阅读说明：本技术 一种金纳米棒-硫化铅量子点光探测器及其制备方法 (Gold nanorod-lead sulfide quantum dot light detector and preparation method thereof ) 是由 赵新宏 李亮亮 段永胜 李凯 方永初 于 2019-09-25 设计创作，主要内容包括：本发明提供一种金纳米棒-硫化铅量子点光探测器及其制备方法,包括以下步骤：硫化铅量子点PbS QDs溶液的制备、金纳米棒Au NRs溶液的制备和金纳米棒-硫化铅量子点光探测器的制备,本发明在背栅基底上分层旋涂的方法制备硫化铅量子点PbS QDs-金纳米棒Au NRs-硫化铅量子点PbS QDs三明治层状结构的金纳米棒-硫化铅量子点光探测器。采用这种方法制备的光探测器的量子效率、响应度、探测度相较于单纯硫化铅光探测器均有大幅度的提高,表现出良好的光电性能,可实现从可见光到近红外光的宽光谱探测。本发明的方法具有方法简易,成本低,快速,可大面积生产,实用性强等特点。(The invention provides a gold nanorod-lead sulfide quantum dot photodetector and a preparation method thereof, wherein the preparation method comprises the following steps: the invention discloses a preparation method of a lead sulfide quantum dot PbS QDs solution, a preparation method of a gold nanorod Au NRs solution and a preparation method of a gold nanorod-lead sulfide quantum dot light detector. The photodetector prepared by the method has greatly improved quantum efficiency, responsivity and detectivity compared with a pure lead sulfide photodetector, shows good photoelectric property, and can realize wide spectrum detection from visible light to near infrared light. The method has the characteristics of simplicity, low cost, rapidness, large-area production, strong practicability and the like.)

1.A preparation method of a gold nanorod-lead sulfide quantum dot photodetector is characterized by comprising the following steps:

preparing a lead sulfide quantum dot PbS QDs solution;

preparing a gold nanorod Au NRs solution: preparing gold seed solution and growth solution, adding the gold seed solution into the growth solution to prepare gold nanorod Au NRs solution;

preparing a gold nanorod-lead sulfide quantum dot photodetector: spin-coating the lead sulfide quantum dot PbS QDs solution on a back gate substrate, then performing surface ligand exchange on the quantum dots, spin-coating a gold nanorod Au NRs solution on the back gate substrate after the first quantum dot spin coating and ligand exchange, and then placing the back gate substrate in a vacuum drying oven for standing to obtain a gold nanorod Au NRs coating; and then carrying out secondary quantum dot spin coating and ligand exchange on the gold nanorod Au NRs coating by the same method, putting the gold nanorod Au NRs coating into a vacuum drying oven to stand after the secondary quantum dot spin coating and the ligand exchange are finished, and forming the gold nanorod-lead sulfide quantum dot light detector with the lead sulfide quantum dot PbS QDs-gold nanorod Au NRs-lead sulfide quantum dot PbS QDs sandwich layered structure on the back gate substrate.

2. The method for preparing a gold nanorod-lead sulfide quantum dot photodetector as claimed in claim 1, wherein the preparation of the lead sulfide quantum dot PbS QDs solution specifically comprises the following steps:

preparing a cadmium sulfide quantum dot CdS QDs solution;

lead chloride PbCl is added₂Mixing powder, oleylamine and oleic acid in a container, introducing high-purity argon, exhausting air, heating, cooling after the solution becomes clear, quickly injecting the cadmium sulfide quantum dot CdS QDs solution, continuously cooling after the solution becomes black, and adding n-hexane; continuously cooling, adding ethanol, centrifuging, removing supernatant, adding n-hexane, centrifuging, collecting upper black liquid, adding ethanol, centrifuging, removing supernatant to obtain black lead sulfide, oven drying, weighing, adding n-hexane, and making into 50mg.mL^-1The lead sulfide quantum dot PbS QDs solution.

