CN100506945C - Semiconductor luminescent material excited by near ultraviolet or ultraviolet light and its preparation method - Google Patents

Abstract

The invention discloses a semiconductor emitting material that is stimulated by near ultraviolet or ultraviolet. The constituents are ZnO: Sx, My and 10-4<=x<=10-2, 0<=y<=0.2. M is selected from Li, Na, K or rare earth of Eu, Tb. When M is Na, it has better emitting effect. The invention also discloses the manufacture method and the performance testing result. The invention has strong absorption near 370-440nm wavelength ultraviolet and blue light zone, and has strong emission between 450-600nm wavelengths. It could be used in LED and LD.

Description

Semiconductor luminescent material excited by near ultraviolet or ultraviolet light and its preparation method

technical field

The invention belongs to the field of luminescent materials, and more specifically relates to the field of semiconductor luminescent materials.

Background technique

In recent years, with the wide application of various functional materials, the research on the luminescent properties of materials has been deepened. At the same time, due to the most potential of yellow-green light-emitting devices (LEDs), laser diodes (LDs), vacuum fluorescent displays (VFDs) and recent new developments The huge market demand such as field emission flat panel displays (FEDs) has promoted the research on III-V and II-VI semiconductor materials. The unique optical properties of nano-semiconductor materials make them possible to have new potential applications in the field of optoelectronics, and become an important branch of research in the field of material luminescence. ZnO is an important semiconductor material. It is not easy to be oxidized in the atmosphere and has high chemical and thermal stability. It is also one of the few oxide semiconductors that are easy to achieve quantum size effects. It has been widely used in photovoltaic cells, ceramics, pressure Sensitivity, sensors, catalysts, luminescent materials, etc.

Due to the large exciton binding energy and wide bandgap properties of ZnO, people have aroused great interest in its optical applications. The exciton binding energy of ZnO is 60meV, which is three times that of ZnSe and GaN-based materials. It is not easy to be thermally excited at room temperature, and it is easy to achieve stimulated emission, allowing excitons to recombine at high temperatures. Therefore, ZnO is the most promising material for fabricating exciton-related optical devices.

Meanwhile, ZnO is a hexagonal crystal having a wurtzite structure. According to the energy band structure, the forbidden band width of ZnO is about 3.2eV, and the lattice defects inside the crystal of ZnO or doping with other ions will have a huge impact on its electrical and optical properties. Lattice defects in ZnO crystals such as oxygen defects, zinc defects, zinc interstitials, oxygen inversion sites, etc. can lead to visible emission at 400-730nm, which has attracted the attention of extensive researchers, but due to its physical properties, especially thermal stability The disadvantages such as poor performance, difficult to control defects, and weak light color limit its development and utilization. Since 1997, a lot of research has been done on photoluminescent materials doped with rare earth elements in ZnO in China, especially the exploration and research on ZnO photoradiation ultraviolet light, blue light and green light. Its purpose is mainly to make ZnO blue light-emitting diodes and ZnO ultraviolet lasers. Although the preparation process of using ZnO doped rare earth elements to synthesize green and blue light-emitting materials has gradually matured, it is difficult to achieve effective doping of ZnO semiconductor materials doped with rare earth elements, and rare earths are expensive, and the prepared materials are mostly short-wavelength. UV-excited fluorescence has a short lifetime.

Contents of the invention

The technical problem to be solved by the present invention is to provide a semiconductor luminescent material excited by near-ultraviolet or ultraviolet light and its preparation method, so as to overcome the high price of raw materials, complicated preparation steps, difficult control of reaction conditions and the large particle size of the obtained material in the original method. Uniformity, chemical and optical properties are not stable enough, and the defects of low luminous efficiency.

Technical solutions

One of the technical solutions provided by the present invention is a yellow-green fluorescent material, the composition of which includes:

ZnO: S _x , M _y

Among them, 10 ^-4 ≤ x ≤ 10 ^-2 and 0 ≤ y ≤ 0.2;

Wherein, M is selected from alkali metal elements or rare earth elements.

One of the preferred versions of the above-mentioned yellow-green fluorescent material is that the alkali metal element is selected from one or a combination of lithium, sodium, and potassium, preferably sodium.

The second preferred solution of the above-mentioned yellow-green fluorescent material is that the rare earth element is selected from europium or terbium, or a combination thereof.

