL layer 21 is closer to the heat source LED chip 10, the first polymer material 211 needs to have better heat resistance, such as a thermal-curing silica gel material (Silicone), which may include a Platinum silica gel (Platinum Silicone) or a tin silica gel (TinSilicone), wherein the Platinum silica gel has better heat resistance, and therefore the light-emitting device 1 preferably selects the Platinum silica gel as the first polymer material 211. The platinum catalyst silica gel is silica gel containing a platinum catalyst, and can help the silica gel to be quickly cured after being heated; however, platinum catalysts are susceptible to deactivation (Deactivated) or poisoning (Poisoned) by chemical components, such that the curing reaction of the silica gel is inhibited (Inhibition), which in turn results in the silica gel not being cured, or only partially cured. Chemical components that may deactivate or poison platinum catalysts include: sulfur (sulfur), sulfides (sulfides), sulfur compounds (thio compounds), tin (tin), fatty acid tin salts (fatty acids) phosphorous (phosphorous), phosphine (phosphinies), phosphite (phosphinites), arsenic (arsenic), arsine (arsines), antimony (antimony), stilbene (stilbenes), selenium (selenium), selenide (selenide), tellurium (tellurium), telluride (telluride), amines (amines), amides (amides), ethanolamine (ethanolamines), N-methylethanolamine (N-methylethanolamines), triethanolamine (triethanolamine), chelates (chelates), ethylenediaminetetraacetic acid tetrasodium salt (EDTA, ethylenediaminetetraacetic acid), nitrilotrisodium triacetate (a, trivalent isocyanate), methanol (methanol), and the like. Therefore, when the platinum-catalyzed silica gel is used as the first polymer material 211, the passivation or poisoning problem of the platinum catalyst should be preferably considered.
The second PL layer 23 can generate a light with a higher energy level (e.g. green light) when excited by the first light, and it can include a second polymer material 231 and a quantum dot material with a higher excitation energy level (e.g. green quantum dot material, hereinafter referred to as green QD material) 232, for simplicity, the green QD material 232 and the green light emitted therefrom will be described as an example. The green QD material 232 may be uniformly mixed and glued (fixed) in the second polymer material 231. Green QD material 232 may produce green light when illuminated with the first light of the higher energy level. The green QD material 232 may include, for example, but is not limited to: cadmium selenide (CdSe), indium phosphide (InP), zinc sulfide (ZnS), zinc selenide (ZnSe), zinc telluride (ZnTe), or the like, which can generate green light. Furthermore, the quantum dot crystal structure of the green QD material 232 typically includes a core and a protective shell.
Because the red light generated by the fluoride fluorescent material when being excited by the first light has narrower half-height width, the high-purity red light can be comparable to the high-purity red light generated by the quantum dot material. Therefore, in the application of the backlight source of the wide color gamut display, a preferred embodiment of the light-emitting device 1 is: the LED chip 10 is a blue emitting LED chip, the fluorescent material contained in the first PL layer 21 is a fluoride fluorescent material capable of emitting high purity red light, and the second PL layer 23 contains a green quantum dot material capable of emitting high purity green light.
Second polymeric material 231 may include, but is not limited to: a resin material or a silica gel material having good light transmittance. Since the quantum dot material is easily oxidized at high temperature, it is not suitable for using a thermosetting adhesive material, and therefore the second polymer material 231 is preferably an ultraviolet curing adhesive, and the second polymer material 231 can be cured by being irradiated by ultraviolet light at normal temperature and does not need to be cured at high temperature as the thermosetting adhesive. Thus, the second polymer material 231 is not subjected to high temperature during curing, so that the performance of the green QD material 232 is not degraded.
The UV curable gel typically contains chemical components that deactivate or poison the platinum catalyst, rendering the silicone gel to be cured uncured. Therefore, the second polymer material 231 made of the uv curable adhesive cannot contact the first polymer material 211 made of the uv curable adhesive during the manufacturing process, otherwise the first polymer material 211 cannot be cured.
In the present embodiment, the light-transparent isolation layer 22 can isolate the first PL layer 21 and the second PL layer 23, and the chemical component of the second polymer material 231 that can deactivate or poison the platinum catalyst cannot diffuse into the first polymer material 211, so that the first polymer material 211 can be completely cured. Therefore, the optically transparent isolation layer 22 can improve the problem that the first polymer material 211 and the second polymer material 231 are incompatible with each other in terms of material characteristics or curing process. Specifically, the optically transparent isolation layer 22 is used to isolate the first PL layer 21 and the second PL layer 23 from each other, and to make the second PL layer 23 farther away from the LED chip 10, so as to reduce the influence of the thermal energy of the LED chip 10 on the second PL layer 23. The optically transparent isolation layer 22 can include, but is not limited to, a transparent inorganic material (e.g., quartz or glass) or a polymer material with good light transmittance. In addition, the light transparent isolation layer 22 preferably does not contain chemical components that can deactivate or poison platinum catalysts, and thus can contact the first polymer material 211.
