阅读说明：本技术 用于调制太阳光谱的金纳米棒-单层上转换纳米颗粒复合薄膜及其制备方法 (Gold nanorod-single layer up-conversion nanoparticle composite film for modulating solar spectrum and preparation method thereof ) 是由 林林 戴琼花 郑志强 冯卓宏 王哲哲 于 2020-07-24 设计创作，主要内容包括：本发明公开了用于调制太阳光谱的金纳米棒-单层上转换纳米颗粒复合薄膜及其制备方法,所述复合薄膜为CAu&NaYF<Sub>4</Sub>:Er<Sup>3+</Sup>,Yb<Sup>3+</Sup>@NaYF<Sub>4</Sub>单层纳米复合薄膜。所述方法为首先制备NaYF<Sub>4</Sub>:Er<Sup>3+</Sup>,Yb<Sup>3+</Sup>@NaYF<Sub>4</Sub>溶液,加入甲苯和PMMA的甲苯溶液,然后将混合溶液滴加在硅片上,用旋涂法制得单层膜,干燥后在膜上滴加CAu,吹打干燥,得到CAu&NaYF<Sub>4</Sub>:Er<Sup>3+</Sup>,Yb<Sup>3+</Sup>@NaYF<Sub>4</Sub>单层纳米复合薄膜。将该纳米复合薄膜做成光转换层放置在太阳能电池上,可以将太阳能电池响应差的低能光子转换为与太阳能电池频率匹配的高能光子,进而提高太阳能电池的光电转换效率。(The invention discloses gold nanorod-monolayer up-conversion nanoparticles for modulating solar spectrumCAu composite film and preparation method thereof&NaYF 4 :Er 3+ ,Yb 3+ @NaYF 4 A single layer nanocomposite film. The method is to prepare NaYF firstly 4 :Er 3+ ,Yb 3+ @NaYF 4 Adding toluene solution of toluene and PMMA, dripping the mixed solution on a silicon wafer to obtain a single-layer film by using a spin coating method, dripping CAu on the film after drying, and blowing and drying to obtain CAu&NaYF 4 :Er 3+ ,Yb 3+ @NaYF 4 A single layer nanocomposite film. The nano composite film is made into a light conversion layer and is placed on the solar cell, so that low-energy photons with poor response of the solar cell can be converted into high-energy photons with the frequency matched with the frequency of the solar cell, and the photoelectric conversion efficiency of the solar cell is improved.)

1. CAu for modulating the solar spectrum&NaYF₄:Er³⁺,Yb³⁺@NaYF₄The preparation method of the single-layer nano composite film is characterized by comprising the following steps: which comprises the following steps:

a: preparation of NaYF₄:Er³⁺,Yb³⁺Nanoparticles

A-1: weighing RECl with the total amount of 2mmol according to the molar ratio₃•6H₂O, RE = Y/Er/Yb, 12 mL of oleic acid and 30 mL of 1-octadecene are added, the mixed solution is vacuumized and heated to 125-135 ℃, and the mixed solution is naturally cooled to room temperature after being kept for 40-45 min, so as to obtain a solution A;

a-2: 0.2000 g of NaOH and 0.2963 g of NH were weighed out₄F, dissolving in methanol, dropwise adding the mixed methanol solution into the solution A, stirring at room temperature for 30-40min, heating to 62-63 ℃ under the argon atmosphere to distill out the methanol, then heating to 300-320 ℃, maintaining for 1-1.2 hours, and then cooling to room temperature to obtain a solution B;

a-3: centrifuging the solution B, and ultrasonically cleaning particles obtained after centrifugation to obtain NaYF₄:Er³⁺,Yb³⁺Nanoparticles, finally dispersed in cyclohexane;

b: preparation of NaYF₄:Er³⁺,Yb³⁺@NaYF₄Nanoparticles

B-1: weighing 2mmol YCl₃•6H₂O, adding 12 mL of oleic acid and 30 mL of 1-octadecene, vacuumizing the mixed solution, heating to 125-135 ℃, keeping the temperature for 40-45 min, and naturally cooling to room temperature to obtain a solution C;

