KR102358260B1 - Nanophosphor for ultraviolet imaging device - Google Patents

Abstract

The present invention relates to a nanophosphor having a core-shell structure capable of emitting visible light of a specific color by selectively absorbing an incident ultraviolet light in a specific wavelength band. A nanophosphor for an ultraviolet imaging device according to an embodiment is doped with cerium (Ce) for absorbing ultraviolet light into NaLuF ₄ nanocrystals as an activator, and gadolinium (Gd) for transferring energy absorbed from ultraviolet light to the activator is studied It is synthesized by doping with a lubricant, and doping europium (Eu) for emitting light by receiving the absorbed energy with an activator. Since the size of the nanophosphor according to the embodiment does not exceed 60 nm, it is easy to fabricate a pattern having a fine pixel size, so that an ultraviolet imaging device having superior resolution compared to the prior art can be realized.

Description

Nanophosphor for ultraviolet imaging device {NANOPHOSPHOR FOR ULTRAVIOLET IMAGING DEVICE}

The present invention relates to a nanophosphor for an ultraviolet imaging device, and more particularly, to a high-efficiency nanophosphor having a core-shell structure capable of emitting visible light of a specific color by selectively absorbing an incident ultraviolet light in a specific wavelength band.

[Description of state-funded R&D]

This study was conducted under the supervision of the Korea Institute of Science and Technology, and the mid-level researcher support project of the Ministry of Science and ICT (development of high-efficiency up-conversion nanophosphor based on study activity control for fluorescent imaging application, unique project number: 1711084598) and the Ministry of Trade, Industry and Energy's new and renewable energy. This was done with the support of the Energy Core Technology Project (development of a transparent solar cell platform that is easy to expand, unique project number: 20193091010240).

The human body can recognize only visible light corresponding to a wavelength band of about 400 to 700 nm, and cannot recognize ultraviolet light having a shorter wavelength or infrared light having a longer wavelength than this. Recently, the demand for such infrared and ultraviolet sensing application technology is increasing. Infrared rays can be used for night vision, thermal imaging cameras, gas sensing, etc., and ultraviolet rays are used in various fields such as drug detection, medical imaging, and protein analysis. can be

In particular, by using ultraviolet rays having a shorter wavelength than visible light, it is possible to find very fine curves or irregularities on the surface of an object that are difficult to photograph with visible light, or to selectively distinguish and image chemical components that react to ultraviolet rays. have.

In order to visualize ultraviolet rays having a shorter wavelength than visible light, an ultraviolet imaging device is required. Using a wavelength conversion material that absorbs ultraviolet light and emits visible light, it is possible to image invisible ultraviolet light. As these wavelength conversion materials, special dyes, quantum dot materials, and phosphors capable of wavelength-selective absorption are used.

In order to realize a practical UV imaging device, it is necessary to pattern a material capable of emitting light by selectively absorbing UV light in a specific wavelength band. Therefore, there is a disadvantage that the efficiency is lowered, and in the case of an existing phosphor capable of selectively absorbing wavelengths, it has a size of a micrometer region, so it is difficult to pattern with a small pixel size.

Republic of Korea Patent Publication No. 10-1616363

The present invention was conceived to solve the above problems, and provides a nano-phosphor with high UV-visible light conversion efficiency that can emit light in a specific color by reacting with UV light in a specific wavelength band without exceeding 60 nm in size. aim to do

Embodiments of the present invention for achieving the above object are provided as follows.

In the nanophosphor for an ultraviolet imaging device according to an embodiment, cerium (Ce) for absorbing ultraviolet rays to NaLuF ₄ nanocrystals is used as an activator, and gadolinium (Gd) for transferring energy absorbed from ultraviolet rays to an activator is used as a co-active agent. It can be synthesized by doping europium (Eu) for emitting light by receiving the absorbed energy with an activator.

In one embodiment, in order to increase the light emission intensity of the nanophosphor, the nanophosphor may be a core and further include a NaLuF ₄ crystalline shell formed around it to have a core-shell structure.

In one embodiment, the size of the nanophosphor having the core-shell structure is characterized in that it does not exceed 60 nm.

In an embodiment, the nanophosphor may selectively absorb ultraviolet light of a specific wavelength band to emit visible light of a specific color.

In one embodiment, the ultraviolet light has a wavelength band of 230 to 250 nm, it is characterized in that the visible light represents red.

In an embodiment, the nanophosphor may further include a fluorescent material for selectively absorbing and emitting ultraviolet rays having a wavelength band different from that of the ultraviolet rays.

