A two-dimensional (Rc0.5Mo0.25V0.25)S2-based photoelectric detector and a preparation method thereof

Abstract

The application belongs to the technical field of photoelectric sensors, and discloses a photoelectric detector based on two-dimensional Re0.5Mo0.25V0.25S2 and a preparation method thereof. The structure of the photoelectric detector is sequentially from bottom to top as a substrate, a bottom electrode, a photoelectric conversion layer and a top electrode, and the photoelectric conversion layer is a two-dimensional Re0.5Mo0.25V0.25S2 film, which is formed by spin coating and annealing of Re0.5Mo0.25V0.25S2 nano slurry. The light absorption utilization rate of ReS2 is improved by co-doping of Mo and V, a higher photocurrent is obtained, and the detection performance is improved. The device can generate a photocurrent of 0.42 mA under zero bias, and has a self-power supply characteristic. The application has a simple process, and is easy to prepare in a large area and mass production.

Description

Technical Field

[0001] This invention relates to the field of photoelectric sensor technology, and more particularly to a photodetector based on two-dimensional (Rc0.5Mo0.25V0.25)S2 and its fabrication method. Background Technology

[0002] Photodetectors are core devices that convert optical signals into electrical signals, and they have significant applications in environmental monitoring, biomedical detection, optical communication, and industrial automation. However, traditional photodetectors are limited by the physical properties of the materials themselves, resulting in shortcomings in sensitivity, response speed, power consumption, and the ability to detect light of specific wavelengths. These limitations make it difficult to meet the ever-increasing demands for high-precision and high-sensitivity detection, necessitating the development of novel photoelectric conversion materials to overcome these performance bottlenecks.

[0003] Two-dimensional transition metal sulfides, due to their unique atomic layered structure, possess high carrier mobility, excellent optical absorption properties, and good chemical stability, making them ideal materials for constructing high-performance photodetectors. However, existing photodetectors based on two-dimensional sulfides still face several challenges in their fabrication: the limited light absorption utilization of single-component two-dimensional sulfide materials restricts further improvement in photoelectric conversion efficiency; the poor quality of the contact interface between the two-dimensional sulfide and the electrode leads to low charge transport efficiency; and the fabrication processes mostly rely on mechanical exfoliation or chemical vapor deposition, which are complex and costly, making it difficult to achieve large-scale, highly consistent mass production. Therefore, developing a two-dimensional sulfide photodetector with high light absorption utilization, a simple fabrication process, and self-powered characteristics has significant practical implications and application prospects. Summary of the Invention

[0004] The purpose of this invention is to provide a photodetector based on two-dimensional (Rc0.5Mo0.25V0.25)S2 and its fabrication method, so as to solve the problems existing in the prior art.

[0005] This invention provides a photodetector based on two-dimensional Re0.5Mo0.25V0.25S2. The structure of the photodetector, from bottom to top, consists of a substrate, a bottom electrode, a photoconversion layer, and a top electrode. The photoconversion layer is a two-dimensional Re0.5Mo0.25V0.25S2 thin film, which is formed by spin-coating and annealing Re0.5Mo0.25V0.25S2 nano-slurry.

[0006] The above technical solution utilizes a two-dimensional Re0.5Mo0.25V0.25S2 thin film as the photoelectric conversion layer. By co-doping ReS2 with Mo and V, the electronic band structure of the material is altered, broadening the light absorption range and improving light absorption utilization. This results in a significant photoelectric response under visible light irradiation, achieving a larger open-circuit voltage and short-circuit current, thus significantly enhancing photoelectric detection performance. Furthermore, the device generates a photocurrent of 0.42 mA under zero-bias conditions, exhibiting self-powered characteristics and enabling photoelectric signal detection and output without an external bias voltage. In addition, the photoelectric conversion layer is prepared using Re0.5Mo0.25V0.25S2 nano-slurry through spin-coating and annealing. Combined with a bottom-up vertical stack configuration of substrate, bottom electrode, photoelectric conversion layer, and top electrode, the process is simple and convenient, facilitating large-area fabrication and mass production, and exhibiting good process repeatability.

[0007] Furthermore, the substrate is a silicon substrate with a silicon dioxide layer on its surface, the thickness of which is 200 to 300 nm.

[0008] Furthermore, the number of spin-coated layers of the two-dimensional Re0.5Mo0.25V0.25S2 thin film is 3 to 6, and the film thickness is 100 to 400 nm.

