A double-equivalent-element-induced upconversion-enhanced composite film, a preparation method thereof and application thereof in the field of anti-counterfeiting

Abstract

The application belongs to the technical field of rare earth doped upconversion materials, and relates to a composite film with double-equivalent excitation induced upconversion enhancement and a preparation method and application thereof in the field of anti-counterfeiting. The application discloses a preparation method of a composite film with double-equivalent excitation induced upconversion enhancement, and the preparation method comprises the following steps: S1, preparation of MoO 3‑x nanosheets; S2, preparation of W 18 O 49 nanowires / MoO 3‑x nanosheets; S3, preparation of rare earth doped core-shell structure NaYF4 nanoparticles / W 18 O 49 nanowires / MoO 3‑x nanosheets; the rare earth doped core-shell structure NaYF4 nanoparticles are dispersed in a cyclohexane solution, and after being uniformly mixed, the rare earth doped core-shell structure NaYF4 nanoparticles are put into W 18 O 49 nanowires / MoO 3‑x nanosheets, and the composite film with double-equivalent excitation induced upconversion enhancement is obtained after heating and keeping warm. The application further discloses application of the composite film with double-equivalent excitation induced upconversion enhancement in the field of anti-counterfeiting, and the composite film with double-equivalent excitation induced upconversion enhancement emits light of different colors under different excitation powers of 980nm diode excitation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rare earth doped upconversion materials, and relates to a composite film with double plasmon induced upconversion enhancement and a preparation method and application thereof in the field of anti-counterfeiting. BACKGROUND

[0002] Nanomaterials with plasmonic properties have been widely used in optoelectronics, biological detection, and nanotechnology in recent years, and their interaction with luminescent materials has been more widely studied, especially the study of localized field enhanced upconversion luminescence has attracted more attention. The resonant behavior of plasmon on the irradiated area of the material surface by incident light causes the surface localized electric field strength of the plasmonic nanomaterial to greatly increase, thereby enhancing the absorption of light. The collective oscillation of intrinsic holes of heavily doped semiconductor materials or more than free carriers related to ion doping can cause plasmonic resonance effect, and there is a strong absorption band in the near-infrared region, and the surface plasmon resonance energy of the nanomaterial can be controlled by controlling the doping amount, thereby controlling the enhancement of upconversion luminescence. However, due to the relatively weak plasmonic effect of semiconductor materials, the enhancement effect on upconversion luminescence is still not ideal, and therefore, further improving the localized surface plasmon effect of semiconductor materials is still a problem to be solved. SUMMARY

[0003] The purpose of the present application is to solve the above-mentioned problems existing in the prior art, and a composite film with double plasmon induced upconversion enhancement is provided, which can obtain good upconversion luminescence enhancement under the excitation of a 980 nm diode, and emit different colors of light under different excitation powers, and can be applied in the field of anti-counterfeiting.

[0004] The purpose of the present application can be achieved by the following technical solutions:

[0005] A preparation method of a composite film with double plasmon induced upconversion enhancement, the preparation method comprising:

[0006] S1, MoO 3-x Preparation of nanosheets:

[0007] After dissolving molybdenum powder in anhydrous ethanol and hydrogen peroxide, a first hydrothermal reaction is performed to grow MoO 3-x nanosheets;

[0008] S2, W 18 O 49 nanowires / MoO 3-x Preparation of nanosheets:

[0009] After dissolving tungsten hexacarbonyl in anhydrous ethanol, a second hydrothermal reaction is performed, and the hydrothermal reaction is placed with MoO 3-xThe reaction kettle of nanosheet is carried out;

[0010] S3, rare earth doped core-shell structure NaYF4 nanoparticles / W 18 O 49 Nanowire / MoO 3-x Preparation of nanosheet:

[0011] S31, the first group of composite rare earth acetate salt and oleic acid, octadecene are weighed and uniformly mixed, then stirred and heated, after cooling, ammonium fluoride and sodium hydroxide are added, and the first heating is carried out, then vacuumized, the second heating is carried out, and then the NaYF4 nanoparticles as the core are obtained;

[0012] S32, the second group of composite rare earth acetate salt and oleic acid, octadecene are weighed and uniformly mixed, then stirred and heated, after cooling, the NaYF4 nanoparticles as the core, ammonium fluoride and sodium hydroxide are added, and the first heating is carried out, then vacuumized, the second heating is carried out, and then the rare earth doped core-shell structure NaYF4 nanoparticles are obtained;

[0013] S33, the rare earth doped core-shell structure NaYF4 nanoparticles are dispersed in cyclohexane solution, uniformly mixed, and then put into W 18 O 49 Nanowire / MoO 3-x Nanosheet, after heating and keeping warm, it is obtained.

[0014] As preferred, the mass-volume ratio of molybdenum powder, anhydrous ethanol and hydrogen peroxide in step S1 is (55-70) mg:(18-30) ml:(0.8-1) ml.

[0015] As preferred, the hydrothermal reaction temperature in step S1 is 150-170℃, and the time is 8-14h.

[0016] As preferred, the mass-volume ratio of tungsten hexacarbonyl and anhydrous ethanol in step S2 is (20-25) mg:(20-25) ml.

[0017] As preferred, the mass ratio of molybdenum powder and tungsten hexacarbonyl is (2-3):1.

[0018] As preferred, the first group of composite rare earth acetate salt in step S31 is thulium acetate, ytterbium acetate and yttrium acetate with a molar ratio of 1:6:139.

