CN114574206A - Fluorescent powder for white light-emitting diode and synthetic method and application thereof - Google Patents

Abstract

A fluorescent powder for white light-emitting diodes and a synthesis method and application thereof belong to the technical field of white light-emitting diodes. The matrix of the fluorescent powder is CaYGaO₄The activating ion comprises Sm³⁺Wherein Sm³⁺In CaYGao₄The mole fraction of the medium doping is 1-11%, the exciting light of the fluorescent powder is blue light with the wavelength of 404nm, the emitted light is orange light with the wavelength of 550-750 nm, and the optimal doping concentration is 1% Sm³⁺(ii) a The active ion further comprises Bi³⁺，Bi³⁺In CaYGao₄:1%Sm³⁺The mole fraction of the medium doping is 3-7%. When Bi is present³⁺In CaYGaO₄:1%Sm³⁺When the doping mole fraction is 3%, exciting light of the fluorescent powder is near ultraviolet light of 315nm, and blue light of 350-750 nm is emitted; when Bi is present³⁺In CaYGao₄:1%Sm³⁺When the medium doping mole fraction is 7%, the exciting light of the fluorescent powder is near ultraviolet light with the wavelength of 315nm, and the emitted light is white light with the wavelength of 350-750 nm. The fluorescent powder synthesized by the invention has the characteristics of simple synthesis, no toxicity, no harm, stable physical and chemical properties, low cost, strong weather resistance, stable performance under long-time ultraviolet and blue light irradiation and the like.

Description

Fluorescent powder for white light-emitting diode and synthetic method and application thereof

Technical Field

The invention relates to the technical field of white light-emitting diodes, in particular to fluorescent powder for a white light-emitting diode and a synthesis method and application thereof.

Background

In recent years, White Light Emitting Diodes (WLEDs) have been widely studied to replace conventional incandescent and fluorescent lamps because of their advantages of small size, environmental friendliness, ease of manufacture, long operating time, high efficiency, energy saving, etc., as compared to conventional lighting. In general, white light can be generated from a device that is a combination of a light emitting diode chip and a suitable phosphor, and thus, a WLED device is referred to as a phosphor-converted light emitting diode. At present, there are two common methods for preparing WLED, one is Y₃Al₅O₁₂:Ce³⁺Phosphor-converted light emitting diode (pc-LEDs) devices synthesized from (YAG) yellow phosphor and blue InGaN light emitting diode chips that achieve the highest luminous efficiency but have a relatively high Correlated Color Temperature (CCT) due to their lack of red component in the Electroluminescent (EL) spectrum>4000 K) Sum and poor Color Rendering Index (CRI)<80) Limiting its advancement. The other is composed of a near ultraviolet chip and red, green and blue fluorescent powder. However, there is a serious problem of re-absorption between the three-color phosphors, resulting in a decrease in luminous efficiency and a low brightness of the finished product. Also, this problem is exacerbated for red phosphors because the human eye does not maintain high sensitivity to the red spectral region. Whichever method is chosen to package pc-WLEDs devices, phosphor is always a critical component because it has a large impact on device performance, such as luminous efficiency, critical current, critical temperature, and thermal stability.

Disclosure of Invention

The technical problem to be solved is as follows: aiming at the problems in the prior art, the invention provides the fluorescent powder for the white light-emitting diode and the synthesis method and the application thereof, and the fluorescent powder has the advantages of simple synthesis, no toxicity, no harm, stable physical and chemical properties, low cost, strong weather resistance, stable performance under long-time ultraviolet and blue light irradiation and the like.

The technical scheme is as follows: aThe fluorescent powder can be used for a white light-emitting diode, and the matrix of the fluorescent powder is CaYGaO₄The activating ion comprises Sm³⁺Wherein Sm³⁺In CaYGao₄The mole fraction of the medium doping is 1-11%.

Preferably, the active ion further comprises Bi³⁺，Bi³⁺In CaYGao₄:1% Sm³⁺The mole fraction of the medium doping is 3-7%.

Preferably, Sm is the above-mentioned compound³⁺In CaYGao₄The mole fraction of the medium doping is 1 percent, and the Bi is³⁺In CaYGao₄The mole fraction of the medium doping is 3% or 7%.

