Lanthanide-doped single nanoparticle luminous photoelectric device and preparation method thereof

Abstract

The invention relates to the technical field of photoelectric devices, and provides a lanthanide-doped single nanoparticle luminous photoelectric device and a preparation method thereof. On the basis of a graphene point electrode, a molecular heterojunction is introduced, the molecular heterojunction comprises a single lanthanide-doped nanoparticle, the structure of the single lanthanide-doped nanoparticle is a sandwich core-shell structure, and the sandwich core is a gold nanosheet; the shell is a lanthanide element doped # imgabs0 # matrix; the gold nanosheets wrapped in the lanthanide-doped single nanoparticles have a surface plasmon resonance effect and high conductivity, so that not only is a better conductive effect achieved, but also the luminescence effect can be enhanced by utilizing the plasmon resonance effect.

Description

Technical Field

[0001] The invention relates to a lanthanide-doped single nanoparticle luminescent photoelectric device and a preparation method thereof, belonging to the technical field of photoelectric devices. Background Art

[0002] With the continuous advancement of nanotechnology, electroluminescent upconversion light-emitting devices have gradually become an important research direction in the field of optoelectronic devices due to their unique optoelectronic properties. In particular, lanthanide-doped nanoparticles not only show long photoluminescence lifetime and narrow emission bandwidth, but also have excellent chemical stability due to the sealing layer of nanoparticles, making them an ideal choice for electroluminescent upconversion light-emitting materials. The core mechanism of upconversion luminescence of lanthanide-doped nanoparticles is to use two different lanthanide ions with matching energy levels as sensitizers and activators, respectively, and achieve upconversion luminescence through efficient energy transfer between them. However, the existing luminescent particles are mostly arranged in a stacked state, the distance between the luminescent particles is close, and the particles affect each other, and the conductivity of the particles is poor, which will cause problems such as poor power supply stability and low luminescence efficiency.

[0003] CN116744755B discloses a photoelectric device based on a single perovskite quantum dot and a preparation method thereof. However, the photoelectric device based on a single perovskite quantum dot has a single luminous point and the luminous efficiency needs to be improved.

[0004] The electroluminescent upconversion light-emitting devices in the prior art still have deficiencies in electroluminescent efficiency and stability, which to some extent limits their wide application. In order to solve this problem, it is urgent to provide new solutions for achieving high-performance electroluminescent upconversion light-emitting devices through innovative material design and process optimization. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a photoelectric device based on lanthanide-doped single nanoparticle luminescence and a preparation method thereof.

[0006] According to an embodiment of the present invention, a first solution is provided: A method for preparing a photoelectric device based on lanthanide-doped single nanoparticle luminescence comprises the following steps: S1. preparing a graphene dot electrode on a transparent insulating layer on a substrate layer; S2, introducing a molecular heterojunction into the graphene point electrode to form a graphene point electrode-molecular heterojunction array; The molecular heterojunction is composed of a bridging molecule and a single nanoparticle doped with a lanthanide element. The bridging molecule is connected to the graphene point electrode through an amide condensation reaction, and then an esterification reaction occurs between the single-terminal thiol group and the carboxyl group on the surface of the single nanoparticle doped with the lanthanide element, so that the bridging molecule is connected to the single nanoparticle doped with the lanthanide element. The structure of the single nanoparticle doped with lanthanide elements is a sandwich core-shell structure, wherein the sandwich core is a gold nanosheet and the shell is a lanthanide element doped Matrix; S3. Covering the upper surface of the graphene point electrode-molecule heterojunction array with a protective layer to obtain a photoelectric device based on lanthanide-doped single nanoparticle electro-upconversion luminescence.

[0007] Furthermore, in step S2, the preparation of a single lanthanide-doped nanoparticle comprises the following steps: S221, preparing a precursor containing gold nanocapsules by hydrothermal reaction in a nitrogen environment with a gold nanocapsule and a yttrium source solution doped with a lanthanide element, a fluorine source and a sodium source; S222, calcining the precursor in a nitrogen environment to obtain @Gold nanosheet intermediate, the gold nanosheet is formed by the transformation of gold nanovesicles during the calcination process, has a flat sheet shape, and R1 and R2 are lanthanide elements.

[0008] Further, S223, the step S222 obtained @Gold nanosheet intermediates undergo surface treatment to remove @Amorphous layer on the surface of gold nanosheet intermediate and introduction of carboxyl groups; The step of removing the amorphous layer and introducing carboxyl groups is to @After the gold nanosheet intermediate reacts with the alkali solution, it is washed with deionized water and ethanol several times until the solution is neutral; After reacting with citric acid solution, the solution was washed with deionized water until it was neutral, and centrifuged to obtain single nanoparticles doped with lanthanide elements: @Gold nanosheets.

