TWI383519B - Preparation method of white light emitting diode and its fluorescent material for ultraviolet light and blue light - Google Patents

Description

White light emitting diode suitable for ultraviolet light and blue light excitation and preparation method thereof

The invention relates to a light-emitting diode, in particular to exciting two kinds of phosphor powder by ultraviolet light to respectively generate yellow light and blue light and to mix white light, or to use blue light to excite a fluorescent powder to generate yellow light, and to make blue light and yellow light. Light mixes white light. The above-mentioned fluorescent powder which is excited by the ultraviolet light and the yellow light is the same as the fluorescent powder which is excited by the blue light. In addition, the present invention further discloses a method for producing the yellow fluorescent powder.

A general light-emitting diode is mainly a semiconductor material as a light-emitting material, and when a voltage is applied to the semiconductor material, a light-emitting phenomenon can be generated to emit different monochromatic lights, such as blue light, red light, green light, and the like. The white light emitting diode is made up of a mixture of different colored lights.

U.S. Patent No. 6,252,254 discloses a phosphor powder which, according to the teachings of the patent, is only excited by ultraviolet light and emits green light, and the phosphor powder can be represented by the following chemical formula: (Ba _{1- Xyz} , Ca _x , Sr _y , Eu _z ) ₂ (Mg _1-w ,Zn _w )Si ₂ O ₇ ; wherein x+y+z=1; 0<z<0.05, 0.05>w; the phosphor powder system It is made in a solid state method, and the phosphor powder emits green light, so it is necessary to additionally mix a fluorescent powder capable of emitting red light and blue light to form white light. In other words, this patent discloses a white light emitting element that emits a three-wavelength pattern using three types of phosphor powder.

European Patent No. WO 018 9001 discloses a phosphor powder, and according to the teachings of the patent, the phosphor is only excited by ultraviolet light and emits blue-green light. The composition of the phosphor powder can be represented by the following chemical formula: AP ₂ O ₇ :Eu; wherein A=Sr, Ca, Ba, Mg; the phosphor powder is prepared by a solid state method, and the firefly disclosed in the patent The light powder emits blue-green light, so it is necessary to mix the fluorescent powder that emits red light to form white light. In other words, the patent discloses a white light-emitting element that emits a two-wavelength light pattern using two types of phosphor powder.

U.S. Patent No. 7,169,326 discloses a phosphor powder which, according to the teachings of the patent, is only excited by blue light and emits yellow light. The phosphor powder can be represented by the following chemical formula: (Tb _3-xy Ce _x Re _y ) (Al _5-z O ₁₂ Me _z ); wherein 0<x 0.8;0<y 2.0;0<z 1.0; Re=Gd, Rb, Tm, Pr, Sm, Eu, Dy, Ho, Er, Yb, Lu, Sr, Y and V; Me=Silicone

The method for synthesizing the phosphor powder disclosed in the patent is a solid state method, and the phosphor powder emits yellow light, so that it must be mixed with blue light to form white light. In other words, the patent is a two-wavelength light type white light emitting element.

U.S. Patent No. 7,029,602 discloses a phosphor powder which, according to the teachings of the patent, is only excited by blue light and emits yellow light. The phosphor powder can be represented by the following chemical formula: MLn ₂ QR ₄ O ₁₂ ; wherein M = Mg, Ca, Sr, Ba; Ln = Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd , Tb, Dy, Ho, Er, Tm, Yb, Lu; Q = Si, Ge, Sn, Pb; R = B, Al, Ga, In, Tl; for example Ba(Y _0.98 Ce _0.02 ) ₂ SiAl ₄ O ₁₂ The fluorescent powder conforming to the above chemical formula is synthesized by a solid state method, and the yellow light emitted by the fluorescent powder is required to be combined with blue light to form white light. Therefore, the patent is a two-wavelength light type white light emitting element.

Taiwan Patent Publication No. 200422376 discloses a method for preparing a fluorescent powder for a white light emitting diode excited by ultraviolet light. According to the teaching of the patent, the light source for exciting the fluorescent powder is only ultraviolet light, and the fluorescent powder can be It is represented by the following chemical formula: ZnS _x Se _1-x , where x = 0 to 1.