3. The method for preparing a gold nanorod-lead sulfide quantum dot photodetector as claimed in claim 1, wherein the preparation of the cadmium sulfide quantum dot CdS QDs solution specifically comprises:

adding reddish brown cadmium oxide powder CdO, oleic acid OA and octadecene ODE into a container, putting in a rotating magneton, introducing high-purity argon, exhausting air, heating to 260 ℃, removing a heat source after the solution becomes clear, and cooling; adding an ammonium sulfide solution into oleylamine, and uniformly mixing and stirring; when the temperature in the container is reduced to 30 ℃, quickly injecting the prepared ammonium sulfide solution into the flask, mixing uniformly, stopping stirring, and keeping the temperature; adding excessive ethanol to terminate the reaction, centrifuging, removing supernatant, drying the remaining lemon-yellow cadmium sulfide precipitate, weighing, adding n-hexane, and preparing into 100mg.mL^-1The cadmium sulfide quantum dot CdS QDs solution is reserved.

4. The method for preparing a gold nanorod-lead sulfide quantum dot photodetector as claimed in claim 1, wherein the preparation of the gold seed solution specifically comprises:

the chloroauric acid tetrahydrate HAuCl₄·4H₂And adding the O solution into a CTAB solution of cetyl trimethyl ammonium bromide to obtain a mixed solution, and adding a newly prepared ice-cold sodium borohydride solution into the mixed solution to prepare a gold seed solution.

5. The method for preparing a gold nanorod-lead sulfide quantum dot photodetector as claimed in claim 1, wherein the growth solution is prepared by:

adding silver nitrate solution into cetyl trimethyl ammonium bromide CTAB solution, stirring, adding HAuCl₄·4H₂And (3) uniformly mixing the solution O, adding a hydrochloric acid solution, stirring, adding an ascorbic acid solution, and stirring to obtain a colorless solution, thereby obtaining the growth solution.

6. The method for preparing a gold nanorod-lead sulfide quantum dot photodetector as claimed in claim 1, wherein the preparation of the gold nanorod Au NRs solution specifically comprises:

adding the gold seed solution into the growth solution, stirring, standing, centrifuging the standing solution for 5 minutes at a rotating speed of 7500 rpm, removing supernatant, adding appropriate amount of distilled water, centrifuging for 3 minutes for the second time at a rotating speed of 6000 rpm; and re-dispersing the precipitate after the supernatant liquid is removed in distilled water to obtain a gold nanorod Au NRs solution.

7. The method for preparing a gold nanorod-lead sulfide quantum dot photodetector as claimed in claim 1, wherein the surface ligand exchange is specifically:

the lead sulfide quantum dot PbS QDs solution is coated on a back gate substrate in a spinning mode to form a long-chain ligand coated film, then a CTAB methanol solution is coated on the substrate in a spinning mode, the short-chain ligand solution covers the film and is aired until the film layer presents oily organic matters, then the methanol solution is coated on the substrate in a spinning mode at the same rotating speed to wash away redundant CTAB, and ligand exchange is completed.

8. The method for preparing a gold nanorod-lead sulfide quantum dot photodetector as claimed in claim 1, wherein the spin-coating rotation speed of the first quantum dot spin-coating and the second quantum dot spin-coating is not less than 2500 revolutions per minute, and the spin-coating time is not less than 15 seconds; after the first quantum dot spin coating and the second quantum dot spin coating, the device needs to be placed in a vacuum drying oven to stand for no less than 30 minutes.

9. The method for preparing a gold nanorod-lead sulfide quantum dot photodetector as claimed in claim 7, wherein the surface ligand exchange rotation speed is not less than 2500 rpm, the spin coating time is 10-15s, and the air-drying time is not less than 30 s.

10. A gold nanorod-lead sulfide quantum dot photodetector, characterized in that the gold nanorod-lead sulfide quantum dot photodetector is prepared by the method of any one of claims 1 to 9.

Technical Field

The invention belongs to the technical field of nano semiconductor devices, and particularly relates to a gold nanorod-lead sulfide quantum dot photodetector and a preparation method thereof.

Background

The colloidal lead sulfide quantum dot has the outstanding characteristics of size tunable band gap, multiple exciton effect, high fluorescence quantum yield and the like, and is regarded as one of the most promising photoelectric materials. The solution preparation is another advantage of the lead sulfide quantum dot, and the synthetic method is mature and can be divided into the preparation of lead precursor solution and the injection of sulfur source.

The gold nanorods have stable chemical properties, can be fully absorbed in a visible light region, can form plasmons on the surface under illumination, and have surface enhanced Raman scattering, biocompatibility and the like.

