CN110635047A

CN110635047A - Photoelectric detector and preparation method thereof

Info

Publication number: CN110635047A
Application number: CN201910901573.4A
Authority: CN
Inventors: 徐文; 宋宏伟; 季亚楠; 白雪; 董彪; 徐琳
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2019-09-23
Filing date: 2019-09-23
Publication date: 2019-12-31

Abstract

The invention is suitable for the photoelectric field, has provided a photoelectric detector and its preparation method, the photoelectric detector includes: a base layer; and a perovskite thin film layer, a semiconductor plasma layer, and a NaYF layer sequentially stacked on the base layer₄An intermediate layer, an upconversion layer, and an electrode layer; the up-conversion layer is made of NaYF₄:Yb³⁺，Tm³⁺Is a shell coated with NaYF₄:Yb³⁺，Er³⁺The resulting upconversion nanoparticle layer. The response rate and the photoelectric detection rate of the photoelectric detector to the narrow band of 980nm near infrared light can reach 0.331A/W at most and 4.23 multiplied by 10¹⁰Jones, external quantum efficiency of 41.92%, and good stability, after 100 days of storage, the photoelectric detectivity can still be maintained at 70% of the initial value.

Description

Photoelectric detector and preparation method thereof

Technical Field

The invention belongs to the field of photoelectricity, and particularly relates to a photoelectric detector and a preparation method thereof.

Background

A photodetector refers to a physical phenomenon in which radiation causes a change in the conductivity of an irradiated material. The photoelectric detector has wide application in various fields of military and national economy.

The narrow-band response photoelectric detector has spectral selectivity, so that the narrow-band response photoelectric detector is widely applied to the fields of biomedical sensing, imaging, national defense and the like.

The existing narrow-band response photoelectric detector generally realizes narrow-band response photoelectric detection by a plasma-assisted method which is provided with a band-pass filter or enhances the absorption of specific wavelength, but the optical system of the narrow-band photoelectric detector manufactured by the methods is quite complex in design and integration, high in manufacturing cost and difficulty, low in response rate to infrared light and poor in stability in air.

Disclosure of Invention

The embodiment of the invention provides a photoelectric detector, and aims to solve the problems that an optical system of the conventional narrow-band response photoelectric detector is complex in design and integration, high in preparation cost and difficulty, low in infrared light response rate and poor in stability in air.

The embodiment of the present invention is implemented as follows, and a photodetector includes: a base layer; and

a perovskite thin film layer, a semiconductor plasma layer, and NaYF layer sequentially stacked on the substrate layer₄An intermediate layer, an upconversion layer, and an electrode layer; the up-conversion layer is made of NaYF₄:Yb³⁺，Tm³⁺Is a shell coated with NaYF₄:Yb³⁺，Er³⁺The resulting upconversion nanoparticle layer.

The embodiment of the invention also provides a preparation method of the photoelectric detector, which comprises the following steps:

sequentially spin coating MAPbI on the substrate layer₃Forming a perovskite thin film layer by the perovskite precursor solution and chlorobenzene; preparing a semiconductor plasma layer on the perovskite thin film layer by an interface assembly method; through an interface assembly methodPreparing NaYF on the semiconductor plasma layer₄An intermediate layer; through an interface assembly method on the NaYF₄NaYF is prepared on the intermediate layer₄:Yb³⁺，Tm³⁺Is a shell coated with NaYF₄:Yb³⁺，Er³⁺The resulting upconverting nanoparticle layer; and evaporating and plating an electrode layer on the up-conversion layer to obtain the photoelectric detector.

The photoelectric detector provided by the embodiment of the invention is a substrate layer/perovskite thin film layer/semiconductor plasma layer/NaYF₄Intermediate layer/upper conversion layer/electrode layer structure due to semiconductor plasma effect of semiconductor plasma layer and formed by arranging NaYF₄Intermediate layer of NaYF₄:Yb³⁺，Tm³⁺Is a shell coated with NaYF₄:Yb³⁺，Er³⁺The photoinduced upconversion luminous intensity of the prepared upconversion nanoparticle layer is obviously enhanced, and the absorption range of the perovskite thin film layer can cover the upconversion emission wave band of the whole material. The response rate and photoelectric detection rate of the device to the narrow band of 980nm near infrared light can reach 0.331A/W at most and 4.23 multiplied by 10¹⁰Jones, external quantum efficiency of 41.92%, and good stability, after 100 days of storage, the photoelectric detectivity can still be maintained at 70% of the initial value.