Preferably, when Bi is present³⁺In CaYGao₄When the doping mole fraction is 3%, exciting light of the fluorescent powder is near ultraviolet light of 315nm, and blue light of 350-750 nm is emitted; when Bi³⁺In CaYGao₄When the medium doping mole fraction is 7%, the exciting light of the fluorescent powder is near ultraviolet light with the wavelength of 315nm, and the emitted light is white light with the wavelength of 350-750 nm.

The synthesis method of the fluorescent powder for the white light-emitting diode is characterized by comprising the following steps:

step one, calculating raw material CaCO according to the molar ratio of each component in the fluorescent powder₃、Y2O₃、Ga2O₃、Sm₂O₃、Bi₂O₃Weighing, pouring the weighed materials into a container, mixing and grinding for 15-30 min;

placing the ground sample in an alumina crucible, and placing the crucible in a muffle furnace to calcine for 5-6 h at 1200-1300 ℃;

and step three, putting the sample obtained in the step two into a container, and grinding for 15-30 min again.

The method as claimed in claim 5, wherein the container in the first step and the third step is agate mortar.

The fluorescent powder for the white light-emitting diode is applied to the preparation of pc-WLEDs devices.

Has the advantages that: the fluorescent powder synthesized by the invention has the characteristics of simple synthesis, no toxicity, no harm, stable physical and chemical properties, low cost, strong weather resistance, stable performance under long-time ultraviolet and blue light irradiation and the like;

CaYGaO₄in the presence of Sm³⁺In the process, orange light emitting fluorescent powder which can be effectively excited by blue light LED and near ultraviolet LED can be synthesized, a theoretical improvement scheme is provided for subsequently improving the condition that the current WLED red emission is lack, and Sm is co-doped³⁺And Bi³⁺Then, Bi³⁺And Sm³⁺Energy transfer of enhanced Sm³⁺By changing Bi under co-doping³⁺Adjusting the concentration of Bi^{3 +}And Sm³⁺The emission intensity of the LED enables the emission color to be changed from blue to white light emission, white light emission which can be effectively excited by the near ultraviolet LED is achieved, and an improvement scheme is provided for solving the problem of serious reabsorption among three-color fluorescent powder when the WLED is formed by the current near ultraviolet chip and red, green and blue fluorescent powder.

Drawings

FIG. 1 shows CaYGaO example 1₄Doping with 1% of Sm³⁺The obtained fluorescent powder emits an excitation spectrogram under 604 nm;

FIG. 2 shows CaYGaO example 1₄ Sm doped with x%³⁺(x =1,3,5,7,9, 11) contrast plot of emission spectra excited at 404 nm;

FIG. 3 is a diagram showing Sm in example 1³⁺Doped CaYGao₄A plot of integrated intensity of orange emission at 550-750 nm;

FIG. 4 shows CaYGaO example 1₄Doping with 1% of Sm³⁺A subsequent CIE coordinate diagram;

FIG. 5 shows CaYGaO example 2₄Doping with 1% of Sm³⁺，3%Bi³⁺Emission spectrum at 315nm excitation;

FIG. 6 shows CaYGaO example 2₄Doping with 1% of Sm³⁺，3%Bi³⁺A subsequent CIE coordinate diagram;

FIG. 7 shows CaYGaO example 3₄Doping with 1% of Sm³⁺，7%Bi³⁺Emission spectrum of excitation at 315 nm;

FIG. 8 shows CaYGaO example 3₄Doping with 1% of Sm³⁺，7%Bi³⁺Excitation spectra emitted at 604nm and 445 nm;

FIG. 9 shows CaYGaO example 3₄Doping with 1% of Sm³⁺，7%Bi³⁺A subsequent CIE coordinate diagram;

FIG. 10 is CaYGaO comparative example 1₄Doping with 7% Bi³⁺Emission spectrum of excitation at 328 nm;

FIG. 11 is CaYGaO comparative example 1₄Doping with 7% Bi³⁺Excitation spectra emitted at 442 nm;