[0009] Further, in step S1, a plasma nanoarray gate layer is introduced between the substrate layer and the transparent insulating layer; S101, spin-coating photoresist on the surface of the substrate layer and performing ultraviolet lithography to obtain a square nanorod array, and performing thermal resistance evaporation coating to obtain a plasma nanoarray gate layer; S102, depositing SiO2 on the plasma nanoarray gate layer to obtain a transparent insulating layer.

[0010] Further, in step S2, a plasma nanoantenna is introduced on the graphene point electrode; S211, spin-coating polymethyl methacrylate on the surface of the graphene point electrode, and etching above the graphene point electrode to obtain a graphene point electrode device with collinear gold nanorods on the surface; S212, sputtering-coating the graphene point electrode device using a gold target to obtain a plasma nanoantenna.

[0011] Further, in step S2, the molecular heterojunction is introduced by the following steps: S201, placing the graphene dot electrode, the bridging molecule and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide in anhydrous pyridine under a nitrogen atmosphere, and reacting for 24 h to 48 h in a light-proof condition to obtain a bridging molecule device; S202. Place the bridging molecular device, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and single nanoparticles doped with lanthanide elements in anhydrous pyridine under a nitrogen atmosphere, and react for 24 h to 48 h in a light-proof condition, so that the single nanoparticles doped with lanthanide elements are connected to the bridging molecular device through a thioester bond to obtain a graphene point electrode-molecular heterojunction array.

[0012] According to an embodiment of the present invention, using the method for preparing a photoelectric device based on lanthanide-doped single nanoparticle luminescence in the first embodiment provided by the present invention, a second embodiment is provided: A photoelectric device based on lanthanide-doped single nanoparticle luminescence, comprising a substrate layer, a transparent insulating layer and an array layer composed of graphene point electrodes and molecular heterojunctions arranged in sequence from bottom to top; The two ends of the molecular heterojunction are respectively connected to the graphene point electrodes through amide bonds to form a graphene point electrode-molecular heterojunction array; The molecular heterojunction is composed of a bridging molecule and a single nanoparticle doped with a lanthanide element. The structural formula of the single nanoparticle doped with a lanthanide element is @Gold nanosheets; The single nanoparticle doped with lanthanide elements is a sandwich core-shell structure, wherein the sandwich core is a gold nanosheet and the shell is a lanthanide element doped Matrix; the gold nanosheet is in the shape of a flat sheet; Among them, gold nanosheets are encapsulated in co-doped In the sphere, R1 is any one of ytterbium (Yb), neodymium (Nd) or cerium (Ce), and R2 is any one of erbium (Er), thulium (Tm) or europium (Eu).

[0013] Furthermore, a pair of plasma nanoantennas are arranged on the graphene point electrode, and the plasma nanoantennas are arranged in the high line direction of the upper surface of the graphene point electrode. The graphene point electrode includes a graphene source terminal electrode and a graphene drain terminal electrode. A pair of plasma nanoantennas are respectively arranged on the graphene source electrode and the graphene drain electrode; The plasma nanoantenna is a pair of colinear metal films, and the material is gold.

[0014] Furthermore, a plasma nano-array gate layer is provided between the substrate layer and the transparent insulating layer, wherein the plasma nano-array gate layer comprises a square nano-column array, and the square nano-column array is in a strip shape and covers the substrate layer; The material of the square nanocolumn array of the plasma nanoarray gate layer is selected from any one of gold and silver, and the thickness of the plasma nanoarray gate layer is 20-60nm; The thickness of the SiO2 transparent insulating layer deposited on the plasma nano-array gate layer is 30-50 nm.

[0015] Furthermore, the graphene point electrode is arranged on the upper surface of the transparent insulating layer; Metal electrodes are also arranged at both ends of the graphene point electrode, and the metal electrodes are a pair, which are arranged at the outer ends of the graphene source electrode and the graphene drain electrode respectively; The electrode material of the metal electrode is selected from any one of Cu, Cr and Au, and the thickness thereof is 30-100 nm.

[0016] Compared with the prior art, the technical solution provided by this application has beneficial effects.

[0017] 1. Connect a single lanthanide-doped nanoparticle between graphene point electrodes, inject electrons through the metal electrode, induce the rare earth ion electrons in the single nanoparticle as a sensitizer to transition to an excited state high energy level, and transfer them to the rare earth ion as an activator through multiple non-radiative transitions, so that it transitions to a higher excited state energy level and finally releases high-energy photons, achieving efficient energy transfer.