[0019] As preferred, the second group of composite rare earth acetate salt in step S32 is erbium acetate, ytterbium acetate and yttrium acetate with a molar ratio of 1:(9-11):(38-39).

[0020] As preferred, the temperature of the first temperature-rising heating in step S31 is the same as the temperature of the first temperature-rising heating in step S32; the temperature and time of the second temperature-rising heating in step S31 are the same as the temperature and time of the second temperature-rising heating in step S32.

[0021] Further preferably, the temperature of the first temperature-rising heating is 110-125℃; the temperature of the second temperature-rising heating is 260-290℃, and the time is 0.5-2h.

[0022] As preferred, the concentration of the rare earth doped core-shell structure NaYF4 nanoparticles in step S33 in cyclohexane solution is 1.5-3.0%.

[0023] As preferred, the MoO 3-x The nanosheet is grown on an FTO substrate.

[0024] Further preferably, the FTO substrate is fluorine-doped SnO2 transparent conductive glass (SnO2:F), abbreviated as FTO.

[0025] The application also discloses a composite film with double-equivalent excitation induced up-conversion enhancement, which is a rare earth doped core-shell structure NaYF4 nanoparticle / W 18 O 49 nanowire / MoO 3-x nanosheet.

[0026] As preferred, the rare earth doped core-shell structure NaYF4 nanoparticles are NaYF4:Yb 3+ ,Tm 3+ @NaYF4:Yb 3+ ,Er 3+ ; Yb 3+ As preferred, Er 3+ and Tm 3+ are used as the sensitizing agent and the light emitting center.

[0027] As preferred, in the rare earth doped core-shell structure NaYF4 nanoparticles, NaYF4:Yb 3+ 30%, Tm 3+ 5% @ NaYF4:Yb 3+ (18-22%), Er 3+ 2%.

[0028] As preferred, the particle size of the rare earth doped core-shell structure NaYF4 nanoparticles is 43-48nm.

[0029] Further preferably, the rare earth doped core-shell structure NaYF4 nanoparticles NaYF4:Yb 3+ ,Tm 3+ @NaYF4:Yb3+ ,Er 3+ ,NaYF4:Yb 3+ ,Tm 3+ The particle size ratio of the nanometer particles is (1.01-1.5):1.

[0030] As preferred, the rare earth doped core-shell structure NaYF4 nanometer particles are prepared by covering the surface of the NaYF4:Yb 3+ ,Tm 3+ nanometer particles with NaYF4:Yb 3+ ,Er 3+ shell layer.

[0031] The application also discloses an application of the double-equivalent excitation induced up-conversion enhanced composite film in the field of anti-fake.

[0032] As preferred, under the excitation of a 980nm diode, the double-equivalent excitation induced up-conversion enhanced composite film emits blue light under an excitation power of 2190mW, and emits green light under an excitation power of 644mW.

[0033] As preferred, the double-equivalent excitation induced up-conversion enhanced composite film can obtain better up-conversion luminescence enhancement under the excitation of a 980nm diode.

[0034] Compared with the prior art, the application has the following beneficial effects:

[0035] 1、The application obtains excellent double-equivalent excitation coupling effect by compounding MoO 3-x nanometer sheets, W 18 O 49 nanometer wires, which have the plasmon resonance characteristics, and the double LSPR effect of the composite film makes it have strong extinction performance in the visible light and near infrared regions.

[0036] 2. Compared with the single-layer structure of NaYF4 nanoparticles, the rare-earth-doped core-shell structure of NaYF4 nanoparticles of the present invention can, on the one hand, passivate the quenching centers formed by surface defects, thereby reducing the energy loss of activator ions during non-radiative transitions; on the other hand, it can effectively dope activator ions with different luminescence properties into different shells of the same system, achieving spatial isolation of rare-earth ion types and concentrations, thereby suppressing cross-relaxation caused by co-doping or heavy doping of rare-earth ions, and ultimately achieving an enhanced effect on the multiphoton upconversion process.

[0037] 3. The rare earth-doped core-shell structured NaYF4 nanoparticles of this invention are NaYF4:Yb 3+ 30%, Tm 3+ 5%@NaYF4:Yb 3+ (18-22%) Er 3+ 2%; Under the same excitation power, W 18 O 49 Nanowires / MoO 3-x The reinforcing effect of nanosheets on rare-earth-doped core-shell NaYF4 nanoparticles is significantly higher than that of single MoO. 3-x Nanosheets or single W 18 O 49 The role of nanowires.

[0038] 4. The composite thin film with dual plasmon resonance-induced upconversion enhancement of the present invention is easy to prepare, highly reproducible, safe and non-toxic.

[0039] 5. The bipolar-induced upconversion enhanced composite film of the present invention emits light of different colors under different excitation powers, which can be applied to the field of anti-counterfeiting. Attached Figure Description

[0040] Figure 1 MoO in Embodiment 2 of the present invention 3-x Nanosheets (a), W 18 O 49 Nanowires / MoO 3-x Nanosheets (b), rare earth-doped core-shell structured NaYF4 nanoparticles / W 18 O 49 Nanowires / MoO 3-x SEM image of nanosheet (c).

[0041] Figure 2 The core NaYF4:Yb of the NaYF4 nanoparticles in Example 2 of this invention. 3+ ,Tm 3+ Nanoparticles (a), and rare earth-doped core-shell structured NaYF4 nanoparticles Yb 3+ ,Tm3+ @NaYF4:Yb 3+ ,Er 3+ SEM image of (b).