The phosphor powder is synthesized in a solid state method, and the phosphor powder is excited to emit a full range of yellow and white light.

Taiwan Patent No. I257182 discloses a three-wavelength light type white light emitting diode which emits red, green and blue light by exciting three kinds of phosphor powders by ultraviolet light. Wherein: the fluorescent powder emitting red light has a chemical composition of Y ₂ O ₃ :Eu; the fluorescent powder emitting green light has a chemical composition of SrAl ₂ O ₄ :Eu; the chemical group of the fluorescent powder emitting blue light BaMgAl ₁₀ O ₁₇ :Eu; each of the above phosphor powders is synthesized by a solid state method and is only excited by ultraviolet light.

Taiwan Patent Publication No. 200519187 discloses a method for preparing a phosphor powder of a white light emitting diode which can be excited by ultraviolet light; according to the teaching of the patent, it has two kinds of phosphor powder and is excited only by ultraviolet light to generate orange light and Blue-green light, wherein: the orange-emitting phosphor powder has a chemical composition of CaMn(PO ₄ ) ₃ Cl:Eu; the blue-green phosphor powder has a chemical composition of (Ba _1-x Sr _x )MgAl ₁₀ O ₇ :Eu; The above two kinds of phosphor powders can be synthesized by a solid state method, and the two kinds of color light are mixed into white light, so that a two-wavelength light type white light emitting element can be constructed.

Taiwan Patent Publication No. 431000 discloses a white-violet light-emitting diode; according to the teaching of the patent, the light source for exciting the phosphor powder is blue light, and the chemical composition of the phosphor powder is: (Y _0.983-x Ce _0.017) Gd _x ) ₃ Al ₅ O ₁₂ ; the phosphor powder is excited to emit yellow light, and the blue light excitation source generates white light; the above-mentioned phosphor powder is synthesized by a solid state method, and the light-emitting element is a two-wavelength light type white light. Light-emitting element.

Taiwan Patent Publication No. 559627 discloses a method for producing a high-brightness white light diode by using a phosphor powder; according to the teaching of the patent, the light source for exciting the phosphor powder is blue light, and the chemical composition of the phosphor powder is: (Y _x M _y Ce _z )Al ₅ O ₁₂ , wherein x+y=3, and x, y≠0, 0.5>z>0; M is selected from the group consisting of metal elements such as Tb, Lu, Yb; The phosphor powder is yellow-excited to generate yellow light, and the blue light excitation source generates white light; the above-mentioned phosphor powder system is synthesized by a solid state method, and the light-emitting element is a two-wavelength light type white light-emitting element.

According to the teachings of the above patents, the phosphor powder is excited by only one light source (such as ultraviolet light or blue light) to generate a visible color light, while the unexposed fluorescent powder can be excited by two kinds of light sources, and two different kinds. The excitation light source can produce the same color light. Further, the synthesis methods of the above respective phosphor powders are all solid state methods.

According to Applied Physics Chem. B 2005, 109 , 9490-9494, "Strong Green Emission from α-SiAlON Activated by Divalent Ytterbium under Blue Light Irradiation", which is synthesized by solid state method and can be excited by 300 nm ultraviolet light and 445 nm blue light. The green fluorescent material (530~580nm), the chemical composition of the fluorescent material is: (M _{1-2 x} /vYb _x ) _m /vSi _{12- m - n} Al _{m + n} O _n N _{16- n} ; wherein M = Ca, Li, Mg, and Y, V is the valence of M; 0.002 < x <0.10; 0.5 < m = 2 n < 3.5.

According to Chem. Mater. 2006, 18 , 5578-5583, "A Simple, Efficient Synthetic Route to Sr ₂ Si ₅ N ₈ :Eu ²⁺ -Based Red Phosphors for White Light-Emitting Diodes", which is synthesized by solid state method A fluorescent material (620-670 nm) which is excited by 340 nm ultraviolet light and 450 nm blue light to emit red light, and its chemical composition is Sr ₂ Si ₅ N ₈ :Eu ²⁺ .