Drawings

FIG. 1 is a schematic cross-sectional view of a photodetector provided in accordance with an embodiment of the present invention;

FIG. 2 is a schematic product diagram of a photodetector provided by an embodiment of the present invention;

FIG. 3 is a NaYF diagram provided by an embodiment of the present invention₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺Transmission electron microscopy of nanoparticles;

FIG. 4 is a NaYF diagram provided by an embodiment of the present invention₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺An X-ray diffraction pattern of the nanoparticles;

FIG. 5 shows Cs according to an embodiment of the present invention_xWO₃nanoparticle/NaYF of 15nm thickness₄Single layerNaYF₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺Nanoparticle normalized emission spectra;

FIG. 6 shows Cs according to an embodiment of the present invention_xWO₃Layer/15 nmNaYF₄/NaYF₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺Fluorescence spectrogram of the up-conversion layer of the composite structure;

FIG. 7 shows Cs according to an embodiment of the present invention_xWO₃Layer/15 nmNaYF₄/NaYF₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺Of composite construction¹D₂-³F₄；²H_11/2, ⁴S_3/2-⁴I_15/2；⁴F_9/2-⁴I_15/2A fluorescence lifetime spectrum of the up-converted emission of the three different emissions;

FIG. 8 shows the test result of the minimum detection power detection performed on the photo detector provided in the embodiment of the present invention;

FIG. 9 shows the test result of the photo-responsivity test of the photo-detector provided in the embodiment of the present invention;

FIG. 10 shows the result of testing the photoelectric detection rate of the photoelectric detector provided by the embodiment of the present invention;

FIG. 11 shows the result of testing the external quantum efficiency of the photodetector provided in the embodiment of the present invention;

FIG. 12 shows the response time of a photodetector provided by an embodiment of the present invention;

fig. 13 is a test result of detecting a photo-electric response current of a photodetector manufactured by changing the number of layers of an upconversion layer provided in an embodiment of the present invention;

fig. 14 is a test result of long-term stability detection performed on the photodetector provided in the embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

As shown in fig. 1, an embodiment of the present invention provides a photodetector including: a base layer 1; and a perovskite thin film layer 2, a semiconductor plasma layer 3, and NaYF sequentially stacked on the base layer 1₄An intermediate layer 4, an up-conversion layer 5 and an electrode layer 6; the up-conversion layer 5 is made of NaYF₄:Yb³⁺，Tm³⁺Is a shell coated with NaYF₄:Yb³⁺，Er³⁺The resulting upconversion nanoparticle layer.

In an embodiment of the present invention, the substrate layer 1 may be a glass material.

In a preferred embodiment of the invention, the semiconductor plasma layer 3 is Cs_xWO₃A nanoparticle layer. Cs_xWO₃The nanoparticle layer is provided in a single layer structure, and Cs is controlled_xWO₃The total height of the nanoparticle layer and the up-conversion layer 5 is not more than 50 nanometers, so that the perovskite thin film layer and the electrode layer of the device can be in contact with each other to form a conductive loop, and the photoelectric conversion efficiency of the device is improved. In addition, Cs_xWO₃The nanoparticle layer is an insulating material layer, which can enhance the water and moisture resistance of the entire photodetector.

In a preferred embodiment of the present invention, the NaYF₄The middle layer is provided with three layers, the total thickness is 13-15 nanometers, and NaYF is arranged₄The middle layer is regulated and controlled to have the optimal reinforced thickness of 13-15 nanometers and the more optimal thickness of 15 nanometers, so that NaYF can be used₄:Yb³⁺，Tm³⁺Is a shell coated with NaYF₄:Yb³⁺，Er³⁺The photoinduced upconversion luminous intensity of the prepared upconversion nanoparticle layer is obviously enhanced, and the absorption range of the perovskite thin film layer can cover the upconversion emission wave band of the whole material.

In embodiments of the present invention, the electrode layer may be a silver electrode, a platinum electrode, or a gold electrode.

In the embodiment of the present invention, NaYF will be used as the NaYF₄:Yb³⁺，Tm³⁺Is a shell coated with NaYF₄:Yb³⁺，Er³⁺The prepared up-conversion nano particle layer is arranged below the electrode layer, so that the effect of isolating air can be achieved, the stability of the device in the air is improved, the perovskite thin film layer can be protected, and the long-term stability and the waterproof performance of the device are improved.

sequentially spin coating MAPbI on the substrate layer₃Forming a perovskite thin film layer by the perovskite precursor solution and chlorobenzene; preparing semiconductors and the like on the perovskite thin film layer by an interface assembly methodAn ion layer; preparing NaYF on the semiconductor plasma layer by an interface assembly method₄An intermediate layer; through an interface assembly method on the NaYF₄NaYF is prepared on the intermediate layer₄:Yb³⁺，Tm³⁺Is a shell coated with NaYF₄:Yb³⁺，Er³⁺The resulting upconverting nanoparticle layer; and evaporating and plating an electrode layer on the up-conversion layer to obtain the photoelectric detector.