An ultraviolet imaging device comprising the nanofluorescent agent according to the above-described embodiments may be provided.

A method of synthesizing a nanophosphor for an ultraviolet imaging device according to an embodiment includes lutetium chloride hydrate (LuCl _{3.6H 2} O), gadolinium chloride hydrate (GdCl 3.6H ₂ O), cerium chloride hydrate (CeCl _{3.7H 2} O) _. ), and europium chloride hydrate (EuCl ₃ .6H ₂ O), mixed with oleic acid as a solvent and 1-octadicene, and then heated to form a lanthanide complex solution; forming a reaction solution by mixing the lanthanide complex compound solution with a mixed solution of sodium hydroxide, ammonium fluoride and methanol; And after removing methanol from the reaction solution, heat treatment to form beta (β)-NaLu _0.35 F ₄ :Ce _0.1 , Gd _0.5 , Eu _0.05 nanoparticles.

In one embodiment, the step of mixing lutetium chloride hydrate (LuCl ₃ .6H ₂ O) with oleic acid as a solvent and 1-octadicene and heating to form a second lanthanide complex solution; A solution containing the beta (β)-NaLu _0.35 F ₄ :Ce _0.1 , Gd _0.5 , and Eu _0.05 nanoparticles was injected into the second lanthanide complex solution, and then mixed with a mixed solution of sodium hydroxide, ammonium fluoride and methanol to prepare 2 forming a reaction solution; and synthesizing a core-shell structured nanophosphor by heat-treating after removing methanol from the second reaction solution.

According to an embodiment of the present invention, a core nanophosphor in which NaLuF ₄ nanocrystals are doped with cerium (Ce), gadolinium (Gd), and europium (Eu), and a crystalline shell formed around the core nanophosphor have a core-shell structure There is provided a nano-phosphor for an ultraviolet imaging device having.

The nanophosphor selectively absorbs only ultraviolet rays of a specific wavelength band to emit visible light of a specific color, and it is possible to realize various colors by combining with other fluorescent materials. In addition, since it is formed in a core-shell structure and has excellent ultraviolet-visible light conversion efficiency, it is suitable for use in an ultraviolet imaging device.

Since the size of the nanophosphor according to the embodiment does not exceed 60 nm, it is easy to fabricate a pattern having a fine pixel size, so that an ultraviolet imaging device having superior resolution compared to the prior art can be realized.

1 is a transmission electron micrograph of a nanophosphor having a core-shell structure formed according to an exemplary embodiment.
2 shows a transmission electron micrograph of a core nanophosphor formed according to an exemplary embodiment.
3 is a graph illustrating an X-ray diffraction pattern of a core nanophosphor formed according to an exemplary embodiment.
4 is a graph illustrating a PL emission spectrum of a core nanophosphor formed according to an exemplary embodiment.
5 is a graph illustrating an X-ray diffraction pattern of a nanophosphor having a core-shell structure formed according to an exemplary embodiment.
6 is a graph illustrating a PL emission spectrum of a nanophosphor having a core-shell structure formed according to an exemplary embodiment.
7 shows a photograph of a nanophosphor solution having a core-shell structure prepared according to an embodiment and a photograph of emission under ultraviolet lamp (λ=254 nm) excitation.

Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings and the contents described in the accompanying drawings, but the scope of the claims is not limited or limited by the embodiments.

The terms used in this specification have been selected as currently widely used general terms as possible while considering their functions, but may vary depending on the intention or custom of a person skilled in the art or the emergence of new technology. In addition, in a specific case, there is a term arbitrarily selected by the applicant, and in this case, the meaning will be described in the description of the corresponding specification. Therefore, it is intended to clarify that the terms used in this specification should be interpreted based on the actual meaning of the terms and the contents of the entire specification, rather than the simple names of terms.

Hereinafter, preferred embodiments will be described in more detail with reference to the drawings.

1 shows a transmission electron micrograph of a nanophosphor having a core-shell structure prepared according to an embodiment. As illustrated, since each nanophosphor has a size of nanometers, it is possible to pattern it in a fine size when manufacturing an imaging device.

The nanophosphor according to an embodiment of the present invention has a NaLuF ₄ nanocrystal as a matrix, doped with cerium (Ce) for absorbing ultraviolet rays as an activator, and gadolinium (Gd) for transferring energy absorbed from ultraviolet rays to the activator ) can be synthesized by doping with a co-activator, and doping europium (Eu) for emitting light by receiving the absorbed energy with an activator.