In addition, the optically transparent moisture barrier layer 24 of the light emitting device 1 is used to block the passage of moisture to protect the quantum dot material of the second PL layer 23 from oxidation. The optically transparent moisture barrier layer 24 may include, but is not limited to, a transparent inorganic material (e.g., quartz or glass) or a polymer material with good light transmittance; if the polymer material is a polymer material, the material is selected to have a low water vapor permeability, for example, a thickness of 1 mm is not more than 20 g/(m)2day) water vapor permeability. The optically transparent barrier layer 22 may also be selected to have a low moisture vapor transmission rate, for example, at a thickness of 1 mmHas a molar mass of not more than 20 g/(m)2day), the light transparent moisture barrier layer 24 and the light transparent isolation layer 22 sandwich the second PL layer 23 containing the quantum dot material therebetween, so that moisture or oxygen in the external environment is difficult to contact the green QD material 232 in the second PL layer 23, and moisture or oxygen permeation from above or below to the green QD material 232 is reduced or prevented.
The moisture barrier reflection structure (hereinafter, simply referred to as a reflection structure) 30 may reflect light emitted from the side of the light emitting device and direct the light to the front side. Specifically, the reflection structure 30 covers the side surface 203 of the PL structure 20 and the vertical surface 103 of the LED chip 10, but does not cover the top surface 201 of the PL structure 20, and therefore, light emitted from the vertical surface 103 and the side surface 203 can be reflected and emitted toward the top surface 201 of the PL structure 20. The reflective structure 30 is not lower than the bottom surface 102 of the LED chip 10, and does not cover the bottom surface 102 and the electrode assembly 104. The top surface 301 of the reflective structure 30 may be substantially flush with the top surface 201 of the PL structure 20, and since the light emitting device 1 is a chip scale package light emitting device that can be directly bonded to a printed circuit board or other application substrate, and thus has a low thermal resistance to reduce the operating temperature of the light emitting device, the bottom surface 302 of the reflective structure 30 may not be lower than the height of the electrode surface 102 to avoid poor bonding between the electrode set 104 and the substrate pad, and preferably, the bottom surface 302 of the reflective structure 30 may be substantially flush with the electrode surface 102 of the LED chip 10. Furthermore, the reflective structure 30 may also cover the portion of the bottom surface 202 of the PL structure 20 beyond the upper surface 101 of the LED chip 10. Although the second PL layer 23 containing quantum dot material is disposed between the light transparent moisture barrier layer 24 and the light transparent isolation layer 22, such that moisture in the external environment is difficult to contact the green QD material 232 in the second PL layer 23, moisture may still permeate through the side of the second PL layer 23. Another effect of the reflective structure 30 of the light emitting device is to block moisture from penetrating into the environment, so as to reduce or prevent moisture or oxygen from contacting the green QD material 232 from the side; therefore, the encapsulation of the moisture barrier reflection structure 30, the light transparent moisture barrier layer 24 and the light transparent isolation layer 22 can further provide moisture barrier protection for the green QD material 232, so as to reduce photo-oxidation.
To make the reflecting structure 30 haveThe above characteristics preferably include a third polymer material 31 and a light scattering particle 32 mixed in the third polymer material 31; the third high molecular material 31 can be selected from those having a low water vapor permeability (for example, not more than 20g/m at a thickness of 1 mm)2/day), for example, may include a resin material or a silica gel material to make it difficult for moisture to pass through; the light scattering fine particles 32 may specifically be titanium dioxide (TiO)2) Boron Nitride (BN), silicon dioxide (SiO)2) Or aluminum oxide (Al)2O3) And the like, and a weight percentage thereof in the reflective structure 30 is not less than 20% to achieve a good reflective effect.
Referring to fig. 2A, it will be further described how the first PL layer 21 is utilized to reduce the intensity of the first light to the intensity that the green QD material 232 can bear, so as to prevent photo-oxidation of the quantum dot material. Specifically, the first light emitted from the LED chip 10 is exemplified by blue light B, which has an initial light intensity of L0, and a portion (i.e., a first portion) of the blue light B is converted into red light R when passing through the first PL layer 21. The remaining unconverted other portion (i.e., the second portion) of blue light B has a light intensity of L1, which is less than the initial light intensity of L0. The remaining second portion of blue light B then partially excites green QD material 232 and is then converted to green light G (i.e., a portion of the second portion is converted back to green light G). Therefore, the light finally emitted from the top surface 201 of the PL structure 20 (i.e., the light emitting surface of the light emitting device 1) includes blue light B, red light R and green light G, which can be mixed to form white light.
