阅读说明：本技术 一种上转换荧光防伪标签的制备方法 (Preparation method of up-conversion fluorescent anti-counterfeiting labels ) 是由 李岳彬 赵倩茹 王成 柳维端 赵江 黄浩 胡永明 顾豪爽 于 2019-05-10 设计创作，主要内容包括：本发明公布了一种上转换荧光防伪标签的制备方法,包括步骤：导电衬底表面处理、制备图案化光刻胶导电衬底、配置电解液、电化学沉积制备图案化导电衬底、去胶及热处理,最后得到上转换发光特性的图案化薄膜,本方法结合溶液电化学沉积和微电子加工的方法使上转换荧光防伪标签具备高空间分辨率和高隐蔽性,制备的图案化薄膜具有多个可发出不同荧光的子图形,每个图形在不可见近红外光照射下激发出不同颜色的可见荧光。(The invention discloses a preparation method of up-conversion fluorescent anti-counterfeiting labels, which comprises the steps of conducting substrate surface treatment, patterned photoresist conducting substrate preparation, electrolyte preparation, electrochemical deposition preparation of patterned conducting substrate, photoresist removal and heat treatment, and finally obtaining a patterned film with up-conversion luminescence characteristics.)

1, up-conversion fluorescent anti-counterfeiting label preparation method, characterized by, the step is as follows:

s1, sequentially carrying out ultrasonic cleaning on a conductive substrate by using deionized water, a glass cleaning agent, alcohol and acetone, and then carrying out wettability treatment on the surface of the conductive substrate by using plasma, or carrying out wettability treatment on the surface of the conductive substrate by using ultraviolet irradiation and ozone radiation;

s2, coating photoresist on the conductive substrate obtained in the step S1, baking for 3min at 97 ℃, and then exposing the patterned photoresist on the conductive substrate to expose the patterned conductive substrate for later use;

s3, preparing electrolyte; adding 0.1mol/L chloride/nitrate solution of a rare earth activator and 0.1mol/L chloride/nitrate solution of a rare earth sensitizer into 0.1mol/L yttrium nitrate or yttrium chloride solution to prepare a rare earth ion mixed solution; adjusting the pH value of 0.003-0.3 mol/L complexing agent solution to 7.0-9.0, adding the solution into a rare earth ion mixed solution, reacting the complexing agent and the rare earth ions to form a complex solution, adding a sodium ascorbate solution with the solubility of 0.5mol/L, and adjusting the pH value of the mixed solution to 7.0-8.0, wherein the volume ratio of the rare earth ion mixed solution to the complexing agent solution to the sodium ascorbate solution is 2: 1: and 2, adding ammonia fluoride or sodium fluoride solution to ensure that the molar ratio of fluorine ions to rare earth ions is 4-5: 1, adjusting the pH value to 5.0-7.0 to obtain transparent colloid electrolyte for later use;

s4, taking the patterned conductive substrate in the step S2 as a working electrode, a platinum electrode as a counter electrode and an Ag/AgCl electrode as a reference electrode, and carrying out electrodeposition in the electrolyte in the step S3, wherein the deposition potential of the electrolyte is 0.6-1.2V relative to that of the Ag/AgCl electrode, the deposition time is 5-10 min, the water bath deposition temperature is 20-80 ℃, and the rare earth doped up-conversion fluorescent nano-crystals are deposited and grown on the exposed conductive substrate to prepare an up-conversion fluorescent film;

s5, placing the patterned conductive substrate in an acetone solution for 10 minutes at room temperature, and dissolving to remove the residual photoresist on the surface of the conductive substrate;

s6, placing the patterned conductive substrate processed in the step S5 in a tube furnace for annealing for 1-5 hours at the annealing temperature of 300-600 ℃, or selectively and rapidly heat-treating the film on the conductive substrate by using a 100-300 ℃ low-temperature near infrared sintering method by utilizing the absorption difference of the upconversion fluorescent film and the conductive layer substrate to near infrared band light to obtain the patterned upconversion fluorescent film with the upconversion luminescence characteristic.