b-2: the NaYF obtained in the step A-3₄:Er³⁺,Yb³⁺Dropwise adding the nanoparticles into the solution C, stirring at room temperature for 30-40min, heating to 62-63 ℃ under the argon atmosphere to distill out methanol, then heating to 300-320 ℃, maintaining for 40-50 min, and cooling to room temperature to obtain a solution D;

b-3: 0.2000 g of NaOH and 0.2963 g of NH were weighed out₄F, dissolving the mixed methanol solution in a methanol solution, dropwise adding the mixed methanol solution into the solution D to obtain an emulsion, stirring at room temperature for 30-40min, heating to 62-63 ℃ under an argon atmosphere to distill off methanol, then heating to 300-320 ℃, maintaining for 1-1.2 hours, and then cooling to room temperature to obtain a solution E;

b-4: centrifuging the solution E, and ultrasonically cleaning particles obtained after centrifugation to obtain NaYF₄:Er³⁺,Yb³⁺@NaYF₄Dispersing the nano particles in cyclohexane to obtain NaYF₄:Er³⁺,Yb³⁺@NaYF₄A solution;

c: preparation CAu

C-1: preparing a growth solution:

weighing 7 g of CTAB and 1.234 g of NaOL, pouring into a conical flask, adding 250 mL of deionized water, stirring for 20-30min, standing the mixed solution in a drying oven at 28-32 ℃ for 15-20 min;

② Erlenmeyer flask was charged with 24 mL of AgNO₃Standing the mixed solution in a drying oven at 28-32 deg.C for 15-20 min;

③ into the Erlenmeyer flask was added 250 mL of HAuCl₄Solution, stirring the obtained solution at the rotating speed of 700-800 rpm for 90-110 min to obtain growth liquid;

c-2: preparing seeds:

① mix 5 mL of HAuCl₄Mixing the solution and 5 mL CTAB solution into a 15 mL centrifuge tube;

② Add 600. mu.L of NaBH to the 15 mL centrifuge tube₄Uniformly shaking the ice water solution, and placing the ice water solution into a drying box at the temperature of 28-32 ℃ for 30-40min to obtain seed liquid;

c-3: adding the reagent dropwise to prepare CAu

Adding 37 wt% of HCl into the growth solution, and uniformly stirring for one time;

adding 1.25 mL of AA solution into the conical flask, and uniformly stirring for the second time;

③ adding 0.4 mL of prepared seed liquid into the conical flask, stirring evenly for three times, and then placing the conical flask into a drying oven at 28-32 ℃ for 12-14 h to obtain CAu;

D. the preparation of the nano-composite system is carried out,

2mmol of NaYF is taken₄:Er³⁺,Yb³⁺@NaYF₄500 mu L of solution is centrifuged, 1.8 mL of toluene and 0.2mL of PMMA toluene solution are added after supernatant is removed, ultrasonic dispersion is uniform, the mixed solution is dripped on a cleaned silicon wafer, a single-layer film is prepared by a spin coating method, CAu is dripped on the film after natural drying, and blowing and drying are carried out to obtain CAu&NaYF₄:Er³⁺,Yb³⁺@NaYF₄A single layer nanocomposite film.

2. CAu for modulating the solar spectrum according to claim 1&NaYF₄:Er³⁺,Yb³⁺@NaYF₄The preparation method of the single-layer nano composite film is characterized by comprising the following steps: in the step A-3 and the step B-4, the centrifugation is carried out for 15-20min at the rotating speed of 9000-10000rpm, and the cleaning takes absolute ethyl alcohol as a cleaning solution.

3. CAu for modulating the solar spectrum according to claim 1&NaYF₄:Er³⁺,Yb³⁺@NaYF₄The preparation method of the single-layer nano composite film is characterized by comprising the following steps: in step C-1, the AgNO₃The molar concentration of the solution is 4 mM, and the HAuCl is₄The molarity of the solution was 1 mM.