According to an embodiment, the hexagonal NaLuF ₄ nanocrystals have a size within 50 nm. The nanophosphor doped with the lanthanide trivalent ion emits visible light of a unique color according to the doped lanthanide element regardless of the type of the parent. This is because the light emission of the nanophosphor is caused by the transition of 4f electrons of the doped lanthanide trivalent ion. Using this principle, it is possible to manufacture a phosphor that emits a desired color according to a doping element while controlling the particle size.

However, among the existing phosphors, dyes or quantum dot materials having a nano size do not selectively absorb ultraviolet rays but absorb ultraviolet rays in a wide wavelength range, so there is a disadvantage in that efficiency is lowered. On the other hand, existing phosphors capable of selectively absorbing wavelengths have a size of a micrometer region, so it is difficult to pattern them with a small pixel size.

In the present invention, by using NaLuF ₄ crystal having a size of 50 nm or less as a core of the phosphor and appropriately doping with an activator to be described later, a nano phosphor capable of selectively absorbing ultraviolet light while having a nano size is provided.

Cerium (Ce) is doped as an activator so that the nanophosphor can absorb ultraviolet light of a specific wavelength. When cerium is applied to NaLuF ₄ particles, it absorbs ultraviolet (UV-C) near 250 nm.

Europium (Eu) is doped as an activator and serves to emit visible light of a specific color by receiving the absorbed ultraviolet energy. In an embodiment, europium (Eu) emits red visible light (light in a wavelength band of about 620 to 750 nm) by receiving energy from ultraviolet rays near 250 nm.

Gadolinium (Gd) is doped as a co-activator (共賦活劑), and serves to transfer the ultraviolet energy absorbed by the activator (Ce) to the activator (Eu).

In order to achieve the intrinsic effect of the present invention, a nanophosphor having a core-shell structure can be prepared by using the nanophosphor prepared according to the above embodiment as a core, and further including a NaLuF ₄ crystalline shell formed around the core. . Nanophosphors having a core-shell structure can emit light more clearly than conventional phosphors, so they are suitable for application to ultraviolet imaging devices.

Since the nanophosphor having a core-shell structure manufactured according to the embodiment does not exceed 60 nm in total size, it is easy to form a pattern having a fine pixel size. Therefore, using this, it is possible to manufacture an ultraviolet imaging device having superior resolution compared to the conventional one.

Hereinafter, the present invention will be described in more detail through specific examples. The embodiments to be described below exemplarily describe preferred methods for synthesizing a core nanophosphor and a nanophosphor having a core-shell structure, and the technical spirit and claims of the present invention are not limited thereto.

<Example 1> NaLu _0.35 F ₄ :Ce _0.1 ,Gd _0.5 ,Eu _0.05 Core nanophosphor synthesis method

First mixed solution preparation step: 0.35 mmol of lutetium chloride hydrate ( _{LuCl 3.6H 2} O), 0.5 mmol of gadolinium chloride hydrate (GdCl 3.6H ₂ O), 0.1 mmol of cerium chloride hydrate (CeCl _{3.7H 2} O), and 0.05 mmol of europium chloride hydrate (EuCl ₃ .6H ₂ O) was mixed with 6 mL of oleic acid as a solvent and 15 mL of 1-octadicene, and then heated to 150° C. to a solution containing a lanthanide complex (1) to form

Reaction solution preparation step: A reaction solution (3) is prepared by mixing the solution (1) containing the lanthanide complex with a solution (2) in which 2.5 mmol of sodium hydroxide and 4 mmol of ammonium fluoride are mixed with methanol.

Nanoparticle formation step: Remove methanol from the reaction solution (3), and heat treatment at a temperature of 320° C. for 60 minutes under an argon gas atmosphere. During the heat treatment, beta (β)-NaLu _0.35 F ₄ :Ce _0.1 , Gd _0.5 , Eu _0.05 nanoparticles are formed. After washing the formed nanoparticles with ethanol, they are dispersed and stored in a non-polar solvent such as hexane, toluene, and chloroform.

2 shows a transmission electron micrograph of a core nanophosphor formed according to an exemplary embodiment.

3 is a graph illustrating an X-ray diffraction pattern of a core nanophosphor formed according to an exemplary embodiment. It can be seen that the hexagonal NaGd _0.75 Lu _0.25 F ₄ phase, which is a reference, is consistent with the hexagonal phase, and a hexagonal phase without impurities is synthesized.

4 is a graph illustrating a PL emission spectrum of a core nanophosphor formed according to an exemplary embodiment. Red emission peaks are observed around 593 nm and 617 nm.