FIG. 12 shows CaYGaO₄Doping with 7% Bi³⁺The obtained fluorescent powder emits a spectrogram under the excitation of 328nm and is doped with 1% Sm³⁺Then obtaining an excitation spectrogram normalization contrast diagram of the fluorescent powder under 604nm emission;

FIG. 13 shows CaYGaO₄Doping with 1% of Sm³⁺，5%Bi³⁺Emission spectrum of excitation at 315 nm;

FIG. 14 shows CaYGaO₄Doping with 1% of Sm³⁺，5%Bi³⁺A subsequent CIE coordinate diagram;

FIG. 15 shows CaYGaO₄Doping with 1% of Sm³⁺，9%Bi³⁺Emission spectrum at 315nm excitation;

FIG. 16 shows CaYGaO₄Doping with 1% of Sm³⁺，9%Bi³⁺A subsequent CIE coordinate diagram;

FIG. 17 shows CaYGaO₄Doping with 1% of Sm³⁺，y%Bi³⁺Bi excited at (y =3,5,7, 9) 315nm³⁺A change in emission intensity;

FIG. 18 shows CaYGaO₄Doping with 1% of Sm³⁺，y%Bi³⁺Sm excited at (y =3,5,7, 9) 315nm³⁺The emission intensity varies.

Detailed Description

The invention is further described below with reference to the accompanying drawings and specific embodiments.

In the examples of this specification, "% Sm³⁺"and"% Bi³⁺"percentage number represents mole fraction.

Example 1

Preparation of CaYGaO₄：x%Sm³⁺(x =1,3,5,7,9, 11) phosphor,the method comprises the following steps:

(1) according to CaYGaO₄： x%Sm³⁺(x =1,3,5,7,9, 11) stoichiometric CaCO for phosphor calculation₃、Y₂O₃、Ga₂O₃、Sm₂O₃The required amount of the raw materials is accurately weighed by using an analytical balance, poured into an agate mortar, mixed and ground for 30 min.

(2) The ground sample was placed in a 5 mL alumina crucible, which was calcined in a muffle furnace at 1300 ℃ for 6 h.

(3) And (3) putting the sample obtained in the step (2) into an agate mortar for grinding for 30 min again.

CaYGaO₄Doping with 1% of Sm³⁺The excitation spectrum of the obtained fluorescent powder is shown in figure 1; CaYGao₄ Sm doped with x%³⁺The emission spectrum of the phosphor obtained after (x =1,3,5,7,9, 11) is shown in fig. 2; different Sm³⁺Doped CaYGao₄The integrated intensity plot of the orange emission at 550-750 nm is shown in FIG. 3; CaYGao₄：1%Sm³⁺The CIE coordinate diagram of (a) is shown in fig. 4, and is the orange emission with coordinates (0.6049, 0.3945). As can be seen from FIG. 1, in CaYGaO₄Doping with 1% of Sm³⁺When the ultraviolet light is excited, the excitation spectrum peak is excited by a broadband of 300 nm-480 nm, which shows that the ultraviolet light can be well excited by a near ultraviolet chip and a blue chip, wherein the highest excitation peak is 404nm and is originated from Sm³⁺Is/are as follows⁶H_5/2→⁶F_7/2And (4) transition. 6 Sm with different concentrations³⁺The emission spectrum of the doped phosphor at 404nm excitation is shown in FIG. 2, where the emission at 564 nm is from Sm³⁺Is⁴G_5/2→⁶H_5/2Transition, 606 nm emission from Sm³⁺Is/are as follows⁴G_5/2→⁶H_7/2Transition, 647 nm emission from Sm³⁺Is/are as follows⁴G_5/2→⁶H_9/2Transition, 712 nm emission from Sm³⁺Is/are as follows⁴G_5/2→⁶H_11/2And (4) transition. As can be seen from FIG. 3, Sm was doped to 1%³⁺When the metal oxide is used, the emission intensity is highest at 550-750 nm, so that 1% of Sm is doped³⁺Is best at the momentAnd (4) doping is preferred.

