JP5045876B2 - Nano-silicon particles having excellent emission brightness and method for producing the same - Google Patents

Description

  The present invention relates to nanosilicon particles having excellent emission luminance sustainability and a method for producing the same.

  At present, semiconductor particle materials that emit fluorescent light with a diameter of several to several tens of nanometers are attracting attention. Fluorescent materials for display, lighting equipment, cosmetics, clothing, clothing, pharmaceuticals, medical devices, etc. It is going to be adapted to various application fields.

  However, some of the fluorescent light-emitting semiconductor nanoparticle materials that have been researched or developed up to this point have a heavy impact on the global environment and are harmful to the human body. In applications that are directly related to the human body, such as appliances, cosmetics, clothing, clothing, pharmaceuticals, medical devices, etc., without confirming the non-toxicity and harmlessness (environmental conservation) to the environment and human body, Conventional fluorescent light-emitting semiconductor nanoparticle materials cannot be used as they are.

  Therefore, in order to apply fluorescent light-emitting semiconductor nanoparticle materials in more fields, it is friendly to the natural environment, especially with no emphasis on non-toxicity and harmlessness to human body. Material development is important.

  Recently, as a fluorescent light-emitting semiconductor nanoparticle material that has been in the spotlight, there is nanosilicon particles that emit fluorescent light in the visible region (blue to red) (see Patent Document 1). The nano-silicon particles have a diameter of about 3.5 nm or less, and the nano-silicon particles themselves are made of silicon, which is friendly to the human body as well as to the environment, and is non-toxic and harmless. Since it is a substance, it is promising as an application material in a wide range of fields.

  However, the brightness and lifetime of the fluorescence emission from the nanosilicon particles vary in an environment where the nanosilicon particles are stored. For example, in the atmosphere, a high-quality silicon oxide film with few defects, which are non-radiative recombination centers, is formed on the surface of nanosilicon particles. In various solutions such as ethanol, toluene, pure water, and physiological saline, a silicon oxide film with many defects is formed on the surface of the nanosilicon particles, so that the luminance decreases with time, resulting in a short life. It is unstable.

  From the above, in order to expand the application of nanosilicon particles, high-luminance and stable fluorescence can be obtained even in an environment such as a solution, and deterioration of nanosilicon particles can be prevented. It is necessary to consider covering a protective film that can be done.

  Furthermore, when applied to the field of medical engineering such as pharmaceuticals and medical devices, the surface of the nanosilicon particles has chemical and corrosion resistance to various solutions, and has excellent biocompatibility protection. It is also important to coat the membrane.

  In the prior art, a silicon oxide film that is most stable with respect to the silicon surface has been generally used as a protective film for nanosilicon particles. However, as a method for forming a silicon oxide film, it has been impossible to obtain a silicon oxide film having the same quality as that in the atmosphere even in a solution. In addition, when applied to the medical engineering field, the silicon oxide film is insufficient for bonding with drugs, polymers such as polysaccharides and proteins, and cells.

JP-A-11-201972

  In the solution, the development of the protective film to prevent the degradation of nano-silicon particles that fluoresce in the visible region is based on the display, lighting equipment, cosmetics, clothing, and clothing using fluorescent light-emitting semiconductor nano-particle materials that are friendly to the environment and the human body. , Will promote the commercialization of pharmaceuticals, medical devices and other products.

  Accordingly, the present invention provides (i) high-luminance and stable fluorescence emission of nanosilicon particles that enable application in various fields in various solutions, and (ii) degradation of nanosilicon particles. An object (or purpose) is to obtain a protective film that prevents the above-described problem.

  Another object of the present invention is to establish a production method for producing nanosilicon particles having a surface coated with a protective film for preventing deterioration.

  As a result of intensive research to solve the above-mentioned problems, the present inventor has (i) chemical resistance, corrosion resistance, and biocompatibility with respect to various solutions using a high-frequency plasma CVD method. We found that high-luminance and stable fluorescence can be obtained in solution by coating the surface of nanosilicon particles with an excellent diamond-like carbon film (hereinafter referred to as DLC; Diamond-like Carbon film). .

  In addition, the present inventors have found a method of (ii) coating the surface of nanosilicon particles with a protective film that prevents the degradation of nanosilicon particles in the solution.

  This invention was made | formed based on the said knowledge, The summary is as follows.

(1) Sustained emission luminance characterized in that nano-silicon particles having a particle size of 3.5 nm or less that emits fluorescence when irradiated with ultraviolet rays or visible rays are coated with a protective film for preventing deterioration of emission intensity comprising a carbon film. Nanosilicon particles with excellent properties.

