Nano composite fluorescent powder, preparation method thereof and light-emitting device

文档序号：1397167 发布日期：2020-03-03 浏览：32次中文

阅读说明：本技术 纳米复合荧光粉及其制备方法和发光装置 (Nano composite fluorescent powder, preparation method thereof and light-emitting device ) 是由杨佳伟黄文泽刘如熹吕侊懋康桀侑林治民郑巧翎包真于 2018-11-27 设计创作，主要内容包括：本发明提供一种纳米复合荧光粉,所述纳米复合荧光粉包括载体及负载于所述载体上的红外荧光粉,其中所述载体为氧化物,所述红外荧光粉的化学通式为ZnGa2-x-yO4:xCr3+,yR,其中x和y均为摩尔分数,且0<x<0.4,0≤y<0.4,R选自Sn4+,Ti3+,V2+,M63+,Fe2+,Co3+,Ni3+,Nb5+,Mo5+,Tc5+,Ru4+,Rh4+,Pd4+,Sb5+,Ta5+,W5+,Re4+,Os4+,Ir4+,Pt4+中的一种或多种。该纳米复合荧光粉具有优异的分散性、发光效率高且封装性好,其粒径尺寸可适配于micro/min-LED等发光装置上,在可见光或紫外光激发下可获得红外光,有望应用于微小型检测装置,虹膜/面部脸部检测、医疗检测或气体检测装置等。(The invention provides a nano composite fluorescent powder, which comprises a carrier and infrared fluorescent powder loaded on the carrier,wherein the carrier is oxide, and the chemical general formula of the infrared fluorescent powder is ZnGa 2‑x‑y O 4 :xCr 3+ yR, where x and y are both mole fractions, and 0<x<0.4，0≤y<0.4, R is selected from Sn 4+ ,Ti 3+ ,V 2+ ,M6 3+ ,Fe 2+ ,Co 3+ ,Ni 3+ ,Nb 5+ ,Mo 5+ ,Tc 5+ ,Ru 4+ ,Rh 4+ ,Pd 4+ ,Sb 5+ ,Ta 5+ ,W 5+ ,Re 4+ ,Os 4+ ,Ir 4+ ,Pt 4+ One or more of (a). The nano composite fluorescent powder has excellent dispersibility, high luminous efficiency and good encapsulation performance, the particle size of the nano composite fluorescent powder can be adapted to micro/min-LED and other light emitting devices, infrared light can be obtained under the excitation of visible light or ultraviolet light, and the nano composite fluorescent powder is expected to be applied to micro detection devices, iris/face detection, medical detection or gas detection devices and the like.)

1. The nano composite fluorescent powder is characterized by comprising a carrier and infrared fluorescent powder loaded on the carrier, wherein the carrier is an oxide, and the chemical general formula of the infrared fluorescent powder is ZnGa_2-x-yO₄:xCr³⁺yR, where x and y are both mole fractions, and 0<x<0.4，0≤y<0.4, R is selected from Sn⁴⁺,Ti³⁺,V²⁺,Mn³⁺,Fe²⁺,Co³ ⁺,Ni³⁺,Nb⁵⁺,Mo⁵⁺,Tc⁵⁺,Ru⁴⁺,Rh⁴⁺,Pd⁴⁺,Sb⁵⁺,Ta⁵⁺,W⁵⁺,Re⁴⁺,Os⁴⁺,Ir⁴⁺,Pt⁴⁺One or more of (a).

2. The nanocomposite phosphor of claim 1, wherein the particle size of the nanocomposite phosphor is less than 200 nm.

3. The nano-composite phosphor according to claim 1, wherein the nano-composite phosphor has a light emission wavelength of 600nm to 2000nm and an excitation wavelength of 250nm to 600 nm.

4. The nanocomposite phosphor of claim 1, wherein the support has a mesoporous structure and the oxide is selected from one or more of silica, titania, and zinc oxide.

5. A method of preparing the nanocomposite phosphor of any of claims 1 to 4, comprising:

according to the general formula ZnGa_2-x-yO₄:xCr³⁺Weighing compounds containing Zn, Ga, Cr and R elements according to the molar ratio of each element in yR, respectively dissolving the compounds to form solutions, and mixing the solutions to form a precursor solution;

placing the carrier in the precursor solution for mixing, and heating and baking the mixed solution to form powder;

and grinding the powder, and calcining for 6-20 h to obtain the nano composite fluorescent powder.