Therefore, the green QD material 232 in the light emitting device 1 disclosed in the present invention is irradiated by the blue light B and the red light R, and since the energy level of the red light R is not sufficient to excite the green QD material 232 to generate the green light G, the green QD material 232 does not generate free electrons and holes, and the free electrons activate the (electron-active) quantum dot material to generate photo-oxidation, so that the green QD material 232 is not easily photo-oxidized when irradiated by the red light R.
Since the green QD material 232 still generates a large amount of free electrons under the irradiation of the blue light B to cause photo-oxidation of the quantum dot material, the light emitting device 1 disclosed in the present invention can greatly reduce the intensity of the blue light B irradiated on the green QD material 232. Specifically, the LED chip 10 provides the blue light B with an initial light intensity L0, which is divided into a first portion and a second portion for convenience of illustration; after passing through the first PL layer 21, the first part of blue light B is converted into red light R and a second part of unconverted blue light B, the initial blue light intensity L0 is reduced to the blue light intensity L1 corresponding to the second part, and the blue light intensity L1 is not greater than the light intensity that the green QD material 232 can bear, so that the green QD material 232 is still not prone to generate photo-oxidation under the irradiation of the blue light B of the light intensity L1, and further the green QD material 232 has a more stable light-emitting spectrum and light-emitting efficiency, and has a longer service life.
The intensity L1 of blue light B (second portion) that is not converted after passing through the first PL layer 21 can be measured as follows: before the second PL layer 23 is disposed (or the second PL layer 23 is removed), the LED chip 10 is driven to emit blue light B, and then the intensity value of the blue light B is measured from above the first PL layer 21. In addition, if the light converted by the green QD material 232 has no significant intensity attenuation (e.g., no greater than 20% or no greater than 10% intensity attenuation) or no significant wavelength shift (e.g., no greater than 10 nm or no greater than 5 nm peak wavelength shift) under the irradiation of the blue light B with the light intensity L1 over a period of time, it can be deduced that the light intensity L1 of the blue light B is not greater than the light intensity that the green QD material 232 can bear.
The green QD material 232 may bear different intensities of the first light according to different structures and materials; for example, the green QD material 232 currently known can tolerate blue light intensities of no more than 10W/cm2Not more than 5W/cm2Or not more than 2W/cm2. Since the development of technology will continuously improve the structure of quantum dot materials, it is expected that the upper limit of the light intensity that can be borne by quantum dot materials should be increased, for example, more than 10W/cm2。
The upper limit of the light intensity of the incident light used to excite the quantum dot material can be provided by the manufacturer or supplier, or can be obtained through experimental tests. For example, blue light B (or other first light of high energy level) with different intensities is irradiated onto the green QD material 232, and then the amount of change of the green intensity and the peak wavelength converted by the green QD material 232 over a period of time is measured; by observing whether the converted light has a significant attenuation in intensity (e.g., no greater than 20% or no greater than 10% attenuation in intensity), and a significant shift in wavelength (e.g., no greater than 10 nm or no greater than 5 nm shift in peak wavelength), the intensity of blue light B that green QD material 232 can withstand over long periods of operation can be measured.
Fig. 2B shows the measurement result of the emission spectrum of a preferred embodiment of the light-emitting device 1, in which the LED chip 10 of this embodiment can emit a blue light B with a peak wavelength of 443 nm, a KSF red phosphor with a peak wavelength of 630 nm is used as the phosphor with a lower excitation energy level of the first PL layer 21, and an InP green quantum dot material with a peak wavelength of 540 nm is used as the quantum dot material with a higher excitation energy level of the second PL layer 23. Under the excitation of blue light, the KSF fluorescent material closer to the LED chip 10 can firstly absorb a part of the blue light B emitted from the LED chip 10 and convert it to emit a red light R with a narrow full width at half maximum, and the unconverted blue light B and red light R are then transmitted to the second PL layer 23, wherein the unconverted blue light B is then partially absorbed by the green quantum dot material of the second PL layer 23 and converted to emit a green light G with a full width at half maximum of 39 nm, and is represented as a green spectrum G in fig. 2B. The blue spectrum B shown in fig. 2B is a portion of the blue light B unconverted by the second PL layer 23, while the red light R is not sufficient to excite the green quantum dot material of the second PL layer 23 due to the lower energy level, and therefore can be mostly output out of the light emitting device and appear as the red spectrum R shown in fig. 2B. Since the first PL layer 21 has converted the intensity of blue light B of about 1/3 into red light R, the intensity of light from blue light B of about 1/3 on the green quantum dot material can be effectively reduced, making it less prone to photo-oxidation and having a longer lifetime. Since the light-emitting device 1 has red, green and blue spectrums with high color purity (narrow full width at half maximum), it is very suitable for being applied to a backlight source of a wide color gamut liquid crystal display.