( 2 ) The nanosilicon particles having excellent emission luminance persistence as described in ( 1 ) above, wherein the carbon film is a diamond-like carbon film.

( 3 ) The nanosilicon particles having excellent emission luminance persistence according to ( 2 ), wherein the diamond-like carbon film is produced by a high-frequency plasma CVD method.

( 4 ) The protective film for preventing deterioration of light emission intensity made of the carbon film has chemical resistance and corrosion resistance with respect to various solutions, and is excellent in biocompatibility. nano silicon particles with excellent persistence of light emission luminance according to any one of (3).

( 5 ) The nanosilicon particles having excellent emission luminance persistence according to ( 4 ), wherein the solution is ethanol, toluene, pure water, or physiological saline.

( 6 ) The nanosilicon particles having excellent persistence of emission luminance according to ( 4 ) or ( 5 ), wherein the nanosilicon particles emit fluorescent light stably with high luminance in the solution.

( 7 ) In the method for producing nanosilicon particles having a particle size of 3.5 nm or less having a protective film for preventing deterioration of emission intensity comprising a carbon film ,
(A) A solution in which nano-silicon particles are dispersed is applied on a substrate, and then
(B) A method for producing nanosilicon particles having excellent durability of emission luminance, wherein the surface of the nanosilicon particles is coated with a protective film for preventing deterioration of emission luminance by a high-frequency plasma CVD method.

( 8 ) The method for producing nanosilicon particles having excellent emission luminance persistence according to ( 7 ), wherein the carbon film is a diamond-like carbon film.

( 9 ) The method for producing nanosilicon particles having excellent emission luminance persistence as described in ( 8 ) above, wherein the diamond-like carbon film is produced by a high-frequency plasma CVD method.

( 10 ) The above-mentioned ( 7 ) to ( 7 ), wherein the protective film for preventing deterioration of light emission intensity comprising the carbon film has chemical resistance and corrosion resistance to various solutions and is excellent in biocompatibility. 9 ) The method for producing nanosilicon particles having excellent emission luminance persistence according to any one of the above.

( 11 ) The method for producing nanosilicon particles having excellent luminescence luminance sustainability according to ( 10 ), wherein the solution is ethanol, toluene, pure water, or physiological saline.

( 12 ) The nanosilicon particles having excellent emission luminance persistence according to ( 10 ) or ( 11 ), wherein the nanosilicon particles emit fluorescent light stably with high luminance in the solution. Production method.

  According to the present invention, in a solution, the surface of nanosilicon particles is covered with a stable protective film, and the nanosilicon particles that emit fluorescent light stably and stably have been difficult to obtain by conventional techniques. Can be manufactured.

  Nanosilicon particles are gentle to the global environment and the human body, are non-toxic and harmless, and emit fluorescent light in the visible range, so they have chemical and corrosion resistance to various solutions, and are biocompatible. The nano-silicon particles of the present invention coated with a particle-deterioration-preventing protective film (diamond-like carbon film) that excels in the use of nano-silicon particles, displays, lighting equipment, cosmetics, clothing, clothing, pharmaceuticals, medical Devices and other fields.

First, an important point in the present invention will be briefly described. It is possible to obtain high-intensity and stable fluorescence emission in the visible region in a solution when a nano-silicon particle surface having a particle size of 3.5 nm or less is coated with a protective film for preventing deterioration of emission intensity made of a carbon film. It can be done.

In order to achieve this, in the manufacturing method of the present invention, the surface of the nanosilicon particles is directly coated with a protective film for preventing deterioration of emission intensity composed of a carbon film , and the protective film is uniformly applied. A high-frequency plasma CVD method is used for coating.

  First, a solution in which nano silicon particles are dispersed is prepared, and the solution is applied onto a substrate with a micropipette. After that, by applying a high-frequency plasma CVD method to form a deterioration-preventing protective film such as a diamond-like carbon film on the surface of the nanosilicon particles, the nanosilicon particles exhibiting high-luminance and stable fluorescence emission in the solution are obtained. Can be manufactured.

As the deterioration preventing protective film, a diamond-like carbon film is optimal in terms of chemical resistance, corrosion resistance, and biocompatibility .

Nanosilicon particles (present invention particles) coated with a protective film for preventing deterioration of emission intensity made of a carbon film by the above method exhibit high-luminance and stable fluorescence emission in the visible region in a solution. Lay a development base as a raw material for cosmetics, clothing, clothing, medical devices, etc.

