A two-dimensional graphene-based photoelectric conversion device and a preparation method thereof

Abstract

The application relates to the technical field of graphene materials, in particular to a two-dimensional graphene-based photoelectric conversion device and a preparation method thereof, the preparation method comprises the following steps: S1. nickel foil pretreatment, S2. obtaining a B-doped P-type graphene-nickel foil film, S3. obtaining a B, P and N co-doped graphene-nickel foil film, S4. gold quantum dot loading, S5. etching, silicon wafer transfer printing, drying and electrode establishment. The two-dimensional graphene-based photoelectric conversion device provided by the application is an ultrathin two-dimensional photoelectric conversion device which can convert light energy into electric energy and can also be used as an energy supply system of a micro device; in-situ doping is realized in the graphene growth stage through CVD doping, two kinds of doping are realized on the same graphene film through a mask method, N-type doped graphene and P-type doped graphene and an ultrathin and stable two-dimensional graphene-based PN junction are obtained.

Description

Technical Field

[0001] This invention relates to the field of graphene materials technology, and in particular to a two-dimensional graphene-based photoelectric conversion device and its preparation method. Background Technology

[0002] Micro-energy systems are a crucial component of electronic devices. Compared to traditional energy systems, micro-energy systems are characterized by their small size and high efficiency, sustainably converting mechanical, light, and thermal energy into electrical energy, making them ideal functional systems for electronic devices. Electronic devices, especially micro / nano devices, often impose extremely stringent requirements on the structural size and weight of energy systems. This is the main reason why traditional energy storage systems are largely unsuitable as power supply systems for micro-devices. The stringent requirements of small size and low mass eliminate the possibility of using most 3D materials as functional materials for power supply systems of micro-devices. Using low-dimensional materials as power supply materials for micro-energy systems is a possible strategy, but low-dimensional materials are generally more fragile, have weaker fatigue strength, and many have poor stability, making it difficult to meet the material requirements for converting mechanical and thermal energy into electrical energy.

[0003] Photovoltaic conversion is one of the few energy conversion methods that does not have high requirements for the physicochemical properties of materials. Photovoltaic micro-energy systems are gentle and non-destructive energy systems that achieve sustainable conversion of solar energy into the electrical energy required by devices through low-dimensional materials. Photovoltaic low-dimensional materials are an ideal solution for many energy conversion methods that can meet the requirements of small size, low mass, material physicochemical properties, and long-life operation. Graphene is a two-dimensional carbon material with ideal electrical and thermal conductivity and stable physicochemical properties, possessing both low dimensional size and light mass, making it a candidate for functional materials in micro-device power supply systems. Chinese patent CN112133777A discloses a core-shell structured quantum dot broadband photodetector and its fabrication method, including a single-crystal silicon substrate layer, a silicon oxide insulating layer, and a graphene channel layer stacked sequentially from bottom to top. However, in practice, the size and thickness of the detector cannot meet the requirements. Therefore, developing a smaller, lighter, and more practical photovoltaic conversion device is very promising. Summary of the Invention

[0004] The first aspect of this invention provides a method for fabricating a two-dimensional graphene-based photoelectric conversion device, the method comprising the following steps:

[0005] S1. Nickel foil pretreatment;

[0006] S2. Place the pretreated nickel foil on the surface of a graphite plate, cover the surface of the nickel foil, and then place the graphite plate, nickel foil, and cover material together into a cold-wall CVD furnace (chemical vapor deposition furnace). In an inert gas atmosphere, ethyl boric acid is introduced. After the reaction is completed, a P-type graphene-nickel foil film with B doping is obtained.

[0007] S3. Remove the masking material from the surface of the B-doped P-type graphene-nickel foil film and place it on the area of ​​the B-doped P-type graphene on the nickel foil surface. Place the graphite plate, the B-doped P-type graphene-nickel foil film, and the masking material together into a cold-wall CVD furnace. Under an inert gas atmosphere, introduce pentachloropyridine and a phosphorus source. After the reaction is complete, obtain a P-doped N-type graphene-nickel foil film. Remove the masking material to obtain a B, P, and N co-doped graphene-nickel foil film with alternating P-type and N-type graphene regions. The P and N co-doped regions are N-type graphene, and the B-doped regions are P-type graphene. A PN junction is formed at the junction of the P-type and N-type graphene.

[0008] S4. Sputter gold onto the surface of the graphene-nickel foil film with B, P, and N co-doped growth to obtain an Au quantum dot-modified B, P, and N co-doped graphene-nickel foil film.