Referring to fig. 2C, how the first PL layer 21 increases the light extraction efficiency of the green light G will be further described. A portion of the green light G1 converted from the green QD material 232 is output to the outside of the PL structure 20, but another portion of the green light G2 is reversely forwarded toward the LED chip 10; if the red phosphor 212 of the first PL layer 21 is a fluoride phosphor of a specific type, it is not excited by light having a wavelength greater than about 500nm, and thus the green light G2 scattered toward the chip 10 is not absorbed by the red phosphor 212 and converted. In this way, the green light G2 heading in the reverse direction toward the LED chip 10 can be effectively scattered (scattering) outward by the red fluorescent material 212, and the green light is outputted to the outside of the light emitting device 1. Therefore, the light extraction efficiency of the green light G (G1, G2) can be effectively increased.
Referring to fig. 1C, in another embodiment, the second PL layer 23 may further include a light scattering particle 233 mixed in the second polymer material 231. The quantum dot material is a nano-scale particle, and the first light is easily transmitted without exciting the quantum dot material, so the light scattering particle 233 is used to scatter the first light in the second PL layer, thereby increasing the probability that the green QD material 232 is excited by the first light. In other words, the light scattering particles 233 may increase the total light path of the first light passing through the second PL layer 23 to increase the proportion of the first light converted into green light. In addition, the weight percentage of the light scattering particles 233 in the second PL layer 23 is preferably not greater than 20%, not greater than 15%, or not greater than 10% to provide suitable light transmittance and avoid over-blocking the first light.
In another embodiment, the LED chip 10 is a deep blue LED chip, a violet LED chip or a uv LED chip, and the first light emitted therefrom is deep blue light, violet light or uv light. In this case, the second PL layer 23 may further include another quantum dot material 234 with a higher excitation energy level, such as a blue quantum dot material 234, which may be mixed in the second polymer material 231, or may be mixed in another polymer material (not shown) different from the second polymer material 231. The deep blue light or ultraviolet light can be converted into blue light by the blue quantum dot material 234, so that the light generated by the light-emitting device 1 can include blue light, red light, green light and other spectrums.
The technical contents of the light-emitting device 1 are described above, and the technical contents of other embodiments according to the present invention are described below, but the technical contents of the embodiments should be referred to each other, so the same parts will be omitted or simplified. In addition, the technical contents of the embodiments can be applied to and combined with each other.
Fig. 3 is a schematic view of a light emitting device 2 according to a 2 nd preferred embodiment of the invention. The PL structure 20 of the light emitting device 2 further comprises an optically transparent heat conducting layer 25; the optically transparent thermally conductive layer 25 may be disposed between the second PL layer 23 and the optically transparent moisture barrier layer 24, and/or between the second PL layer 23 and the optically transparent isolation layer 22, in other words, the top and/or bottom surface of the second PL layer 23 may be disposed over an optically transparent thermally conductive layer 25.
The optically transparent thermally conductive layer 25 has good thermal conductivity (i.e., low thermal resistance) and is greater than the thermal conductivity of the optically transparent moisture barrier layer 24 or the optically transparent isolation layer 22; in addition, the optically transparent heat conductive layer 25 also needs to have good light transmittance. Thus, the optically transparent thermally conductive layer 25 may include, but is not limited to: a thin film metal, a grid metal, a transparent conductive oxide or graphene; the transparent conductive Oxide can be Indium Tin Oxide (ITO), for example, and has a light transmittance of greater than 90% and a thermal conductivity (at 25 ℃) of about 10-12W/mK; the thermal conductivity of graphene is even more as high as 5300W/mK. The optically transparent and thermally conductive layer 25 can rapidly transfer or disperse the heat generated by the second PL layer 23 during light conversion, so as to reduce the operating temperature of the green QD material 232, and further reduce the influence of the heat on the green QD material 232.
The reflective structure 30 may also optionally include a thermal conductive material (not shown) mixed in the third polymer material 31, so that the thermal conductivity of the reflective structure 30 is not less than that of the optically transparent moisture barrier layer 24 or the optically transparent isolation layer 22. Thus, the heat energy of the second PL layer 23 can also be effectively transferred outward through the reflective structure 30, reducing the effect of high temperature on the green QD material 232. The thermally conductive material may comprise graphene, ceramic material, or the like, wherein the ceramic material may be aluminum nitride (thermal conductivity about 285W/mK) or aluminum oxide. The heat conductive material may also include a metal material, which is preferably prevented from contacting the LED chip 10, for example, the reflecting structure 30 including the metal heat conductive material covers the light guiding structure 40 (as shown in fig. 4B), i.e., the reflecting structure 30 indirectly covers the vertical surface 103 of the LED chip 10.