In an embodiment of the invention, the base layer is spin coated with MAPbI sequentially₃The perovskite precursor solution and chlorobenzene are used for forming the perovskite thin film layer, and the method specifically comprises the following steps: configuring MAPbi₃Perovskite precursor solution, under the protection of nitrogen, the MAPbI is added₃The perovskite precursor solution is spin-coated on the substrate layer, the rotation speed during spin-coating is 1000-2000 rpm, and the spin-coating time is 10-20 seconds; and spin-coating chlorobenzene on the substrate layer at the rotating speed of 3000-5000 rpm for 30-50 seconds, and annealing at the temperature of 100 ℃ for 10-20 minutes after the spin-coating is finished to form the perovskite thin film layer on the substrate layer.

In an embodiment of the present invention, the step of preparing a semiconductor plasma layer on the perovskite thin film layer by an interface assembly method includes: preparing a cesium tungstate solution, slowly dripping the cesium tungstate solution into a container containing a diethylene glycol solution, and flatly paving the cesium tungstate solution on the surface of the diethylene glycol solution; and inserting the substrate layer with the perovskite thin film layer formed thereon into the container, slowly pulling out the substrate layer, and putting the substrate layer into an oven to dry a diethylene glycol solution on the surface of the substrate layer so as to prepare the semiconductor plasma layer on the perovskite thin film layer.

In the embodiment of the invention, the NaYF is arranged on the substrate through an interface assembly method₄NaYF is prepared on the intermediate layer₄:Yb³⁺，Tm³⁺Is a shell coated with NaYF₄:Yb³⁺，Er³⁺The step of producing an upconverting nanoparticle layer comprising: respectively configuring NaYF₄:Yb³⁺，Er³ ⁺Cyclohexane nucleus solution and NaYF₄:Yb³⁺，Tm³⁺A shell solution; the NaYF is adopted₄:Yb³⁺，Er³⁺Cyclohexane nucleus solution and NaYF₄:Yb³⁺，Tm³⁺Shell solution, preparation of NaYF₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺A solution; by an interface assembly method, NaYF is adopted₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺Solution in the NaYF₄An upconversion nanoparticle layer is prepared on the intermediate layer.

In an embodiment of the present invention, the step of depositing an electrode layer on the upper conversion layer by evaporation includes: and under the temperature condition of 900-1000 ℃, evaporating and plating an electrode layer with the thickness of 100-300 nanometers on the up-conversion nano particle layer.

Illustratively, the photodetector of the present invention can be prepared by the following steps:

MAPbI was prepared by mixing MAI and lead iodide in dimethyl sulfoxide₃(methyl ammonium iodide) perovskite precursor solution. Under the protection of nitrogen, the perovskite precursor solution is spin-coated on the substrate layer by adopting a spin-coating method, the rotation speed during the spin-coating is 1200rpm, and the spin-coating time is 12 seconds. And then, continuously spin-coating 100uL chlorobenzene on the substrate layer, wherein the rotation speed during the spin-coating is 4100rpm, the spin-coating time is 30 seconds, and after the spin-coating is finished, the substrate layer is annealed for 10 minutes under the temperature condition of 100 ℃ so as to form a perovskite thin film layer on the substrate layer.

Putting 60mg of tungsten chloride powder and 20mg of cesium chloride powder into a three-necked bottle, pouring 0.2mL of oleylamine and 5.2mL of octadecenoic acid solution into the three-necked bottle, introducing nitrogen for protection, putting into a condenser tube, and stirring at 300 ℃ for 150min to obtain a blue-green cesium tungstate solution. The high temperature cesium tungstate solution was then cooled to 25 deg.C and 0.5mL of toluene solution was added. And then taking 2mL of toluene and cesium tungstate mixed solution into a centrifugal tube, adding 10mL of acetone solution, centrifuging for 10min at the speed of 3500rpm, pouring the upper layer liquid, dissolving the precipitate in 0.5mL of toluene, ultrasonically dispersing, repeating the centrifuging step twice to obtain cesium tungstate precipitate, and finally dissolving the cesium tungstate precipitate in 2.4mL of toluene solution to obtain cesium tungstate solution.