[0009] S5. Cut Au quantum dot-modified B, P, N co-doped graphene-nickel foil film to obtain a sample strip, ensuring that the PN junction is located at the center of the sample strip. Then, etch the sample strip, transfer it to a silicon wafer, dry it, and establish the electrode to obtain a two-dimensional graphene-based photoelectric conversion device.

[0010] This invention uses graphene as a substrate, and obtains N-type graphene and P-type graphene through doping to form a PN junction. Under light irradiation, electrons in the PN junction gain energy to form electron-hole pairs, and generate micro-currents and potential differences in the electric field within the PN junction, which are used to drive the external circuit load. In addition, by modifying with gold quantum dots, the photogenerated carrier density is increased to improve the current density of the micro-current.

[0011] In some embodiments, the nickel foil pretreatment includes: immersing the cut nickel foil in a 0.5-1M hydrochloric acid aqueous solution for 1-5 minutes; first, spraying with deionized water to remove burrs and protrusions from the nickel foil surface; connecting the cleaned nickel foil to the positive electrode of an electrochemical workstation and the negative electrode to a nickel or carbon rod, placing it in a 0.1-1M orthophosphoric acid electrolyte, and performing chemical polishing treatment for 1-10 minutes at a voltage of 2-6V and a current of 0.1-0.6A; finally, spraying with deionized water again and drying with a nitrogen stream for later use.

[0012] In some embodiments, the covering is a graphite plate, the same length as the graphite flat plate, and 2-6 cm wide.

[0013] The area covered by the graphite plate is a shading area that restricts growth, while the area without the graphite plate is a blank area, which serves as the growth area for B-doped graphene.

[0014] In order to obtain a smooth and clean photoelectric conversion device, in some embodiments, in S2, the cold-wall CVD furnace is heated to 900-1000°C, and gaseous ethylboric acid is introduced into the CVD furnace cavity using an H2 / Ar mixed gas as a carrier gas under an inert gas atmosphere.

[0015] In some embodiments, the flow rate of the H2 / Ar mixed gas is 20-100 sccm, and the introduction time is 10-60 min.

[0016] Furthermore, the volume ratio of H2 / Ar is 1:10.

[0017] In some embodiments, in S3, the cold-wall CVD furnace is heated to 900-1000°C. Under an inert gas atmosphere, Ar gas is used as a carrier gas to send gaseous pentachloropyridine into the CVD furnace cavity, and a phosphorus source is simultaneously introduced. The phosphorus source is introduced into the CVD furnace cavity in the form of a PH3 / Ar mixed gas.

[0018] In some embodiments, the flow rate of the Ar mixed gas is 20-100 sccm, the flow rate of the PH3 / Ar mixed gas is 10-50 sccm, and the introduction time is 10-60 min.

[0019] Furthermore, the volume ratio of PH3 / Ar is 1:10.

[0020] In some embodiments, in S3, after removing the mask and placing it on the area of ​​B-doped P-type graphene on the surface of the nickel foil, a graphene film is used to support the mask at the edge area of ​​the mask, the thickness of the graphene film being <100μm and the gap between the mask and the nickel foil being less than 1mm.

[0021] Furthermore, the gold sputtering process specifically includes: placing a graphene-nickel foil film with B, P, and N co-doped surfaces in a gold sputtering instrument, using an Au target as the target material, setting the distance between the sample and the target material to 5-10 cm, setting the working current to 10 mA, setting the time to 5-10 s, performing gold sputtering after vacuuming, with the gold sputtering location being the boundary region between N-type doping and P-type doping, to obtain an Au quantum dot-modified B, P, and N co-doped graphene-nickel foil film.

[0022] In some embodiments, S5 specifically includes: cleaning the sample strip and transferring it to a potassium persulfate aqueous solution, etching until the nickel foil is semi-transparent, immediately injecting deionized water, diluting the potassium persulfate aqueous solution, and stopping the etching.

[0023] Furthermore, the sample cleaning process involves placing the sample in a 1M potassium persulfate aqueous solution, at which point the sample floats on the solution surface; after 1-5 minutes, the sample is removed by grasping the edge with ceramic tweezers, and the graphene film on the back of the sample is rinsed clean with deionized water to facilitate subsequent etching.

[0024] In order to ensure that the etched graphene film is not damaged and to solve the defect of residual adhesive after transfer printing in the prior art, in some embodiments, the silicon wafer transfer in S5 specifically includes: picking up the etched sample with a clean silicon wafer and laying it flat on the surface of the silicon wafer, while continuously adding ethanol to the potassium persulfate aqueous solution during the picking process.