Example 2

Preparation of CaYGaO₄：3%Bi³⁺，1%Sm³⁺The fluorescent powder comprises the following steps:

(1) according to CaYGaO₄：3%Bi³⁺，1%Sm³⁺CaCO calculation of stoichiometric ratio of phosphor₃、Y₂O₃、Ga₂O₃、Sm₂O₃、Bi₂O₃The required amount of the raw materials is accurately weighed by using an analytical balance, poured into an agate mortar, mixed and ground for 30 min.

(2) The ground sample was placed in a 5 mL alumina crucible, which was calcined in a muffle furnace at 1300 ℃ for 6 h.

(3) And (3) putting the sample obtained in the step (2) into an agate mortar for grinding for 30 min again.

The emission spectrum of the obtained phosphor is shown in FIG. 5. The CIE diagram is shown in fig. 6, and is a blue emission with coordinates (0.2062, 0.122). As can be seen from FIG. 5, at Sm³⁺And Bi³⁺Bi with the emission spectrum of 350-550 nm under the optimal excitation of 315nm after co-doping³⁺Emission of (A) and Sm 550 to 750nm³⁺Is transmitted.

Example 3

Preparation of CaYGaO₄：7%Bi³⁺，1%Sm³⁺The fluorescent powder comprises the following steps:

(1) according to CaYGaO₄：7%Bi³⁺，1%Sm³⁺CaCO calculation of stoichiometric ratio of phosphor₃、Y₂O₃、Ga₂O₃、Sm₂O₃、Bi₂O₃The required amount of the raw materials is accurately weighed by using an analytical balance, poured into an agate mortar, mixed and ground for 30 min.

(2) The ground sample was placed in a 5 mL alumina crucible, which was calcined in a muffle furnace at 1300 ℃ for 6 h.

(3) And (3) putting the sample obtained in the step (2) into an agate mortar for grinding for 30 min again.

The emission spectrum of the obtained phosphor at 315nm is shown in FIG. 7. CaYGaO₄Doping with 1% of Sm³⁺，7%Bi³⁺The excitation spectra at 604nm and 445nm are shown in FIG. 8. The CIE diagram is shown in fig. 9, and is white light emission with coordinates (0.2572, 0.1824). As can be seen from FIG. 8, in the co-doping of Bi³⁺Sm at rear 604nm³⁺The excitation spectrum peak of the crystal is changed into Bi at 445nm³⁺Bi similar to the excitation pattern of³⁺The highest excitation peak is positioned at 315nm, and Bi is shown³⁺Emitter and Sm³⁺There is an energy transfer effect.

Comparative example 1

Preparation of CaYGaO₄：7%Bi³⁺The fluorescent powder comprises the following steps:

(1) according to CaYGaO₄：7%Bi³⁺CaCO calculation of stoichiometric ratio of phosphor₃、Y₂O₃、Ga₂O₃、Bi₂O₃The required amount of the raw materials is accurately weighed by using an analytical balance, poured into an agate mortar, mixed and ground for 30 min.

(2) The ground sample was placed in a 5 mL alumina crucible, which was calcined in a muffle furnace at 1300 ℃ for 6 h.

(3) And (3) putting the sample obtained in the step (2) into an agate mortar for grinding for 30 min again.

In CaYGao₄Doping with 7% Bi³⁺And then, excitation of a broadband with an excitation spectrum peak of 280 nm-410 nm shows that the blue light can be well excited by the near ultraviolet chip, wherein the highest excitation peak is 328nm, and the emission peak under the excitation of 328nm is broadband blue light emission of 350-650 nm. CaYGao₄Doping with 7% Bi³⁺Emission spectrum at 328nm excitation see FIG. 10, CaYGaO₄Doping with 7% Bi³⁺The excitation spectrum of the emission at 442 nm is shown in FIG. 11.

FIG. 12 shows CaYGaO₄Doping with 7% Bi³⁺Emission spectrum of 328nm excitation with 1% of Sm³⁺The obtained fluorescent powder has an excitation spectrogram normalized contrast diagram under 604nm emission, and the doped Bi can be seen from the graph in FIG. 12³⁺Emission spectrum peak and doping Sm³⁺Has good overlapping of excitation spectrum peaksDescription in doping Sm³⁺When Bi is doped in the alloy³⁺To strengthen Sm³⁺Emission of (B), Bi³⁺And Sm³⁺There is an energy transfer between the ions.