[0042] Figure 3 NaYF4:Yb 3+ ,Tm 3+ @NaYF4:Yb 3+ ,Er 3+ HTEM image (a) and SAED image (b) of.

[0043] Figure 4 MoO 3-x nanosheet, W 18 O 49 nanowire, W 18 O 49 nanowire / MoO 3-x nanosheet.

[0044] Figure 5 NaYF4:Yb 3+ ,Tm 3+ @NaYF4:Yb 3+ ,Er 3+ and NaYF4:Yb 3+ ,Tm 3+ nanoparticles as core under different wavelengths.

[0045] Figure 6 UCL spectra of the composite films with dual-equivalent excitation induced upconversion enhancement in Examples 1, 2 and 3.

[0046] Figure 7 UCL spectra of the individual rare earth doped core-shell structure NaYF4 nanoparticles in Examples 1, 2 and 3.

[0047] Figure 8 Comparison of enhancement factors of the composite films with dual-equivalent excitation induced upconversion enhancement in Examples 1, 2 and 3 under blue light, green light and red light in turn.

[0048] Figure 9 Chromaticity coordinate diagram of the composite films with dual-equivalent excitation induced upconversion enhancement in Example 2 under different excitation light powers.

[0049] Figure 10 Comparison of enhancement factors of the composite films in Example 2, Comparative Example 1 and Comparative Example 2 under blue light, green light and red light in turn.

[0050] Figure 11 The composite film of Example 2 is used as an anti-counterfeiting material for the application of Example 1, blue light emitting pattern at 2190 mW (left), green light emitting pattern at 644 mW (right). DETAILED DESCRIPTION

[0051] The following are specific embodiments of the present application, which further describe the technical solutions of the present application, but the present application is not limited to these embodiments.

[0052] Unless otherwise specified, the materials used in the present application are conventional commercially available products, and the methods used are conventional technical means.

[0053] Example 1

[0054] This embodiment is a composite film of plasmon-induced upconversion enhancement:

[0055] NaYF4:Yb 3+ 30%, Tm 3+ 5% @ NaYF:Yb 3+ 18%, Er 3+ 2% nanoparticles / W 18 O 49 Nanowire / MoO 3-x Nanosheet.

[0056] S1, place 2*3cm FTO glass conductive surface downward into a polytetrafluoroethylene high-pressure reactor (50mL), while weighing 60mg molybdenum powder into 25mL anhydrous ethanol solution, magnetic stirring for 30min, then add 0.94ml H2O2, continue stirring for 30min, after stirring, pour into the reactor, put into a 160℃ oven, keep the temperature for 12h, cool down to room temperature, take out the grown MoO 3-x Nanosheet film glass and rinse with anhydrous ethanol, dry, get MoO 3-x Nanosheet.

[0057] S2, place the FTO glass with grown MoO 3-x Nanosheet downward into a polytetrafluoroethylene high-pressure reactor (50mL), while weighing 25mg tungsten hexacarbonyl into 20mL anhydrous ethanol solution, magnetic stirring for 40min, then pour into the reactor, put into a 160℃ oven, keep the temperature for 12h, cool down to room temperature, take out the grown W 18 O 49 Nanowire / MoO 3-x Nanosheet film glass and rinse with anhydrous ethanol, dry, get W 18 O 49 Nanowire / MoO 3-x Nanosheet.

[0058] S31, Thulium acetate, Ytterbium acetate, Yttrium acetate with a molar ratio of 1:6:139 were weighed and added to a three-neck flask containing 3 mL of oleic acid solution and 7 mL of octadecene solution, fixed on a heating jacket, heated to 140℃, and stirred rapidly to remove water and acetic acid, then cooled to room temperature, a mixed solution of 1 mL of ammonium fluoride (0.4 mol / L) and 4 mL of sodium hydroxide (1 mol / L) was added to the solution, then heated to 50℃ and stirred for 30 min to remove methanol, the temperature was continuously increased to 120℃ and vacuumed for 30 min, then the temperature was increased to 280℃ and kept for 1 h, cooled to room temperature, after the reaction, the obtained product was centrifugally washed with a liquid with a volume ratio of cyclohexane to ethanol of 1:3, and rare earth-doped NaYF4:Yb 3+ ,Tm 3+ nanoparticles (particle size 25 nm) were obtained as the core.

[0059] S32, Erbium acetate, Ytterbium acetate, Yttrium acetate with a molar ratio of 1:8:39 were weighed and added to a three-neck flask containing 3 mL of oleic acid solution and 7 mL of octadecene solution, fixed on a heating jacket, heated to 140℃, and stirred rapidly to remove water and acetic acid, then cooled to room temperature, the above-obtained NaYF4 nanoparticles as the core were added to the solution, a mixed solution of 1 mL of ammonium fluoride (0.4 mol / L) and 4 mL of sodium hydroxide (1 mol / L) was added to the solution, then heated to 50℃ and stirred for 30 min to remove methanol, the temperature was continuously increased to 120℃ and vacuumed for 30 min, then the temperature was increased to 280℃ and kept for 1 h, cooled to room temperature, after the reaction, the obtained product was centrifugally washed with a liquid with a volume ratio of cyclohexane to ethanol of 1:3, and rare earth-doped core-shell structure NaYF4 nanoparticles (particle size 45 nm) were obtained; the obtained product was dispersed in cyclohexane and placed in a glass bottle for storage.