[0025] Furthermore, the cleaning steps for the silicon wafer are as follows: ultrasonic cleaning with acetone, isopropanol, and deionized water in sequence, followed by drying.

[0026] Furthermore, the electrode establishment steps are as follows: using a mask spraying method, the middle position of the sample (PN junction position) is blocked by a masking material with a blocking length of 1-5mm, and a 10nm-30μm Au layer is sprayed on both ends of the sample. There should be a significant color difference between the sprayed gold layer at both ends and the functional layer in the middle.

[0027] A second aspect of the present invention provides a two-dimensional graphene-based photoelectric conversion device, obtained by the aforementioned preparation method.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The two-dimensional graphene-based photoelectric conversion device provided by the present invention is a micro-power supply system that converts light energy into electrical energy, and can be used as a power supply component that provides energy for micro-devices.

[0030] 2. The present invention provides a two-dimensional graphene-based photoelectric conversion device, which is an ultrathin two-dimensional photoelectric conversion device. Its thickness is the sum of the thickness of B, P, and N co-doped graphene and the electrode, which is only 10nm-30μm. It can convert light energy into electrical energy and can also serve as a power supply system for micro-devices. In-situ doping of graphene is achieved during the graphene growth stage through CVD doping. Two types of doping are achieved on the same graphene film through the mask method, resulting in N-type doped graphene and P-type doped graphene and an ultrathin and stable two-dimensional graphene-based PN junction.

[0031] 3. This invention enables the loading of liquid or solid growth sources through the reserved window of the CVD furnace and the assistance of carrier gas, so that the growth source of graphene is no longer limited to a gas source; through the pretreatment of chemical polishing, a metal growth substrate with a very smooth surface is obtained, which is beneficial to reduce the intrinsic defects of graphene.

[0032] 4. This invention uses ethylboric acid as the sole carbon and boron source to achieve in-situ growth of boron-doped graphene, which differs from heteroatom-doped graphene strategies obtained by high-energy particle bombardment and etching, resulting in fewer defects. The external carrier gas method simplifies the simultaneous doping of multiple heteroatoms and is highly compatible with traditional CVD growth processes.

[0033] 5. This invention uses a novel adhesive-free transfer process that eliminates the polymer support film, resulting in a cleaner graphene surface after transfer. The additional modification with gold nanoparticles can reduce the energy barrier of free electrons to a certain extent, making it easier to generate photogenerated electron-hole pairs in the PN junction. This provides important reference and guidance for the practical application of graphene devices and similar research. Attached Figure Description

[0034] Figure 1 The photoresponse voltage of the photoelectric conversion device prepared in Example 1 under illumination and shading conditions.

[0035] Figure 2 The image shows a SEM image of the PN junction of the photoelectric conversion device prepared in Example 1.

[0036] Figure 3 This is a SEM image of the photoelectric conversion device prepared in Example 4. Detailed Implementation

[0037] Example 1

[0038] A method for fabricating a two-dimensional graphene-based photoelectric conversion device, the method comprising the following steps:

[0039] S1. Nickel foil pretreatment: Immerse a 10μm thick, 20cm long and 6cm wide nickel foil in a 0.5M hydrochloric acid aqueous solution for 2 minutes. First, spray with deionized water to remove burrs and protrusions from the surface of the nickel foil. Connect the cleaned nickel foil to the positive electrode of the electrochemical workstation and the negative electrode to the carbon rod. Place it in a 0.2M orthophosphoric acid electrolyte and perform chemical polishing treatment for 8 minutes at a voltage of 4V and a current of 0.4A. Finally, spray with deionized water again and dry with nitrogen gas for later use.

[0040] S2. Place the pretreated nickel foil on the surface of a graphite plate. Use two graphite plates, each 5 cm wide, as a cover and press them onto the nickel foil surface with a lateral spacing of 5 cm. Place the graphite plate, nickel foil, and cover together into a cold-wall CVD furnace. Clean the furnace with high-purity argon gas at a flow rate of 500 sccm for 30 min. Heat the CVD furnace to 980°C at a heating rate of 5°C / min, using high-purity Ar gas as a protective gas during this process. Use a H2 / Ar mixed gas (volume ratio of 1:10) as a carrier gas to send gaseous ethylboric acid into the CVD furnace chamber at a flow rate of 60 sccm for a reaction time of 30 min. After the reaction, stop the loading of the reaction gas, use Ar as a protective gas, stop heating, and allow the furnace to cool naturally to room temperature (25°C). After the reaction, a B-doped P-type graphene-nickel foil film is obtained.