4. CAu for modulating the solar spectrum according to claim 1&NaYF₄:Er³⁺,Yb³⁺@NaYF₄The preparation method of the single-layer nano composite film is characterized by comprising the following steps: in step C-2, the HAuCl₄The molarity of the solution was 0.5 mM, the molarity of the CTAB solution was 0.2M, and the NaBH was added₄The molar concentration of the ice-water solution was 0.01M.

5. CAu for modulating the solar spectrum according to claim 1&NaYF₄:Er³⁺,Yb³⁺@NaYF₄The preparation method of the single-layer nano composite film is characterized by comprising the following steps: in the step C-3, the molar concentration of the AA solution is 0.064M, the primary stirring is carried out for 15-20min at the rotating speed of 350-1600 rpm, and the secondary stirring is carried out for 30-35 s at the rotating speed of 1400-1600 rpm; the three times of stirring are evenly stirred for 30-35 s at the rotating speed of 1400-1600 rpm.

6. CAu for modulating the solar spectrum according to claim 1&NaYF₄:Er³⁺,Yb³⁺@NaYF₄The preparation method of the single-layer nano composite film is characterized by comprising the following steps: in the step D, the centrifugation is carried out for 15-20min at the rotating speed of 9000-11000 rpm, and the concentration of the PMMA toluene solution is 10 mg/mL.

7. CAu for modulating the solar spectrum according to claim 1&NaYF₄:Er³⁺,Yb³⁺@NaYF₄The preparation method of the single-layer nano composite film is characterized by comprising the following steps: in the step D, during spin coating, the spin coating is performed for 5 s at a rotation speed of 600rpm, and then the spin coating is performed for 30 s at a rotation speed of 2000 rpm.

8. CAu obtained by the process according to any one of claims 1 to 7&NaYF₄:Er³⁺,Yb³⁺@NaYF₄A single layer nanocomposite film.

9. CAu according to claim 8&NaYF₄:Er³⁺,Yb³⁺@NaYF₄A single layer nanocomposite film characterized by: the effective excitation wavelength of the composite film is 980 nm.

10. The CAu of claim 8&NaYF₄:Er³⁺,Yb³⁺@NaYF₄The application of the single-layer nano composite film in a solar cell.

Technical Field

The invention relates to the technical field of composite nano materials, in particular to a gold nanorod-single layer up-conversion nano particle composite film for modulating solar spectrum and a preparation method thereof.

Background

Upconversion refers to the phenomenon of converting two or more low energy photons into one high energy photon. The single-layer nanoparticle film made of the up-conversion material is placed on the solar cell, so that the high transmittance of photons with other wavelengths can be ensured, the film can be efficiently utilized by the solar cell, and the film can not be absorbed by the film, and the photoelectric conversion efficiency of the solar cell is effectively improved. However, the conventional up-conversion materials have weak emission intensity as a light conversion layer.

Disclosure of Invention

The invention aims to solve the problem that the traditional up-conversion material is used as a light conversion layer and has weak luminous intensity, and provides a gold nanorod-single layer up-conversion nanoparticle composite film for modulating solar spectrum and a preparation method thereof, wherein the nano composite film is CAu&NaYF₄:Er³⁺,Yb³⁺@NaYF₄A single layer nanocomposite film.

In order to achieve the purpose, the technical scheme of the invention is as follows:

CAu for modulating the solar spectrum&NaYF₄:Er³⁺,Yb³⁺@NaYF₄The preparation method of the single-layer nano composite film comprises the following steps:

a: preparation of NaYF₄:Er³⁺,Yb³⁺Nanoparticles

A-1: weighing RECl with the total amount of 2mmol according to the molar ratio₃•6H₂O, RE = Y/Er/Yb, 12 mL of oleic acid and 30 mL of 1-octadecene are added, the mixed solution is vacuumized and heated to 125-135 ℃, and the mixed solution is naturally cooled to room temperature after being kept for 40-45 min, so as to obtain a solution A;