The above two papers teach that different light sources can be used to excite the same phosphor powder, and can be used as the color light of the mixed white light emitting diode; however, the blue light is used as the excitation light source to respectively perform the phosphor powder mentioned in the paper. Excitation, one of which produces green light, so it is necessary to add red light to form white light; the other system produces red light, so it is necessary to add green light to form white light; therefore, it is made of the fluorescent powder taught by the above paper. The white light emitting diode is a light emitting element having a three-wavelength light type.

Further, each of the above-mentioned phosphor powders is produced by a solid state method, and its main disadvantages include problems such as requiring a high sintering temperature and uniformity of the particle size of the phosphor powder to be difficult to control.

The main object of the present invention is to provide a white light emitting diode suitable for ultraviolet light and blue light excitation. It has the effect of mixing white light with two kinds of light of yellow light and blue light.

In order to achieve the white light mixed by two kinds of color light, the method is to use blue light as the excitation light source, and the yellow light generated by the blue light source after the fluorescent powder of the invention is excited by the blue light source can achieve the mixture of yellow light and blue light. The effect of white light.

The second method is to use ultraviolet light source to excite two kinds of phosphor powder to respectively generate blue light and yellow light, thereby achieving the effect of mixing white light with yellow light and blue light. Among them, yellow light is emitted from the phosphor powder of the present invention.

Another object of the present invention is to provide a method for producing a yellow fluorescent powder, which has a lower sintering temperature for the phosphor powder during molding, and a firefly The effect of high uniformity of particle size of the light powder.

According to the object and effect of the present invention, the composition of the white light emitting diode comprises an ultraviolet light source, and a phosphor powder layer is disposed in the optical path of the ultraviolet light emitted by the ultraviolet light source, and can be separately emitted after being excited by the ultraviolet light. Two kinds of phosphors of blue light and yellow light, wherein the fluorescent powder emitting yellow light has a chemical formula of Ca _0.625 Si _0.75-x Al _1.25+3x O _x N _16-x : xEu ²⁺ , wherein the range of x is 0.05 x 0.1; and the blue light-emitting phosphor has a chemical formula of MSi ₂ O _2-d N _2+0.67d :Ce ³⁺ , wherein M is at least one element including Ca, Sr, and Ba.

Another white light emitting diode of the present invention comprises a blue light source, and a phosphor powder layer is disposed in the light path of the light emitted by the blue light source, and has a fluorescent powder that emits yellow light after being excited by blue light. The chemical formula of the yellow fluorescent powder is Ca _0.625 Si _0.75-x Al _1.25+3x O _x N _16-x :xEu ²⁺ , wherein the range of x is 0.05 x 0.1.

Further, the method for fabricating the yellow light phosphor comprises the steps of: (1) taking a preparation material, the material comprising a host material and a dopant material; and (2) preparing an alkaline solution by mixing the host material and the dopant material. In the water, an alkaline substance is added to make the solution alkaline; (3) a phosphor powder precursor obtaining step is performed by hydrothermally treating an alkaline solution containing a host material and a doping material to obtain a phosphor powder precursor. Further, centrifugal cleaning and drying are performed; (4) the sintering treatment step is performed by sintering at a suitable temperature in a predetermined atmosphere to obtain a phosphor powder.

The phosphor powder disclosed by the invention can be excited by blue light or ultraviolet light to generate yellow light, so that the white light can be directly mixed with the blue light source; or the fluorescent powder capable of emitting blue light when excited by ultraviolet light, that is, It can be mixed into white light when excited by ultraviolet light at the same time. Therefore, the present invention is a two-wavelength light type white light emitting diode.

In addition, the preparation method disclosed in the present invention is different from the solid state method described above, and has the advantages of lower sintering temperature, relatively uniform average particle diameter of the phosphor powder, and difficulty in agglomeration of the powder.

In the following, according to the objects and effects disclosed by the present invention, preferred embodiments are described. Detailed description with the drawings.

Referring to FIG. 1 , a white light emitting diode 10 including a substrate 12 and an ultraviolet light source 14 disposed on the substrate 12 is disclosed. A phosphor powder layer 20 is disposed on the ultraviolet light source 14, and the phosphor powder layer 20 is in the optical path of the ultraviolet light emitted by the ultraviolet light source 14.