  Below, the manufacturing method (this invention manufacturing method) which manufactures this invention particle | grain is explained in full detail.

FIG. 1 shows an outline of the process of coating the surface of nanosilicon particles with a protective film for preventing deterioration of emission intensity made of a carbon film . The board | substrate 1 is installed on the thermal plate 2 (refer FIG. 1 (A)). On the substrate 1, nanosilicon particles 3 extracted by a micropipette 5 from a solution (using highly volatile ethanol 4) in which the nanosilicon particles 3 are dispersed are applied. The size of the nanosilicon particles 3 at this time is 3.5 nm or less indicating fluorescence emission in the visible region.

  The temperature of the hot plate 2 is adjusted to about 30 to 100 ° C, but preferably 40 to 60 ° C. The treatment time is 5 to 120 seconds, preferably 15 to 60 seconds, and more preferably 25 to 35 seconds. After the coating process, the substrate 1 is heated with the hot plate 2 to evaporate the ethanol 4 adhering to the nanosilicon particles on the substrate 1 and completely remove impurities from the surface of the nanosilicon particles 3 together with ethanol.

  Next, a diamond-like carbon film 7 is uniformly deposited on the surface of the nanosilicon particles 3 using a high-frequency plasma CVD method 6 (see FIG. 1B). At this time, a diamond-like carbon film is deposited so as to cover the entire surface of the nanosilicon particles 3.

  Here, FIG. 6 shows one mode of a high-frequency plasma CVD apparatus. This apparatus is roughly attached to a vacuum chamber 14 having a methane gas inlet 12 and an exhaust outlet 13 at the lower side of the side, and an upper surface of the vacuum chamber 14 via an insulating material 15, and cooling water 17 introduced and discharged from a cooling pipe 16. From a high frequency electrode 20 provided with a substrate holder 18 that is cooled by the above and a cathode shield 19 that is attached to the lower surface of the vacuum chamber 14 via an insulating material 15 and cooled by cooling water 17 introduced and discharged from the cooling pipe 16. It is configured.

  In the above apparatus, methane gas is introduced into the vacuum chamber 14 from the methane gas inlet 12, the methane gas is ionized by the high frequency controller 21, and the ionized methane ions are placed on the substrate 1 disposed on the high frequency electrode 20. A chemical reaction is performed on the surface of the nanosilicon particles 3 to form a diamond-like carbon film 7 on the surface.

  The deposition conditions at this time are high-frequency power, gas pressure (pressure during production, methane gas pressure in this manufacturing process), and deposition time of the diamond-like carbon film 7 that covers the surface of the nanosilicon particles 3. Directly related to film thickness.

Since the film thickness of the diamond-like carbon film 7 affects the light transmittance, it is a very important factor for the luminance of the fluorescence emitted from the nanosilicon particles 3. Therefore, the high frequency power is 50 to 250 W, preferably 75 to 150 W, and more preferably 80 to 120 W. The gas pressure is adjusted to 1.332 to 133.2 Pa , preferably 6.66 to 66.6 Pa , and more preferably 66.6 to 20.0 Pa . Further, the deposition time is adjusted to 30 to 300 seconds, preferably 60 to 240 seconds, and more preferably 100 to 140 seconds.

  Under these conditions, a diamond-like carbon film 7 having a film thickness of 10 to 100 nm is deposited on the surface of the nanosilicon particles 3, and the film thickness is preferably 15 to 80 nm, and more preferably 15 to 25 nm. .

  Next, after the surface of the nanosilicon particles 3 on the substrate 1 is coated with the diamond-like carbon film 7, the substrate 1 is placed in a container containing a solution 9 (ethanol 4, toluene, pure water, or physiological saline). 10, the container 10 is placed on the ultrasonic cleaner 11, and a stirring process 8 is performed (see FIG. 1C).

  The treatment time of the stirring treatment 8 is usually 10 to 600 seconds, preferably 30 to 300 seconds, and more preferably 60 to 120 seconds. By the stirring process 8, the nano silicon particles 3 on the substrate 1 are separated and separated from the substrate 1 and dispersed in the solution 9 (see FIG. 1C). When the substrate 1 is taken out from the container 10 after the stirring process 8, a solution 9 in which the nanosilicon particles 3 coated with the diamond-like carbon film 7 are dispersed in the solution can be obtained (FIG. 1D). reference).

  Even if the nanosilicon particles 3 coated with the diamond-like carbon film 7 are stored in the solution 9 for a long period of time, the fluorescence emission luminance does not decrease, and stably emits fluorescence with any color in the visible region.