[0018] 2. Through the gold nanorod plasma antenna above the graphene nanodot electrode and the silver plasma nanoarray gate layer below, the optoelectronic device couples the excellent upconversion luminescence ability of single lanthanide-doped nanoparticles with the surface plasmon resonance effect, thereby improving the luminescence intensity of the optoelectronic device at the single-molecule level.

[0019] 3. The lanthanide-doped nanoparticles prepared by the present application have good photostability in electro-upconversion luminescence and can maintain stable luminescence performance under long-term illumination, which is beneficial to improving the stability and service life of optoelectronic devices.

[0020] 4. The gold nanosheets wrapped inside the single nanoparticles doped with lanthanide elements have surface plasmon resonance effect and high conductivity, which not only plays a better conductive role, but also can enhance the luminescence effect by utilizing the plasmon resonance effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] in: Figure 1 A schematic diagram of the three-dimensional structure of an optoelectronic device based on lanthanide-doped single nanoparticle light emission in one embodiment; Figure 2 is a current-bias diagram of an optoelectronic device based on lanthanide-doped single nanoparticle light emission in one embodiment; Figure 3 An energy level diagram of an up-conversion luminescence process of an optoelectronic device based on lanthanide-doped single nanoparticle luminescence in one embodiment; Figure 4 The figure is a lifetime diagram of up-conversion luminescence of a photoelectric device based on lanthanide-doped single nanoparticle luminescence in one embodiment; Figure 5 A diagram of a preparation process of a single nanoparticle based on lanthanide doping in one embodiment; Figure 6 FIG. 1 is a diagram showing the doping lanthanide element identification of a single nanoparticle based on lanthanide doping in one embodiment.

[0023] Reference numerals: 1. Substrate layer; 2. Plasma nanoarray gate layer; 3. Transparent insulating layer; 4. Graphene point electrode; 5. Plasma nanoantenna; 6. Metal electrode; 7. Molecular heterojunction; 8. Protective layer. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of this application.

[0025] In view of the fact that the electroluminescent upconversion light-emitting devices in the existing technology still have shortcomings in electroluminescent efficiency and stability, by redesigning the structure of nanoparticles, optimizing the ratio of internal sensitizers and activators, and rationally designing the means of electric field distribution, the power supply stability is improved and the overall luminescence effect is enhanced, providing a new approach for the development of new high-performance optoelectronic devices.

[0026] In the following examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all available from commercial sources unless otherwise specified.

[0027] The Schlenk technique is an experimental technique for providing an inert environment and vacuum conditions. All chemical reactions in this application were performed using the standard Schlenk technique in a dry solvent and inert gas atmosphere.

[0028] Example 1 Preparation of lanthanide-doped single nanoparticles.

[0029] The preparation route of lanthanide-doped single nanoparticles is as follows: Silver nitrate (AgNO3, 0.002mmol, 0.1mM) solution and sodium citrate (0.2mM, 0.004mmol) were added to a dry double-necked flask equipped with a stirrer in sequence and allowed to stand at room temperature to generate silver colloid. Sodium borohydride (NaBH4, 0.5mL, 100mM) was then added to the mixed solution as a reducing agent and stirred rapidly to form uniform silver nanoparticles. Ammonium hydroxide solution (0.5mL, 100mM) was then added to adjust the particle size, and silver seeds of uniform size were obtained by centrifugation. The reaction system was then heated to 65°C, and then chloroauric acid (HAuCl4, 10mM, 0.01mmol) solution was slowly added dropwise. After the reaction was completed, pure gold nanovesicles were obtained by centrifugation and washing with deionized water. The particle size of the gold nanovesicles was 15-30nm.

[0030] The structure of the gold nanovesicle is as follows Figure 5 shown.

[0031] Gold nanovesicles (10 mM, 0.01 mmol) were mixed with a diluted nitrate solution ( , 0.2mmol, , 0.08mmol, , 0.02mmol) were added to a dry double-necked flask and mixed, and ammonium fluoride ( , 1.6mmol) and sodium chloride (NaCl, 0.4mmol) were used as the sources of fluorine and sodium, and EDTA (0.1mmol) was subsequently added as a complexing agent to increase the stability of the solution. Through a hydrothermal reaction, the reaction was carried out at 180°C for 12 hours in a nitrogen-filled environment to promote the complete reaction and generate Na(Yb / Er) x Y y F z Precursor, the precursor particle size is 25-40nm.

[0032] The Na(Yb / Er) x Y y F z The structure of the precursor is Figure 5 shown.