Fig. 4A is a schematic view of a light emitting device 3 according to a 3 rd preferred embodiment of the invention. The PL structure 20 of the light emitting device 3 further comprises a light transparent spacer layer 26 disposed on the upper surface 101 of the LED chip 10; the first PL layer 21 is disposed on the optically transparent spacer layer 26 and does not directly cover, contact the LED chip 10. As such, the second PL layer 23 may be farther away from the hotter LED chip 10 to further reduce the effect of the high temperature LED chip 10 on the green QD material 232. The optically transparent separation layer 26 can include, but is not limited to, a transparent inorganic material (e.g., quartz or glass, etc.) or a polymer material (e.g., silica gel, etc.); in the case of a polymer material, it is preferable to select one having a low moisture permeability so as to reduce the possibility of moisture and oxygen permeating inside the light emitting device.
Referring to fig. 4B, in another aspect of the 3 rd preferred embodiment of the present invention, the light emitting device 3 further includes a light guiding structure 40. The light guiding structure 40 may include a polymer material (e.g., silicone, epoxy, rubber, etc.) with good light transmittance, and may cover the vertical surface 103 of the LED chip 10 and then be covered by the reflective structure 30. More specifically, the light guiding structure 40 may include a top surface 401 and an inclined side surface 402, the top surface 401 may be flush with the upper surface 101 of the LED chip 10, and the inclined side surface 402 is inclined with respect to the vertical surface 103 of the LED chip 10; the inclined side 402 may be a concave curve (as shown) or a flat or convex curve (not shown). In addition, the inclined side 402 is also directly covered by the reflective structure 30, so that the reflective structure 30 has an inner inclined surface (or inner inclined side) corresponding to the inclined side 402. When the inclined side 402 is directly covered by the reflective structure 30, the elevation 103 of the LED chip 10 is indirectly covered by the reflective structure 30.
In addition, since the chip-scale package light emitting device does not need a package support, under the same package volume, the light emitting device disclosed by the present invention can have a larger light emitting area, i.e. the area of the PL structure 20 can be larger, so that when the blue light B emitted by the LED chip 10 irradiates the PL structure 20 with a larger area, the intensity of the blue light per unit area of the quantum dot material irradiated in the PL structure 20 can be effectively reduced, and the photo-oxidation phenomenon of the quantum dot material can be further reduced. The light guide structure 40, in cooperation with the reflection structure 30, can effectively reflect the first light emitted from the side direction of the LED chip 10 into the PL structure 20, so that the first light can more uniformly irradiate the PL structure 20, reduce the intensity of blue light in unit area, and reduce the photo-oxidation phenomenon of the quantum dot material to increase the service life thereof; the technical content of the light guiding structure 40 in combination with the reflecting structure 30 can be further referred to taiwan patent application No. 106103239 previously filed by the applicant.
Referring to fig. 5A to 5I, a method for manufacturing a light emitting device according to a preferred embodiment of the present invention is described, which can manufacture the light emitting devices 1 to 3 similar to or the same as the above embodiments, so that the technical contents of the manufacturing method and the technical contents of the light emitting devices 1 to 3 can be mutually referred and applied.
As shown in fig. 5A, a light transparent moisture barrier layer 24 is provided or formed, and then a second PL layer 23 is formed directly on the light transparent moisture barrier layer 24 by spraying (spraying), spin coating (spin coating), printing (printing), or the like; that is, the uncured second polymer material 231 and the green QD material 232 are mixed, and then formed on the light transparent moisture barrier layer 24 through the above-mentioned manner, and the second PL layer 23 is formed after the second polymer material 231 is cured, and if the second polymer material 231 is a thermosetting silica gel, the thermosetting is performed in an inert gas or vacuum environment. Alternatively, the second PL layer 23 may be formed separately and then bonded to the light transparent moisture barrier layer 24.
As shown in fig. 5B, an optically transparent isolation layer 22 is then formed directly on the second PL layer 23, for example, by spraying, spin coating, or printing, or the optically transparent isolation layer 22 is attached to the second PL layer 23. As shown in fig. 5C, a first PL layer 21 is then formed directly on the optically transparent isolation layer 22, for example, by spraying, spin coating or printing, or by the technique disclosed in U.S. patent application publication No. US2010/0119839 (taiwan patent corresponding to certificate No. I508331); alternatively, the first PL layer 21 is formed separately and then bonded to the optically transparent isolation layer 22.