The colloidal lead sulfide quantum dots are widely applied to micro-nano optoelectronic devices such as photodetectors, solar cells, light emitting diodes and the like. The traditional photoelectric detector adopts single semiconductors such as silicon, gallium phosphide, gallium indium arsenide and the like as materials for response of the photoelectric detector, and the photoelectric detector is high in production cost and harsh in preparation conditions. The photosensitive layer of the light detector adopts a simple P-N structure, the absorption efficiency of light is low, the spectral response range is only limited to 0.4-0.76um, and the light detector generally cannot respond to ultraviolet light with the wavelength less than 0.4um and infrared light with the wavelength more than 0.76 um. The PbS quantum dot-based photodetector has a broad spectrum detection capability from visible light to near infrared. However, for photodetectors consisting of PbS quantum dots only, their relatively small light absorption cross-section and low carrier mobility limit their large-scale applications.

Disclosure of Invention

Aiming at the technical problems, the invention provides a gold nanorod-lead sulfide quantum dot optical detector and a preparation method thereof, wherein the optical detector adopts a special sandwich structure, the gold nanostructure is doped in a photosensitive layer of a device, the local electromagnetic field enhancement caused by the plasmon resonance of the local surface of a metal nanoparticle is utilized to improve the optical absorption efficiency of a semiconductor, and the detection of near infrared light is realized by spin coating two layers of colloid lead sulfide quantum dots. The gold nanorod @ lead sulfide quantum dot (Au NRs @ PbS QDs) photodetector with the sandwich layered structure has greatly improved quantum efficiency, responsivity and detectivity compared with a pure lead sulfide photodetector, and shows good photoelectric property. The optical detection is more sensitive than the traditional optical detector, and the detection range is wider.

The technical scheme adopted by the invention for solving the technical problems is as follows: a preparation method of a gold nanorod-lead sulfide quantum dot photodetector comprises the following steps:

preparing a lead sulfide quantum dot PbS QDs solution;

preparing a gold nanorod Au NRs solution: preparing gold seed solution and growth solution, adding the gold seed solution into the growth solution to prepare gold nanorod Au NRs solution;

preparing a gold nanorod-lead sulfide quantum dot photodetector: spin-coating the lead sulfide quantum dot PbS QDs solution on a back gate substrate, then carrying out surface ligand exchange on the quantum dots, spin-coating a gold nanorod Au NRs solution on the back gate substrate after the first quantum dot spin-coating and ligand exchange, and then placing the gold nanorod Au NRs solution in a vacuum drying oven for standing to obtain a gold nanorod Au NRs coating; and then carrying out secondary quantum dot spin coating and ligand exchange on the gold nanorod Au NRs coating by the same method, putting the gold nanorod Au NRs coating into a vacuum drying oven for standing after the secondary quantum dot spin coating and the ligand exchange are finished, and forming the gold nanorod-lead sulfide quantum dot light detector with the sandwich layered structure of the lead sulfide quantum dots PbS QDs-the gold nanorod AuNRs-lead sulfide quantum dots PbS QDs on the back gate substrate.

In the scheme, the preparation of the lead sulfide quantum dot PbS QDs solution specifically comprises the following steps:

preparing a cadmium sulfide quantum dot CdS QDs solution;

lead chloride PbCl is added₂Mixing powder, oleylamine and oleic acid in a container, introducing high-purity argon, exhausting air, heating, cooling after the solution becomes clear, quickly injecting the cadmium sulfide quantum dot CdS QDs solution, continuously cooling, and adding n-hexane; continuously cooling, adding ethanol, centrifuging, removing supernatant, adding n-hexane, centrifuging, collecting upper black liquid, adding ethanol, centrifuging, removing supernatant to obtain black lead sulfide, oven drying, weighing, adding n-hexane, and making into 50mg.mL^-1The lead sulfide quantum dot PbS QDs solution.

In the scheme, the preparation of the cadmium sulfide quantum dot CdS QDs solution specifically comprises the following steps:

adding reddish brown cadmium oxide powder CdO, oleic acid OA and octadecene ODE into a container, putting in a rotating magneton, introducing high-purity argon, exhausting air, heating to 260 ℃, removing a heat source after the solution becomes clear, and cooling; adding an ammonium sulfide solution into oleylamine, and uniformly mixing and stirring; when the temperature in the container is reduced to 30 ℃, quickly injecting the prepared ammonium sulfide solution into the flask, mixing uniformly, stopping stirring, and keeping the temperature; adding excessive ethanol to terminate the reaction, centrifuging, removing supernatant, drying the remaining lemon-yellow cadmium sulfide precipitate, weighing, adding n-hexane, and preparing into 100 mg/mL^-1The cadmium sulfide quantum dot CdSQDs solution is reserved.