The luminescent powder prepared by the yellow-green fluorescent material of the invention has strong absorption in the long-wave ultraviolet and blue-violet visible light regions of 370-440nm, and strong emission in 450-600nm.

The second technical solution provided by the present invention is a method for preparing the above-mentioned yellow-green fluorescent material, which includes the following steps:

(1) mixing elemental sulfur, elemental zinc, and soluble salts of alkali metals or rare earth elements and dispersing them in the solution;

(2) Prepare the precursor after reacting and dispersing at 45-95°C;

(3) Grinding after sintering at 800-1000°C to obtain the target product.

One of the preferred schemes of the preparation method of the above-mentioned yellow-green fluorescent material is that the sulfur and zinc elements are selected from zinc sulfide, or thioacetamide and zinc acetate, or zinc oxide and sulfur powder, or a combination of the three.

The second preferred solution of the above-mentioned preparation method of the yellow-green fluorescent material is that the alkali metal soluble salt is selected from lithium, sodium or potassium chloride or nitrate, or a combination thereof.

The third preferred solution of the above-mentioned preparation method of the yellow-green fluorescent material is that the soluble salt of the rare earth element is selected from the chloride salt or nitrate salt of europium or terbium, or a combination thereof.

The fourth preferred version of the above-mentioned preparation method of yellow-green fluorescent material is that the solvent of the reaction solution is one or a combination of water, ethanol or methanol; the reaction temperature in step (2) is 60-70 ℃, and disperse the reactants in ultrasonic waves; the solvent can be removed by distillation under reduced pressure at 70-85 ℃; the sintering temperature in step (3) is 800-900 ℃, and sintering in air atmosphere for 0.5-2.0 hours .

In the actual preparation process, the preferred method is: mix and disperse the stoichiometric zinc sulfide and alkali metal chloride in ethanol solution (or dissolve the stoichiometric thioacetamide in ethanol, and slowly add into a mixed ethanol solution of zinc acetate and alkali metal chloride), stirred in a water bath at 65°C for 1 hour, dispersed by ultrasonic waves for 5 minutes, and evaporated under reduced pressure at 70-85°C to remove ethanol to obtain a precursor. The target product was obtained after sintering at 850°C for 2h in a Furnace; the matrix was prepared with thioacetamide and zinc acetate and sintered at 800°C for 0.5h in an air atmosphere.

The third technical solution provided by the present invention is an application of the above-mentioned yellow-green fluorescent material, that is, using the fluorescent material to prepare yellow-green light-emitting devices LED, laser diode LD, vacuum fluorescent display VFDs, or field emission flat panel display FEDs.

Those skilled in the art can determine how to apply the luminescent material of the present invention to the preparation of yellow-green light emitting devices LED, laser diode LD, vacuum fluorescent display VFDs, or field emission flat panel display FEDs without too many experiments. One of the optional ways is to mix the luminescent material with epoxy resin, and coat it on the lamp board of a light-emitting diode (LED) emitting near-ultraviolet or violet light, as an illumination light-emitting device. The structure of the LED and the position of the luminescent material coating are shown in FIG. 3 . Or the above-mentioned luminescent material is hybridized with a conductive polymer material to form a thin film to form an electroluminescent device. It can also be physically evaporated on conductive glass as an electroluminescent device.

Beneficial effect

In the present invention, the low temperature liquid phase method is combined with the air oxidation method, the sintering temperature is low, and a little grinding can be used to obtain ultra-fine and efficient long-wave band excitation fluorescent powder materials, and the obtained products have high chemical and optical stability. The production process is simple and easy to operate, and the raw materials are cheap and easy to be suitable for industrial production. The reaction process basically has no industrial three wastes and the solvent can be recycled and reused. It belongs to the industry of green environmental protection, low energy consumption and high efficiency, and the obtained products have high light efficiency and fine particle size. , stable chemical and optical properties, and its long-wave ultraviolet excitation performance makes the material have a wide range of application prospects.

In the fluorescent material of the present invention, ZnO is used as a matrix, oxygen defects in the ZnO are used as luminescent centers, and M is a sensitizer, which can significantly increase the luminous intensity. The incorporation of S can red-shift the excitation spectrum to the long-wave ultraviolet region. Especially its LED long-wave ultraviolet excitation performance makes this material have a wide range of application prospects.