[0060] S33, 200 μL of the NaYF4:Yb 3+ ,Tm 3+ @NaYF4:Yb 3+ ,Er 3+ solution was again dispersed in 10 mL of a cyclohexane solution to obtain a mixed solution, and W 18 O 49 nanowire / MoO 3-x nanosheet film was placed in the solution, and then moved into an oven and heated to 50℃ for 6 h to obtain a composite film with dual plasmonic-induced upconversion enhancement.

[0061] The composite film with dual plasmonic-induced upconversion enhancement in this example had an enhancement factor of 176 under blue light, an enhancement factor of 94 under green light, and an enhancement factor of 112 under red light; the enhancement factors of the three were lower than those in Example 1.

[0062] Example 2

[0063] The present embodiment induces plasmonic upconversion-enhanced composite film:

[0064] NaYF4:Yb 3+ 30% Tm 3+ 5% NaYF:Yb 3+ 20% Er 3+ 2% / W 18 O 49 Nanowire / MoO 3-x Nanosheet.

[0065] Compared with Example 1, the difference lies in that the molar ratio of erbium acetate, ytterbium acetate and yttrium acetate is 1:10:39 in step S32.

[0066] S1, place 2*3cm FTO glass conductive surface downward into a polytetrafluoroethylene high-pressure reactor (50mL), while weighing 60mg molybdenum powder into 25mL anhydrous ethanol solution, magnetically stir for 30min, then add 0.94ml H2O2, and continue to stir for 30min, after stirring, pour into the reactor, put into a 160℃ oven, keep the temperature for 12h, cool down to room temperature, take out the grown MoO 3-x Nanosheet film glass and rinse with anhydrous ethanol, dry, get MoO 3-x Nanosheet; its SEM graph is shown in Figure 1 a.

[0067] S2, place the FTO glass grown with MoO 3-x Nanosheet downward into a polytetrafluoroethylene high-pressure reactor (50mL), while weigh 25mg tungsten hexacarbonyl into 20mL anhydrous ethanol solution, magnetically stir for 40min, then pour into the reactor, put into a 160℃ oven, keep the temperature for 12h, cool down to room temperature, take out the grown W 18 O 49 Nanowire / MoO 3-x Nanosheet film glass and rinse with anhydrous ethanol, dry, get W 18 O 49 Nanowire / MoO 3-x Nanosheet; its SEM graph is shown in Figure 1 b.

[0068] S31, Th (III) acetate, Yb (III) acetate, Y (III) acetate with a molar ratio of 1:6:139 were weighed and added into a three-neck flask containing 3 mL of oleic acid solution and 7 mL of octadecene solution, fixed on a heating mantle, heated to 140°C, and stirred rapidly to remove water and acetic acid, then cooled to room temperature, a mixed solution containing 1 mL of ammonium fluoride (0.4 mol / L) and 4 mL of sodium hydroxide (1 mol / L) was added into the solution, then heated to 50°C and stirred for 30 min to remove methanol, the temperature was continuously increased to 120°C and vacuumized for 30 min, then the temperature was increased to 280°C and kept for 1 h, cooled to room temperature, and the obtained product was centrifugally washed with cyclohexane and ethanol (1:3 by volume) to obtain rare earth-doped NaYF4:Yb 3+ ,Tm 3+ nanoparticles (25 nm in diameter); the SEM image thereof is shown in Figure 2 a.

[0069] S32, Er (III) acetate, Yb (III) acetate, Y (III) acetate with a molar ratio of 1:9:40 were weighed and added into a three-neck flask containing 3 mL of oleic acid solution and 7 mL of octadecene solution, fixed on a heating mantle, heated to 140°C, and stirred rapidly to remove water and acetic acid, then cooled to room temperature, the obtained NaYF4 nanoparticles as the core were added into the solution, a mixed solution containing 1 mL of ammonium fluoride (0.4 mol / L) and 4 mL of sodium hydroxide (1 mol / L) was added into the solution, then heated to 50°C and stirred for 30 min to remove methanol, the temperature was continuously increased to 120°C and vacuumized for 30 min, then the temperature was increased to 280°C and kept for 1 h, cooled to room temperature, and the obtained product was centrifugally washed with cyclohexane and ethanol (1:3 by volume) to obtain rare earth-doped core-shell structure NaYF4 nanoparticles (45 nm in diameter); the SEM image thereof is shown in Figure 2 b; the obtained product was dispersed in cyclohexane and placed in a glass bottle for storage.

[0070] S33, 200 μL of the NaYF4:Yb 3+ ,Tm 3+ @NaYF4:Yb 3+ ,Er 3+ solution was again dispersed into 10 mL of a cyclohexane solution to obtain a mixed solution, and the W 18 O 49 nanowire / MoO 3-x nanosheet film was placed in the solution, and then transferred into an oven and heated to 50°C for 6 h to obtain a composite film with enhanced dual-equivalent excitation induced upconversion; the SEM image thereof is shown in Figure 1 c.

[0071] Figure 3The HTEM image and the SAED image of the rare earth doped core-shell structure NaYF4 nanoparticles are shown in the following figure;

[0072] Figure 4 The MoO 3-x nanosheet, W 18 O 49 nanowire, W 18 O 49 nanowire / MoO 3-x nanosheet. The extinction spectrum of the nanosheet can be known that the W 18 O 49 nanowire / MoO 3-x nanosheet has stronger light absorption intensity and light absorption capacity.