Thus, a plurality of PL structures 20 of light emitting devices 1 can be fabricated, still integrally connected to each other. In addition, in the step shown in fig. 5A, the optically transparent and thermally conductive layer 25 may be selectively formed before and/or after the second PL layer 23 is formed, so as to fabricate a plurality of PL structures 20 of the light emitting devices 2. As shown in fig. 5D, an optically transparent spacer layer 26 is optionally formed on the first PL layer 21 to fabricate a plurality of PL structures 20 of light emitting devices 3.
As shown in fig. 5E, after the PL structure 20 is fabricated, the LED chips 10 are then inverted with their upper surfaces 101 facing down (lower surfaces 102 facing up) and facing the bottom surface 202 of the PL structure 20, and the LED chips 10 are then bonded to the inner layers of the PL structure 20 (i.e., the light transparent spacer layer 26 or the first PL layer 21). After the LED chip 10 is bonded, the light guiding structure 40 is optionally formed on the first PL layer 21 or the light transparent separation layer 26, and the specific forming manner of the light guiding structure 40 can refer to the chinese patent application No. 201710057384.4 filed by the applicant.
As shown in fig. 5F, after the LED chip 10 is attached, the integrally connected PL structures 20 are cut and separated; each PL structure 20 is attached to one of the LED chips 10 to form a light emitting structure. As shown in fig. 5G, the light emitting structures are arranged on a release material 900 to form a light emitting structure array; in alignment, the top surface 201 of the PL structure 20 may be selectively attached to the release material 900 (as shown), or the bottom surface 102 of the LED chip 10 may be attached to the release material 900, and the electrode assembly 104 may be embedded in the release material 900 (not shown).
As shown in fig. 5H, a reflective structure 30 is then formed on the release material 900 and between the light emitting structure to cover the side surface 203 of the PL structure 20 and the inclined side surface 402 of the light guiding structure 40 (indirectly covering the elevation surface 103 of the LED chip 10), but not the lower surface 102 of the LED chip 10; the reflective structure 30 can be formed by molding or dispensing. After the reflective structure 30 is formed, a plurality of light emitting devices 3 (or other types of light emitting devices) can be obtained, and the light emitting devices 3 are connected to each other. As shown in fig. 5I, finally, a cutting step is taken to separate the connected light emitting devices 3, so as to obtain the light emitting devices 3 separated from each other; wherein the release material 900 can be separated from the light emitting device 3 before or after cutting.
Referring back to fig. 5C or 5D, after the integrally connected PL structures 20 are fabricated, a cutting step may be performed directly to separate the integrally connected PL structures 20 into a plurality of PL structures 20; then, the PL structure 20 is bonded to the LED chip 10, and the reflection structure 30 is formed to cover both, thereby completing the fabrication of the light emitting device 3 (or other types of light emitting devices).
Referring to fig. 6A-6D, the PL structure 20 may also be fabricated in the following manner. As shown in fig. 6A, a light transparent moisture barrier layer 24 is first provided or formed, and then a second PL layer 23 is formed on the light transparent moisture barrier layer 24. As shown in fig. 6B, next, an optically transparent isolation layer 22 is additionally provided or formed, and a first PL layer 21 is formed on the optically transparent isolation layer 22; neither the optically transparent isolation layer 22 nor the first PL layer 21 are formed sequentially on the second PL layer 23 as in fig. 5B.
In other words, the combination of the optically transparent moisture barrier layer 24 and the second PL layer 23, and the combination of the optically transparent isolation layer 22 and the first PL layer 21 are fabricated separately, and the processes of the two layers will not affect each other. Therefore, if the first polymer material 211 of the first PL layer 21 is a thermal curing adhesive, the high temperature for thermal curing does not affect the green QD material 232 of the second PL layer 23, and the performance of the green QD material 232 is not degraded by the thermal curing process of the first PL layer 21.
As shown in fig. 6C, the LED chip 10 is then attached to the first PL layer 21, and optionally, a light transparent spacer layer 26 and/or a light guiding structure 40 is formed on the first PL layer 21. Further as shown in FIG. 6D, the optically transparent spacer layer 22 is laminated to the second PL layer 23 to produce the PL structure 20 as shown in FIG. 5E. Steps as in fig. 5F to 5I can then be taken to obtain mutually separated light emitting devices 3 or other light emitting devices.
In summary, the light emitting device provided in the preferred embodiment of the present invention can effectively improve the oxidation phenomenon of the quantum dot material, and can reduce or prevent moisture and oxygen in the outside air from contacting the quantum dot material; the problem that the material characteristics of a high polymer material for fixing the quantum dot material and a high polymer material for fixing the fluorescent material are incompatible can be effectively solved; the thermal decay phenomenon of the quantum dot material can be effectively improved, the temperature born by the quantum dot material is reduced, and the light extraction efficiency of the light-emitting device is increased. The manufacturing method of the light-emitting device can manufacture various light-emitting devices with the above effects, and the quantum dot material can not bear high temperature in the manufacturing process.