In the above scheme, the preparation of the gold seed solution specifically comprises:

the chloroauric acid tetrahydrate HAuCl₄·4H₂And adding the O solution into a CTAB solution of hexadecyl trimethyl ammonium bromide to obtain a mixed solution, and adding a newly prepared ice-cold sodium borohydride solution into the mixed solution to prepare a gold seed solution.

In the above scheme, the preparation of the growth liquid specifically comprises:

adding silver nitrate solution into cetyl trimethyl ammonium bromide CTAB solution, stirring, adding HAuCl₄·4H₂And (3) uniformly mixing the solution O, adding a hydrochloric acid solution, stirring, adding an ascorbic acid solution, and stirring to obtain a colorless solution, thereby obtaining the growth solution.

In the scheme, the preparation of the gold nanorod Au NRs solution specifically comprises the following steps:

adding the gold seed solution into the growth solution, stirring, standing, centrifuging the standing solution for 5 minutes at a rotating speed of 7500 rpm, removing supernatant, adding appropriate amount of distilled water, centrifuging for 3 minutes for the second time at a rotating speed of 6000 rpm; and re-dispersing the precipitate after the supernatant liquid is removed in distilled water to obtain a gold nanorod Au NRs solution.

In the above scheme, the surface ligand exchange specifically comprises:

the lead sulfide quantum dot PbS QDs solution is coated on a back gate substrate in a spinning mode to form a layer of thin film coated by long-chain ligands, then CTAB methanol solution is coated on the substrate in a spinning mode, the thin film is covered by the short-chain ligand solution and aired until the film layer presents oily organic matters, then the methanol solution is coated on the substrate in a spinning mode at the same rotating speed to wash away redundant CTAB, and ligand exchange is completed.

In the scheme, the spin-coating rotating speed of the first quantum dot spin-coating and the second quantum dot spin-coating is not less than 2500 revolutions per minute, and the spin-coating time is not less than 15 seconds; after the first quantum dot spin coating and the second quantum dot spin coating, the device needs to be placed in a vacuum drying oven to stand for no less than 30 minutes.

In the scheme, the rotating speed of the surface ligand exchange is not less than 2500 revolutions per minute, the spin coating time is 10-15s, and the airing time is not less than 30 s.

A gold nanorod-lead sulfide quantum dot photodetector is prepared by using a preparation method of the gold nanorod-lead sulfide quantum dot photodetector.

Compared with the prior art, the invention has the beneficial effects that: the gold nanorod-lead sulfide quantum dot photodetector with the sandwich layered structure in the gold nanorod-lead sulfide quantum dot photodetector has greatly improved quantum efficiency, responsivity and detectivity compared with a pure lead sulfide photodetector. The preparation method can be used for simply, quickly and stably preparing the gold nanorod-lead sulfide quantum dot sandwich structure photodetector, and has the advantages of mild preparation conditions, controllable process parameters and high repeatability. The cost of optical detector preparation has been reduced, has realized simultaneously and has promoted at near infrared band detection performance, realizes the broad spectrum detection from visible light to near infrared light, and is more sensitive to the light signal, and the detectable scope is also wider.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic diagram of a sandwich layered structure of a gold nanorod-lead sulfide quantum dot photodetector according to an embodiment of the invention;

FIG. 2 is an X-ray diffraction spectrum of lead sulfide quantum dots (black) and gold nanorods (gray) according to an embodiment of the present invention;

FIG. 3 is an electron microscope image of quantum dots and gold nanorods according to an embodiment of the present invention, FIG. 3(a) is a transmission electron microscope image of PbS QDs, FIG. 3(b) is a high-resolution transmission electron microscope image of PbS QDs, FIG. 3(c) is a fast Fourier transform image of PbS QDs, and FIG. 3(d) is a transmission electron microscope image of Au NRs;

FIG. 4 is a cross-sectional SEM image of a device according to an embodiment of the present invention, FIG. 4(a) is a field effect transistor of PbS QDs, and FIG. 4(b) is a field effect transistor of Au NRs @ PbS QDs;