[0073] Figure 5 The fluorescence spectrum of the double-equivalent excitation induced upconversion enhanced composite film under 980nm laser excitation can be known that, compared with the rare earth doped core-shell structure NaYF4 nanoparticles alone, the double-equivalent excitation induced upconversion enhanced composite film has better upconversion luminescence enhancement;

[0074] Figure 6 The UCL spectrum of the double-equivalent excitation induced upconversion enhanced composite film under 980nm excitation is shown in the following figure, Figure 7 The UCL spectrum of the double-equivalent excitation induced upconversion enhanced composite film under 980nm excitation is shown in the following figure, Figure 6 、 7 It can be known by comparison that Figure 8 , Figure 8 The enhancement factors of the double-equivalent excitation induced upconversion enhanced composite film under blue light, green light and red light are shown in the following table, the enhancement factor of the double-equivalent excitation induced upconversion enhanced composite film in the embodiment under blue light is 337, the enhancement factor under green light is 236, and the enhancement factor under red light is 249.

[0075] Figure 9 The chromaticity coordinates of the composite film under different excitation light powers are shown in the following table.

[0076] Embodiment 3

[0077] The double-equivalent excitation induced upconversion enhanced composite film in the embodiment has the following characteristics:

[0078] NaYF4:Yb 3+ 30%, Tm 3+ 5% @ NaYF:Yb 3+ 22%, Er 3+ 2% / W 18 O 49 nanowire / MoO 3-x nanosheet.

[0079] The difference compared with Example 1 is that the molar ratio of erbium acetate, ytterbium acetate, and yttrium acetate in step S32 is 1:11:38.

[0080] S1, place 2*3cm FTO glass conductive surface downward into a polytetrafluoroethylene high-pressure reactor (50mL), while weighing 60mg of molybdenum powder into a 25mL anhydrous ethanol solution, magnetically stir for 30min, then add 0.94ml H2O2, and continue to stir for 30min, after stirring, pour into the reactor, put into a 160℃ oven, keep the temperature for 12h, cool down to room temperature, take out the grown MoO 3-x nanoparticle film glass, rinse with anhydrous ethanol, dry, and obtain MoO 3-x nanoparticle.

[0081] S2, place the FTO glass grown with MoO 3-x nanoparticle with the growth surface downward into a polytetrafluoroethylene high-pressure reactor (50mL), while weighing 25mg of tungsten hexacarbonyl into a 20mL anhydrous ethanol solution, magnetically stir for 40min, then pour into the reactor, put into a 160℃ oven, keep the temperature for 12h, cool down to room temperature, take out the grown W 18 O 49 nanowire / MoO 3-x nanoparticle film glass, rinse with anhydrous ethanol, dry, and obtain W 18 O 49 nanowire / MoO 3-x nanoparticle.

[0082] S31, weigh terbium acetate, ytterbium acetate, and yttrium acetate with a molar ratio of 1:6:139 into a three-necked flask containing 3mL of oleic acid solution and 7mL of octadecene solution, fix it on a heating jacket, heat to 140℃, and stir quickly to remove water and acetic acid, then cool to room temperature, add a mixed solution containing 1mL of ammonium fluoride (0.4mol / L) and 4mL of sodium hydroxide (1mol / L) to the solution, then heat to 50℃ and stir for 30min to remove methanol, continue to heat to 120℃ and vacuum for 30min, then heat to 280℃ for 1h, cool to room temperature, after reaction, centrifugal wash the obtained product with a liquid mixture of cyclohexane and ethanol with a volume ratio of 1:3, and obtain rare earth-doped NaYF4:Yb 3+ ,Tm 3+ nanoparticles (particle size 24nm).

[0083] S32, again, the molar ratio of 1:11:38 of erbium acetate, ytterbium acetate, yttrium acetate is mixed into a three-necked flask with 3 mL of oleic acid solution and 7 mL of octadecene solution, fixed on a heating jacket, heated to 140°C, and rapidly stirred to remove water and acetic acid, then reduced to room temperature to add the above obtained NaYF4 nanoparticles as the core to the solution, and add a mixed solution of 1 mL of ammonium fluoride (0.4 mol / L) and 4 mL of sodium hydroxide (1 mol / L) dissolved in the solution, then heated to 50°C and stirred for 30 min to remove methanol, continue to increase the temperature to 120°C and vacuum for 30 min, then increase the temperature to 280°C and keep for 1 h, cool down to room temperature, after reaction, the obtained product is centrifuged and washed with liquid of cyclohexane and ethanol in a volume ratio of 1:3 to obtain rare earth doped core-shell structure NaYF4 nanoparticles (particle size 46 nm); the obtained product is dispersed in cyclohexane and stored in a glass bottle.

[0084] S33, take 200 μL of NaYF4:Yb 3+ ,Tm 3+ @NaYF4:Yb 3+ ,Er 3+ solution again dispersed in 10 mL of cyclohexane solution to obtain a mixed solution, and W 18 O 49 nanowire / MoO 3-x nanoplate film is placed in the solution, and then moved into an oven and heated to 50°C for 6 h to obtain a double-equivalent excitation induced upconversion enhanced composite film.

[0085] The double-equivalent excitation induced upconversion enhanced composite film of the present example has an enhancement factor of 152 under blue light, 85 under green light, and 117 under red light; the enhancement factors of the three in the present example are lower than those of Example 1, and are similar to those of Example 2.