[0009] Furthermore, both the bottom electrode and the top electrode are Au electrodes, with the bottom electrode having a thickness of 30 to 50 nm and the top electrode having a thickness of 50 to 200 nm.

[0010] A method for fabricating a photodetector, characterized by comprising the following steps: S1, NH4ReO4, MoO2(C5H7O2)2, and VO(C5H7O2)2 are mixed in a molar ratio of 2:1:1, with a total amount of 0.5 mmol. This mixture is then dissolved together with 5 mmol of CH3CSNH2 in 5 mL of N-methyl-2-pyrrolidone. The mixture is stirred at 300 rpm for 2 hours to obtain a precursor mixed solution. S2, the precursor mixture solution was transferred to a high-pressure reactor and reacted at 200 degrees Celsius for 12 hours. After the reaction was completed, it was cooled to room temperature, centrifuged to collect the product, washed three times each with anhydrous ethanol and deionized water, and dried at 50 degrees Celsius for 24 hours to obtain Re0.5Mo0.25V0.25S2 nanopowder. S3. Re0.5Mo0.25V0.25S2 nanopowder was placed in a tube furnace and heated to 400 degrees Celsius at a heating rate of 5 degrees Celsius per minute under argon protection. After holding at this temperature for 60 minutes, it was naturally cooled to room temperature to obtain annealed two-dimensional Re0.5Mo0.25V0.25S2 nanomaterials. S4. Two-dimensional Re0.5Mo0.25V0.25S2 nanomaterials were ultrasonically dispersed in ethylene glycol methyl ether solution. A mixed solution of ethyl cellulose and terpineol with a mass ratio of 1.5:1 was added. After ultrasonic dispersion for 2 hours, the mixture was stirred at low speed on a magnetic stirrer for 20 hours to obtain Re0.5Mo0.25V0.25S2 colloid. S5, The bottom electrode is prepared by vacuum evaporation on the cleaned and dried substrate; S6. The Re0.5Mo0.25V0.25S2 colloid was spin-coated onto the substrate with the bottom electrode deposited using a spin coater. After spin coating, it was heated at 100 degrees Celsius for 5 minutes. After cooling, the spin coating and heating operations were repeated 3 times. S7. Place the spin-coated sample in a tube furnace and anneal it at 200 degrees Celsius for 1 hour in a nitrogen atmosphere. S8, the top electrode was prepared by vacuum evaporation on the surface of the annealed Re0.5Mo0.25V0.25S2 thin film.

[0011] Furthermore, the flow rate of argon gas in S3 is 30 standard cubic centimeters per minute.

[0012] Furthermore, the substrate cleaning steps in S5 are as follows: ultrasonically cleaned with deionized water, acetone, and ethanol for 10 minutes each, dried with nitrogen, and then baked in an oven at 80 degrees Celsius for 30 to 60 minutes.

[0013] Furthermore, the spin coating speed in S6 is 2000 rpm, and the spin coating time is 30 seconds.

[0014] The beneficial effects of this invention are: 1. By co-doping Mo and V in ReS2 to form a Re0.5Mo0.25V0.25S2 ternary alloy thin film as a photoelectric conversion layer, the light absorption range of the material is effectively broadened and the light absorption utilization rate is improved. This enables the device to exhibit obvious photoelectric response under visible light irradiation, obtain a larger open-circuit voltage and short-circuit current, and significantly improve the detection performance of the photodetector.

[0015] 2. The photodetector can generate photocurrent when illuminated under zero bias conditions, with a photocurrent value of 0.42mA. It has self-powered characteristics and can realize the detection and output of photoelectric signals without the need for an external bias voltage, thereby reducing the power consumption of the device and expanding the application range of the photodetector in scenarios without external power supply.

[0016] 3. The photodetector uses Re0.5Mo0.25V0.25S2 nano-slurry to form the photoelectric conversion layer by spin coating and annealing. The process is simple, convenient, and low-cost. The device structure is a vertical stacked configuration of substrate / bottom electrode / photoelectric conversion layer / top electrode, which is conducive to large-area preparation and mass production, and has good process repeatability. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Appendix Figure 1 This is a schematic diagram of the structure of the photodetector provided by the present invention.

[0019] Appendix Figure 2 The diagram shows the photovoltaic safety characteristic curve provided by this invention.

[0020] Appendix Figure 3 This is a schematic diagram of the process flow provided by the present invention.