[0041] S3. After removing the masking material from the surface of the B-doped P-type graphene-nickel foil film and placing it on the area of ​​the B-doped P-type graphene on the nickel foil surface, use a graphene film with a thickness of 50 μm to support the masking material at the edge area. The gap between the masking material and the nickel foil is less than 1 mm. Place the graphite plate, the B-doped P-type graphene-nickel foil film, and the masking material together into a cold-wall CVD furnace. Clean the furnace with high-purity argon gas at a flow rate of 500 sccm for 30 min to purge the air from the furnace. Heat the CVD furnace to 980°C at a heating rate of 5°C / min, using Ar gas as a protective gas. Ar gas was used as the carrier gas to introduce gaseous pentachloropyridine into the CVD furnace chamber at a flow rate of 50 sccm. At the same time, a PH3 / Ar mixed gas (volume ratio 1:10) was introduced into the CVD furnace chamber at a flow rate of 20 sccm. The reaction time was 30 min. After the reaction, a P-doped N-type graphene-nickel foil film was obtained. The covering was removed to obtain a B, P, and N co-doped graphene-nickel foil film with alternating P-type and N-type graphene regions. The P and N co-doped regions were N-type graphene, and the B-doped regions were P-type graphene. A PN junction was formed at the junction of the P-type and N-type graphene.

[0042] S4. Place the B, P, N co-doped graphene-nickel foil film on the surface into a JEC-3000FC sputtering machine, using an Au target as the target material. Set the distance between the sample and the target material to 10 cm, the working current to 10 mA, and the time to 5 s. After vacuuming, perform sputtering treatment. The sputtering position is the boundary region between N-type doping and P-type doping to obtain Au quantum dot modified B, P, N co-doped graphene-nickel foil film.

[0043] S5. Cut Au quantum dot-modified B, P, N co-doped graphene-nickel foil film into strips 10 cm long, 1 cm wide, and 10 μm thick, ensuring the PN junction is centered. Place the strips in a 1 M potassium persulfate aqueous solution; they will float on the surface. After 2 minutes, use ceramic tweezers to pick up the strips by the edges and rinse the graphene film on the back with deionized water to facilitate subsequent etching. Transfer the strips to a 0.5 M potassium persulfate aqueous solution and etch until the nickel foil is semi-transparent. Immediately inject deionized water to dilute the potassium persulfate to 0.05 M, then dilute the potassium persulfate solution and stop etching. Clean the etched strips sequentially with acetone, isopropanol, and deionized water using ultrasonic cleaning. After drying, retrieve the silicon wafer and lay it flat on the silicon wafer surface. Dry it again to obtain an ultrathin metal foil with a graphene film, with the graphene film side facing upwards and the nickel foil side in contact with the silicon wafer surface. During the retrieval process, ethanol was continuously added dropwise to the potassium persulfate aqueous solution. A 1M potassium persulfate solvent was dripped onto the edge of the nickel foil to dissolve the remaining nickel foil. The potassium persulfate solvent was then absorbed cleanly from the edge using lint-free paper. The film was then placed on an 80°C heating platform to dry. The film was then slowly immersed in deionized water for 30 minutes, and then removed and dried again on the 80°C heating platform to obtain a translucent film with the outline of the nickel foil. A multimeter was used to gently measure the resistance at a distance of 3 cm between the two ends of the film, and the resistance was measured to be 3.45 mΩ, indicating that the film had been completely transferred to the silicon wafer. Finally, using a mask-spraying method, the middle position of the sample (PN junction position) was masked with a 2cm masking material, creating contact electrodes 1cm away from the middle position. The electrodes were constructed by spraying a thick Au layer. A significant color difference was required between the gold layer at both ends and the functional layer in the middle. The spraying instrument parameters were: sample-target distance 4cm, current 40mA, time 60s.

[0044] Example 2

[0045] A method for preparing a two-dimensional graphene-based photoelectric conversion device is described. The specific implementation method is the same as in Example 1, except that it does not contain S4. Instead, the graphene-nickel foil film with B, P, and N co-doped growth on the surface is directly cleaned and etched.

[0046] Example 3

[0047] A method for fabricating a two-dimensional graphene-based photoelectric conversion device is described, with the specific implementation method being the same as in Example 1, except that the gold sputtering time in step S4 is set to 8 seconds.