Further, the phosphor powder layer 20 is a fluorescent glue 22 uniformly mixed with the yellow light phosphor powder 24 and the blue light phosphor powder 26 into a slurry, and the slurry is coated on the ultraviolet light source 14, and the ultraviolet light source 14 is coated. It may be an ultraviolet light emitting diode chip.

The substrate 12, the ultraviolet light source 14 and the phosphor powder layer 20 are combined with a negative electrode 15 and a positive electrode 16, and a package material 18 is formed of a resin material to cover the substrate 12, the ultraviolet light source 14 and the phosphor powder. Layer 20 constitutes a light emitting diode.

It is worth noting that the yellow fluorescent powder 24 is excited by the ultraviolet light source 14 to emit yellow light, and its chemical composition is Ca _0.625 Si _0.75-x Al _1.25+3x O _x N _16-x :xEu ²⁺ ; The range is 0.05 x 0.1.

The blue phosphor powder 26 is excited by the ultraviolet light source 14 to emit blue light, and its chemical composition is MSi ₂ O _2-d N _2+0.67d :Ce ³⁺ ; wherein M is at least including Ca, Sr, Ba An element; the range of d is 0 d 2.

Therefore, the ultraviolet light source 14 excites the yellow phosphor powder 24 and the blue phosphor powder 26 in the phosphor powder layer 20 to generate yellow light and blue light, respectively, and the two colors combine to form white light. Therefore, the present invention is a two-wavelength light type white light emitting diode.

Referring to FIG. 2, a white light emitting diode 30 including a base is disclosed. A plate 32, and a blue light source 34 are disposed on the substrate 32. A phosphor powder layer 40 is disposed on the blue light source 34, and the phosphor powder layer 40 is in the optical path of the blue light emitted by the blue light source 34.

Furthermore, the phosphor powder layer 40 is uniformly mixed with the yellow phosphor powder 44 into a slurry, and the slurry is coated on the blue light source 34, and the blue light source 34 may be a blue light emitting diode. Body wafer.

The substrate 32, the combination of the blue light source 34 and the phosphor powder layer 40 are provided with a negative electrode 35 and a positive electrode 36, and a package body 38 is formed of a resin material to cover the substrate 32, the blue light source 34 and the phosphor powder. Layer 40 constitutes a light emitting diode.

It is worth noting that the yellow fluorescent powder 44 is excited by the blue light source 34 to emit yellow light, and its chemical composition is Ca _0.625 Si _0.75-x Al _1.25+3x O _x N _16-x :xEu ²⁺ ; The range is 0.05 x 0.1.

The white light is formed by mixing the blue light source 34 and the yellow light emitted by the yellow light fluorescent powder 44 by blue light. Therefore, the present invention is a two-wavelength light type white light emitting diode.

Referring to FIG. 3, the method for preparing the yellow phosphor powder comprises the following steps: S51 takes a step of preparing a material. The material comprises a host material and a doping material, wherein the host material is calcium nitrate (Ca(NO ₃ ) ₂ ), sodium citrate (Na ₂ SiO ₃ ), sodium metaaluminate (NaAlO ₂ ), and the doping material is nitric acid.铕 (Eu(NO ₃ ) ₃ ).

S53 is made into an alkaline solution step. The host material and the doping material are mixed in the ionic water, and the alkaline substance is added to make the solution alkaline. At this time, the host material can form calcium oxynitride strontium calcium after chemical reaction, and the doping material can dissociate the cerium ions in the alkaline solution, and some cerium ions can enter the host lattice structure to form a luminescent center.

S55 phosphor powder precursor acquisition step. Hydrothermal treatment of an alkaline solution containing a host material and a dopant material to obtain a phosphor powder precursor, followed by a phosphor powder precursor The ion water is added to the centrifuge for centrifugation, and the cleaned phosphor powder precursor is dried.

S57 sintering treatment step. The sintering treatment is performed at a suitable temperature and time in a predetermined atmosphere to obtain a phosphor powder. The above predetermined atmosphere is nitrogen: hydrogen = 95%: 5%, and the preset sintering temperature and time are 1000 ° C and 2 hours, respectively.