2. The method for preparing according to claim 1, wherein the conductive substrate is made of ITO, FTO conductive glass, or flexible conductive glass: PET-ITO, PI-ITO.

3. The method of claim 1, wherein the plasma is nitrogen or argon activated by a plasma generator.

4. The method for preparing a composite material according to claim 1, wherein the method further comprises the steps between steps S2 and S3: the conductive substrate was baked at 110 ℃ for 80s to harden.

5. The method according to claim 1, wherein the rare earth-doped upconversion fluorescent film is a sodium yttrium fluoride film co-doped with a rare earth activator and a rare earth sensitizer, the rare earth activator is erbium and thulium, and the rare earth sensitizer is ytterbium and neodymium.

6. The preparation method of claim 1, wherein the rare earth doped upconversion fluorescent film is a ytterbium and erbium co-doped sodium yttrium fluoride film, the molar content of ytterbium is 20%, the molar content of erbium is 2%, and the film emits green fluorescence under laser irradiation with a wavelength of 980 nm;

the rare earth doped up-conversion fluorescent nanoparticle is an ytterbium and thulium co-doped sodium yttrium fluoride film, the molar content of ytterbium is 20%, the molar content of thulium is 0.2-2%, and the nanoparticle emits blue fluorescence under the irradiation of laser with the wavelength of 980 nm;

the rare earth doped upconversion fluorescent nanoparticle is a ytterbium and erbium co-doped sodium yttrium fluoride film, the molar content of ytterbium is 60%, the molar content of erbium is 2%, and the nanoparticle emits red fluorescence under the irradiation of laser with the wavelength of 980 nm;

the rare earth doped up-conversion fluorescent nanoparticle is a ytterbium-neodymium-thulium-codoped sodium yttrium fluoride film, the molar content of ytterbium is 2-20%, the molar content of neodymium is 3%, the molar content of erbium is 0.2-2%, and green fluorescence is emitted under laser irradiation with wavelength of 808 nm.

7. The method according to claim 1, wherein the mixed solution in step S3 includes the following ions in molar content:

Y³⁺38～88％

Yb³⁺10～60％

Er³⁺2％；

or

Y³⁺78～79.8％

Yb³⁺20％

Tm³⁺0.2～2％。

Or

8. The method of claim 1, wherein the complex is disodium edetate or ethylenediaminetetraacetic acid.

9. The method of claim 1, wherein the photoresist patterning in step S2 is performed by any of methods including exposing the patterned photoresist by UV exposure on the homogenized conductive substrate using a mask, developing, and baking the hardened film to obtain a patterned conductive substrate with the patterned photoresist attached thereon, or by directly patterning the exposed photoresist using Electron Beam Lithography (EBL), X-ray lithography (XRL), and Laser Direct Writing (LDW), developing to dissolve the photoresist in the exposed region, baking the hardened film, and patterning the conductive substrate by patterning the photoresist on the surface.

10. The method of any one of claims 1 to 9 to , wherein the method further comprises a step of repeating the steps S2 to S5 a plurality of times in sequence between the steps S5 and S6.

Technical Field

The invention belongs to the field of photoelectronic information materials, and particularly relates to a preparation method of up-conversion fluorescent anti-counterfeiting labels.

Background

The fluorescence label can display specific fluorescence coding information under the irradiation of light, which is important commercial anti-counterfeiting technologies, the commonly used organic fluorescent dye molecules, semiconductor fluorescent quantum dots and other materials have the advantages of high luminous efficiency and adjustable luminous color, but face the limitation of the leakage toxicity and photobleaching of heavy metal ions, and in addition, the fluorescent dye has natural background color due to short wavelength absorption and is easy to leak coding information.