Performance studies on the fluorescent material of the present invention, including XRD and fluorescence spectra, show that the luminescent powder has strong absorption in the long-wave ultraviolet and blue-visible light regions of 370-440nm, and strong emission in 450-600nm. These performances are much better than the existing fluorescent materials of the same type.

The term "matrix" as used herein refers to a material, such as ZnO, that constitutes the main component in the phosphor.

The term "activator" as used herein refers to a luminescent center of a phosphor, such as an oxygen defect in ZnO.

The term "sensitizer" used herein refers to a moiety that promotes the fluorescence intensity of the phosphor, such as alkali metal or rare earth element ions.

The term "precursor" as used herein refers to the product before sintering, such as ZnS.

The term "ultrafine" as used herein means that the particle size of the fluorescent material is less than 1000 nanometers.

Description of drawings

Figure 1 is the excitation and emission spectra of samples doped with different metal ions. In the figure, Exitation is the excitation spectrum of the sample, and Emission is the emission spectrum of the corresponding sample.

Figure 2 is the X-ray diffraction pattern of samples doped with different metal ions. 100, 002, 101, etc. marked in the figure are the diffraction crystal planes of ZnO crystal, and this figure can prove that the obtained material is a ZnO-based material.

Fig. 3 is a schematic diagram of the application of the semiconductor luminescent material of the present invention in the preparation of LED lighting. In the figure, the material of the present invention is coated on the LED lamp board with epoxy resin.

Detailed ways

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. After reading the above teaching content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

For the experimental methods without specific conditions indicated in the following examples, the conventional conditions or the conditions suggested by the manufacturer are usually followed.

Example 1

Weigh 9.7g ZnS and 0.6030g NaCl, add them to 50mL ethanol solution, stir in a water bath at 65°C for 10 minutes, then disperse ultrasonically for 5 minutes, keep heating in a water bath at 65°C and continue stirring for 30 minutes, then distill the ethanol under reduced pressure at 70°C To obtain the precursor, put the above precursor in a muffle furnace for sintering at 850°C for 2 hours, and then grind it a little to obtain the target product.

Example 2

Weigh 9.7g ZnS and 0.6042g LiCl.H20, add to 50mL ethanol solution, stir in 65℃ water bath for 10min, then ultrasonically disperse for 5min, keep stirring in 65℃ water bath for 30min, then distill under reduced pressure at 70℃ The ethanol was removed to obtain the precursor, and the above precursor was sintered in a muffle furnace at 850°C for 2 hours, and then ground slightly to obtain the target product.

Example 3

Weigh 9.7g ZnS and 0.7455g KCl, add to 50mL ethanol solution, stir in 65°C water bath for 10min, then ultrasonically disperse for 5min, keep heating in 65°C water bath and continue stirring reaction for 30min, then remove ethanol by distillation under reduced pressure at 70°C To obtain the precursor, put the above precursor in a muffle furnace for sintering at 850°C for 2 hours, and then grind it a little to obtain the target product.

Example 4

Weigh 9.7g ZnS and 2.4426g BaCl.2H20, add to 50mL ethanol solution, stir in 65°C water bath for 10min, then ultrasonically disperse for 5min, keep stirring in 65°C water bath for 30min, then distill under reduced pressure at 70°C The ethanol was removed to obtain the precursor, and the above precursor was sintered in a muffle furnace at 850°C for 2 hours, and then ground slightly to obtain the target product.

Example 5

Dissolve 30mL 0.1102g/mL thioacetamide in ethanol, slowly add it into 150mL ethanol solution of zinc acetate (8.78g) and NaCl (0.234g) through a dropping funnel under magnetic stirring, and stir in a water bath at 65°C for 10min , then ultrasonically dispersed for 5 minutes, kept heating in a water bath at 65°C and continued to stir for 30 minutes, then distilled off ethanol under reduced pressure at 70°C to obtain a precursor, put the above precursor in a muffle furnace for sintering at 800°C for 0.5h, and then ground it slightly to obtain the target product.

Example 6

A certain amount of ZnS was weighed and directly sintered in a muffle furnace at 850°C for 2h, and then ground slightly to obtain the target product.