The above-mentioned embodiments are only used to illustrate the implementation of the present invention and to explain the technical features of the present invention, and are not used to limit the protection scope of the present invention. Any modifications or equivalent arrangements which may occur to those skilled in the art and which fall within the spirit and scope of the appended claims should be construed as limited only by the scope of the claims.

Claims (22)

1. A light emitting device, comprising:
the flip chip type LED chip is used for providing a first light ray, and the first light ray is a blue light ray, a deep blue light ray, a purple light ray or an ultraviolet light ray;
a photoluminescent structure disposed on an upper surface of the flip-chip LED chip and including a first photoluminescent layer, a light-transparent isolation layer, a second photoluminescent layer, and a light-transparent moisture barrier layer, the light-transparent isolation layer being disposed on the first photoluminescent layer, the second photoluminescent layer being disposed on the light-transparent isolation layer, and the light-transparent moisture barrier layer being disposed on the second photoluminescent layer, wherein the first photoluminescent layer includes a first polymer material and a fluorescent material of a lower excitation energy level mixed in the first polymer material, and the second photoluminescent layer includes a second polymer material and a quantum dot material of a higher excitation energy level mixed in the second polymer material; and
a moisture barrier reflection structure covering one side of the photoluminescence structure and one vertical surface of the flip chip LED chip and not lower than an electrode surface of the flip chip LED chip, wherein the moisture barrier reflection structure comprises a third high molecular material and light scattering particles mixed in the third high molecular material, and the third high molecular material has a thickness of not more than 1 mm20g/(m2day) water vapor permeability;
the fluorescent material with lower excitation energy level of the first photoluminescence layer is used for converting one part of the first light into visible light with longer wavelength, so that the light intensity of the other part of the first light which is not converted is not more than the light intensity which can be borne by the quantum dot material with higher excitation energy level.
2. The light emitting device of claim 1, wherein the lower excitation energy level phosphor material comprises a red phosphor material and the higher excitation energy level quantum dot material comprises a green quantum dot material.
3. The light-emitting device of claim 2, wherein the intensity of the first light that the green quantum dot material can bear is not more than 10W/cm2。
4. The light-emitting device of claim 2, wherein the photoluminescent structure further comprises an optically transparent thermally conductive layer disposed between the second photoluminescent layer and the optically transparent moisture barrier layer and/or between the second photoluminescent layer and the optically transparent barrier layer; wherein the thermal conductivity of the optically transparent thermal conductive layer is greater than the thermal conductivity of the optically transparent moisture barrier layer or the optically transparent isolation layer.
5. The light emitting device of claim 4, wherein the optically transparent thermally conductive layer comprises a thin film metal, a mesh metal, a transparent conductive oxide, or a graphene.
6. The light-emitting device of any one of claims 2-5, wherein the photoluminescent structure further comprises an optically transparent spacer layer, the first photoluminescent layer being disposed on the optically transparent spacer layer.
7. The light emitting device according to any one of claims 2 to 5, further comprising a light guiding structure covering the vertical face of the flip-chip LED chip, the light guiding structure comprising an inclined side face inclined with respect to the vertical face of the flip-chip LED chip and covered by the moisture blocking reflective structure.
8. The light-emitting device according to any one of claims 2-5, wherein the first polymer material is a heat-curable adhesive and the second polymer material is an ultraviolet-curable adhesive.
9. The light-emitting device of any one of claims 2-5, wherein the optically transparent isolation layer and the optically transparent moisture barrier layer each comprise a transparent inorganic material.
10. The light-emitting device of any one of claims 2-5, wherein the light-transparent release layer and the light-transparent moisture-blocking layer each comprise a polymer material having a thickness of not greater than 20 g/(m) at 1 mm2day) Water Vapor Transmission Rate (WVTR).
11. The light emitting device of any one of claims 2 to 5, wherein the thermal conductivity of the moisture barrier reflective structure is not less than the thermal conductivity of the optically transparent isolation layer or the optically transparent moisture barrier layer.
12. The light-emitting device of any one of claims 2-5, wherein the second photoluminescent layer further comprises light-scattering particles, and the light-scattering particles are mixed in the second polymer material.
13. The light-emitting device according to any one of claims 2 to 5, wherein the red phosphor comprises a fluoride phosphor or a nitride phosphor.