Referring to Fig. 4, the phosphor powder Ca _0.625 Si _0.75-x Al _1.25+3x O _x N _16-x :xEu ^{2+ is} sintered in an atmosphere of N ₂ :H ₂ =95%:5%, and is passed through The crystallization characteristics of XRD can be used to find the optimum sintering temperature. The doping concentration of the cerium ions was fixed at 0.075 mole, and the sintering time was 2 hours. It can be seen from the figure that the optimum sintering temperature is 1000 °C.

Further, the JCPDS card in Fig. 4 is a control group which uses a solid state method and has a cerium ion doping concentration of 0.075 mole, a sintering temperature of 1800 ° C, and a sintering time of 2 hours. As is apparent from the figure, the phosphor powder obtained by the hydrothermal treatment of the present invention has a lower sintering temperature and has preferable crystal characteristics.

Referring to Fig. 5, the phosphor powder Ca _0.625 Si _0.75-x Al _1.25+3x O _x N _16-x :xEu ^{2+ is} sintered in an atmosphere of N ₂ :H ₂ =95%:5%. The sintering temperature was fixed at 1000 ° C, and the sintering time was 2 hours, and the doping concentration of the optimum cerium ions was found by measuring the crystallization characteristics of XRD. It is found from the figure that the optimum cesium ion doping concentration is 0.075 mole. Further, the JCPDS card in Fig. 5 is a control group which uses a solid state method and has a doping concentration of 0.075 mole, a sintering temperature of 1800 ° C, and a sintering time of 2 hours.

Please refer to Fig. 6. Fluorescent powder Ca _0.625 Si _0.75-x Al _1.25+3x O _x N _16-x :xEu ²⁺ at a doping concentration of 0.075 mole, a sintering temperature of 1000 ° C, and a sintering time of 2 hours. Sintering is carried out, and the ratio of the optimum sintering atmosphere can be found by measuring the crystal characteristics of XRD. As can be seen from the figure, the optimum sintering atmosphere ratio is N ₂ : H ₂ = 95%: 5%. Further, the JCPDS card in Fig. 6 is a control group which uses a solid state method and has a doping concentration of 0.075 mole, a sintering temperature of 1800 ° C, and a sintering time of 2 hours.

Please refer to Figure 7 for the phosphor powder prepared according to the above optimal sintering temperature, optimum doping concentration and optimum sintering atmosphere (Ca _0.625 Si _0.75-x Al _1.25+3x O _x N _16-x :xEu ²⁺ ) Performs characteristic measurements of the absorption spectrum. It can be seen from the figure that an absorption region is formed in the ultraviolet light range of 280 nm to 350 nm, and the absorption wavelength peak appears at 320 nm; in addition, another absorption region appears in the blue light region of 380 nm to 480 nm, and the absorption wavelength peak appears at 420 nm. In other words, the phosphor powder can be excited by ultraviolet light and blue light, respectively.

Please refer to Figure 8 for the phosphor powder prepared according to the above optimum sintering temperature, optimum doping concentration, and optimum sintering atmosphere (Ca _0.625 Si _0.75-x Al _1.25+3x O _x N _16-x :xEu ²⁺ ) Perform measurement of luminescence characteristics. It can be seen that the phosphor powder is excited by ultraviolet light having a wavelength of about 320 nm and blue light having a wavelength of about 420 nm, and can emit yellow light having a wavelength ranging from 500 nm to 600 nm, and the peak appears at 570 nm; In other words, the phosphor is indeed capable of producing yellow light after being excited.

The present invention discloses that a phosphor powder can be excited by ultraviolet light and blue light, and the phosphor powder can emit yellow light regardless of which excitation light source is used. Therefore, the phosphor powder is combined with a blue excitation light source, that is, a two-wavelength light-emitting white light-emitting diode can be constructed; in addition, the invention can also use an ultraviolet light source to excite the yellow light-emitting phosphor of the present invention and can be combined with another ultraviolet light. The light-excited blue phosphor can be mixed into another two-wavelength white light-emitting diode. As for the yellow fluorescent powder of the present invention, it is hydrothermally treated, which has the advantage of having a low sintering temperature and a uniform average particle diameter of the fluorescent powder.