  FIG. 2 shows changes in the quantitative strength of carbon and silicon when the surface layer of the sample coated with the deterioration preventing protective film is subjected to argon ion etching from the outermost surface layer by X-ray photoelectron spectroscopy.

  From the X-ray photoelectron spectroscopic spectrum of the carbon 1s orbit and silicon 2p orbit, the sample coated with the deterioration preventing protective film has a signal with binding energy peaks at 284.2 eV and 99.3 eV, respectively. Here, the signal of 284.2 eV is caused by the graphite structure (π bond) in the diamond-like carbon film, and the signal of 99.3 eV is caused by the silicon-silicon bond in the nanosilicon particle. Is.

  Looking at changes in the depth direction of these signals, as shown in FIG. 2, the carbon signal is detected for ion etching up to 400 seconds, but not thereafter. In contrast, the silicon signal is detected after 400 seconds. This indicates that a diamond-like carbon film as a deterioration preventing protective film is deposited on the entire surface of the nanosilicon particles.

FIG. 3 shows Raman spectra of a sample coated with a protective film for preventing deterioration and a sample uncoated. In the sample coated with the deterioration preventing protective film, Raman signals having peaks at 1260 cm ⁻¹ and 1510 cm ⁻¹ appear.

Here, the Raman signal at 1260 cm ⁻¹ is due to the D (Disorder) band resulting from the sp ² hybrid orbital-bonded carbon disordered structure. The Raman signal of 1510 cm ⁻¹ is due to the G (Graphitic) band resulting from the in-plane vibration E _2g mode of graphite. These peaks are signals peculiar to the diamond-like carbon film, and have a spectrum shape in which the D band and the G band are mixed.

  On the other hand, in the sample not coated with the deterioration preventing protective film, the Raman signal due to the D band and the G band is not detected. This suggests that the deterioration preventing protective film covering the surface of the nanosilicon particles is a diamond-like carbon film having a structure similar to that of a generally formed film.

  FIG. 4 shows the fluorescence emission spectra of the sample coated with the deterioration preventing protective film and the sample not coated. Both the sample coated with the deterioration preventing protective film and the uncoated sample show red light emission having a peak at 720 nm, but the fluorescence emission luminance is different.

  This difference in fluorescence emission luminance is due to the influence of the light transmittance of the diamond-like carbon film coated on the surface of the nanosilicon particles as a protective film for preventing deterioration. Since the transmittance with respect to the film thickness of the diamond-like carbon film is about 75% at a wavelength of 720 nm, the fluorescence emission luminance is lower than that of the sample not coated with the deterioration preventing protective film.

  However, the fluorescence emission luminance of the sample coated with the deterioration preventing protective film is very strong by irradiation with ultraviolet rays or visible rays, and can be sufficiently confirmed with the naked eye under room lighting.

  FIG. 5 shows changes over time in the fluorescence emission intensity of the sample coated with the deterioration preventing film in the solution and the sample not coated. In the sample not coated with the deterioration preventing protective film, the fluorescence emission intensity is attenuated as time passes immediately after being immersed in the solution. On the other hand, the sample coated with the protective film for preventing deterioration maintains stable fluorescence even after being immersed in the solution, and the fluorescence emission retains luminance that can be recognized with the naked eye even after long-term storage. ing.

  As described above, according to the production method of the present invention, high-frequency plasma CVD is used, high-luminance and stable fluorescence emission is exhibited in the solution, and it is gentle to the environment and the human body (non-toxic and harmless). Further, nanosilicon particles coated with a deterioration-preventing protective film having chemical resistance and corrosion resistance to various solutions and excellent in biocompatibility can be produced.

  The “nanosilicon particles having a protective film for preventing deterioration” of the present invention actively utilizes the unique property of exhibiting high-luminance and stable fluorescence emission in a solution, and can be used for displays, lighting equipment, cosmetics, clothing, It can be used as a material useful for apparel, pharmaceuticals, medical devices, and other applications.

  As described above, the nano of the present invention coated with an anti-deterioration protective film that is gentle to the environment and the human body (harmless and non-toxic), has chemical resistance and corrosion resistance to various solutions, and is excellent in biocompatibility. Since silicon particles exhibit high-intensity and stable fluorescence emission in a solution, the present invention uses nano-silicon particles in the display field, lighting field, cosmetic field, clothing / design field, medical field / pharmaceutical field. It will be expanded to other fields.

