Fluorescent powder for LED

A technology of light-emitting diodes and phosphors, applied in the fields of phosphor materials and phosphate-based phosphors, can solve the problems of shortage of phosphors, poor color reproduction of white LEDs, and lack of red light components.

Inactive Publication Date: 2010-04-21
HUAZHONG UNIV OF SCI & TECH
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AI Technical Summary

Problems solved by technology

[0003] At present, the mainstream method of obtaining white light-emitting diodes is the light conversion method using phosphor powder as the light conversion material, which can be divided into two categories: one is to use blue GaN-based LED chip + yellow phosphor powder or use blue LED chip + green and red Phosphor powder can obtain white light. Most of the white light LED products currently on the market are obtained by using blue LED + yellow phosphor (YAG: Ce) technology, but the white light LED obtained by this method has poor color reproduction, and the color rendering index is generally low. Below 75, the color temperature is usually higher than 5500K, and warm LED devices with high color rendering cannot be obtained, which is mainly due to the lack of red light components in its spectrum
To solve this problem, you can add red phosphor to YAG yellow powder or replace yellow powder with green and red powder, but the red and green powders that match blue LEDs are mainly alkaline earth sulfides (such as CaS:Eu 2+ , SrY 2 S 4 :Eu 2+ , SrGa 2 S 4 :Eu 2+ etc.) and the stability of sulfide is very poor, which seriously affects the life of LED
The second is to use near-ultraviolet (340-410nm) InGaN-based n-UV LED chip + red, green, blue (RGB) three primary color phosphors to obtain white light. The white light LED device obtained by this method has good color reproduction , stable color, high color rendering index (Ra>90), adjustable color temperature and other advantages, this kind of white light LED is the hot spot of current research, and is considered to be the leading of the new generation of white light LED lighting; but the current and near-ultraviolet LED chip There is a shortage of matching phosphors, and white phosphors are generally made by mixing red, green, and blue phosphors. The commonly used red powder is Y 2 o 2 S:Eu 3+ , the green powder is ZnS:Cu + , Al 3+ , the blue powder is BaMgAl 10 o 17 :Eu 2+ , due to the problems of color reabsorption, energy loss, ratio control, aging rate and stability among them, the lumen efficiency and life of white LED devices are greatly affected, and the cost is increased

Method used

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preparation example Construction

[0012] The preparation method of the fluorescent powder that the light-emitting diode provided by the invention comprises the following steps:

[0013] ① Weigh the raw materials according to a certain stoichiometric ratio. The raw materials of alkaline earth metals can be selected from carbonates, basic carbonates, nitrates, etc.; the raw materials of phosphate can be selected from NH 4 h 2 PO 4 , can also choose SrHPO 4 etc. to provide alkaline earth metal ions and phosphate radicals at the same time; the raw materials of europium ions can use corresponding oxides, nitrates, oxalates, etc., and the raw materials of manganese ions can use their carbonates.

[0014] ② Add appropriate amount of ethanol to various raw material mixtures and stir to make them fully mixed, and then dry;

[0015] ③ Fully grind the dried raw materials again, then move them to a corundum crucible, and heat them to 1000-1100°C under a reducing atmosphere of activated carbon (or hydrogen, ammonia, etc...

example 1

[0019] Blue phosphor for LED, chemical formula is Sr 1.99 Mg 3 P 4 o 15 :1%Eu 2+ , the preparation method is as follows: Weigh the SrCO 3 0.8814g, (MgCO 3 ) 4 ·Mg(OH) 2 ·5H 2 O 0.8744g, NH 4 h 2 PO 4 1.3804g, Eu 2 o 3 0.0053g, add an appropriate amount of ethanol to fully mix various raw materials, dry them and then grind them fully, then move them to a corundum crucible, use a high-temperature muffle furnace to heat to 1070°C under the reducing condition of activated carbon, and keep it warm for 2 hours. After cooling down to room temperature, the samples were taken out and ground into powder to obtain blue-violet phosphors for LEDs. figure 2 The excitation and emission spectra of this phosphor are given.

example 2

[0021] Red phosphor powder for LED, the chemical formula is Sr 2 Mg 2.80 P 4 o 15 :20%Mn 2+ , the preparation method is as follows:

[0022] Weigh Sr(NO 3 ) 2 1.2698g, MgCO 3 0.7082g, NH 4 h 2 PO 4 1.3804g, MnCO 3 0.0690g, add an appropriate amount of ethanol to mix various raw materials thoroughly, dry them and then grind them fully, then move them to a corundum crucible, use a high-temperature muffle furnace to heat to 1050°C under the reducing condition of ammonia gas, and keep it warm for 4 hours , and then lowered to room temperature, the sample was taken out and ground into powder to obtain the red fluorescent powder for LED. image 3 The excitation and emission spectra of this phosphor are given.

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Abstract

The invention discloses fluorescent powder for an LED. A structural general formula of the fluorescent powder is Sr2-mMg3-nP4O15:mEu2+, nMn2+, wherein m and n are mol percentages of activators of Eu2+ and Mn2+ in the compounds respectively, m is more than or equal to 0 and less than or equal to 20 percent, n is more than or equal to 0 and less than or equal to 25 percent, m and n are not equal to 0 at the same time, and an optimum value of m is more than or equal to 10 percent and less than or equal to 20 percent, and the optimum value of n is more than or equal to 12 percent and less than or equal to 20 percent. For the fluorescent powder, by adjusting the concentration of the activators, the red fluorescent powder suitable for blue-violet light LED chips, the blue fluorescent powder suitable for near ultraviolet LED chips and the single multi-color fluorescent powder with red and blue emission peaks simultaneously can be obtained respectively.

Description

technical field [0001] The invention belongs to the fluorescent powder material technology, and relates to a phosphate-based fluorescent powder for a light-emitting diode (LED), in particular to a phosphate-based single-matrix two-color fluorescent powder for a near-ultraviolet LED. Background technique [0002] Compared with traditional lighting technology, light-emitting diodes (LEDs) are energy-saving and efficient (power consumption is only 1 / 8-1 / 10 of ordinary incandescent lamps), green and environmentally friendly, long life (up to 100,000 hours), and fast response , good security and many other advantages. With the deepening of GaN-based LED chip growth technology and phosphor research, it is likely to replace traditional lighting tools such as fluorescent lamps and incandescent lamps, and become a new generation of lighting sources. [0003] At present, the mainstream method of obtaining white light-emitting diodes is the light conversion method using phosphor powde...

Claims

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Application Information

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IPC IPC(8): C09K11/81
Inventor 郭崇峰栾林丁旭
Owner HUAZHONG UNIV OF SCI & TECH
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