And preparing single-layer cesium tungstate nano particles on the perovskite thin film layer by an interface assembly method by taking 40 mu L of cesium tungstate solution. Taking any one container (which can be a 30mL beaker or a 5mL multiplied by 5mL bottle cap of a reaction kettle), pouring the diethylene glycol solution (the pouring amount can be approximately full of the bottom of the container and is convenient for lifting MAPbI at later stage)₃The cesium tungstate solution is coated on a glass substrate), 40 mu L of the cesium tungstate solution is slowly dripped onto the liquid surface of diethylene glycol by using a liquid transfer gun, and a clean cover glass (the material is not required, the container can be covered for 1 hour), so that toluene in the cesium tungstate solution is evaporated, and the cesium tungstate solution can be flatly paved on the surface of the diethylene glycol solution. Clamping MAPbI Using forceps₃And slowly pulling the glass substrate obliquely inserted into the surface of the diethylene glycol solution to attach a single-layer cesium tungstate solution to the substrate layer, putting the substrate layer into an oven to be dried for 1 hour to volatilize redundant diethylene glycol on the surface of the substrate layer, and thus obtaining a semiconductor plasma layer (namely a single-layer cesium tungstate nanoparticle layer) on the perovskite thin film layer.

Putting 0.24g of yttrium chloride hexahydrate powder, 0.08g of ytterbium chloride hexahydrate powder and 0.01g of erbium chloride hexahydrate powder into a three-necked bottle, adding 6mL of oleic acid and 15mL of octadecene solution, fixing a heating sleeve (or an oil bath kettle), stirring at the stirring speed of 800rpm under the protection of nitrogen at 160 ℃ until the medicines are completely dissolved, and cooling to room temperature. 0.148g of ammonium fluoride, 0.1g of sodium hydroxide powder was then dissolved in 5mL of methanol solution. And dropwise adding the solution into the cooled solution in the three-necked bottle, fully stirring for 0.5h, heating to 125 ℃, introducing into a condenser pipe until no foam exists in the three-necked bottle, gradually heating to 300 ℃, stirring for 1.5h, stopping heating, and cooling the solution to room temperature. Pouring the cooled solution into six 50mL centrifuge tubes on average, adding 20mL ethanol solution into the centrifuge tubes, centrifuging at 11000rpm for 10min, separating to obtain precipitates, adding 10mL cyclohexane solution into the precipitates, dissolving the precipitates by ultrasonic waves, adding 20mL ethanol solution, centrifuging again, repeating the step twice to obtain NaYF₄:Yb³⁺，Er³⁺Precipitating, collecting precipitates in six centrifuge tubes, adding 5mL of cyclohexane, and performing ultrasonic treatment to obtain NaYF₄:Yb³⁺，Er³⁺Cyclohexane nucleus solution.

Putting 0.24g of yttrium chloride hexahydrate powder, 0.08g of ytterbium chloride hexahydrate powder and 0.001g of thulium chloride hexahydrate powder into a three-necked bottle, adding 6mL of oleic acid and 15mL of octadecene solution, fixing a heating sleeve (or an oil bath kettle), stirring at the rotating speed of 800rpm under the protection of 160 ℃ nitrogen until the medicines are completely dissolved, and cooling to room temperature. Then adding the prepared NaYF₄:Yb³⁺，Er³⁺The cyclohexane nucleus solution was stirred at 800rpm for 0.5h, and NaYF was prepared as described above₄:Yb³⁺，Er³⁺Repeating the steps of the cyclohexane nucleus solution, adding 20mL of cyclohexane into the centrifuged precipitate to obtain NaYF₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺And (3) solution.

NaYF₄The preparation method of the interlayer solution is the same as that of NaYF except that rare earth ion powder is not added₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺And (4) solution preparation operation.

120 mu L of NaYF is taken₄Solution in MAPbI by the above interface assembly method₃/Cs_xWO₃Preparation of a monolayer NaYF on a layer₄And the operation is repeated three times to obtain three layers of NaYF4 intermediate layers with the thickness of 15 nm. Take 40 μ L NaYF₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺Solution in MAPbI by interface assembly method₃/Cs_xWO₃Layer/15 nmNaYF₄A single layer upconversion layer is prepared on the composite structure. Finally, a silver electrode (or a platinum electrode, a gold electrode) with a thickness of 150nm was deposited on the upconversion layer at a temperature of 900 ℃ to obtain a photodetector according to an embodiment of the present invention (as shown in fig. 2).