14. The light emitting device of claim 13, wherein the fluoride phosphor comprises at least one of: (A) a. the2[MF6]:Mn4+Wherein A is selected from Li, Na, K, Rb, Cs and NH4And combinations thereof, M is selected from Ge, Si, Sn, Ti, Zr, and combinations thereof; (B) e2[MF6]:Mn4+Wherein E is selected from the group consisting of Mg, Ca, Sr, Ba, Zn, and combinations thereof, and M is selected from the group consisting of Ge, Si, Sn, Ti, Zr, and combinations thereof; (C) ba0.65Zr0.35F2.70:Mn4+(ii) a Or (D) A3[ZrF7]:Mn4+Wherein A is selected from Li, Na, K, Rb, Cs and NH4And combinations thereof.
15. The light emitting device of claim 13, wherein the fluoride phosphor comprises at least one of:
(x-a)MgO.(a/2)Sc2O3.yMgF2.cCaF2.(1-b)GeO2.(b/2)Mt2O3:zMn4+；
wherein x is more than or equal to 2.0 and less than or equal to 4.0, y is more than 0 and less than 1.5, z is more than 0 and less than 0.05, a is more than or equal to 0 and less than 0.5, b is more than 0 and less than 0.5, c is more than or equal to 0 and less than 1.5, y + c is less than 1.5, and Mt is selected from at least 1 of Al, Ga and In.
16. The light-emitting device of any one of claims 2-5, wherein the second photoluminescent layer further comprises a blue quantum dot material.
17. A method of manufacturing a light emitting device, comprising:
attaching a photoluminescence structure to a flip-chip LED chip; and
forming a moisture barrier reflection structure to cover one side surface of the photoluminescence structure and one vertical surface of the flip chip type LED chip;
the photoluminescence structure comprises a first photoluminescence layer, a light transparent isolation layer, a second photoluminescence layer and a light transparent moisture barrier layer, wherein the light transparent isolation layer is arranged on the first photoluminescence layer, the second photoluminescence layer is arranged on the light transparent isolation layer, the light transparent moisture barrier layer is arranged on the second photoluminescence layer, the first photoluminescence layer covers the upper surface of the flip chip type LED chip, the first photoluminescence layer comprises a first high polymer material and a fluorescent material with a lower excitation energy level mixed in the first high polymer material, the second photoluminescence layer comprises a second high polymer material and a quantum dot material with a higher excitation energy level mixed in the second high polymer material, and the moisture barrier reflection structure is not lower than the lower surface of an electrode of the flip chip type LED chip;
wherein the moisture barrier reflection structure comprises a third polymer material and a light scattering particle mixed in the third polymer material, and the third polymer material has a thickness of not more than 20 g/(m) when the thickness is 1 mm2day) water vapor permeability
The flip chip type LED chip is used for providing a first light ray, the first light ray is a blue light ray, a deep blue light ray, a purple light ray or an ultraviolet light ray, the fluorescent material with lower excitation energy level of the first photoluminescence layer is used for converting one part of the first light ray into a visible light with longer wavelength, and the light intensity of the other part of the first light ray which is not converted is not more than the light intensity which can be borne by the quantum dot material with higher excitation energy level.
18. The method of claim 17, further comprising: forming the photoluminescent structure comprising:
providing the optically transparent moisture barrier layer;
forming the second photoluminescent layer on the optically transparent moisture barrier layer;
forming the light transparent isolation layer on the second photoluminescence layer; and
forming the first photo-luminescent layer on the light transparent isolation layer.
19. The method of claim 17, further comprising: forming the photoluminescent structure comprising:
providing the light transparent moisture barrier layer and forming the second photoluminescent layer on the light transparent moisture barrier layer;
providing the light transparent isolation layer and forming the first photoluminescence layer on the light transparent isolation layer; and
and attaching the light transparent isolation layer to the second photoluminescent layer.
20. The method of claim 17, wherein the photoluminescent structure further comprises an optically transparent thermally conductive layer formed between the second photoluminescent layer and the optically transparent moisture barrier layer and/or between the second photoluminescent layer and the optically transparent barrier layer; wherein the thermal conductivity of the optically transparent thermal conductive layer is greater than the thermal conductivity of the optically transparent isolation layer or the optically transparent moisture barrier layer.
21. The method of any one of claims 17 to 20, wherein the photoluminescent structure further comprises an optically transparent spacer layer formed on the first photoluminescent layer; wherein, the light transparent separation layer covers the upper surface of the flip chip type LED chip.
22. The method according to any one of claims 17 to 20, further comprising forming a light guiding structure formed on the first photoluminescent layer to cover the vertical surface of the flip-chip LED chip, wherein the light guiding structure comprises an inclined side surface, the inclined side surface being inclined with respect to the vertical surface of the flip-chip LED chip;
wherein, when the moisture barrier reflection structure is formed, the moisture barrier reflection structure covers the inclined side face of the light guide structure.
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