Up-conversion phosphor passing sensitizer (Yb)³⁺,Nd³⁺) And an activator (Er)³⁺,Tm³⁺, Ho³⁺And Eu³⁺) The fluorescent anti-counterfeiting label material is fluorescent anti-counterfeiting label materials with great commercial application potential, in recent years, the synthesis of upconversion nanocrystals and the improvement of optical performance regulation and control technology promote the application research of related anti-counterfeiting labelsThe method comprises the steps of preparing the fluorescent label by using an equal method, modifying hydrophobic ligand molecules on the surface of the fluorescent label, having good dispersibility in an organic solvent, adding a thickening agent to form ink, and printing a patterned up-conversion fluorescent label, wherein the resolution can reach 100 mu m, viscosity, surface tension and particle aggregation directly influence the printing performance of the ink.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a preparation method of up-conversion fluorescent anti-counterfeiting labels, and the up-conversion fluorescent anti-counterfeiting labels have high spatial resolution and high concealment by combining a solution electrochemical deposition and microelectronic processing method.

The technical scheme adopted for realizing the purpose of the invention is as follows:

the preparation method of kinds of up-conversion fluorescent anti-counterfeiting labels comprises the following steps:

s1, sequentially carrying out ultrasonic cleaning on a conductive substrate by using deionized water, a glass cleaning agent, alcohol and acetone, and then carrying out wettability treatment on the surface of the conductive substrate by using plasma, or carrying out wettability treatment on the surface of the conductive substrate by using ultraviolet irradiation and ozone radiation;

s2, coating photoresist on the conductive substrate obtained in the step S1, baking for 3min at 97 ℃, and then exposing the patterned photoresist on the conductive substrate to expose the patterned conductive substrate for later use;

s3, preparing electrolyte; adding 0.1mol/L chloride/nitrate solution of a rare earth activator and 0.1mol/L chloride/nitrate solution of a rare earth sensitizer into 0.1mol/L yttrium nitrate or yttrium chloride solution to prepare a rare earth ion mixed solution; adjusting the pH value of 0.003-0.3 mol/L complexing agent solution to 7.0-9.0 by adopting 5mol/L sodium hydroxide solution, adding the solution into the rare earth ion mixed solution, reacting the complexing agent with rare earth ions to form complex solution, adding 0.5mol/L sodium ascorbate solution, adjusting the pH value of the mixed solution to 7.0-8.0 by adopting 5mol/L sodium hydroxide solution, wherein the volume ratio of the rare earth ion mixed solution to the complexing agent solution to the sodium ascorbate solution is 2: 1: and 2, adding ammonia fluoride or sodium fluoride solution to ensure that the molar ratio of fluorine ions to rare earth ions is 4-5: 1, adjusting the pH value to 5.0-7.0 by adopting a 5mol/L sodium hydroxide solution to obtain a transparent colloid electrolyte for later use;

s4, taking the patterned conductive substrate in the step S2 as a working electrode, a platinum electrode as a counter electrode and an Ag/AgCl electrode as a reference electrode, and carrying out electrodeposition in the electrolyte in the step S3, wherein the deposition potential of the electrolyte is 0.6-1.2V relative to that of the Ag/AgCl electrode, the deposition time is 5-10 min, the water bath deposition temperature is 20-80 ℃, and the rare earth doped up-conversion fluorescent nano-crystals are deposited and grown on the exposed conductive substrate to prepare an up-conversion fluorescent film;

s5, placing the patterned conductive substrate in an acetone solution, and dissolving to remove the residual photoresist on the surface of the conductive substrate;

s6, placing the patterned conductive substrate processed in the step S5 in a tube furnace for annealing for 1-5 hours at the annealing temperature of 300-600 ℃, or selectively and rapidly heat-treating the film on the conductive substrate by using a 100-300 ℃ low-temperature near infrared sintering method by utilizing the absorption difference of the upconversion fluorescent film and the conductive layer substrate to near infrared band light to obtain the rare earth doped upconversion fluorescent film with the upconversion luminescence characteristic.