[0033] The precursor was heated to 850°C at a heating rate of 1°C / min and calcined at high temperature for 4 hours. During the calcination process, the gold nanovesicles were transformed into flat gold nanosheets, and Yb / Er-doped Matrix, @Gold nanosheet intermediate, particle size is 15-35nm.

[0034] Said @The structure of the gold nanosheet intermediate is as follows Figure 5 shown.

[0035] Will @The gold nanosheet intermediates were dispersed in a sodium hydroxide (NaOH, 1.5 M) solution with a volume ratio of 1:10 and stirred at room temperature or 60 °C for 10 h to remove the amorphous layer that may exist on the surface of the particles. Finally, the particles were washed with deionized water and ethanol several times until the solution was neutral to ensure that there was no residual alkaline solution on the particles.

[0036] Further, 30 mL of 2 mM citric acid solution was added and stirred at room temperature for 12 hours. After the reaction was completed, the particles were recovered by centrifugation (10000 rpm, 10 min) and washed with deionized water 3 times to finally obtain single lanthanide-doped nanoparticles: @Gold nanosheets, Y:Yb:Er is 10:8:1.

[0037] Said @The structure of gold nanosheets is as follows Figure 5 shown.

[0038] The particle surface carries carboxyl groups (–COOH), and the purpose of introducing carboxyl groups is to form thioester bonds with the thiol groups of the bridging molecules in the subsequent steps.

[0039] Except that the ratio changes due to the amount of doping elements, the synthesis process and conditions of other verification ratio schemes are consistent with Example 1. The gold nanovesicles are all (10mM, 0.01mmol), and the chemical preparations used are all prepared by weighing quantitative chemical substances and then preparing a fixed volume solution. The amounts of specific reactants in other ratios are as follows.

[0040] Ratio 2: The number of moles is: ]=0.204mmol, [ ]=0.075mmol, [ ]=0.021mmol, [ ]=1.7mmol, [NaCl]=0.4mmol, [EDTA]=0.15mmol; Solvent concentration: ]=20.4mM, [ ]=7.5mM, [ ]=2.1mM, [ ]=170mM, [NaCl]=40mM, [EDTA]=15mM.

[0041] product @Gold nanosheets. Y:Yb:Er is 68:25:7.

[0042] Ratio 3: The number of moles is: ]=0.234mmol, [ ]=0.06mmol, [ ]=0.006mmol, [ ]=1.8mmol, [NaCl]=0.4mmol, [EDTA]=0.15mmol; concentration:[ ]=23.4mM, [ ]=6mM, [ ]=0.6mM, [ ]=180mM, [NaCl]=40mM, [EDTA]=15mM.

[0043] product @Gold nanosheets. Y:Yb:Er is 78:20:2.

[0044] At the same time, in order to compare the experimental results, single nanoparticles doped with lanthanide elements without gold nanosheets were prepared. The process conditions used were the same as those in Example 1, except that gold nanocapsules were not added, and the chemical preparation ratio used was consistent with Ratio 3.

[0045] The Yb and Er nitrates used in the preparation can be replaced by Nd and Tm or Ce and Eu nitrates. The same process and process parameters can also be used to prepare @Gold nanosheets or @Gold nanosheets.

[0046] The dosage of gold nanocapsules and the doping The molar ratio of transition metal elements in the matrix is ​​1-3:60, and the ratio used in Example 1 is 2:60; The transition metal element is any one or more of yttrium (Y), ytterbium (Yb), erbium (Er), neodymium (Nd), thulium (Tm), cerium (Ce), and europium (Eu).

[0047] The structural formula of the lanthanide-doped single nanoparticle is @Gold nanosheets, such as Figure 6 shown.

[0048] The structure of the single nanoparticle doped with lanthanide elements is a sandwich core-shell structure, wherein the sandwich core is a gold nanosheet; the shell is a lanthanide element-doped Matrix.

[0049] Gold nanosheets encapsulated in co-doped In the sphere, R1 is any one of ytterbium (Yb), neodymium (Nd) or cerium (Ce), and R2 is any one of erbium (Er), thulium (Tm) or europium (Eu).

[0050] When selecting elements, the best matching pair has higher luminous efficiency. Group 1: R1 is ytterbium (Yb), R2 is erbium (Er); Group 2 R1 is neodymium (Nd), R2 is thulium (Tm); In group three, R1 is cerium (Ce), and R2 is europium (Eu).

[0051] The surface plasmon resonance phenomenon of nanomaterials originates from the coupled oscillation of their free electrons and incident light, and has significant optical property differences and application potential. In this application, the gold nanosheets encapsulated inside the synthesized single nanoparticles not only play a better conductive role in electroluminescence, but also can enhance the luminescence effect by utilizing the plasma resonance effect.