FIG. 5 is a graph showing the output characteristic and transfer characteristic of the PbS QDs photodetector and the Au NRs @ PbS QDs photodetector according to an embodiment of the present invention, wherein FIGS. 5(a) and 5(b) are the output characteristic and transfer characteristic of the PbS QDs photodetector under different light power irradiation, respectively, and FIGS. 5(c) and 5(d) are the output characteristic and transfer characteristic of the Au NRs @ PbS QDs photodetector under different light power irradiation, respectively;

FIG. 6 shows responsivities of the PbS QDs photodetector and the Au NRs @ PbS QDs photodetector according to an embodiment of the present invention, wherein (a) shows responsivity spectra of the PbS QDs photodetector and the Au NRs @ PbS QDs photodetector, and FIG. 6(b) shows a responsivity enhancement ratio;

fig. 7 shows the detectivity of the photodetector according to an embodiment of the present invention, where fig. 7(a) shows the detectivity of the photodetector under the excitation of 808nm with different optical power densities, VG ═ VSD ═ 4V, and fig. 7(b) shows the detectivity spectra of the PbS QDs photodetector and the Au NRs @ PbS QDs photodetector;

fig. 8 is an external quantum efficiency of the photodetector according to an embodiment of the present invention, fig. 8(a) is an external quantum efficiency of the photodetector under the excitation of 808nm laser with different optical powers, VG ═ VSD ═ 4V, fig. 8(b) is an external quantum efficiency spectrum of the PbS QDs photodetector and the AuNRs @ PbS QDs photodetector, and fig. 8(c) is an external quantum efficiency enhancement ratio of the Au NRs @ PbS QDs photodetector;

in the figure, 1.Au source; 2, Au drain electrode; 3. a silicon dioxide gate insulating layer; an n-type heavily doped silicon wafer; 5. gold nanorod-lead sulfide quantum dot sandwich structure.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

The preparation method of the gold nanorod-lead sulfide quantum dot photodetector comprises the following steps:

preparing a lead sulfide quantum dot PbS QDs solution;

preparing a gold nanorod Au NRs solution: preparing gold seed solution and growth solution, adding the gold seed solution into the growth solution to prepare gold nanorod Au NRs solution;

preparing a gold nanorod-lead sulfide quantum dot photodetector: spin-coating the lead sulfide quantum dot PbS QDs solution on a back gate substrate, then carrying out surface ligand exchange on the quantum dots, spin-coating a gold nanorod Au NRs solution on the back gate substrate after the first quantum dot spin-coating and ligand exchange, and then placing the gold nanorod Au NRs solution in a vacuum drying oven for standing to obtain a gold nanorod Au NRs coating; and then carrying out secondary quantum dot spin coating and ligand exchange on the gold nanorod Au NRs coating by the same method, putting the gold nanorod Au NRs coating into a vacuum drying oven for standing after the secondary quantum dot spin coating and the ligand exchange are finished, and forming the gold nanorod-lead sulfide quantum dot light detector with the sandwich layered structure of the lead sulfide quantum dots PbS QDs-the gold nanorod AuNRs-lead sulfide quantum dots PbS QDs on the back gate substrate.

The preparation method of the lead sulfide quantum dot PbS QDs solution specifically comprises the following steps:

preparing a cadmium sulfide quantum dot CdS QDs solution;

lead chloride PbCl is added₂Mixing powder, oleylamine and oleic acid in a container, introducing high-purity argon, exhausting air, heating, cooling after the solution becomes clear, and injecting into the container rapidlyThe solution of the cadmium sulfide quantum dots CdS QDs is changed into black, the temperature is continuously reduced, and normal hexane is added; continuously cooling, adding ethanol, centrifuging, removing supernatant, adding n-hexane, centrifuging, collecting upper black liquid, adding ethanol, centrifuging, removing supernatant to obtain black lead sulfide, oven drying, weighing, adding n-hexane, and making into 50mg.mL^-1The lead sulfide quantum dot PbS QDs solution.

The preparation of the cadmium sulfide quantum dot CdS QDs solution specifically comprises the following steps:

adding reddish brown cadmium oxide powder CdO, oleic acid OA and octadecene ODE into a container, putting in a rotating magneton, introducing high-purity argon, exhausting air, heating to 260 ℃, removing a heat source after the solution becomes clear, and cooling; adding an ammonium sulfide solution into oleylamine, and uniformly mixing and stirring; when the temperature in the container is reduced to 30 ℃, quickly injecting the prepared ammonium sulfide solution into the flask, mixing uniformly, stopping stirring, and keeping the temperature; adding excessive ethanol to terminate the reaction, centrifuging, removing supernatant, oven drying the remaining lemon-yellow cadmium sulfide precipitate, weighing, adding n-hexane, and making into 100 mg/mL^-1The cadmium sulfide quantum dot CdSQDs solution is reserved.