In the scheme, in step , the conductive substrate is made of ITO (indium tin oxide), FTO (fluorine-doped tin oxide) conductive glass or flexible conductive glass such as PET-ITO (polyethylene terephthalate-indium tin oxide) and PI-ITO;

in the scheme, steps are further included, and the step of baking the conductive substrate at 110 ℃ for 80S for hardening is further included between the steps S2 and S3.

In the above scheme, preferably, the rare earth-doped up-conversion fluorescent film is a sodium yttrium fluoride film co-doped with a rare earth activator and a rare earth sensitizer, the rare earth activator is erbium and thulium, and the rare earth sensitizer is ytterbium and neodymium.

In the above scheme, preferably, the rare earth-doped upconversion fluorescent film is a ytterbium and erbium-codoped sodium yttrium fluoride film, the molar content of ytterbium is 20%, the molar content of erbium is 2%, and the film emits green fluorescence under laser irradiation with a wavelength of 980 nm;

the rare earth doped up-conversion fluorescent film is an ytterbium and thulium co-doped sodium yttrium fluoride film, the molar content of ytterbium is 20%, the molar content of thulium is 0.2-2%, and blue fluorescence is emitted under the irradiation of laser with the wavelength of 980 nm;

the rare earth doped up-conversion fluorescent film is a ytterbium and erbium co-doped sodium yttrium fluoride film, the molar content of ytterbium is 60%, the molar content of erbium is 2%, and red fluorescence is emitted under laser irradiation with the wavelength of 980 nm;

the rare earth doped up-conversion fluorescent film is a ytterbium neodymium thulium co-doped sodium yttrium fluoride film, the molar content of ytterbium is 2-20%, the molar content of neodymium is 3%, the molar content of erbium is 0.2-2%, and green fluorescence is emitted under laser irradiation with wavelength of 808 nm.

In the above scheme, preferably, the mixed solution in step S3 includes the following mole contents of ions:

Y³⁺38～88％

Yb ³⁺10～60％

Er³⁺2％。

in the above scheme, preferably, the mixed solution in step S3 includes the following mole contents of ions:

Y³⁺78～79.8％

Yb ³⁺20％

Tm³⁺0.2～2％。

in the above scheme, preferably, the mixed solution in step S3 includes the following mole contents of ions:

in the above scheme, preferably, the complex is disodium edetate or ethylenediaminetetraacetic acid.

In the above scheme, preferably, in the step S2, the photoresist patterning is performed by any one of methods, that is, exposing the patterned photoresist by ultraviolet light exposure on the conductive substrate after photoresist leveling with a mask, developing, and finally baking to obtain a patterned conductive substrate with the patterned photoresist attached on the surface, or directly exposing the patterned conductive substrate by Electron Beam Lithography (EBL) and X-ray lithography (XRL), and then developing to dissolve the photoresist in the exposed region to leak the patterned conductive substrate.

In the above scheme, it is preferable that steps S2 to S5 are further repeated a plurality of times in sequence between steps S5 and S6.

Specifically, A method for preparing mask by direct laser writing includes using pulse fiber laser (SPILases)G420W) was directly written on the Al film-plated quartz with a pulse width of 100ns, a repetition frequency of 50kHz, an average power of 3W (1062. + -.3 nm), and a writing speed controlled at 1000 mm/s. And taking the laser direct writing Al film quartz mirror as a mask.

Specifically, steps are carried out, EBL electron beam exposure etching is carried out to prepare patterned photoresist on a conductive substrate, firstly, a spin coater is arranged to rotate at a low speed of 500rpm for 6 seconds and at a high speed of 4000rpm for 30 seconds, polymethyl methacrylate (PMMA) electron beam resist is uniformly coated on the conductive substrate obtained in the S1 step, a pattern generating system (NPGS) is used for designing a pattern, generating a running file, aligning and engraving the pattern, the conductive substrate is directly patterned with the photoresist on the surface of the conductive substrate after exposure for 1.5 hours by adopting 30keV accelerating voltage and 2.5nA electron beam current, and finally, development and film hardening are carried out for 60 seconds, and the patterning of the conductive substrate is realized through the patterning of the photoresist on the surface.