[0052] Gold nanosheets in co-doping Inside the sphere, there is a unique two-dimensional structure and a strong localized surface plasmon resonance effect, which can significantly enhance the light field intensity, improve the energy transfer efficiency and up-conversion luminescence performance. At the same time, its excellent conductivity, thermal stability and large surface area give it higher functionalization potential and optical signal enhancement capabilities. Lanthanide ions with energy absorption and transfer, including ytterbium (Yb), neodymium (Nd) or cerium (Ce), are selected as sensitizers, and erbium (Er), thulium (Tm) or europium (Eu) with matching energy levels and long fluorescence lifetimes are selected as activators. The core-shell structure is designed to optimize the spatial distribution of the sensitizer and activator, improve the energy transfer efficiency, reduce non-radiative losses, and enhance the electron-photon conversion efficiency, thereby achieving efficient and stable electro-induced up-conversion luminescence.

[0053] Example 2 Structure of an optoelectronic device based on lanthanide-doped single nanoparticle electroluminescent upconversion.

[0054] like Figure 1 As shown, a photoelectric device based on lanthanide-doped single nanoparticle electro-upconversion luminescence comprises a substrate layer 1, a plasma nano-array gate layer 2 and a transparent insulating layer 3 arranged in sequence from bottom to top; The plasma nano-array gate layer 2 includes a square nano-column array, which is in a strip shape and covers the substrate layer 1, and the transparent insulating layer 3 is arranged on the upper surface of the plasma nano-array gate layer 2; An array layer consisting of graphene point electrodes 4 and molecular heterojunctions 7 is also provided on the transparent insulating layer 3; The graphene point electrode 4 is arranged at the side edge of the upper surface of the transparent insulating layer 3 in the width direction, and the two ends of the molecular heterojunction 7 are respectively connected to the graphene point electrode 4 through amide bonds to form a graphene point electrode-molecular heterojunction array.

[0055] A metal electrode 6 is provided on the outer edge of the upper surface of the graphene point electrode 4 in the width direction.

[0056] A plasma nanoantenna 5 is arranged on the upper surface of the graphene point electrode 4 in the high line direction.

[0057] Among them, the molecular heterojunction 7 is composed of a bridging molecule and a single nanoparticle doped with lanthanide elements, wherein the two ends of the bridging molecule are an amino group and a thiol group, respectively, and the carbon chain length n is 3, 4 or 5; the amino group of the bridging molecule is covalently linked to the graphene electrode by amide, and then the single-ended thiol group undergoes an esterification reaction with the carboxyl group on the surface of the single nanoparticle doped with lanthanide elements to form a thioester bond.

[0058] The substrate layer 1 is a P-type doped silicon-based (P-type Si) substrate coated with a 300nm SiO2 oxide layer; The material of the plasma nanoarray gate layer 2 is selected from Ag, and its thickness is 40nm; The transparent insulating layer 3 is formed by depositing silicon dioxide and has a thickness of 30 nm; The plasma nanoantenna 5 is an Au thin film with an end width of 13 nm, a length of 76 nm, and a thickness of 26 nm; The metal electrode 6 is made of Au and has a thickness of 70 nm. The protective layer 8 is an h-BN protective layer with a thickness of 100 nm.

[0059] Example 3 Preparation of optoelectronic devices based on lanthanide-doped single nanoparticle electroluminescence upconversion The specific process is as follows: There is no particular limitation on the type of the substrate, as long as the purpose of the present application can be achieved. For example, the substrate may be an atomically flat silicon wafer, mica or sapphire.

[0060] S1, in this embodiment, a P-type doped silicon-based substrate (P-type Si) coated with a 300nm SiO2 oxide layer is selected, and it is placed in a 110°C piranha solution and heated for 4 hours, then taken out and ultrasonically cleaned with ultrapure water, and then blown dry with nitrogen for use. The piranha solution is a mixed solution of 35% H2O2 and concentrated H2SO4 in a volume ratio of 3:7; Using ultraviolet lithography, a square nanocolumn array is etched on the surface of the substrate, wherein the square nanocolumn array is in a strip shape, and then Ag with a thickness of 40 nm is deposited by thermal resistance evaporation coating to obtain a plasma nanoarray gate layer; The upper surface of the plasma nanoarray gate layer is coated by electron beam evaporation to prepare a transparent insulating layer with a thickness of 30nm; the thickness of the transparent insulating layer is 30nm to 50nm.

[0061] The material of the transparent insulating layer is selected from any one of aluminum oxide material and silicon dioxide material. In this embodiment, silicon dioxide is used.