6. The method according to claim 5, wherein the calcination treatment comprises:

heating the ground powder to 200-700 ℃ at the speed of 2-5 ℃/min, and continuously calcining for 1-10 h;

then heating to 500-1200 ℃ at the speed of 2-5 ℃/min, and continuously calcining for 1-10 h.

7. The production method according to claim 5, wherein a solid-to-liquid ratio of the carrier to the precursor solution is mg: ml is 100: 0.5-100: 20; the molar concentration of the precursor solution is 0.1-1.5M.

8. A light emitting device comprising: an excitation light source and an encapsulation layer on the excitation light source, wherein the material of the encapsulation layer comprises the nanocomposite fluorescent powder of any one of claims 1 to 4 and an encapsulant.

9. The light-emitting device according to claim 8, wherein the nanocomposite phosphor is included in an amount of 50 to 100% by mass based on the total mass of the encapsulating layer.

10. The light-emitting device according to claim 9, wherein the mass fraction of the nanocomposite phosphor varies in a gradient or a continuous manner as the thickness of the encapsulation layer varies, and the average mass fraction of the nanocomposite phosphor is 50% to 100%.

11. The light-emitting device according to claim 8, wherein the excitation light source is a micro led chip, a micro laser diode chip, a sub-millimeter led chip, or a sub-millimeter laser diode chip, and the chip is a horizontal chip, a vertical chip, or a flip chip.

Technical Field

The invention belongs to the technical field of semiconductors, and particularly relates to a nano composite fluorescent powder, a preparation method thereof and a light-emitting device.

Background

With the continuous development of semiconductor technology, micro-LEDs (micro light emitting diodes) and mini-LEDs (sub-millimeter light emitting diodes) are driving another revolution of LED display technology. The Micro-LED technology is to make the LED (light emitting diode) backlight source thin, tiny and arrayed, so that the size of an LED unit is smaller than 100 micrometers, the Micro-LED technology inherits the characteristics of high efficiency, high brightness, high reliability, fast reaction time and the like of an inorganic LED, has the characteristics of self-luminescence without backlight source, is small in size, light and thin, and can easily realize the effect of energy conservation. The Mini-LED is an LED with a grain size of about 100 to 200 microns, has better color rendering due to a local dimming design, can provide a liquid crystal panel with a finer HDR partition, has a thickness approaching to that of an OLED, can save electricity by 80%, is therefore appealing for backlight applications such as power saving, thinning, HDR and non-conventional displays, and is suitable for products such as mobile phones, televisions, vehicle panels, and electronic competitive notebook computers.

Compared to quantum dot LEDs (QLEDs), LEDs using phosphor as the light emitting center (pc-LEDs) have more stable performance. However, with the development of the micro-and mini-LEDs, the chip size is continuously shrinking, so that the pc-LED material size also faces the bottleneck. Generally, the luminous flux (luminous flux) increases with the thickness of the phosphor layer or the concentration of the phosphor, but most phosphors are micron-sized and non-uniform, and the phosphor layer too thick causes problems of high scattering effect and low dispersibility.

Therefore, there is a need for a new phosphor and a method for preparing the same, which can be applied to a light emitting device such as a micro/mini-LED to solve the problems of the prior art.

It is noted that the information disclosed in the foregoing background section is only for enhancement of background understanding of the invention and therefore it may contain information that does not constitute prior art that is already known to a person of ordinary skill in the art.

Disclosure of Invention

The invention aims to provide a nano composite fluorescent powder and a preparation method thereof, the nano composite fluorescent powder can be applied to luminescent devices such as a micro/mini-LED and a micro/min-LD, and is used for solving the problems of low luminous efficiency, limited size, poor dispersibility and the like of the existing fluorescent powder.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a nano composite fluorescent powder, which comprises a carrier and an infrared fluorescent powder loaded on the carrier, wherein the carrier is an oxide, and the chemical general formula of the infrared fluorescent powder is ZnGa_2-x-yO₄:xCr³⁺yR, where x and y are both mole fractions, and 0<x<0.4，0≤y<0.4, R is selected from Sn⁴⁺,Ti³⁺,V²⁺,Mn³⁺,Fe²⁺,Co³ ⁺,Ni³⁺,Nb⁵⁺,Mo⁵⁺,Tc⁵⁺,Ru⁴⁺,Rh⁴⁺,Pd⁴⁺,Sb⁵⁺,Ta⁵⁺,W⁵⁺,Re⁴⁺,Os⁴⁺,Ir⁴⁺,Pt⁴⁺One or more of (a).