In the actual production process, the rotation speed of spin coating the perovskite precursor solution on the substrate layer by using a spin coating method is preferably 1000-2000 rpm, and the spin coating time is 10-20 seconds. When the spin-coating speed is lower than 1000rpm, as the spin-coating speed is lower, if the thickness of the spin-coating layer of the perovskite precursor solution is required to be preset, longer spin-coating time is needed, and the improvement of the operation efficiency is not facilitated; when the spin coating speed is higher than 2000rpm, the perovskite precursor solution is easily attached to the glass substrate layer due to the generated high-speed rotation centrifugal force, namely, the perovskite precursor solution is easily splashed out, so that the thickness of the spin coating layer is not uniform, and the spin coating effect is influenced. Therefore, the invention preferably controls the spin-coating rotating speed of the perovskite precursor solution on the glass substrate layer to be 1000-2000 rpm. In order to ensure that the perovskite precursor solution can obtain a spin-coating liquid layer with uniform thickness on the glass substrate layer, the spin-coating rotation speed and the spin-coating time can be comprehensively regulated and controlled to be matched with each other to achieve a better spin-coating effect, for example, when the spin-coating rotation speed is lower, the spin-coating time is appropriately shortened, and when the spin-coating rotation speed is higher, the spin-coating time is appropriately prolonged. According to the invention, a great number of experiments prove that when the spin-coating rotating speed is controlled to be 1000-2000 rpm, and the spin-coating time is controlled to be 10-20 seconds, the perovskite precursor solution layer with uniform thickness can be obtained by spin-coating on the glass substrate layer, and the working efficiency is high.

Based on the same reason, the rotating speed of the chlorobenzene spin-coating on the substrate layer is preferably 3000-5000 rpm, the spin-coating time is 10-20 seconds, and the rotating speed and the spin-coating time of the chlorobenzene spin-coating can be flexibly regulated and controlled in the actual production process to achieve a relatively balanced state, so that the chlorobenzene spin-coating with uniform thickness can be prepared on the substrate layer.

In the actual production process, after chlorobenzene is spin-coated, the substrate layer attached with the perovskite precursor solution and chlorobenzene is placed at 100 ℃ for annealing for 10-20 minutes. In order to ensure that chlorobenzene can fully react with a perovskite precursor solution to form a stable lattice structure, the annealing time can be flexibly regulated and controlled in the actual production process, and the perovskite precursor film after the chlorobenzene is spin-coated can be changed from yellow to black.

In the actual production process, when preparing the cesium tungstate solution, specifically, the cesium tungstate solution can be controlled to be introduced into a condensing tube for protection by nitrogen gas, and stirred at 300 ℃ for 100-200 min to obtain a blue-green cesium tungstate solution. And then cooling the high-temperature cesium tungstate solution to 25-40 ℃, and adding 0.5mL of toluene solution. And then taking 2mL of toluene and cesium tungstate mixed solution, adding 5-20 mL of acetone solution into the centrifugal tube, and centrifuging at the speed of 3500-4500 rpm for 10-15 min. Experiments prove that the medicine in the three-necked bottle can be completely dissolved by stirring for 100-200 min at 300 ℃. And cooling the high-temperature cesium tungstate solution to 25-40 ℃, wherein the aim is to prevent the cesium tungstate solution from reacting with oxygen in the air to generate other oxides, such as tungsten oxide, when the three-necked bottle is opened at high temperature. And the temperature of 25-40 ℃ is actually the room temperature range in the reaction environment, namely, the cesium tungstate solution can be prevented from being oxidized at the temperature.

After adding the acetone, the centrifugal speed is preferably 3500-4500, and the centrifugation is carried out for 10-15 min. The purpose of adding acetone for centrifugation is to separate the excess oleic acid and oleylamine solution in the cesium tungstate solution from the cesium tungstate precipitate. Based on the above-mentioned substantially same preferred reason for the spin-coating rotation speed and the spin-coating time, the rotation speed and the centrifugation time of the centrifugation can be flexibly controlled within this range in the actual production process.

In the actual production, when a single-layer cesium tungstate nanoparticle layer is prepared by lifting, slowly dropping a cesium tungstate solution on the liquid surface of diethylene glycol, covering a cover glass for 0.5-2 hours, wherein the diethylene glycol and the cesium tungstate solution are not mutually soluble, and the volatilization of the diethylene glycol can be prevented after covering the cover glass, so that the cesium tungstate solution can be gradually spread and diffused on the liquid surface of the diethylene glycol to form a single-layer cesium tungstate solution layer. And (3) putting the substrate layer material attached with the single-layer cesium tungstate solution into an oven to be dried for 0.5-2 h, and volatilizing the residual diethylene glycol on the surface of the substrate layer.