a-2: 0.2000 g of NaOH and 0.2963 g of NH were weighed out₄F, dissolving in methanol, dropwise adding the mixed methanol solution into the solution A, stirring at room temperature for 30-40min, heating to 62-63 ℃ under the argon atmosphere to distill out the methanol, then heating to 300-320 ℃, maintaining for 1-1.2 hours, and then cooling to room temperature to obtain a solution B;

a-3: centrifuging the solution B, and ultrasonically cleaning particles obtained after centrifugation to obtain NaYF₄:Er³⁺,Yb³⁺Nanoparticles, finally dispersed in cyclohexane;

b: preparation of NaYF₄:Er³⁺,Yb³⁺@NaYF₄Nanoparticles

B-1: weighing 2mmol YCl₃•6H₂O, adding 12 mL of oleic acid and 30 mL of 1-octadecene, vacuumizing the mixed solution, heating to 125-135 ℃, keeping the temperature for 40-45 min, and naturally cooling to room temperature to obtain a solution C;

b-2: the NaYF obtained in the step A-3₄:Er³⁺,Yb³⁺Dropwise adding the nanoparticles into the solution C, stirring at room temperature for 30-40min, heating to 62-63 ℃ under the argon atmosphere to distill out methanol, then heating to 300-320 ℃, maintaining for 40-50 min, and cooling to room temperature to obtain a solution D;

b-3: 0.2000 g of NaOH and 0.2963 g of NH were weighed out₄F, dissolving the mixed methanol solution in a methanol solution, dropwise adding the mixed methanol solution into the solution D to obtain an emulsion, stirring at room temperature for 30-40min, heating to 62-63 ℃ under an argon atmosphere to distill off methanol, then heating to 300-320 ℃, maintaining for 1-1.2 hours, and then cooling to room temperature to obtain a solution E;

b-4: centrifuging the solution E, and ultrasonically cleaning particles obtained after centrifugation to obtain NaYF₄:Er³⁺,Yb³⁺@NaYF₄Dispersing the nano particles in cyclohexane to obtain NaYF₄:Er³⁺,Yb³⁺@NaYF₄A solution;

c: preparation CAu

C-1: preparing a growth solution:

weighing 7 g of CTAB (cetyl trimethyl ammonium bromide) and 1.234 g of NaOL (sodium oleate) and pouring into a conical flask, adding 250 mL of deionized water, stirring for 20-30min, standing the mixed solution in a drying oven at 28-32 ℃ for 15-20 min;

② Erlenmeyer flask was charged with 24 mL of AgNO₃Standing the mixed solution in a drying oven at 28-32 deg.C for 15-20 min;

③ into the Erlenmeyer flask was added 250 mL of HAuCl₄Solution, stirring the obtained solution at the rotating speed of 700-800 rpm for 90-110 min to obtain growth liquid;

c-2: preparing seeds:

① mix 5 mL of HAuCl₄Mixing the solution and 5 mL CTAB solution into a 15 mL centrifuge tube;

② Add 600. mu.L of NaBH to the 15 mL centrifuge tube₄Rapidly shaking the centrifugal tube with an ice water solution covered, observing that the solution turns to light brown from yellow, and placing the solution into a drying box at 28-32 ℃ for 30-40min to obtain a seed solution;

c-3: adding the reagent dropwise to prepare CAu

Adding 3.6 mL of 37 wt% HCl into the growth solution, and uniformly stirring for one time;

adding 1.25 mL of AA (ascorbic acid) solution into the conical flask, and uniformly stirring for the second time;

③ adding 0.4 mL of prepared seed liquid into the conical flask, stirring evenly for three times, and then placing the conical flask into a drying oven at 28-32 ℃ for 12-14 h to obtain CAu;

D. the preparation of the nano-composite system is carried out,

2mmol of NaYF is taken₄:Er³⁺,Yb³⁺@NaYF₄500 μ L of the solution was centrifuged, and after removing the supernatant, the solution was addedAdding 1.8 mL of toluene and 0.2mL of PMMA (polymethyl methacrylate) toluene solution, performing ultrasonic dispersion uniformly, dropwise adding the mixed solution on a cleaned silicon wafer, preparing a single-layer film by using a spin-coating method, naturally drying, dropwise adding CAu on the film, and blow-drying to obtain CAu&NaYF₄:Er³⁺,Yb³⁺@NaYF₄A single layer nanocomposite film.