  Thus, the present invention utilizes the innovative fluorescent light-emitting semiconductor nanoparticle material in the 21st century in the display field, lighting field, cosmetic field, clothing / design field, medical / pharmaceutical field, and other fields. It is very likely to be applied to the development of various commercialization technologies.

It is a figure which shows the process which coat | covers the deterioration prevention protective film on the surface of a nano silicon particle. (A) is a figure which shows the aspect which apply | coated the nano silicon particle to the board | substrate on a thermal plate, (B) is the aspect which deposited the diamond-like carbon film on the surface of the nano silicon particle by the high frequency plasma CVD method. (C) is a figure which shows the aspect of the stirring process by an ultrasonic cleaner, and (D) is the dispersion | distribution aspect in the solution of the nano silicon particle coat | covered with the deterioration prevention protective film. FIG. It is a figure which shows the change of the fixed intensity | strength of carbon and silicon when the sample which coat | covered the deterioration prevention protective film is argon-ion etched from the outermost surface layer. It is a figure which shows the Raman spectrum which concerns on the sample which coat | covered the deterioration prevention protective film, and the sample which is not coat | covered. It is a figure which shows the fluorescence emission spectrum which concerns on the sample which coat | covered the deterioration prevention protective film, and the sample which is not coat | covered. It is a figure which shows the time-dependent change of the fluorescence emission intensity concerning the sample which coat | covered the deterioration prevention film | membrane in a solution, and the sample which is not coat | covered. It is a figure which shows the aspect of a high frequency plasma CVD apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Hot plate 3 Nano silicon particle 4 Ethanol 5 Micropipette 6 High frequency plasma CVD method 7 Diamond-like carbon film 8 Stirring process 9 Solution 10 Container 11 Ultrasonic cleaner 12 Methane gas inlet 13 Exhaust port 14 Vacuum chamber 15 Insulating material 16 Cooling pipe 17 Cooling water 18 Substrate holder 19 Cathode shield 20 High frequency electrode 21 High frequency controller

Claims (12)

Excellent persistence of emission brightness characterized by coating nanosilicon particles with a particle size of 3.5 nm or less that emit fluorescence when irradiated with ultraviolet rays or visible rays with a protective film that prevents deterioration of emission intensity consisting of a carbon film. Nano-silicon particles. 2. The nanosilicon particles having excellent emission luminance persistence according to claim 1 , wherein the carbon film is a diamond-like carbon film. The nano-silicon particles having excellent emission luminance persistence according to claim 2 , wherein the diamond-like carbon film is produced by a high-frequency plasma CVD method. Degradation preventing protective layer of the light emitting intensity composed of the carbon film, with respect to various solutions, chemical resistance and corrosion resistance, claim 1-3, characterized in that is excellent in biocompatibility 2. Nanosilicon particles excellent in sustainability of light emission luminance according to item 1 . The nanosilicon particles having excellent emission luminance persistence according to claim 4 , wherein the solution is ethanol, toluene, pure water, or physiological saline. 6. The nanosilicon particles having excellent emission luminance persistence according to claim 4 or 5 , wherein the nanosilicon particles emit fluorescent light stably with high luminance in the solution. In the method for producing nanosilicon particles having a particle size of 3.5 nm or less having a protective film for preventing deterioration of emission intensity made of a carbon film ,
(A) A solution in which nano-silicon particles are dispersed is applied on a substrate, and then
(B) A method for producing nanosilicon particles having excellent durability of emission luminance, wherein the surface of the nanosilicon particles is coated with a protective film for preventing deterioration of emission luminance by a high-frequency plasma CVD method. The method for producing nanosilicon particles having excellent emission luminance persistence according to claim 7 , wherein the carbon film is a diamond-like carbon film. 9. The method for producing nanosilicon particles having excellent emission luminance sustainability according to claim 8 , wherein the diamond-like carbon film is produced by a high-frequency plasma CVD method. Degradation preventing protective layer of the light emitting intensity composed of the carbon film, chemical resistance against various solutions, there is corrosion resistant, any one of claims 7 to 9, characterized in that is excellent in biocompatibility 1 The manufacturing method of the nano silicon particle excellent in the persistence of the light-emitting luminance as described in a term . The method for producing nanosilicon particles having excellent luminescence luminance sustainability according to claim 10 , wherein the solution is ethanol, toluene, pure water, or physiological saline. The method for producing nanosilicon particles having excellent emission luminance persistence according to claim 10 or 11 , wherein the nanosilicon particles emit fluorescent light stably with high luminance in the solution.

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