In actual production, NaYF can be prepared by the following steps₄:Yb³⁺，Er³⁺Cyclohexane nucleus solution: putting 0.24g of yttrium chloride hexahydrate powder, 0.08g of ytterbium chloride hexahydrate powder and 0.01g of erbium chloride hexahydrate powder into a three-necked bottle, adding 6mL of oleic acid and 15mL of octadecene solution, fixing a heating sleeve (or an oil bath pot), stirring at the stirring speed of 650-1000 rpm under the protection of nitrogen at 160 ℃ until the medicines are completely dissolved, and cooling to room temperature. Then 0.148g of ammonium fluoride and 0.1g of sodium hydroxide powder are dissolved in 5-6 mL of methanol solution. Then the solution is gradually droppedAnd (3) putting the mixture into the cooled solution in the three-necked bottle, fully stirring for 0.5-1 h, heating to 125 ℃, introducing the mixture into a condenser pipe until no foam exists in the three-necked bottle, and gradually heating to 290-310 ℃. Uniform and well-dispersed nanoparticles can be formed in the temperature range of 290-310 ℃, when the temperature is lower than 290 ℃, the uniform and well-dispersed nanoparticles cannot be formed, and when the reaction temperature exceeds 310 ℃, the lattice structure of the nanoparticles is damaged, so that the nanoparticles with uniform particle size and good dispersion are difficult to form. In addition, in actual production, it is prevented that the solution reaction is not sufficiently performed due to too fast temperature rise, and the particle diameter of the formed upconversion nanoparticles is not uniform. After stirring for 1.5h, heating was stopped and the solution was cooled to room temperature. And pouring the cooled solution into six 50mL centrifuge tubes on average, adding 20-30 mL ethanol solution into the centrifuge tubes, and controlling the rotation speed within the range in the actual production process at the rotation speed of 9000-11000 rpm, wherein the rotation speed is too low to separate the nanoparticles from the ethanol solution. Centrifuging for 10-20 min, separating to obtain a precipitate, adding 5-15 mL of cyclohexane solution into the precipitate, ultrasonically dissolving the precipitate, adding 20-30 mL of ethanol solution, centrifuging again, adding cyclohexane to disperse the precipitate in the solution, and controlling the adding amount to be 10-30% of the capacity of a centrifugal tube if a 50mL centrifugal tube is selected, wherein the precipitate is insoluble in ethanol, so that the ethanol is added to separate the upconversion nanoparticles from the cyclohexane in the centrifuging process, the adding amount is 40-60% of the capacity of the centrifugal tube, and the specific adding amount can be flexibly changed within the range. The step is repeated twice to obtain NaYF₄:Yb³⁺，Er³⁺Precipitating, namely collecting precipitates in six centrifuge tubes, adding 5-15 mL of cyclohexane, and performing ultrasonic treatment to obtain NaYF₄:Yb³⁺，Er³⁺The cyclohexane core solution enables the precipitate to be dissolved in cyclohexane, so that the precipitate can fully react with the shell layer solution in the coating process to form the up-conversion nano-particles with uniform particle size and good dispersibility. An excessive amount of the cyclohexane solution may result in insufficient dissolution of the core nanoparticles into cyclohexane, and an excessive amount of the cyclohexane solution may result in reflection after the addition of the core solutionThe time is prolonged, and the experimental efficiency is reduced.

In actual production, NaYF is prepared₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺During solution, the related stirring rotating speed is preferably 650-1000 rpm, and the prepared NaYF is added₄:Yb³⁺，Er³⁺After the cyclohexane nucleation solution is mixed, the stirring time is controlled to be 0.5-1 h, so that NaYF is obtained₄:Yb³⁺，Er³⁺The cyclohexane nucleus solution is fully dispersed in the solution of the three-necked flask, so that NaYF₄:Yb³ ⁺，Er³⁺The cyclohexane core solution is used as a core to be coated by the solution in the three-necked flask to form NaYF₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³ ⁺And (3) solution.

In actual production, a silver electrode (or a platinum electrode, or a gold electrode) with a thickness of 100-300 nm can be evaporated on the up-conversion layer at a temperature of 900-1000 ℃ to obtain the photodetector of the embodiment of the invention. If the temperature does not reach the melting point of silver, the solid silver can not be melted and evaporated, and the evaporation process of the silver electrode can not be completed. Extensive testing has shown that silver electrodes can be damaged when the thickness of the silver electrode is below 100nm, and is too low to penetrate the single upconverting nanolayer, rendering the photodetector device inadequate for forming a closed, electrically conductive loop. While too thick a silver electrode may affect device performance, such as extending response time. Silver electrodes, platinum electrodes, and gold electrodes are preferred because these evaporation methods are well-established, silver electrodes have the advantage of being relatively inexpensive, and platinum electrodes and gold electrodes have the advantage of being relatively stable and not easily oxidized when exposed to air for a long period of time.

The structural composition and performance of the photodetector manufactured by the manufacturing method of the above exemplary embodiment are tested below to further illustrate the technical effects of the present invention.

Measurement of Transmission Electron microscope

The photoelectric detector provided by the embodiment of the invention is tested by using a Hitachi H-8100IV transmission electron microscope under the acceleration voltage of 200 kV.As shown in fig. 3 and 4, the transmission electron microscope images show that the semiconductor plasma layer of the photodetector prepared by the preparation method provided by the embodiment of the invention is monodisperse Cs_xWO₃Nanoparticles, the upper conversion layer is hexagonal NaYF₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺Up-converting nanoparticles (average size about 30 nm).