<Example 2> NaLu _0.35 F ₄ :Ce _0.1 ,Gd _0.5 ,Eu _0.05 /NaLuF ₄ Method for synthesizing core-shell structured nanophosphor

First mixed solution preparation step: 1 mmol of lutetium chloride hydrate (LuCl ₃ .6H ₂ O) was mixed with 6 mL of oleic acid as a solvent and 15 mL of 1-octadicene, and then heated to 150° C. to obtain a lanthanide complex. A solution (4) comprising

Reaction solution preparation step: 10 mL of the core nanophosphor solution synthesized according to Example 1 was injected into the solution (4) containing the lanthanide complex compound, and 2.5 mmol of sodium hydroxide and 4 mmol of ammonium fluoride were mixed with methanol and A reaction solution (6) is prepared by mixing with the mixed solution (5).

Nanoparticle formation step: Remove methanol from the reaction solution (6), and heat treatment for 60 minutes at a temperature of 320 °C in an argon gas atmosphere. During the heat treatment, beta (β)- NaLu _0.35 F ₄ :Ce _0.1 , Gd _0.5 , Eu _0.05 /NaLuF ₄ nanoparticles are formed. After washing the formed core/shell nanoparticles with ethanol, they are dispersed and stored in a non-polar solvent such as hexane, toluene, or chloroform.

Comparing FIG. 1 showing a transmission electron micrograph of a nanophosphor having a core-shell structure formed according to an embodiment with FIG. 2 , it can be seen that the shell is formed and the size of the particles is increased.

5 is a graph illustrating an X-ray diffraction pattern of a nanophosphor having a core-shell structure formed according to an exemplary embodiment. A peak was formed between the NaGd _0.75 Lu _0.25 F ₄ phase and the NaLuF ₄ phase as a reference, confirming that the hexagonal shell was well formed around the core without impurities.

6 is a graph illustrating a PL emission spectrum of a nanophosphor having a core-shell structure formed according to an exemplary embodiment. A strong emission peak is observed through the shell formation. In addition to the red emission peaks centered at about 593 nm and 617 nm, an additional peak centered at 625 nm is observed.

=254 nm) 여기 하에서의 발광 사진을 나타낸다. 도시된 바와 같이, 투명한 용액으로부터 강한 적색 발광이 관찰됨을 알 수 있다.7 is a photograph of a nanophosphor solution having a core-shell structure and an ultraviolet lamp (

=254 nm) shows the photoluminescence under excitation. As shown, it can be seen that strong red emission is observed from the transparent solution.

The nanophosphor according to an embodiment may further include a fluorescent material for selectively absorbing ultraviolet rays of a specific wavelength band to emit light in different colors. Recently, ultraviolet imaging devices have been used in various fields, and for this purpose, it is necessary to implement a richer color than a single color.

For example, when terbium (Tb) rather than europium (Eu) is doped as an activator, green visible light is emitted instead of red, and when dysprosium (Dy) is doped, blue-green visible light is emitted. In addition, various emission colors may be realized by adjusting the type and doping ratio of the lanthanide element.

The nanophosphor according to an exemplary embodiment may further include other fluorescent materials for selectively absorbing and emitting ultraviolet light of a wavelength band other than the ultraviolet light of a wavelength band of 250 nm. According to this, it is possible to emit light by selectively absorbing UV-A (315 to 400 nm) or UV-B (280 to 315 nm) ultraviolet rays instead of UV-C (100 to 280 nm).

In the case of implementing a multi-wavelength ultraviolet imaging device (for example, an ultraviolet imaging device that outputs multi-wavelength ultraviolet rays instead of short-wavelength ultraviolet rays to a subject, detects reflected ultraviolet rays and outputs them as visible light), It is possible to prepare and apply a nanophosphor to absorb and emit light.

In one embodiment of the present invention, an ultraviolet imaging apparatus including the core nanophosphor or the nanophosphor having a core-shell structure may be provided.

The ultraviolet imaging device includes, for example, an ultraviolet light source unit that outputs short-wavelength or multi-wavelength ultraviolet light, an ultraviolet light transmission filter that blocks infrared and visible light among the light reflected by an object and selectively transmits only ultraviolet light, and absorbs the transmitted ultraviolet light It may include a wavelength down-conversion filter emitting visible light of a specific color, and an imaging module sensing the visible light and storing and outputting the image as an image. However, this is only an exemplary configuration, and components other than the wavelength down filter may be omitted or further added.