According to one embodiment of the present invention, the particle size of the nanocomposite phosphor is less than 200 nm.

According to one embodiment of the invention, the light-emitting wavelength of the nano composite fluorescent powder is 600nm to 2000nm, and the excitation wavelength of the nano composite fluorescent powder is 250nm to 600 nm.

According to one embodiment of the present invention, the support has a mesoporous structure, and the oxide is selected from one or more of silica, titania, and zinc oxide.

The invention also provides a preparation method of the nano composite fluorescent powder, which comprises the following steps:

placing a carrier in the precursor solution for mixing, and heating and baking the mixed solution to form powder;

and grinding the powder, and calcining for 6-20 h to obtain the nano composite fluorescent powder.

According to one embodiment of the invention, the calcination treatment comprises:

heating the ground powder to 200-700 ℃ at the speed of 2-5 ℃/min, and continuously calcining for 1-10 h;

then heating to 500-1200 ℃ at the speed of 2-5 ℃/min, and continuously calcining for 1-10 h.

According to one embodiment of the present invention, the solid-to-liquid ratio of the carrier to the precursor solution is mg: ml is 100: 0.5-100: 20; the molar concentration of the precursor solution is 0.1-1.5M.

The present invention also provides a light emitting device comprising: the fluorescent material comprises an excitation light source and a packaging layer positioned on the excitation light source, wherein the packaging layer is made of the nano composite fluorescent powder and a packaging colloid.

According to one embodiment of the invention, the mass fraction of the nano composite fluorescent powder is 50-100% of the total mass of the encapsulating layer.

According to an embodiment of the invention, the mass fraction of the nano composite phosphor is changed in a gradient manner or continuously along with the change of the thickness of the encapsulation layer, and the average mass fraction of the nano composite phosphor is 50-100%.

According to one embodiment of the present invention, the excitation light source is a micro-LED chip (micro-LEDchip), a micro-laser diode chip (micro-LD chip), a sub-millimeter light emitting diode chip (mini-LED chip), or a sub-millimeter laser diode chip (mini-LD chip), and the chip is a horizontal chip, a vertical chip, or a flip chip.

The invention has the beneficial effects that:

according to the nano composite fluorescent powder provided by the invention, the infrared fluorescent powder is loaded by the oxide carrier with the mesoporous structure, so that the nano composite fluorescent powder has a nano size and good dispersibility; the infrared fluorescent powder takes Cr or a mixture thereof (such as Sn or Ni) as a luminous center, and the fluorescent emission intensity can be improved by adjusting the concentration of the luminous center; in addition, the traditional bulk phosphors are not uniformly dispersed on the microchip and have poor packaging effect, and the phosphor of the invention has good packaging density and light-emitting characteristic when applied to micro/min-LED, micro/min-LD and other light-emitting devices.

In a word, the nano composite fluorescent powder provided by the invention has excellent dispersibility, high luminous efficiency and good encapsulation performance, the particle size can be adapted to micro/min-LED, micro/min-LD and other light emitting devices, infrared light can be obtained under the excitation of visible light or ultraviolet light, and the nano composite fluorescent powder is expected to be applied to micro detection devices, iris/face detection, medical detection or gas detection devices and the like.

Drawings

FIG. 1 is a high resolution electron microscope photograph of mesoporous nano-silica of example 1;

FIG. 2 is a Fourier transform infrared spectroscopy analysis chart of the mesoporous nano-silica of example 1;

FIG. 3 is an X-ray diffraction pattern of the nanocomposite phosphor of example 1;

FIG. 4 is a high resolution electron microscope photograph of the nanocomposite phosphor of example 1;

FIG. 5 is a photoluminescence spectrum of the nanocomposite phosphor of example 1;

FIG. 6 is a graph showing the relative photoluminescence intensity of the phosphors of examples 2 to 7;

FIG. 7 is a graph showing the photoluminescence relative intensity of the phosphors of examples 8 to 11.