[0086] Comparative Example 1

[0087] The composite film in the present comparative example is composed of Yb 3+ ,Tm 3+ @NaYF4:Yb 3+ ,Er 3+ NaYF4 nanoparticles / W 18 O 49 nanowire.

[0088] Compared with Example 1, the difference is that W 18 O 49 nanowire is directly grown on the FTO substrate, and then immersed in a cyclohexane mixed solution of Tm 3+ @NaYF4:Yb 3+ ,Er 3+ .

[0089] S1, 2*3cm FTO glass conductive surface downward into polytetrafluoroethylene high pressure reactor (50mL), while weighing 25mg tungsten carbonyl added to 20mL anhydrous ethanol solution, magnetic stirring 40min, pour into the reactor, put into the oven at 160℃, keep the temperature 12h cooling to room temperature, remove the growth of W 18 O 49 nanowire / MoO 3-x nanosheet film glass and anhydrous ethanol, drying, W 18 O 49 nanowire / MoO 3-x nanosheet.

[0090] S21, weighing the molar ratio of 1:6:139 thulium acetate, ytterbium acetate, yttrium acetate added to the three necked flask dissolved in 3mL oleic acid solution and 7mL octadecene solution, fixed on the heating jacket, heated to 140℃, and fast stirring, remove water and acetic acid, then reduced to room temperature to the solution added to the mixed solution dissolved in 1mL ammonium fluoride (0.4mol / L) and 4mL sodium hydroxide (1mol / L), then heated to 50℃ and stirring for 30min to remove methanol, continue to increase the temperature to 120℃ and vacuum for 30min, then the temperature rises to 280℃ for 1h, cooling to room temperature, after the reaction the product obtained by centrifugal washing with cyclohexane and ethanol volume ratio of 1:3 to obtain rare earth doped as the core of NaYF4:Yb 3+ ,Tm 3+ nanoparticles.

[0091] S22, again weighing the molar ratio of 1:9:40 of erbium acetate, ytterbium acetate, yttrium acetate mixed added to the three necked flask dissolved in 3mL oleic acid solution and 7mL octadecene solution, fixed on the heating jacket, heated to 140℃, and fast stirring, remove water and acetic acid, then reduced to room temperature to the solution added to the above obtained as the core of NaYF4 nanoparticles, to the solution added to the mixed solution dissolved in 1mL ammonium fluoride (0.4mol / L) and 4mL sodium hydroxide (1mol / L), then heated to 50℃ and stirring for 30min to remove methanol, continue to increase the temperature to 120℃ and vacuum for 30min, then the temperature rises to 280℃ for 1h, cooling to room temperature, after the reaction the product obtained by centrifugal washing with cyclohexane and ethanol volume ratio of 1:3 to obtain rare earth doped core shell structure NaYF4 nanoparticles; the product obtained is dispersed in cyclohexane into a glass bottle for storage.

[0092] S23, take 200μL of NaYF4:Yb 3+ ,Tm 3+ @NaYF4:Yb 3+,Er 3+ The solution was again dispersed into 10 mL cyclohexane solution to obtain a mixed solution, and W 18 O 49 The nanowire film was placed in the solution and then moved into an oven to be heated to 50°C for 6 h to obtain a composite film.

[0093] Figure 10 The enhancement factors of the composite film of the present comparative example under blue light, green light and red light were 59, 21 and 35, respectively, which were 17.5%, 8.9% and 14.1% of those of Example 2.

[0094] The enhancement factors of the composite film of the present comparative example under blue light, green light and red light were 59, 21 and 35, respectively, which were 17.5%, 8.9% and 14.1% of those of Example 2.

[0095] Comparative Example 2

[0096] The composite film in the present comparative example was composed of Yb 3+ ,Tm 3+ @NaYF4:Yb 3+ ,Er 3+ nanoparticles / MoO 3-x nanosheets.

[0097] Compared with Example 1, the difference was that the FTO substrate on which MoO 3-x nanosheets were grown was directly immersed in a cyclohexane mixed solution of Tm 3+ @NaYF4:Yb 3+ ,Er 3+ .

[0098] S1, 2*3cm FTO glass was placed into a polytetrafluoroethylene high-pressure reaction kettle (50mL) with the conductive surface facing down, and 60mg of molybdenum powder was weighed and added to a 25mL anhydrous ethanol solution, and then magnetically stirred for 30min, 0.94ml H2O2 was added, and then the stirring was continued for 30min, after the stirring was completed, it was poured into the reaction kettle, and then placed into an oven at 160°C, and the temperature was kept for 12h, and then cooled to room temperature, and then the MoO 3-x nanosheet film glass was taken out and washed with anhydrous ethanol and dried to obtain MoO 3-x nanosheets.

[0099] S21, Thulium acetate, Ytterbium acetate, Yttrium acetate in a molar ratio of 1:6:139 were weighed and added to a three-necked flask containing 3 mL of oleic acid solution and 7 mL of octadecene solution, fixed on a heating mantle, and heated to 140°C with rapid stirring to remove water and acetic acid, and then cooled to room temperature. A mixed solution of 1 mL of ammonium fluoride (0.4 mol / L) and 4 mL of sodium hydroxide (1 mol / L) was added to the solution, and then heated to 50°C with stirring for 30 min to remove methanol. The temperature was further increased to 120°C and vacuumed for 30 min, and then the temperature was increased to 280°C for 1 h. After cooling to room temperature, the obtained product was washed with cyclohexane and ethanol (1:3 by volume) by centrifugation to obtain rare earth-doped NaYF4:Yb 3+ ,Tm 3+ nanoparticles.