Test for second, X-ray diffraction

X-ray diffraction patterns were recorded as thin films on a Bruker AXS D8 diffractometer using alpha radiation (λ ═ 1.54178). The film is prepared by covering the surface of a silicon wafer substrate in a spin coating mode. As shown in FIG. 5, the X-ray diffraction pattern shows Cs_xWO₃、NaYF₄、NaYF₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺The nano particles correspond to the standard cards one by one.

Test for measuring fluorescence Spectrum

Emission spectra of all samples were recorded using a Princeton SP2300 spectrometer under continuous 980nm illumination in a room temperature environment, as shown in FIG. 6 as Cs_xWO₃Layer/15 nmNaYF₄/NaYF₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺Fluorescence spectrum of the up-conversion layer of the composite structure. The fluorescence spectrogram shows that the composite structure has obvious up-conversion emission in near ultraviolet, visible light and near infrared bands.

Test for testing four, time-resolved spectra

Fluorescence lifetime experiments were performed by a single photon counting system (Tektronix AFG1022) under pulsed 980nm light source excitation. As shown in FIG. 7, is Cs_xWO₃Layer/15 nmNaYF₄/NaYF₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺Curve 1 of the composite structure is¹D₂-³F₄(ii) a Curve 2 is²H_11/2, ⁴S_3/2-⁴I_15/2(ii) a Curve 3 is⁴F_9/2-⁴I_15/2The fluorescence lifetimes of the up-converted emissions of these three different emissions are 250 μ s, 330 μ s, 500 μ s, respectively.

Test for testing five, I-V curves

Cs was tested by an I-V curve tester at room temperature in the dark using continuous 980nm light source illumination_xWO₃Layer/15 nmNaYF₄/NaYF₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺The response current of the composite structure to a 980nm light source. The photoelectric detector provided by the embodiment of the invention can detect the lowest 0.5mW/cm²The 980nm light source has a response current of about 0.52 μ A, as shown in FIG. 8. The photoelectric detectivity, photoelectric responsivity, and external quantum efficiency are described by the following equations:

ip and Id are the photocurrent and dark current of the detector respectively, P is the illumination power density of a 980nm light source, A is the effective response area, h is the Planck constant, q is the charge quantity, and v is the speed of light. According to the formula 1, the highest photoelectric response rate of the invention can reach 0.331A/W, as shown in FIG. 9. According to equation 2, the change of the detection rate according to the change of the power density can be obtained, and the maximum detection power can be 4.23 × 1010Jones, as shown in fig. 10. The maximum external quantum efficiency was calculated to be 41.92% from equation 3, as shown in fig. 11. The fastest response times are 130 mus, and 180 mus, respectively, as shown in fig. 12. And, NaYF is added₄/NaYF₄:Yb³⁺，Er³⁺@NaYF⁴:Yb³⁺，Tm³⁺After the number of layers, as shown in fig. 13, one layer of nanoparticles corresponds to the top spectral line in the graph, and two layers of nanoparticlesThe rice particles correspond to the spectral lines at the middle position of the graph, and the three layers of nano particles correspond to the spectral lines at the lowest layer of the graph. Under the excitation of 980nm laser with the same power, the response current of the detector is not found to increase along with the increase of the number of layers, on the contrary, as the up-conversion nano particles are insulating materials, the response current is reduced along with the increase of the number of layers, and in consideration of cost, a single up-conversion layer is preferably arranged.

Test six, long term stability test

After the photodetector provided by the embodiment of the present invention is placed at room temperature for 60 days and 100 days, the photoelectric response current of the device under the irradiation of a 980nm light source is respectively tested, and response efficiencies of about 72% and 68% of the initial values are respectively obtained, as shown in fig. 14.

The photoelectric detector prepared by the preparation method provided by the embodiment of the invention is a substrate layer/perovskite thin film layer/semiconductor plasma layer/NaYF₄Intermediate layer/upper conversion layer/electrode layer structure due to semiconductor plasma effect of semiconductor plasma layer and formed by arranging NaYF₄Intermediate layer of NaYF₄:Yb³⁺，Tm³⁺Is a shell coated with NaYF₄:Yb³⁺，Er³⁺The photoinduced upconversion luminous intensity of the prepared upconversion nanoparticle layer is obviously enhanced, and the absorption range of the perovskite thin film layer can cover the upconversion emission wave band of the whole material. The response rate and photoelectric detection rate of the device to the narrow band of 980nm near infrared light can reach 0.331A/W at most and 4.23 multiplied by 10¹⁰Jones, external quantum efficiency of 41.92%, and good stability, after 100 days of storage, the photoelectric detectivity can still be maintained at 70% of the initial value.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A photodetector, characterized in that the photodetector comprises:

a base layer; and

a perovskite thin film layer, a semiconductor plasma layer, and NaYF layer sequentially stacked on the substrate layer₄An intermediate layer, an upconversion layer, and an electrode layer;

the up-conversion layer is made of NaYF₄:Yb³⁺，Tm³⁺Is a shell coated with NaYF₄:Yb³⁺，Er³⁺The resulting upconversion nanoparticle layer.