[0062] Ag is used as the plasma nanoarray gate layer material, and the thickness of the plasma nanoarray gate layer is 20nm to 60nm. Ag has lower plasma loss and higher quality factor, can effectively reduce the absorption and scattering loss of photon energy during propagation, and can form an extremely narrow plasma resonance mode in the visible light to near-infrared band. Through this plasma resonance effect, the Ag nanoarray can selectively enhance the optical mode matching the target transition wavelength, so that the light signal corresponding to the wavelength is significantly enhanced during the emission process. At the same time, the excellent thermal conductivity of Ag enables it to efficiently dissipate heat and prevent performance degradation caused by local overheating, thereby further ensuring the stability of the photoelectric performance of the device during long-term operation. The local field enhancement effect of the Ag nanocolumn array directly reflects the energy transfer process and upconversion luminescence behavior in a single lanthanide-doped nanoparticle, significantly reducing the electroluminescence threshold of the molecular heterojunction, thereby ensuring that the photoelectric performance of the single-molecule electro-upconversion luminescent device is more stable and efficient.

[0063] The copper foil is cleaned with acetic acid to remove surface oxides, and then chemical vapor deposition is performed on the surface of the copper foil to obtain a single layer of graphene; Using polymethyl methacrylate (PMMA) as a transfer medium, the graphene layer on the copper foil is transferred to the insulating layer through a wet transfer technique. A strip-shaped graphene electrode layer is prepared on the graphene film by using an ultraviolet lithography machine and a reactive ion etcher, wherein the thickness of the graphene electrode layer is 0.7 nm; Using a UV lithography machine and a magnetron sputtering coating machine, an Au metal electrode is prepared on the graphene strip layer, and the thickness of the metal electrode is 70nm; The graphene electrode layer obtained above is subjected to electron beam exposure and reactive ion etching to form a gap of 40-50 nm to obtain a graphene dot electrode; The etching gap size is designed to match the molecular heterojunction, and the etching gap is controlled according to the particle size of the prepared lanthanide-doped single nanoparticle.

[0064] The graphene point electrode comprises a graphene source terminal electrode and a graphene drain terminal electrode located at both ends in the length direction; Electron beam exposure was used to etch the high-line surface of the graphene nanodot electrode to obtain a pattern with an end width of 13nm, a length of 76nm, and a thickness of 26nm. Subsequently, magnetron sputtering was used to obtain a plasma nanoantenna made of Au. S2, connecting the graphene source electrode, the graphene drain electrode and the two ends of the molecular heterojunction through amide bonds to obtain a graphene point electrode-molecular heterojunction array, The graphene dot electrode is placed in a reaction system, and then 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and a bridging molecule are added to the reaction system. Anhydrous pyridine is injected into the reaction system under a N2 gas atmosphere to obtain a mixed solution 2, and the mixed solution is placed in a light-proof condition and reacted for 24h to 48h to obtain a bridging molecule device; The bridging molecular device is placed in a reaction system, and then 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and single nanoparticles doped with lanthanide elements are added to the reaction system. Anhydrous pyridine is injected into the reaction system under a N2 gas atmosphere to obtain a mixed solution. The mixed solution is placed in a light-proof condition and reacted for 24 hours to 48 hours to connect the single nanoparticles doped with the bridging molecular device through a thioester bond to obtain a graphene point electrode-molecular heterojunction array.

[0065] The lanthanide-doped single nanoparticles are prepared in Example 1. @Gold nanosheets or nanoparticles I.

[0066] S3, a protective layer is covered on the upper surface of the dried graphene dot electrode-molecular heterojunction array with a 100 nm thick h-BN protective layer to obtain a photoelectric device based on lanthanide-doped single nanoparticle electro-upconversion luminescence. h-BN has good optical transparency, and can prevent current leakage and reduce interference noise while preventing damage to the device from the external environment.

[0067] The volt-ampere characteristics of the obtained lanthanide-doped single nanoparticle electroluminescent upconversion luminescence photoelectric device were tested, and the following results were obtained: Figure 2 The I / V curve shown indicates that the single lanthanide-doped nanoparticle provided by the present invention is connected to the graphene point electrode, and the electro-upconversion luminescent photoelectric device of the single lanthanide-doped nanoparticle provided by the present invention is successfully prepared.

[0068] Test Example 1 The lanthanide-doped single nanoparticle electro-up-conversion luminescence photoelectric device obtained in Example 2 was subjected to electro-up-conversion luminescence detection.