[0100] S22, Erbium acetate, Ytterbium acetate, Yttrium acetate in a molar ratio of 1:9:40 were weighed and added to a three-necked flask containing 3 mL of oleic acid solution and 7 mL of octadecene solution, fixed on a heating mantle, and heated to 140°C with rapid stirring to remove water and acetic acid, and then cooled to room temperature. The obtained NaYF4 nanoparticles as a core were added to the solution, and a mixed solution of 1 mL of ammonium fluoride (0.4 mol / L) and 4 mL of sodium hydroxide (1 mol / L) was added to the solution, and then heated to 50°C with stirring for 30 min to remove methanol. The temperature was further increased to 120°C and vacuumed for 30 min, and then the temperature was increased to 280°C for 1 h. After cooling to room temperature, the obtained product was washed with cyclohexane and ethanol (1:3 by volume) by centrifugation to obtain rare earth-doped core-shell structure NaYF4 nanoparticles. The obtained product was dispersed in cyclohexane and stored in a glass bottle.

[0101] S23, 200 μL of the NaYF4:Yb 3+ ,Tm 3+ @NaYF4:Yb 3+ ,Er 3+ solution was again dispersed in 10 mL of a cyclohexane solution to obtain a mixed solution. MoO 3-x nanosheet film was placed in the solution, and then moved into an oven and heated to 50°C for 6 h to obtain a composite film.

[0102] Figure 10 The enhancement factors of the composite film of the present comparative example in blue light, green light, and red light.

[0103] The enhancement factors of the composite film of the present comparative example in blue light, green light, and red light were 80, 44, and 41, respectively, which were 23.7%, 18.6%, and 24.5% of those of Example 2.

[0104] Comparative Example 3

[0105] The composite film of the present comparative example in which the double isobal induced upconversion is enhanced:

[0106] NaYF4:Yb 3+ 30% Tm 3+ 5% nanoparticles / W 18 O 49 Nanowire / MoO 3-x Nanoplatelets;

[0107] The difference compared with Example 1 is that the nanoparticles are non-core-shell structure.

[0108] S1, place 2*3cm FTO glass conductive surface downward into a polytetrafluoroethylene high-pressure reactor (50mL), while weighing 60mg molybdenum powder into 25mL anhydrous ethanol solution, after magnetic stirring for 30min, add 0.94ml H2O2, then continue stirring for 30min, after stirring, pour into the reactor, put into a 160℃ oven, keep the temperature for 12h, cool down to room temperature, take out the grown MoO 3-x nanoplatelet film glass and rinse with anhydrous ethanol, dry, get MoO 3-x nanoplatelets.

[0109] S2, place the FTO glass grown with MoO 3-x nanoplatelets conductive surface downward into a polytetrafluoroethylene high-pressure reactor (50mL), while weighing 25mg tungsten hexacarbonyl into 20mL anhydrous ethanol solution, after magnetic stirring for 40min, pour into the reactor, put into a 160℃ oven, keep the temperature for 12h, cool down to room temperature, take out the grown W 18 O 49 Nanowire / MoO 3-x Nanoplatelet film glass and rinse with anhydrous ethanol, dry, get W 18 O 49 Nanowire / MoO 3-x Nanoplatelets.

[0110] S31, weigh thulium acetate, ytterbium acetate and yttrium acetate with a molar ratio of 1:6:139 into a three-necked flask containing 3mL oleic acid solution and 7mL octadecene solution, fix it on a heating jacket, heat to 140℃ and stir quickly, remove water and acetic acid, then cool to room temperature, add a mixed solution containing 1mL ammonium fluoride (0.4mol / L) and 4mL sodium hydroxide (1mol / L) to the solution, then heat to 50℃ and stir for 30min to remove methanol, continue to heat to 120℃ and vacuum for 30min, then heat to 280℃ for 1h, cool down to room temperature, after reaction, centrifugal wash the obtained product with liquid cyclohexane and ethanol with a volume ratio of 1:3, get rare earth doped NaYF4:Yb 3+ ,Tm3+ The obtained product is dispersed in cyclohexane and stored in a glass bottle.

[0111] S33, 200 μL of NaYF4:Yb 3+ ,Tm 3+ The solution is again dispersed in 10 mL of a cyclohexane solution to obtain a mixed solution, and the W 18 O 49 Nanowires / MoO 3-x The nanosheet film is placed in a solution and then moved into an oven to be warmed to 50°C for 6 h to obtain a composite film with dual isobestic point induced upconversion enhancement.

[0112] The composite film of the present comparative example has an enhancement factor of 138, 61 and 101 for blue light, green light and red light, respectively, which are 40.9%, 25.8% and 40.6% of those of Example 2.

[0113] Application Example 1

[0114] The composite film with dual isobestic point induced upconversion enhancement prepared in Example 2 is used as an anti-fake material and can be attached to the surface of paper, card and other materials.

[0115] Figure 11 It is shown that under the excitation of a diode with a wavelength of 980 nm, the blue light emission map under an excitation power of 2190 mW (left) and the green light emission map under an excitation power of 644 mW (right) prove that the composite film with dual isobestic point induced upconversion enhancement can be used in the field of anti-fake.