The wavelength downconversion filter is a component that absorbs ultraviolet light and emits visible light of a specific color. For example, the conversion filter may have a pixel structure emitting visible light of red, green, and blue, respectively, and the red light emitting pixel may include the above-described NaLuF ₄ : Ce, Gd, Eu structure of the nanophosphor, green and The blue light emitting pixel may include a nanophosphor doped with another phosphor.

The above-described nanophosphor for an ultraviolet imaging device selectively absorbs only ultraviolet light in a specific wavelength band to emit visible light of a specific color, and it is possible to realize various colors by combining with other fluorescent materials. In addition, since it is formed in a core-shell structure and has excellent ultraviolet-visible light conversion efficiency, it is suitable for use in an ultraviolet imaging device.

Since the size of the nanophosphor according to the embodiment does not exceed 60 nm, it is easy to fabricate a pattern having a fine pixel size, so that an ultraviolet imaging device having superior resolution compared to the prior art can be realized.

Although the above has been described with reference to the embodiments, those skilled in the art can variously modify and change the present invention within the scope without departing from the spirit and scope of the present invention described in the claims below you will understand

Claims (9)

A nanophosphor for an ultraviolet imaging device, comprising:
In NaLuF4 nanocrystals, cerium (Ce) for absorbing ultraviolet light is used as an activator,
Using gadolinium (Gd) as a co-activator to transfer the energy absorbed from ultraviolet light to the activator,
It is synthesized by doping europium (Eu) with an activator to receive the absorbed energy and emit light,
In order to increase the luminescence intensity of the nanophosphor, the nanophosphor has a core-shell structure, and the size of the nanophosphor having the core-shell structure is 60 nm by further including a NaLuF4 crystalline shell formed around the nanophosphor. Nanophosphor for ultraviolet imaging device, characterized in that it does not exceed.
delete delete The method of claim 1,
The nanophosphor is a nanophosphor for an ultraviolet imaging device, characterized in that it emits visible light of a specific color by selectively absorbing ultraviolet light in a specific wavelength band.
5. The method of claim 4,
The ultraviolet light has a wavelength band of 230 to 250 nm, and the visible light is red, characterized in that it represents a UV imaging device nano-phosphor.
5. The method of claim 4,
The nanophosphor, characterized in that it further comprises a fluorescent material for emitting light by selectively absorbing ultraviolet rays having a wavelength band different from the ultraviolet rays.
An ultraviolet imaging device comprising the nanophosphor according to claim 1, comprising:
The ultraviolet imaging device,
An ultraviolet light source unit for outputting short-wavelength or multi-wavelength ultraviolet;
an ultraviolet transmitting filter that blocks infrared and visible light among the light reflected by the object and selectively transmits only ultraviolet light;
a wavelength down-conversion filter that absorbs the transmitted ultraviolet light and emits visible light of a specific color; and
and an imaging module that detects the visible light, stores it as an image, and outputs the image.
A method of synthesizing a nanophosphor for an ultraviolet imaging device, comprising:
Lutetium chloride hydrate (LuCl3.6H2O), gadolinium chloride hydrate (GdCl3.6H2O), cerium chloride hydrate (CeCl3.7H2O), and europium chloride hydrate (EuCl3.6H2O) were mixed with oleic acid as a solvent and 1-octadicene. and then heating to form a lanthanide complex compound solution;
forming a reaction solution by mixing the lanthanide complex compound solution with a mixed solution of sodium hydroxide, ammonium fluoride and methanol; and
After removing methanol from the reaction solution, heat treatment to form beta (β)-NaLuF4:Ce,Gd,Eu nanoparticles,
In order to increase the luminescence intensity of the nanophosphor, the nanophosphor has a core-shell structure, and the size of the nanophosphor having the core-shell structure is 60 nm by further including a NaLuF4 crystalline shell formed around the nanophosphor. A method of synthesizing a nano-phosphor for an ultraviolet imaging device, characterized in that it does not exceed.
9. The method of claim 8,
forming a second lanthanide complex compound solution by mixing lutetium chloride hydrate (LuCl3.6H2O) with oleic acid as a solvent and 1-octadicene, followed by heating;
A solution containing the beta (β)-NaLuF4:Ce,Gd,Eu nanoparticles is injected into the second lanthanide complex compound solution, and then mixed with a mixed solution of sodium hydroxide, ammonium fluoride and methanol to form a second reaction solution step; and
The method for synthesizing a nanophosphor for an ultraviolet imaging device, further comprising the step of synthesizing a nanophosphor having a core-shell structure by heat-treating the second reaction solution after removing methanol.

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