[0069] In the experiment, a bias voltage of 0-5V (V b) induces molecular luminescence. The emitted photon signal is guided to the CCD spectrometer for collection and recording through the high-sensitivity optical system of the 100x oil-immersion objective. The bias voltage regulates the luminescence color and efficiency by affecting the nonlinear relationship of the multiphoton absorption process. The shell of the core-shell structure passivates surface defects and isolates the environmental quenching effect, making the effect of the bias voltage on the luminescence behavior more controllable, while improving the luminescence stability and efficiency. In the process of electro-upconversion luminescence, the injection and recombination / collision of carriers as sensitizers Yb 3+ From the ground state 2 F 7 / 2 Reaching the excited state 2 F 5 / 2 The energy is then transferred to the activator Er without radiation. 3+ , making Er 3+ from 4 I 15 / 2 or higher energy level from a low energy state to 4 I 11 / 2 , 4 F 9 / 2 , 4 I 7 / 2 At higher energy levels, if Er 3+ First reach the intermediate state 4 I 11 / 2 It can also absorb energy into a higher excited energy level and then return to the ground state or lower energy level through non-radiative transition to achieve up-conversion luminescence, such as Figure 3 As shown. In addition, the bias voltage directly determines the injection efficiency of electrons and holes and the efficiency of the upconversion process by affecting the charge injection efficiency and the local electric field strength. At low bias voltage, the charge injection is insufficient, and the upconversion luminescence is weak or even invisible; as the bias voltage increases, the local electric field is enhanced, which improves the energy transfer efficiency and the collision probability of excited state particles, thereby significantly enhancing the upconversion luminescence intensity.

[0070] By measuring the position of the emission peak in the spectrum, the wavelength (λ) of the photon can be extracted and then the formula Calculate the spectral energy, In the formula, E photon : the energy of a photon, in joules (J) or electron volts (eV); h : Planck constant, approximately 6.626×10 -34 Joule·second (J·s); c: speed of light, about 3×10 8 Meter / second (m / s); λ: wavelength of photons, in meters (m).

[0071] The energy of the input electrons is determined by the input bias voltage ; In the formula, E electron : The energy of an electron, in joules (J) or electron volts (eV); e: elementary charge, about 1.602×10 -19 Coulomb (C); V b : Bias voltage, in volts (V).

[0072] At the same time, the lifetime of upconversion luminescence of a single lanthanide-doped nanoparticle under electric field excitation conditions is detected by a photon counter, such as Figure 4 shown.

[0073] The comparison of the doping and luminescence efficiency of each component is listed in Table 1.

[0074] Table 1:

[0075] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0076] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for preparing a photoelectric device based on lanthanide-doped single nanoparticle luminescence, characterized in that: The steps include: S1. preparing a graphene dot electrode on a transparent insulating layer on a substrate layer; S2, introducing a molecular heterojunction into the graphene point electrode to form a graphene point electrode-molecular heterojunction array, The molecular heterojunction is composed of a bridging molecule and a single nanoparticle doped with a lanthanide element. The bridging molecule is connected to the graphene point electrode through an amide condensation reaction, and then an esterification reaction occurs between the single-terminal thiol group and the carboxyl group on the surface of the single nanoparticle doped with the lanthanide element, so that the bridging molecule is connected to the single nanoparticle doped with the lanthanide element. The structure of the single nanoparticle doped with lanthanide elements is a sandwich core-shell structure, wherein the sandwich core is a gold nanosheet and the shell is a lanthanide element doped Matrix; S3. Covering the upper surface of the graphene point electrode-molecule heterojunction array with a protective layer to obtain a photoelectric device based on lanthanide-doped single nanoparticle electro-upconversion luminescence.

2. The method for preparing a photoelectric device based on lanthanide-doped single nanoparticle luminescence according to claim 1, characterized in that: In step S2, the preparation of a single lanthanide-doped nanoparticle comprises the following steps: S221, preparing a precursor containing gold nanocapsules by hydrothermal reaction in a nitrogen environment with a gold nanocapsule and a yttrium source solution doped with a lanthanide element, a fluorine source and a sodium source; S222, calcining the precursor in a nitrogen environment to obtain @Gold nanosheet intermediate, the gold nanosheet is formed by the transformation of gold nanovesicles during the calcination process, has a flat sheet shape, and R1 and R2 are lanthanide elements.

3. The method for preparing a photoelectric device based on lanthanide-doped single nanoparticle luminescence according to claim 2, characterized in that: include: S223, the step S222 obtained @Gold nanosheet intermediates undergo surface treatment to remove @The amorphous layer on the surface of the gold nanosheet intermediate and the introduction of carboxyl groups, The step of removing the amorphous layer and introducing carboxyl groups is to @After the gold nanosheet intermediate reacts with the alkali solution, it is washed with deionized water and ethanol several times until the solution is neutral; After reacting with citric acid solution, the solution was washed with deionized water until it was neutral, and centrifuged to obtain single nanoparticles doped with lanthanide elements: @Gold nanosheets.