In the step A-3 and the step B-4, the centrifugation is carried out for 15-20min at the rotating speed of 9000-10000rpm, and the cleaning takes absolute ethyl alcohol as a cleaning solution.

In step C-1, the AgNO₃The molar concentration of the solution is 4 mM, and the HAuCl is₄The molarity of the solution was 1 mM.

In step C-2, the HAuCl₄The molarity of the solution was 0.5 mM, the molarity of the CTAB solution was 0.2M, and the NaBH was added₄The molar concentration of the ice-water solution was 0.01M.

In the step C-3, the molar concentration of the AA solution is 0.064M, the primary stirring is carried out for 15-20min at the rotating speed of 350-; the three times of stirring are evenly stirred for 30-35 s at the rotating speed of 1400-1600 rpm.

In the step D, the centrifugation is carried out for 15-20min at the rotating speed of 9000-11000 rpm, and the concentration of the PMMA toluene solution is 10 mg/mL.

In the step D, during spin coating, the spin coating is performed for 5 s at a rotation speed of 600rpm, and then the spin coating is performed for 30 s at a rotation speed of 2000 rpm.

The CAu is prepared for the first time by adopting the technical scheme&NaYF₄:Er³⁺,Yb³⁺@NaYF₄The nano composite film (CAu: gold nanorod with high length-diameter ratio) of the up-conversion nano particles effectively solves the problem that the traditional up-conversion material is weak in luminous intensity when used as a light conversion layer. Firstly, a nano-scale up-conversion luminescent material is selected, and the luminescence of the luminescent material can be obviously enhanced by utilizing the local surface plasmon polariton characteristic of noble metal nano-particles; secondly, the film only comprises a single layer of up-conversion nano particles with the thickness of nano level, and is placed on the surface of the solar cellThe high transmittance of visible light can be ensured, and the photoelectric conversion efficiency of the solar cell is improved. The effective excitation wavelength of the nano composite film is 980 nm, and the emission peaks are 520 nm (green light), 540 nm (green light) and 655 nm (red light). When the aspect ratio of CAu is 5.5 (length is 110 nm, width is 20 nm), the up-conversion red and green luminescence enhancement effect of the nano-composite system is most remarkable, and the maximum enhancement factors of red and green are 1.57 and 1.65 respectively.

The composite film of the invention has the advantages and the purposes that: the invention provides a gold nanoparticle-up-conversion material single-layer nano composite film for modulating solar spectrum for the first time, and the film has the advantages of low cost and high luminous efficiency. The nano composite film is made into a light conversion layer and is placed on the solar cell, so that low-energy photons with poor response of the solar cell can be converted into high-energy photons with the frequency matched with the frequency of the solar cell, and the photoelectric conversion efficiency of the solar cell is improved.

Drawings

FIG. 1 shows NaYF₄:Er³⁺,Yb³⁺@NaYF₄SEM image of monolayer film: (a) a surface map; (b) a cross-sectional view;

FIG. 2 is a related image of CAu, (a) SEM image of morphology and optical properties of CAu; (b) ultraviolet-visible-infrared extinction spectroscopy; (c) field intensity distribution at 970nm light emission; (d) FDTD simulation extinction, absorption and scattering spectrum;

CAu in FIG. 3&NaYF₄:Er³⁺,Yb³⁺@NaYF₄The micro-area up-conversion fluorescence spectrum: (a) converting fluorescence spectrum on the micro-area with or without CAu; the inset is an SEM image; (b) green and red spectral peak areas with or without CAu; the inset is a microscopic field of view.