Comparative example 2

Preparation of CaYGaO₄：y%Bi³⁺(y =5 or 9), 1% Sm³⁺The fluorescent powder comprises the following steps:

(1) according to CaYGaO₄：y%Bi³⁺(y =5 or 9), 1% Sm³⁺CaCO calculation of stoichiometric ratio of phosphor₃、Y₂O₃、Ga₂O₃、Sm₂O₃、Bi₂O₃The required amount of the raw materials is accurately weighed by an analytical balance, poured into an agate mortar, mixed and ground for 30 min.

(2) The ground sample was placed in a 5 mL alumina crucible, which was calcined in a muffle furnace at 1300 ℃ for 6 h.

(3) And (3) putting the sample obtained in the step (2) into an agate mortar for grinding for 30 min again.

CaYGaO₄Doping with 1% of Sm³⁺，5%Bi³⁺Emission spectra at 315nm excitation see FIG. 13, CaYGaO₄Doping with 1% of Sm³⁺，5%Bi³⁺The latter CIE diagram is shown in fig. 14.

CaYGaO₄Doping with 1% of Sm³⁺，9%Bi³⁺Emission spectrum at 315nm excitation see FIG. 15, CaYGaO₄Doping with 1% of Sm³⁺，9%Bi³⁺The latter CIE diagram is shown in fig. 16.

CaYGaO₄Doping with 1% of Sm³⁺，y%Bi³⁺Bi excited at (y =3,5,7, 9) 315nm³⁺Variation in emission intensity see FIG. 17, CaYGaO₄Doping with 1% of Sm³⁺，y%Bi³⁺Sm excited at (y =3,5,7, 9) 315nm³⁺The emission intensity changes are shown in FIG. 18, from which it can be seen that Bi is co-doped with Bi³⁺Increase in concentration of Bi³⁺Sm decreases with increasing y³⁺Increases first with increasing y, reaches a peak when y =7, and then decreases.

It should be noted that the above embodiments are only intended to illustrate the technical solution of the present invention and not to limit the same, and although the present invention has been described in detail by the above preferred embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the present invention.

Claims (7)

1. The fluorescent powder for white light emitting diode is characterized in that the matrix of the fluorescent powder is CaYGaO₄The activating ion comprises Sm³⁺Wherein Sm³⁺In CaYGaO₄The mole fraction of the medium doping is 1-11%.

2. A phosphor as claimed in claim 1, wherein the active ions further comprise Bi³⁺，Bi³⁺In CaYGao₄:1% Sm³⁺The mole fraction of the medium doping is 3-7%.

3. The phosphor of claim 2, wherein Sm is selected from the group consisting of³⁺In CaYGao₄The mole fraction of the medium doping is 1 percent, and the Bi is³⁺In CaYGao₄The mole fraction of the medium doping is 3% or 7%.

4. The phosphor for white light emitting diode of claim 3, wherein Bi is added³⁺In CaYGao₄When the doping mole fraction is 3%, exciting light of the fluorescent powder is near ultraviolet light of 315nm, and blue light of 350-750 nm is emitted; when Bi is present³⁺In CaYGao₄When the medium doping mole fraction is 7%, the exciting light of the fluorescent powder is near ultraviolet light with the wavelength of 315nm, and the emitted light is white light with the wavelength of 350-750 nm.

5. The method for synthesizing phosphor powder for white light emitting diode of claim 2, wherein the steps are as follows:

step one, according to each fluorescent powderCalculating the molar ratio of the components₃、Y2O₃、Ga2O₃、Sm₂O₃、Bi₂O₃Weighing, pouring the weighed materials into a container, mixing and grinding for 15-30 min;

placing the ground sample in an alumina crucible, and placing the crucible in a muffle furnace to calcine for 5-6 h at 1200-1300 ℃;

and step three, putting the sample obtained in the step two into a container, and grinding for 15-30 min again.

6. The method as claimed in claim 5, wherein the container in the first step and the third step is agate mortar.

7. Use of a phosphor according to claim 1 for white light emitting diodes in the manufacture of pc-WLEDs devices.

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