4. The method for preparing a photoelectric device based on lanthanide-doped single nanoparticle luminescence according to claim 1, characterized in that: In step S1, a plasma nanoarray gate layer is introduced between the substrate layer and the transparent insulating layer; S101, spin-coating photoresist on the surface of the substrate layer and performing ultraviolet lithography to obtain a square nanorod array, and performing thermal resistance evaporation coating to obtain a plasma nanoarray gate layer; S102, depositing SiO2 on the plasma nanoarray gate layer to obtain a transparent insulating layer.

5. The method for preparing a photoelectric device based on lanthanide-doped single nanoparticle luminescence according to claim 1, characterized in that: In step S2, a plasma nanoantenna is introduced on the graphene point electrode; S211, spin-coating polymethyl methacrylate on the surface of the graphene point electrode, and etching above the graphene point electrode to obtain a graphene point electrode device with collinear gold nanorods on the surface; S212, sputtering-coating the graphene point electrode device using a gold target to obtain a plasma nanoantenna.

6. The method for preparing a photoelectric device based on lanthanide-doped single nanoparticle luminescence according to claim 1, characterized in that: include: In step S2, the molecular heterojunction is introduced by the following steps: S201, placing the graphene dot electrode, the bridging molecule and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide in anhydrous pyridine under a nitrogen atmosphere, and reacting for 24 h to 48 h in a light-proof condition to obtain a bridging molecule device; S202. Place the bridging molecular device, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and single nanoparticles doped with lanthanide elements in anhydrous pyridine under a nitrogen atmosphere, and react for 24 h to 48 h in a light-proof condition, so that the single nanoparticles doped with lanthanide elements are connected to the bridging molecular device through a thioester bond to obtain a graphene point electrode-molecular heterojunction array.

7. A photoelectric device based on lanthanide-doped single nanoparticle luminescence, characterized in that: It includes a substrate layer, a transparent insulating layer and an array layer composed of graphene point electrodes and molecular heterojunctions arranged in sequence from bottom to top; The two ends of the molecular heterojunction are respectively connected to the graphene point electrodes through amide bonds to form a graphene point electrode-molecular heterojunction array; The molecular heterojunction is composed of a bridging molecule and a single nanoparticle doped with a lanthanide element. The structural formula of the single nanoparticle doped with a lanthanide element is @Gold nanosheets; The single nanoparticle doped with lanthanide elements is a sandwich core-shell structure, wherein the sandwich core is a gold nanosheet and the shell is a lanthanide element doped Matrix; the gold nanosheet is in the shape of a flat sheet; Among them, gold nanosheets are encapsulated in co-doped In the sphere, R1 is any one of ytterbium, neodymium or cerium, and R2 is any one of erbium, thulium or europium.

8. The optoelectronic device based on lanthanide-doped single nanoparticle luminescence according to claim 7, characterized in that: include: A pair of plasma nanoantennas are also arranged on the graphene point electrode, and the plasma nanoantennas are arranged in the high line direction of the upper surface of the graphene point electrode. The graphene point electrode includes a graphene source terminal electrode and a graphene drain terminal electrode. A pair of plasma nanoantennas are respectively arranged on the graphene source electrode and the graphene drain electrode; The plasma nanoantenna is a pair of colinear metal films, and the material is gold.

9. The optoelectronic device based on lanthanide-doped single nanoparticle luminescence according to claim 7, characterized in that: include: A plasma nano-array gate layer is arranged between the substrate layer and the transparent insulating layer, wherein the plasma nano-array gate layer comprises a square nano-column array, and the square nano-column array is in a strip shape and covers the substrate layer; The material of the square nanocolumn array of the plasma nanoarray gate layer is selected from any one of gold and silver, and the thickness of the plasma nanoarray gate layer is 20-60nm; The thickness of the SiO2 transparent insulating layer deposited on the plasma nano-array gate layer is 30-50 nm.

10. The optoelectronic device based on lanthanide-doped single nanoparticle luminescence according to claim 8, characterized in that: include: The graphene point electrode is arranged on the upper surface of the transparent insulating layer; Metal electrodes are also arranged at both ends of the graphene point electrode, and the metal electrodes are a pair, which are arranged at the outer ends of the graphene source electrode and the graphene drain electrode respectively; The electrode material of the metal electrode is selected from any one of Cu, Cr and Au, and the thickness thereof is 30-100 nm.

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