[0021] In the figure: 1. Substrate; 2. Bottom electrode; 3. Photoelectric conversion layer; 4. Top electrode. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should also be noted that, to make the embodiments more comprehensive, the following embodiments are the best and preferred embodiments, and those skilled in the art can use other alternative methods to implement some well-known technologies; moreover, the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0023] It should be noted that the use of terms such as "an embodiment," "an embodiment," "an exemplary embodiment," and "some embodiments" in the specification indicates that the described embodiment may include a specific feature, structure, or characteristic, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments (whether explicitly described or not) should be within the knowledge of those skilled in the art.

[0024] Generally, terms can be understood at least partly from their use in context. For example, depending at least partly on the context, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in a singular sense, or a combination of features, structures, or characteristics in a plural sense. Additionally, the term "based on" can be understood not necessarily to convey an exclusive set of factors, but rather, alternatively, depending at least partly on the context, to allow for the presence of other factors that are not necessarily explicitly described.

[0025] like Figure 1 As shown, the photodetector based on two-dimensional Re0.5Mo0.25V0.25S2 provided by this invention has a structure consisting of a substrate, a bottom electrode, a photoelectric conversion layer, and a top electrode from bottom to top. The photoelectric conversion layer is a two-dimensional Re0.5Mo0.25V0.25S2 thin film, which is formed by spin-coating Re0.5Mo0.25V0.25S2 nano-slurry using a spin coater and then annealing. The number of spin-coating layers is 3 to 6, and the film thickness is 100 to 400 nm. The substrate is a silicon substrate with a silicon dioxide layer on its surface, and the thickness of the silicon dioxide layer is 200 to 300 nm. The bottom electrode and top electrode are made of Au, with the bottom electrode having a thickness of 30 to 50 nm and the top electrode having a thickness of 50 to 200 nm. By co-doping ReS2 with Mo and V, the light absorption utilization rate of the material is effectively improved, resulting in a higher photocurrent and enhanced detection performance of the photodetector. Furthermore, it can still generate a large photocurrent value under zero-voltage conditions, achieving self-powered characteristics. Example

[0026] See Figure 3 As shown, This embodiment provides a photodetector based on two-dimensional Re0.5Mo0.25V0.25S2 and its fabrication method. The substrate of the detector is a silicon substrate with a silicon dioxide layer on the surface. The bottom electrode and the top electrode are both Au electrodes. The photoelectric conversion layer is a two-dimensional Re0.5Mo0.25V0.25S2 thin film. The fabrication process includes three stages: synthesis of two-dimensional Re0.5Mo0.25V0.25S2 nanomaterials, preparation of colloids, and assembly of the device.

[0027] I. Preparation of Two-Dimensional Re0.5Mo0.25V0.25S2 Nanomaterials S101: Weigh 0.5 mmol of a mixture of ammonium perrhenate (NH4ReO4), molybdenum dioxide diacetylacetone (MoO2C5H7O2), and vanadium acetylacetone (VOC5H7O2) dimers in a molar ratio of 2:1:1. Weigh 5 mmol of thioacetamide (CH3CSNH2). Add all the above raw materials to 5 mL of N-methyl-2-pyrrolidone solvent. Stir continuously at 300 rpm for 2 hours on a magnetic stirrer to ensure that all raw materials are fully dissolved and mixed evenly, thus obtaining a precursor mixed solution.

[0028] S102: The precursor mixture obtained in S101 is transferred to the polytetrafluoroethylene liner of the high-pressure reactor. After sealing the high-pressure reactor, it is placed in an oven and the temperature is set to 200 degrees Celsius. The reaction is carried out for 12 hours to allow the precursor to undergo a hydrothermal reaction under high temperature and high pressure to generate Re0.5Mo0.25V0.25S2 nanomaterials.

[0029] S103: After the reaction vessel has cooled to room temperature, the reaction product is taken out and collected by centrifugation. The product is washed three times each with anhydrous ethanol and deionized water to completely remove reaction residues and by-products. The washed product is then placed in an oven and dried at 50 degrees Celsius for 24 hours to obtain Re0.5Mo0.25V0.25S2 nanoparticles.

[0030] S104: Place the dried Re0.5Mo0.25V0.25S2 nanopowder obtained in S103 into a ceramic boat, place the boat in the center of the heating zone of the tube furnace, and introduce high-purity argon gas into the tube furnace. Set the gas flow rate to 30 standard cubic centimeters per minute and continue to ventilate for 10 minutes to remove air from the furnace tube.