[0116] In addition, according to Figure 8 It can be known that when the Yb 3+ doping amount is 20%, the enhancement factor is the largest under the wavelength of 400-750 nm.

[0117] According to Figure 9 , 11 It can be known that the composite film with dual isobestic point induced upconversion enhancement changes from blue to green under the excitation power of 2190 mW-664 mW when the wavelength is 980 nm.

[0118] According to Figure 10 It can be known that compared with the single MoO 3-x nanosheet and W 18 O 49 nanowire, the enhancement effect of the plasmon of the composite of the two on the rare earth doped core-shell structure NaYF4 nanoparticles is better.

[0119] In summary, the MoO 3-x nanosheet and W 18 O​49 The nanowire and the rare earth doped core-shell structure NaYF4 nanoparticles self-assembled thereon make the composite film exhibit better upconversion luminescence enhancement; and the composite film emits light of different colors under different excitation powers.

[0120] The specific embodiments described herein are merely illustrative of the principles of this application. Numerous modifications or adaptations will be readily apparent to those skilled in the art of the present application without departing from the spirit or scope of the present application as defined by the following claims.

Claims

1. A method for preparing a composite film with dual plasmon-induced upconversion enhancement, characterized in that, The preparation method comprises: S1, MoO 3-x Preparation of nanosheets: MoO 3-x nanosheets; S2, W 18 O 49 nanowire / MoO 3-x Preparation of nanosheets: The second hydrothermal reaction was carried out after dissolving tungsten hexacarbonyl in anhydrous ethanol, and the hydrothermal reaction was carried out in a reaction kettle placed with MoO 3-x in the reaction kettle of nanosheet; S3, rare earth doped core-shell structure NaYF4 nanoparticles / W 18 O 49 nanowires / MoO 3-x Preparation of nanosheets: S31, the first group of composite rare earth acetate is mixed with oleic acid and octadecene, and then stirred and heated, and after cooling, ammonium fluoride and sodium hydroxide are added, and the first temperature heating is carried out, and after vacuumizing, the second temperature heating is carried out, and then the NaYF4 nanoparticles as the core are obtained; The first group of composite rare earth acetate in step S31 is thulium acetate, ytterbium acetate and yttrium acetate with a molar ratio of 1:6:139; S32, the second group of composite rare earth acetate is mixed with oleic acid and octadecene, and then stirred and heated, and after cooling, the NaYF4 nanoparticles as the core, ammonium fluoride and sodium hydroxide are added, and the first temperature heating is carried out, and after vacuumizing, the second temperature heating is carried out, and then the rare earth doped core-shell structure NaYF4 nanoparticles are obtained; The second group of composite rare earth acetate in step S32 is erbium acetate, ytterbium acetate and yttrium acetate with a molar ratio of 1:(9-11):(38-39); S33, dispersing the rare earth doped core-shell structure NaYF4 nanoparticles in a cyclohexane solution, mixing uniformly, and then placing into the W 18 O 49 FTO substrate for self-assembly of nanowires / MoO 3-x nanoplatelets, and then heating and keeping warm to obtain.

2. The method of claim 1, wherein the method is performed by the steps of: The mass ratio of the molybdenum powder and the tungsten hexacarbonyl is (2-3):

1.

3. The method of claim 1, wherein the method further comprises: The first temperature heating in step S31 has the same temperature as the first temperature heating in step S32, and the second temperature heating in step S31 has the same temperature and time as the second temperature heating in step S32.

4. The method for preparing the composite thin film with bipolar-induced upconversion enhancement according to claim 1 or 3, characterized in that, The first temperature heating is 110-125℃, and the second temperature heating is 260-290℃, and the time is 0.5-2h.

5. A composite film for bi-excitonic induced upconversion enhancement, characterized in that, The double-equiaxed-inducing upconversion-enhanced composite film is prepared by the preparation method of the double-equiaxed-inducing upconversion-enhanced composite film according to any one of claims 1-4.

6. The dual plasmon-induced upconversion-enhanced composite film according to claim 5, wherein, The composite thin film is a rare earth doped core-shell structure NaYF4 nanoparticle / W 18 O 49 Nanowire / MoO 3-x Nanosheet; in the rare earth doped core-shell structure NaYF4 nanoparticle, NaYF4:Yb 3+ 30%, Tm 3+ 5% @ NaYF4:Yb 3+ (18~22%), Er 3+ 2%.

7. The dual plasmon-induced upconversion-enhanced composite thin film according to claim 5, wherein, The particle size of the rare earth doped core-shell structure NaYF4 nanoparticles is 25-45nm.

8. Use of the double plasmon-induced upconversion enhanced composite film according to claim 5 in the field of anti-counterfeiting. Under the same wavelength, the double-equiaxed-inducing upconversion-enhanced composite film emits different colors of light under different excitation powers.

9. Use of the dual plasmon-induced upconversion-enhanced composite film according to claim 8 in the field of anti-counterfeiting, characterized in that, Under the excitation of a 980nm diode, the double-equiaxed-inducing upconversion-enhanced composite film emits visible blue light under an excitation power of 2190mW, and emits visible green light under an excitation power of 644mW.

10. Use of the dual plasmon-induced upconversion enhanced composite film according to claim 8 in the field of anti-counterfeiting, characterized in that, The double-equiaxed-inducing upconversion-enhanced composite film emits light with a color changing from blue to green under an excitation power of 2190mW-664mW when the wavelength is 980nm.

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