Detailed Description

CAu for modulating the solar spectrum&NaYF₄:Er³⁺,Yb³⁺@NaYF₄The preparation method of the single-layer nano composite film comprises the following steps:

a: preparation of NaYF₄:Er³⁺,Yb³⁺Nanoparticles

A-1: weighing RECl with the total amount of 2mmol according to the molar ratio₃•6H₂O, RE = Y/Er/Yb, 12 mL of oleic acid and 30 mL of 1-octadecene are added, the mixed solution is vacuumized and heated to 130 ℃, and the temperature is kept for 40min and then naturally cooled to room temperature to obtain a solution A;

a-2: 0.2000 g of NaOH and 0.2963 g of NH were weighed out₄F, dissolving in 10 mL of methanol, dropwise adding the mixed methanol solution into the solution A, stirring at room temperature for 30min, heating to 62 ℃ under argon atmosphere to distill out methanol, then heating to 300 ℃, maintaining for 1 hour, and then cooling to room temperature to obtain a solution B;

a-3: centrifuging the solution B at the rotating speed of 9200 rpm for 15 min, taking absolute ethyl alcohol as a cleaning solution, ultrasonically cleaning the particles obtained after centrifugation for 5 min, and repeatedly cleaning for three times to obtain NaYF₄:Er³⁺,Yb³⁺Nanoparticles, finally dispersed in cyclohexane;

b: preparation of NaYF₄:Er³⁺,Yb³⁺@NaYF₄Nanoparticles

B-1: weighing 2mmol YCl₃•6H₂O, adding 12 mL of oleic acid and 30 mL of 1-octadecene, vacuumizing the mixed solution, heating to 130 ℃, keeping for 40min, and naturally cooling to room temperature to obtain a solution C;

b-2: the NaYF obtained in the step A-3₄:Er³⁺,Yb³⁺Dropwise adding the nanoparticles into the solution C, stirring at room temperature for 30min, heating to 62 ℃ under the argon atmosphere to distill out methanol, then heating to 300 ℃, maintaining for 40min, and then cooling to room temperature to obtain a solution D;

b-3: 0.2000 g of NaOH and 0.2963 g of NH were weighed out₄F, dissolving the mixture in 10 mL of methanol solution, dropwise adding the mixed methanol solution into the solution D to obtain an emulsion, stirring at room temperature for 30min, heating to 62 ℃ under argon atmosphere to distill out methanol, heating to 300 ℃, maintaining for 1 hour, and cooling to room temperature to obtain a solution E;

b-4: centrifuging the solution E at the rotating speed of 9200 rpm for 15 min, taking absolute ethyl alcohol as a cleaning solution, ultrasonically cleaning the particles obtained after centrifugation for 5 min, and repeatedly cleaning for three times to obtain NaYF₄:Er³⁺,Yb³⁺@NaYF₄Dispersing the nano particles in cyclohexane to obtain NaYF₄:Er³⁺,Yb³⁺@NaYF₄A solution;

c: preparation CAu

C-1: preparing a growth solution:

weighing 7 g of CTAB and 1.234 g of NaOL, pouring into a conical flask, adding 250 mL of deionized water, stirring for 20-30min, standing the mixed solution in a drying oven at 28-32 ℃ for 15-20 min;

② Erlenmeyer flask was charged with 24 mL of AgNO₃(4 mM) solution, standing the mixed solution in a drying oven at 28-32 ℃ for 15-20 min;

③ into the Erlenmeyer flask was added 250 mL of HAuCl₄(1 mM) solution, stirring the obtained solution for 90-110 min at the rotating speed of 700-800 rpm to obtain a growth solution;

c-2: preparing seeds:

① mix 5 mL of HAuCl₄(0.5 mM) solution and 5 mL CTAB (0.2M) solution were mixed into a 15 mL centrifuge tube;