FIG. 8 is a graph of relative photoluminescence intensity for min-LED light emitting devices of example 13 with different nano-composite phosphors.

Detailed Description

Exemplary embodiments that embody features and advantages of the present disclosure are described in detail below in the specification. It is to be understood that the disclosure is capable of various modifications in various embodiments without departing from the scope of the disclosure, and that the description and drawings are to be regarded as illustrative in nature, and not as restrictive.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to yield one or more new ranges of values, which ranges of values should be considered as specifically disclosed herein.

One aspect of the present invention is to provide a nano composite phosphor, which includes a carrier and an infrared phosphor loaded on the carrier, wherein the carrier is oxygenThe chemical general formula of the infrared fluorescent powder is ZnGa_2-x-yO₄:xCr³⁺yR (ZGOCR), where x and y are both mole fractions and 0<x<0.4，0≤y<0.4, R is selected from Sn⁴⁺,Ti³ ⁺,V²⁺,Mn³⁺,Fe²⁺,Co³⁺,Ni³⁺,Nb⁵⁺,Mo⁵⁺,Tc⁵⁺,Ru⁴⁺,Rh⁴⁺,Pd⁴⁺,Sb⁵⁺,Ta⁵⁺,W⁵⁺,Re⁴⁺,Os⁴⁺,Ir⁴⁺,Pt⁴⁺One or more of (a).

In some embodiments, the carrier in the nanocomposite phosphor has a mesoporous structure, the oxide as the carrier is preferably silica, titania, zinc oxide, etc., and taking mesoporous nano silica (MSNs) as an example of the carrier, the infrared phosphor taking chromium (Cr) or a mixture thereof (for example, tin (Sn) or nickel (Ni), etc.) as a host lattice is loaded, so that the infrared phosphor has a nano size and good dispersibility.

With increasing concentration of luminescent centers in the infrared phosphor, i.e. doped Cr, for example³⁺、Sn⁴⁺The concentration of (3) can be increased to increase the fluorescence emission intensity, but too high a concentration also affects the fluorescence emission intensity. In some embodiments, Cr³⁺I.e. the concentration of Cr incorporated³⁺Partially substituted Ga³⁺The mole number of (3) is 1 to 5%, preferably 2%; the concentration of R ion is 1% -5%.

In some embodiments, the particle size of the nanocomposite phosphor is less than 200 nm. The particle size makes it adaptable to micro-LED or min-LED lighting devices. Wherein the mini-LED size is usually between 100 and 200 μm; the micro-LED size is less than 100 μm.

In some embodiments, the light emitting wavelength of the nano composite fluorescent powder is 600nm to 2000nm, and the excitation wavelength of the nano composite fluorescent powder is 250nm to 600 nm. The nano composite fluorescent powder can generate infrared light under the excitation of visible light or ultraviolet light emitted by micro-LED or min-LED, and can be further applied to small electronic equipment, such as remote controllers, automobile sensors, safety, visual identification, biomedical images and the like.

One aspect of the present invention also provides a method for preparing the above nanocomposite phosphor, comprising:

s1: according to the general formula ZnGa_2-x-yO₄:xCr³⁺Weighing compounds containing zinc (Zn), gallium (Ga), chromium (Cr) and R elements according to the molar ratio of each element in yR, respectively dissolving the compounds to form solutions, and mixing the solutions to form a precursor solution; wherein 0<x<0.4，0≤y<0.4, R is selected from Sn⁴⁺,Ti³⁺,V²⁺,Mn³⁺,Fe²⁺,Co³⁺,Ni³⁺,Nb⁵⁺,Mo⁵⁺,Tc⁵⁺,Ru⁴⁺,Rh⁴⁺,Pd⁴⁺,Sb⁵⁺,Ta⁵⁺,W⁵⁺,Re⁴⁺,Os⁴⁺,Ir⁴⁺,Pt⁴⁺One or more of (a).

Specifically, in some embodiments, the Zn-containing compound is one or more of a Zn-containing oxide, carbonate, nitrate, halide; the Ga-containing compound is one or more of Ga-containing oxide, carbonate, nitrate and halide; the compound containing Cr is one or more of oxide, carbonate, nitrate and halide containing Cr; the compound containing R is one or more of oxide, carbonate, nitrate and halide containing R. Respectively dissolving the compounds containing zinc (Zn), gallium (Ga), chromium (Cr) and R to form respective solutions, and then uniformly mixing to form a precursor solution.