Example 7

Dissolve 30mL of 0.1102g/mL thioacetamide in ethanol, slowly add it into 150mL of ethanol solution of zinc acetate (8.78g) and LiCl (0.2345g) through a dropping funnel under magnetic stirring, and stir in a water bath at 65°C for 10min , then ultrasonically dispersed for 5 minutes, kept heating in a water bath at 65°C and continued to stir for 30 minutes, then distilled off ethanol under reduced pressure at 70°C to obtain a precursor, put the above precursor in a muffle furnace for sintering at 800°C for 0.5h, and then ground it slightly to obtain the target product.

Example 8

Dissolve 30mL of 0.1102g/mL thioacetamide in ethanol, slowly add it into 150mL of zinc acetate (8.78g) and NaCl (0.234g) ethanol solution through a dropping funnel under magnetic stirring, and stir in a water bath at 65°C for 10min , then ultrasonically dispersed for 5 minutes, kept heating in a water bath at 65°C and continued to stir for 30 minutes, then distilled off ethanol under reduced pressure at 70°C to obtain a precursor, put the above precursor in a muffle furnace for sintering at 800°C for 0.5h, and then ground it slightly to obtain the target product.

Example 9

Dissolve 30mL of 0.1102g/mL thioacetamide in ethanol, slowly add it into 150mL of ethanol solution of zinc acetate (8.78g) and KCl (0.2893g) through a dropping funnel under magnetic stirring, and stir for 10min under heating in a water bath at 65°C , then ultrasonically dispersed for 5 minutes, kept heating in a water bath at 65°C and continued to stir for 30 minutes, then distilled off ethanol under reduced pressure at 70°C to obtain a precursor, put the above precursor in a muffle furnace for sintering at 800°C for 0.5h, and then ground it slightly to obtain the target product.

Example 10

Dissolve 30mL of 0.1102g/mL thioacetamide in ethanol, slowly add it into 150mL of zinc acetate (8.78g) ethanol solution through a dropping funnel under magnetic stirring, stir in a water bath at 65°C for 10min, and then ultrasonically disperse for 5min. Keep heating in a water bath at 65°C and continue to stir and react for 30 minutes, then distill off ethanol under reduced pressure at 70°C to obtain a precursor, put the above precursor in a muffle furnace for sintering at 800°C for 0.5h, and then grind slightly to obtain the target product.

Example 11

The luminescent material of the present invention is mixed with epoxy resin, and coated on a lamp plate of a light-emitting diode (LED) emitting near ultraviolet or violet light, as an illumination light-emitting device. The structure of the LED and the position of the luminescent material coating are shown in FIG. 3 .

Claims (8)

1. yellow green light fluorescent material, its composition comprises:

ZnO：S _x，M _y

Wherein, 10 ^-4≤ x≤10 ^-2And 0≤y≤0.2;

Wherein, M is selected from alkali metal.

2. yellow green light fluorescent material according to claim 1 is characterized in that, said alkali metal is selected from a kind of or its combination among lithium, sodium, the potassium.

3. yellow green light fluorescent material according to claim 2 is characterized in that, said alkali metal is a sodium.

4. the described yellow green light Preparation of Fluorescent Material of claim 1 method may further comprise the steps:

(1) element sulphur, zinc element and alkali-soluble salt are mixed and be scattered in solution;

(2) make precursor after 45-95 ℃ time reaction and the dispersion;

(3) grinding promptly obtains target product behind 800-1000 ℃ of sintering.

5. yellow green light Preparation of Fluorescent Material method according to claim 4 is characterized in that said element sulphur, zinc element are selected from zinc sulphide, perhaps thioacetamide and zinc acetate, perhaps zinc oxide and sulphur powder, perhaps three's combination.

6. yellow green light Preparation of Fluorescent Material method according to claim 4 is characterized in that said alkali-soluble salt is selected from the chlorate or the nitrate of lithium, sodium or potassium element, perhaps its combination.

7. yellow green light Preparation of Fluorescent Material method according to claim 4 is characterized in that:

The solvent of said reaction soln is a kind of or its combination among water, ethanol or the methyl alcohol;

The said temperature of reaction of step (2) is 60-70 ℃, and disperses reactant in ultrasonic wave;

Said solvent is removed 70-85 ℃ of following underpressure distillation;

The said sintering temperature of step (3) is 800-900 ℃, and with air atmosphere sintering 0.5-2.0 hour.

8. the application of the described yellow green light fluorescent material of claim 1 is characterized in that preparing yellow green light luminescent device LED, laser diode LD, vacuum fluorescent display VFDs or Field Emission Display FEDs with said fluorescent material.

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