[0031] S105: Under continuous argon gas supply, the tube furnace is heated to 400 degrees Celsius at a heating rate of 5 degrees Celsius per minute. After reaching the target temperature, it is kept constant for 60 minutes to allow the Re0.5Mo0.25V0.25S2 nanomaterials to fully crystallize and improve their crystal quality.

[0032] S106: After annealing, the heating power of the tube furnace was turned off, and the furnace was allowed to cool naturally to room temperature under the protection of continuous argon gas. The ark was then removed, and the annealed two-dimensional Re0.5Mo0.25V0.25S2 nanomaterials were collected.

[0033] II. Preparation of Re0.5Mo0.25V0.25S2 colloid S201: Take an appropriate amount of Re0.5Mo0.25V0.25S2 nanopowder obtained from S106 and add it to ethylene glycol methyl ether solution. Place it in an ultrasonic cleaner for ultrasonic dispersion to make the nanopowder uniformly dispersed in the solution to form Re0.5Mo0.25V0.25S2 dispersion.

[0034] S202: Ethyl cellulose and terpineol are mixed in a mass ratio of 1.5:1 to obtain a mixed solution of ethyl cellulose and terpineol. This mixed solution is added to the Re0.5Mo0.25V0.25S2 dispersion obtained in S201, and ultrasonic dispersion is continued for 2 hours to ensure that ethyl cellulose, terpineol and Re0.5Mo0.25V0.25S2 nanomaterials are fully mixed.

[0035] S203: Take the mixture obtained in S202 out of the ultrasonic cleaner and place it on a magnetic stirrer. Stir continuously at low speed for 20 hours to further distribute the components in the slurry evenly and achieve suitable viscosity and fluidity, and finally obtain Re0.5Mo0.25V0.25S2 colloid.

[0036] III. Assembly of Photodetectors S301: Take a SiO2 / Si substrate and ultrasonically clean it for 10 minutes each in an ultrasonic cleaner with deionized water, acetone, and ethanol. After cleaning, blow the substrate surface dry with high-purity nitrogen and then bake it in an 80-degree oven for 30 to 60 minutes to thoroughly remove impurities and residual moisture from the substrate surface. Remove it and set it aside for use.

[0037] S302: Place the cleaned and dried SiO2 / Si substrate from S301 into a vacuum evaporation equipment and deposit an Au thin film on the substrate surface as the bottom electrode, controlling the thickness of the Au bottom electrode to be 30nm.

[0038] S303: Place the substrate with the bottom electrode deposited in S302 on a spin coater, take an appropriate amount of Re0.5Mo0.25V0.25S2 colloid prepared in S203 and drop it onto the substrate surface. Start the spin coater, set the spin coating speed to 2000 rpm and the spin coating time to 30 seconds, so that the Re0.5Mo0.25V0.25S2 colloid is evenly spread above the bottom electrode to form a thin film.

[0039] S304: Immediately place the sample that has been spin-coated in S303 into an oven at 100 degrees Celsius and heat for 5 minutes to allow the solvent to evaporate initially and the film to set. After removing it, cool it to room temperature and repeat the spin-coating and baking operations of S303 and S304 3 times, for a total of 4 spin-coatings, so that the Re0.5Mo0.25V0.25S2 film reaches the required thickness.

[0040] S305: Place the sample that has been spin-coated multiple times in S304 into a tube furnace, introduce high-purity nitrogen into the tube furnace to establish a nitrogen protective atmosphere, set the annealing temperature to 200 degrees Celsius and the annealing time to 1 hour, so that the organic residues in the Re0.5Mo0.25V0.25S2 film can be fully decomposed and volatilized, while improving the crystal quality and interfacial contact performance of the film.

[0041] S306: After annealing, allow the sample to cool naturally to room temperature. Remove the sample and place it in a vacuum evaporation apparatus. Evaporate an Au film onto the upper surface of the Re0.5Mo0.25V0.25S2 film as the top electrode. Control the thickness of the Au top electrode to be 50nm. This completes the entire fabrication process of the photodetector based on two-dimensional Re0.5Mo0.25V0.25S2.

[0042] like Figure 1 As shown, the structure of the fabricated photodetector, from bottom to top, consists of a substrate 1, a bottom electrode 2, a photoelectric conversion layer 3, and a top electrode 4. Figure 2 The figure shows the current-voltage characteristic curve of the photodetector under visible light illumination. The curve shows that the device exhibits a significant photoelectric response under visible light illumination, demonstrating a large open-circuit voltage and short-circuit current, thus enabling photoelectric detection. Under zero bias conditions, a photocurrent is generated upon application of light, reaching a value of 0.42 mA, indicating that the device has self-powered characteristics and can achieve photoelectric signal detection and output without an external bias voltage.