The above is a preferred embodiment and the design of the present invention. The preferred embodiments and the drawings are merely illustrative and not intended to limit the scope of the invention. The scope of the rights covered by the content of the "Scope of Patent Application" is not within the scope of the invention and is the scope of the applicant's rights.

10‧‧‧White light emitting diode

12‧‧‧Substrate

14‧‧‧UV source

15‧‧‧Negative electrode

16‧‧‧ positive electrode

18‧‧‧Package enclosure

20‧‧‧Fluorescent powder layer

22‧‧‧Fluorescent glue

24‧‧‧Yellow Fluorescent Powder

26‧‧‧Blue Fluorescent Powder

30‧‧‧White light emitting diode

32‧‧‧Substrate

34‧‧‧Blue light source

35‧‧‧Negative electrode

36‧‧‧ positive electrode

38‧‧‧Package enclosure

40‧‧‧Fluorescent powder layer

42‧‧‧Fluorescent glue

44‧‧‧Yellow Fluorescent Powder

S51‧‧‧Preparation of preparation materials

S53‧‧‧Steps for making alkaline solution

S55‧‧‧Fuel powder precursor acquisition steps

S57‧‧‧Sintering process steps

Fig. 1 is a schematic view showing the structure of a white light emitting diode of the present invention.

Figure 2 is a schematic view showing the structure of another white light emitting diode of the present invention.

Fig. 3 is a block diagram showing the flow of the phosphor powder of the present invention.

Fig. 4 is a graph showing the XRD crystallization characteristics of the phosphor powder produced at different sintering temperatures under the conditions of the doping concentration, sintering time and sintering atmosphere of the present invention.

Fig. 5 is a graph showing the XRD crystallization characteristics of the phosphor powder produced by different doping ion doping concentrations under the conditions of the sintering temperature, sintering time and sintering atmosphere of the present invention.

Fig. 6 is a graph showing the XRD crystal characteristics of the phosphor powder produced in different sintering atmospheres under the conditions that the doping concentration, sintering temperature and sintering time of the present invention are fixed.

Fig. 7 is a graph showing the optimum absorption spectrum of the strontium ion, the optimum sintering temperature, and the absorption spectrum characteristics of the phosphor powder obtained under the optimum sintering atmosphere.

Fig. 8 is a graph showing the optimum erbium ion doping concentration, the optimum sintering temperature, and the luminescent properties of the phosphor powder obtained under the optimum sintering atmosphere.

10‧‧‧White light emitting diode

12‧‧‧Substrate

14‧‧‧UV source

15‧‧‧Negative electrode

16‧‧‧ positive electrode

18‧‧‧Package enclosure

20‧‧‧Fluorescent powder layer

22‧‧‧Fluorescent glue

24‧‧‧Yellow Fluorescent Powder

26‧‧‧Blue Fluorescent Powder

Claims (1)

A method for preparing a yellow fluorescent powder for producing a fluorescent powder which is excited by ultraviolet light and blue light to generate yellow light. The chemical formula of the yellow fluorescent powder is Ca _0.625 Si _0.75-x Al _1.25+3x O _x N _{16- x} :xEu ²⁺ ; where x ranges from 0.05 x 0.1; The method for manufacturing the yellow light phosphor comprises the steps of: preparing a material comprising a host material and a doping material, wherein the host material is calcium nitrate, sodium citrate, sodium metaaluminate, and chemically reacting to form aluminum oxynitride. Calcium barium; the doping material is barium nitrate and the doping material can dissociate the barium ions in an alkaline solution; part of the barium ions can enter the host lattice structure to form a luminescent center; the alkaline solution step is to form the host material And the doping material is mixed in water, and the alkaline substance is added to make the solution alkaline; the phosphor powder precursor obtaining step is to hydrothermally treat the alkaline solution containing the host material and the doping material to obtain the phosphor powder precursor. And then performing centrifugal cleaning and drying; the sintering treatment step is performed by sintering in a predetermined atmosphere to obtain a phosphor powder, wherein the preset atmosphere is nitrogen: hydrogen = 95%: 5%, sintering The temperature and time are 1000 ° C and 2 hours, respectively.