Specifically, steps are carried out, ion beam etching is carried out to prepare patterned photoresist on the conductive substrate, firstly, a spin coater is arranged to rotate at a low speed of 500rpm for 6 seconds and at a high speed of 4000rpm for 30 seconds, polymethyl methacrylate (PMMA) electron beam resist is uniformly coated on the conductive substrate obtained in the S1 step, then a graph designed by CAD is introduced into a system, an etching cabin is vacuumized, 30keV accelerating voltage and 65nA ion beam current are adopted to directly etch the photoresist on the surface of the conductive substrate for 8 minutes, finally, 60 seconds of developing and film hardening are carried out to obtain the patterned photoresist, and patterning of the conductive substrate is realized through patterning of the photoresist on the surface.

Specifically, steps are carried out, wherein, the patterned photoresist is prepared on the conductive substrate by X-ray lithography (XRL), firstly, a spin coater is arranged to rotate at a low speed of 500rpm for 6 seconds and at a high speed of 4000rpm for 30 seconds, polymethyl methacrylate (PMMA) electron beam resist is uniformly coated on the conductive substrate obtained in the S1 step, then, the graph designed by CAD is led into a system, X photons with the energy of 1-4kev are obtained by regulating and controlling to directly etch the photoresist on the surface of the conductive substrate for 2-5 minutes, and finally, the developing is carried out for 60 seconds, the film is hardened to obtain the patterned photoresist, and the patterning of the conductive substrate is realized through the patterning of the photoresist on the surface.

Specifically, steps are carried out, Laser Direct Writing (LDW) is carried out to prepare patterned photoresist on the conductive substrate, firstly, a spin coater is arranged for 500rpm time 6 seconds at low speed and 4000rpm time 30 seconds at high speed, polymethyl methacrylate (PMMA) photoresist is uniformly coated on the conductive substrate obtained in S1 step, the graph designed by CAD is led into the system, and a pulse fiber laser (SPI Lasers) is adoptedG420W) directly etching the photoresist, controlling the pulse width to be 100ns, the repetition frequency to be 50kHz, the average power to be 1W (1062 +/-3 nm), controlling the writing speed to be 1000mm/s, finally developing for 60 seconds, hardening to obtain the patterned photoresist, and realizing the patterning of the conductive substrate through the patterning of the surface photoresist.

Compared with the prior art, the invention has the following beneficial effects:

the conductive substrate processed by the step S1 has improved wettability and adhesion, and uses flexible conductive glass: PET-ITO and PI-ITO can be made into anti-counterfeiting label films with ductility.

In step S2, a positive photoresist is used, for example, an ultraviolet lithography mask method is adopted, the irradiated photoresist is dissolved after being irradiated by ultraviolet light, the pattern on the lithography mask is transferred to the conductive substrate in aspect, the transferred pattern has millimeter/micron level resolution, the conductive substrate needing electrodeposition is exposed in aspect, the photoresist dissolved by light exposure can also use EBL electron beam exposure etching method, FIB focused ion beam photoetching method, X-ray lithography (XRL) and Laser Direct Writing (LDW) can directly pattern the etched photoresist without making a mask, and the patterning of the conductive substrate is realized through the patterning of the surface photoresist.

The electrolyte in the step S3 and the conductive substrate exposed in the step S2 are used, the exposed conductive substrate has high wettability and adhesion, and the rare earth doped up-conversion fluorescent nano-crystal is uniformly deposited on the exposed conductive substrate in the step S4 to form the patterned up-conversion fluorescent film, so that the pattern distribution is uniform, the resolution is high, and the problems of nano-particle agglomeration and precipitation and coffee ring effect in the existing ink-jet anti-counterfeiting technology are solved.

The pattern of the patterned film prepared in the step S4 is uniformly distributed, the resolution can reach about 20 microns, and the problems of nanoparticle agglomeration and precipitation and coffee ring effect in the existing ink-jet anti-counterfeiting technology are solved.