② Add 600. mu.L of NaBH to the 15 mL centrifuge tube₄(0.01M) adding an ice water solution, covering the ice water solution, rapidly shaking the centrifugal tube, observing that the solution is changed into light brown from yellow, and putting the solution into a drying box at the temperature of 28-32 ℃ for 30-40min to obtain a seed solution;

c-3: adding the reagent dropwise to prepare CAu

Adding 3.6 mL of HCl (37% wt) into the growth solution, and stirring at the rotation speed of 350-450rpm for 15-20 min;

adding 1.25 mL of AA (0.064M) into the conical flask, and stirring for 30-35 s at the rotating speed of 1400-1600 rpm;

thirdly, 0.4 mL of prepared seed liquid is added into the conical flask, stirred for 30-35 s at the rotating speed of 1400-32 rpm and then placed into a drying box at 28-32 ℃ for 12-14 h to obtain CAu;

D. the preparation of the nano-composite system is carried out,

2mmol of NaYF is taken₄:Er³⁺,Yb³⁺@NaYF₄500 mu L of the solution is centrifuged for 15-20min at the rotating speed of 9000-11000 rpm, and 1.8 mL of toluene and 0.2mL of the supernatant are addedCarrying out ultrasonic 5 min on a toluene solution (10 mg/mL) of mL PMMA to uniformly disperse, dropwise adding the mixed solution on a cleaned silicon wafer to prepare a single-layer film by using a spin coating method (pre-rotation is carried out for 600 rpm/5 s, and forward rotation is carried out for 2000 rpm/30 s), naturally drying, dropwise adding CAu on the film, and blow-drying to obtain CAu&NaYF₄:Er³⁺,Yb^{3 +}@NaYF₄A single layer nanocomposite film.

FIG. 1 (a) shows NaYF₄:Er³⁺,Yb³⁺@NaYF₄SEM image of single layer film, it can be seen that the size of the particles is about 45nm, the uniformity of the particles is better, FIG. 1 (b) is NaYF₄:Er³⁺,Yb³⁺@NaYF₄SEM of the cross section of the single-layer film shows that the cross section thickness is about 45nm and is consistent with the particle size, which indicates that NaYF is successfully prepared₄:Er³⁺,Yb³⁺@NaYF₄A single layer film.

FIG. 2 (a) is an SEM of CAu, from which it can be seen that: CAu has good dispersibility, uniform appearance and size, and particle diameter of about 110 nm and 20 nm. Fig. 2 (b) shows the uv-vis-ir extinction spectrum of CAu, from which: CAu has two extinction peaks, located at 517 nm and 970nm, wherein 517 nm is a transverse resonance extinction peak, 970nm is a longitudinal resonance extinction peak, at this time, CAu longitudinal resonance extinction peak can be matched with excitation light (980 nm), excitation efficiency can be enhanced, up-conversion rare earth ion luminescence is enhanced, and the distance between 517 nm peak position and 980 nm is far away, and the peak position is small, and influence on excitation efficiency can be ignored. Fig. 2 (c) shows the field intensity distribution of a single field CAu simulated by FDTD, which shows that: CAu the tip has a strong enhanced electric field, which in turn creates a hot spot. When the incident light acts on CAu, surface plasmon polaritons are generated around the incident light, the local field intensity effect is enhanced, and the emission efficiency of nearby up-conversion rare earth ions can be effectively enhanced. FIG. 2 (d) shows CAu simulated extinction spectra of FDTD, which shows that there are two plasmon resonance peaks at 517 nm and 970 nm. Compared with the CAu extinction spectrum measured by experiments, the extinction spectrum and the FDTD simulated plasma resonance peak are relatively consistent in peak position.

CAu in FIG. 3&NaYF₄:Er³⁺,Yb³⁺@NaYF₄The fluorescence spectrum is converted on the micro-area. We measured 5 micro-domain up-conversion fluorescence spectra with CAu regions and 5 without CAu regions, as shown in fig. 3 (a), and the peak areas of each spectrum are shown in fig. 3 (b). As can be seen from fig. 3 (a) and 3 (b), the red and green upconversion with CAu regions is enhanced with maximum enhancement factors of 1.57 and 1.65, respectively.