2. The photodetector of claim 1, wherein the semiconductor plasma layer is Cs_xWO₃A nanoparticle layer.

3. The photodetector of claim 1, wherein a total height of the semiconductor plasma layer and the upconversion layer does not exceed 50 nanometers.

4. The photodetector of claim 1, wherein the NaYF₄The middle layer was provided with three layers, with a total thickness of 13 ~ 15 nm.

5. The photodetector of claim 1, wherein the electrode layer is a silver electrode, a platinum electrode, or a gold electrode.

6. The method of fabricating a photodetector of any of claims 1 ~ 5, comprising the steps of:

sequentially spin coating MAPbI on the substrate layer₃Forming a perovskite thin film layer by the perovskite precursor solution and chlorobenzene;

preparing a semiconductor plasma layer on the perovskite thin film layer by an interface assembly method;

preparing NaYF on the semiconductor plasma layer by an interface assembly method₄An intermediate layer;

through an interface assembly method on the NaYF₄NaYF is prepared on the intermediate layer₄:Yb³⁺，Tm³⁺Is a shell, and is characterized in that,coated NaYF₄:Yb³⁺，Er³ ⁺The resulting upconverting nanoparticle layer;

and evaporating and plating an electrode layer on the up-conversion layer to obtain the photoelectric detector.

7. The method of claim 6, wherein the sequentially spin coating the base layer with MAPbI₃Perovskite precursor solution and chlorobenzene, form the step of perovskite thin layer, including:

configuring MAPbi₃Perovskite precursor solution, under the protection of nitrogen, the MAPbI is added₃The perovskite precursor solution is spin-coated on the substrate layer, the rotation speed during spin-coating is 1000 ~ 2000rpm, and the spin-coating time is 10 ~ 20 seconds;

chlorobenzene was spin-coated on the substrate layer at a speed of 3000 ~ 5000rpm for 30 ~ 50 seconds at 3000 ~ rpm for 10 ~ seconds, and after the spin-coating was completed, the substrate was annealed at 100 ℃ for 10 ~ 20 minutes to form a perovskite thin film layer on the substrate layer.

8. The method of fabricating a photodetector according to claim 6, wherein the step of fabricating a semiconductor plasma layer on the perovskite thin film layer by an interface assembly method comprises:

preparing a cesium tungstate solution, slowly dripping the cesium tungstate solution into a container containing a diethylene glycol solution, and flatly paving the cesium tungstate solution on the surface of the diethylene glycol solution;

and inserting the substrate layer with the perovskite thin film layer formed thereon into the container, slowly pulling out the substrate layer, and putting the substrate layer into an oven to dry a diethylene glycol solution on the surface of the substrate layer so as to prepare the semiconductor plasma layer on the perovskite thin film layer.

9. The method of claim 6, wherein the NaYF is fabricated on the substrate by interfacial assembly₄NaYF is prepared on the intermediate layer₄:Yb³⁺，Tm³⁺Is a shell coated with NaYF₄:Yb³⁺，Er³⁺The step of producing an upconverting nanoparticle layer comprising:

respectively configuring NaYF₄:Yb³⁺，Er³⁺Cyclohexane nucleus solution and NaYF₄:Yb³⁺，Tm³⁺A shell solution;

the NaYF is adopted₄:Yb³⁺，Er³⁺Cyclohexane nucleus solution and NaYF₄:Yb³⁺，Tm³⁺Shell solution, preparation of NaYF₄:Yb³⁺，Er³ ⁺@NaYF₄:Yb³⁺，Tm³⁺A solution;

by an interface assembly method, NaYF is adopted₄:Yb³⁺，Er³⁺@NaYF₄:Yb³⁺，Tm³⁺Solution in the NaYF₄An upconversion nanoparticle layer is prepared on the intermediate layer.

10. The method of claim 6, wherein the step of depositing an electrode layer on the upconverting layer comprises:

an electrode layer with a thickness of 100 ~ 300nm was vapor deposited on the upconversion nanoparticle layer at a temperature of 900 ~ 1000 ℃ of 1000 ℃.