Ytterbium and erbium co-doped sodium yttrium fluoride film NaYF₄:Yb,Er(78:20:2)]Visible green fluorescence is excited by near infrared light, cannot be seen under the irradiation of visible light and ultraviolet light, can be hidden under the visible light and is used for anti-counterfeiting marks;

ytterbium and erbium co-doped sodium yttrium fluoride nanoparticle loaded thin film NaYF₄:Yb, Er(38:60:2)]The film can excite visible red fluorescence under near infrared light, cannot be seen under the irradiation of visible light and ultraviolet light, can be hidden under the visible light and is used for anti-counterfeiting marks;

yb-thulium-codoped sodium yttrium fluoride nanoparticle loaded film [ NaYF₄:Yb, Tm(79.8:20:0.2)]And [ NaYF₄:Yb,Tm(79.5:20:0.5)]Exciting visible blue fluorescence in near infrared light, visible light and violetThe anti-counterfeiting label does not emit light under the irradiation of external light, has concealment under visible light and ultraviolet light, and can be used for anti-counterfeiting labels;

Yb-Nd-Tm-codoped sodium yttrium fluoride nanoparticle loaded film [ NaYF₄:Nb,Yb,Tm (76.8～94.8:3:2～20:0.2～2)]The fluorescent material can excite green fluorescence under near infrared light, does not emit light under the irradiation of visible light and ultraviolet light, has concealment under the irradiation of visible light and ultraviolet light, and can be used for anti-counterfeiting marks.

The patterned film obtained in steps S2 to S5 is repeated several times between steps S5 and S6, and has a plurality of sub-patterns capable of emitting different fluorescence, and each sub-pattern excites visible fluorescence of different colors under the irradiation of the near-infrared light with the same wavelength.

In step S6, the conductive layer substrate does not absorb the near-infrared light, and the upconversion fluorescent film absorbs the near-infrared light, so that the upconversion fluorescent film can be differentially heated without heating the flexible conductive substrate.

Drawings

FIG. 1 is a NaYF₄:Yb³⁺,Er³⁺(78:20:2) field emission scanning electron micrographs of the film surface;

FIG. 2 is a NaYF₄:Yb³⁺,Er³⁺(78:20:2) transverse sectional field emission scanning electron micrographs of the film;

FIG. 3 is a NaYF₄:Yb³⁺,Er³⁺(78:20:2) X-ray diffraction pattern of the film;

FIG. 4 is a NaYF₄:Yb³⁺,Er³⁺(78:20:2) a photograph and a UV-VIS near IR transmission spectrum of the film;

FIG. 5 is a NaYF₄:Yb³⁺,Tm³⁺(79.8:20:0.2)，NaYF₄:Yb³⁺, Er³⁺(78:20:2)，NaYF₄:Yb³⁺,Er^{3 +}(38:60:2) fluorescence photograph and up-conversion fluorescence emission spectrum of the film under 980nm near infrared light irradiation;

FIG. 6 is a NaYF₄:Nd³⁺,Yb³⁺,Tm³⁺(92.8:3:4:0.2) fluorescent photograph and up-conversion fluorescence emission spectrum of the film under 808nm near infrared light irradiation;

FIG. 7 shows (a) a mask for preparing a single-color bar code pattern and (b) to (d) masks for preparing a multi-color bar code pattern, respectively;

FIG. 8 is a photograph of (a) "barcode" patterned photoresist in white light and (b) NaYF, respectively₄:Yb³⁺,Tm³⁺(79.5:20:0.5)、(c)NaYF₄:Yb³⁺,Er³⁺(78:20:2)、(d) NaYF₄:Yb³⁺,Er³⁺(38:60:2) thin film and (e) patterning of rare earth doped NaYF by multi-step photolithography and electrochemical deposition₄Up-conversion fluorescence photograph (scale bar 500 μm) of the film at 980nm near infrared.

Detailed Description

The invention is further described with reference to the figures and the specific embodiments.