S2: placing a carrier in the precursor solution for mixing, and heating and baking the mixed solution to form powder; the carrier has a mesoporous structure, and the oxide as the carrier is preferably silica, titania, zinc oxide, or the like.

Specifically, the carrier can be purchased commercially or prepared in situ by a method commonly used in the art. Taking mesoporous nano-silica as an example of a carrier, taking a certain amount of mesoporous nano-silica to be placed in a prepared precursor solution for mixing, placing the mixed solution in a vacuum oven, baking for 1-24 hours at 60-110 ℃, and forming powder after all the solvent is evaporated to dryness.

S3: and grinding the powder, and calcining for 6-20 h to obtain the nano composite fluorescent powder.

Specifically, in some embodiments, the powder is subjected to a milling process and then placed in a boat-shaped crucible for a calcination process comprising:

heating the ground powder to 200-700 ℃ at the speed of 2-5 ℃/min, and continuously calcining for 1-10 h;

then heating to 500-1200 ℃ at the speed of 2-5 ℃/min, and continuously calcining for 1-10 h.

The precursor solution can uniformly form a stable crystal phase in the mesopores by calcining in such a way.

In some embodiments, the solid to liquid ratio of the carrier to the precursor solution is mg: ml is 100: 0.5-100: 20; the molar concentration of the precursor solution is preferably 0.1M-1.5M. Wherein the molar concentration of the precursor solution refers to millimoles of total solutes contained in 1ml of the precursor solution. With the increase of the molar concentration of the precursor solution, the content of the infrared fluorescent powder finally loaded on the carrier is increased, and the fluorescence intensity can be relatively improved. However, the molar concentration of the precursor solution is not necessarily too high, and the above range is preferable.

Another aspect of the present invention provides a light emitting device, including: the fluorescent material comprises an excitation light source and a packaging layer positioned on the excitation light source, wherein the packaging layer is made of the nano composite fluorescent powder and a packaging colloid.

Specifically, in some embodiments, the excitation light source includes, but is not limited to, a micro-light emitting diode chip (micro-LED chip), a micro-laser diode chip (micro-LD chip), a sub-millimeter light emitting diode chip (mini-LED chip), or a sub-millimeter laser diode chip (mini-LD chip), which is a horizontal chip, a vertical chip, or a flip chip. The encapsulating colloid is a common colloid, is commercially available, and is preferably siloxane-based silica gel.

In the manufacturing process, firstly, an excitation light source is bonded on a substrate in a die bonding mode; mixing a certain amount of the nano composite fluorescent powder and silica gel respectively; and then packaging the mixture on a wafer and baking to form the light-emitting device.

In some embodiments, the mass fraction of the nanocomposite phosphor is 50% to 100% based on the total mass of the encapsulation layer. Namely, the mass of the nano composite fluorescent powder accounts for 50-100% of the total mass of the packaging layer.

In some embodiments, the mass fraction of the nanocomposite phosphor varies in a gradient or continuously as the thickness of the encapsulation layer varies, and the average mass fraction of the nanocomposite phosphor is 50% to 100%. That is, the concentration (mass fraction) of the nano-phosphor may be higher or lower as it is closer to the excitation light source wafer, and may exhibit a gradient or continuous change.

The higher the mass ratio of the fluorescent powder is, the thinner the thickness of the fluorescent layer formed by the fluorescent powder is, the higher the density of the fluorescent layer is, the heat dissipation of the chip is facilitated, the occurrence of colloid cracking is reduced, and the luminous efficiency of the LED chip is improved; the lower the mass ratio of the fluorescent powder is, the more transparent the fluorescent layer formed by the fluorescent powder is, so that the larger distance between the adjacent light-emitting chips can be obtained in the later process flow, the precision requirement of cutting and separating the light-emitting chips covered with the fluorescent powder or the fluorescent colloid is reduced, and the reliability and the uniformity of the device are improved. Therefore, the concentration of the fluorescent powder in the packaging layer is in a gradient manner, for example, the concentration of the fluorescent powder close to the wafer is higher, and the concentration of the fluorescent powder far away from the wafer is lower, so that the light efficiency can be improved on the one hand, and the later process flow is facilitated on the other hand.

The following is illustrated by specific examples:

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