[0043] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the following preferred embodiments; however, those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0044] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A photodetector based on two-dimensional Re0.5Mo0.25V0.25S2, characterized in that, The structure of the photodetector, from bottom to top, consists of a substrate, a bottom electrode, a photoelectric conversion layer, and a top electrode. The photoelectric conversion layer is a two-dimensional Re0.5Mo0.25V0.25S2 thin film, which is formed by spin-coating and annealing Re0.5Mo0.25V0.25S2 nano-slurry.

2. The photodetector based on two-dimensional Re0.5Mo0.25V0.25S2 according to claim 1, characterized in that, The substrate is a silicon substrate with a silicon dioxide layer on its surface, and the thickness of the silicon dioxide layer is 200 to 300 nm.

3. The photodetector based on two-dimensional Re0.5Mo0.25V0.25S2 according to claim 1, characterized in that, The two-dimensional Re0.5Mo0.25V0.25S2 thin film has 3 to 6 spin-coating layers and a film thickness of 100 to 400 nm.

4. The photodetector based on two-dimensional Re0.5Mo0.25V0.25S2 according to claim 1, characterized in that, Both the bottom electrode and the top electrode are Au electrodes, with the bottom electrode having a thickness of 30 to 50 nm and the top electrode having a thickness of 50 to 200 nm.

5. A method for fabricating a photodetector based on two-dimensional Re0.5Mo0.25V0.25S2 as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1, NH4ReO4, MoO2(C5H7O2)2, and VO(C5H7O2)2 are mixed in a molar ratio of 2:1:1, with a total amount of 0.5 mmol. This mixture is then dissolved together with 5 mmol of CH3CSNH2 in 5 mL of N-methyl-2-pyrrolidone. The mixture is stirred at 300 rpm for 2 hours to obtain a precursor mixed solution. S2, the precursor mixture solution was transferred to a high-pressure reactor and reacted at 200 degrees Celsius for 12 hours. After the reaction was completed, it was cooled to room temperature, centrifuged to collect the product, washed three times each with anhydrous ethanol and deionized water, and dried at 50 degrees Celsius for 24 hours to obtain Re0.5Mo0.25V0.25S2 nanopowder. S3, the Re0.5Mo0.25V0.25S2 nanopowder is placed in a tube furnace and heated to 400 degrees Celsius at a heating rate of 5 degrees Celsius per minute under argon protection. After holding at this temperature for 60 minutes, it is naturally cooled to room temperature to obtain annealed two-dimensional Re0.5Mo0.25V0.25S2 nanomaterial. S4, the two-dimensional Re0.5Mo0.25V0.25S2 nanomaterials were ultrasonically dispersed in ethylene glycol methyl ether solution, and a mixed solution of ethyl cellulose and terpineol with a mass ratio of 1.5:1 was added. After ultrasonic dispersion for 2 hours, the mixture was stirred at low speed on a magnetic stirrer for 20 hours to obtain Re0.5Mo0.25V0.25S2 colloid. S5, The bottom electrode is prepared by vacuum evaporation on the cleaned and dried substrate; S6. The Re0.5Mo0.25V0.25S2 colloid is spin-coated onto the substrate with the bottom electrode deposited using a spin coater. After spin coating, it is heated at 100 degrees Celsius for 5 minutes. After cooling, the spin coating and heating operations are repeated 3 times. S7. Place the spin-coated sample in a tube furnace and anneal it at 200 degrees Celsius for 1 hour in a nitrogen atmosphere. S8, the top electrode was prepared by vacuum evaporation on the surface of the annealed Re0.5Mo0.25V0.25S2 thin film.

6. The preparation method according to claim 5, characterized in that, The flow rate of argon gas in S3 is 30 standard cubic centimeters per minute.

7. The preparation method according to claim 5, characterized in that, The substrate cleaning steps in S5 are as follows: ultrasonically cleaned with deionized water, acetone and ethanol for 10 minutes each, dried with nitrogen and baked in an oven at 80 degrees Celsius for 30 to 60 minutes.

8. The preparation method according to claim 5, characterized in that, The spin coating speed in S6 is 2000 rpm, and the spin coating time is 30 seconds.

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