The preparation method of the gold seed solution comprises the following specific steps:

the chloroauric acid tetrahydrate HAuCl₄·4H₂And adding the O solution into a CTAB solution of hexadecyl trimethyl ammonium bromide to obtain a mixed solution, and adding a newly prepared ice-cold sodium borohydride solution into the mixed solution to prepare a gold seed solution.

The preparation of the growth liquid comprises the following specific steps:

adding silver nitrate solution into cetyl trimethyl ammonium bromide CTAB solution, stirring, adding HAuCl₄·4H₂And (3) uniformly mixing the solution O, adding a hydrochloric acid solution, stirring, adding an ascorbic acid solution, and stirring to obtain a colorless solution, thereby obtaining the growth solution.

The preparation method of the gold nanorod Au NRs solution comprises the following steps:

adding the gold seed solution into the growth solution, stirring, standing, centrifuging the standing solution for 5 minutes at a rotating speed of 7500 rpm, removing supernatant, adding appropriate amount of distilled water, centrifuging for 3 minutes for the second time at a rotating speed of 6000 rpm; and re-dispersing the precipitate after the supernatant liquid is removed in distilled water to obtain a gold nanorod Au NRs solution.

The surface ligand exchange is specifically as follows:

the lead sulfide quantum dot PbS QDs solution is coated on a back gate substrate in a spinning mode to form a layer of thin film coated by long-chain ligands, then CTAB methanol solution is coated on the substrate in a spinning mode, the thin film is covered by the short-chain ligand solution and aired until the film layer presents oily organic matters, then the methanol solution is coated on the substrate in a spinning mode at the same rotating speed to wash away redundant CTAB, and ligand exchange is completed.

The spin-coating rotating speed of the first quantum dot spin-coating and the second quantum dot spin-coating is not less than 2500 revolutions per minute, and the spin-coating time is not less than 15 seconds; after the first quantum dot spin coating and the second quantum dot spin coating, the device needs to be placed in a vacuum drying oven to stand for no less than 30 minutes.

The rotating speed of the surface ligand exchange is not less than 2500 revolutions per minute, the spin coating time is 10-15s, and the airing time is not less than 30 s.

Fig. 1 shows an embodiment of the gold nanorod-lead sulfide quantum dot photodetector according to the present invention, which is prepared by using the method for preparing the gold nanorod-lead sulfide quantum dot photodetector. The gold nanorod-lead sulfide quantum dot light detector comprises an Au source electrode 1, an Au drain electrode 2, a silicon dioxide gate insulating layer 3, an n-type heavily doped silicon chip 4 and a gold nanorod-lead sulfide quantum dot sandwich structure 5; the silicon dioxide gate insulating layer 3 is positioned on the n-type heavily doped silicon chip 4, the Au source electrode 1 and the Au drain electrode 2 are positioned on the silicon dioxide gate insulating layer 3 to form a back gate substrate, and the gold nanorod-lead sulfide quantum dot sandwich structure 5 is spin-coated on the back gate substrate and positioned between the Au source electrode 1 and the Au drain electrode 2; the gold nanorod-lead sulfide quantum dot sandwich structure 5 is a structure that a layer of gold nanorod Au NRs is sandwiched between two layers of lead sulfide quantum dots PbS QDs.

The invention discloses a preparation method for preparing a gold nanorod-lead sulfide quantum dot sandwich-layer structured photodetector by adopting a low-cost liquid phase spin coating technology and a ligand exchange technology. Lead sulfide quantum dots PbS QDs with good dispersibility are prepared by a cation replacement method and a thermal injection method, and gold nanorods Au NRs with uniform size are prepared by a seed method. The sandwich layer structure field effect optical transistor type optical detector is prepared by adopting a method of layered spin coating on a back gate substrate. The photodetector prepared by the method has greatly improved quantum efficiency, responsivity and detectivity compared with a pure lead sulfide photodetector, shows good photoelectric property, and can realize wide spectrum detection from visible light to near infrared light. The method has the characteristics of simplicity, low cost, rapidness, large-area production, strong practicability and the like.