[0048] Example 4

[0049] A method for fabricating a two-dimensional graphene-based photoelectric conversion device, the specific implementation of which is the same as in Example 1, except that a traditional liquid-phase transfer process is used, which includes the following steps:

[0050] S1. The specific implementation method is the same as in Example 1;

[0051] S2. The specific implementation method is the same as in Example 1;

[0052] S3. The specific implementation method is the same as in Example 1;

[0053] S4. The specific implementation method is the same as in Example 1;

[0054] S5. Cut the Au quantum dot-modified B, P, N co-doped graphene-nickel foil film to obtain a sample with a length of 10 cm, a width of 1 cm, and a thickness of 10 μm. Ensure that the PN junction is located in the center of the sample. Place the sample in a 1M potassium persulfate aqueous solution. At this point, the sample floats on the surface of the solution. After 2 minutes, use ceramic tweezers to pick up the sample by its edge and remove it. Rinse the graphene film on the back of the sample with deionized water to facilitate subsequent etching. Transfer the sample to a 0.5M potassium persulfate aqueous solution and etch until the nickel foil is semi-transparent. Immediately inject deionized water to dilute the potassium persulfate aqueous solution and stop etching.

[0055] The etched sample was transferred using a traditional liquid phase transfer process, which included: first, spin-coating two layers of PMMA reagent onto the sample surface to obtain a PMMA support film. The PMMA reagent was obtained by dissolving PMMA masterbatch in anisole solution. Both the PMMA masterbatch and the anisole solution were purchased from Maclean's Reagent Network. Then, the nickel foil substrate was etched off in a potassium persulfate aqueous solution. After the film was transferred to the silicon wafer, it was soaked in acetone to remove the adhesive.

[0056] Example 5

[0057] A method for fabricating a two-dimensional graphene-based photoelectric conversion device, the specific implementation of which is the same as in Example 1, except that no graphite plate is used to cover or shield the entire growth process, that is, it includes the following steps:

[0058] S1. The specific implementation method is the same as in Example 1;

[0059] S2. Place the pretreated nickel foil on the surface of a graphite plate, and put the graphite plate and nickel foil together into a cold-wall CVD furnace. Clean the furnace with high-purity argon gas at a flow rate of 500 sccm for 30 min. Heat the CVD furnace to 980℃ at a heating rate of 5℃ / min, using high-purity Ar gas as a protective gas during the process. Use a H2 / Ar mixed gas (volume ratio of 1:10) as a carrier gas to send gaseous ethylboric acid into the CVD furnace chamber at a flow rate of 60 sccm for a reaction time of 30 min. After the reaction is completed, stop the loading of the reaction gas, use Ar as a protective gas, stop heating, and allow the furnace to cool naturally to room temperature (25℃). After the reaction is completed, a B-doped P-type graphene-nickel foil film is obtained.

[0060] S3. Place the B-doped P-type graphene-nickel foil film into a cold-wall CVD furnace and purge the furnace with high-purity argon gas at a flow rate of 500 sccm for 30 min to remove the air. Heat the CVD furnace to 980°C at a heating rate of 5°C / min. Use Ar gas as a protective gas and simultaneously use Ar gas as a carrier gas to send gaseous pentachloropyridine into the CVD furnace chamber at a flow rate of 50 sccm. At the same time, send a PH3 / Ar mixed gas (volume ratio 1:10) into the CVD furnace chamber at a flow rate of 20 sccm. The reaction time is 30 min. After the reaction is completed, a P-doped N-type graphene-nickel foil film is obtained.

[0061] S4. The specific implementation method is the same as in Example 1;

[0062] S5. The specific implementation method is the same as in Example 1.

[0063] Example 6

[0064] A method for preparing a two-dimensional graphene-based photoelectric conversion device is described, with the specific implementation method being the same as in Example 1, except that the temperature inside the CVD furnace in steps S3 and S4 is 940℃.

[0065] Example 7

[0066] A method for preparing a two-dimensional graphene-based photoelectric conversion device is described, with the specific implementation method being the same as in Example 1, except that the thickness of the graphene film covering the shielding material in step S3 is 30 μm.

[0067] Example 8

[0068] A method for preparing a two-dimensional graphene-based photoelectric conversion device is described, with the specific implementation method being the same as in Example 1, except that the thickness of the graphene film covering the shielding material in step S3 is 80 μm.

[0069] Comparative Example 1

[0070] A method for fabricating a two-dimensional graphene-based photoelectric conversion device is described, with the specific implementation method being the same as in Example 1, except that graphene prepared by transfer CVD is used as the functional material of the photoelectric conversion device. Electrodes are fabricated at both ends of the graphene film, and the same photoelectric conversion test is performed. The method includes the following steps:

[0071] S1. The specific implementation method is the same as in Example 1;

[0072] S2. Place the pretreated nickel foil on the surface of a graphite plate, and place the graphite plate and nickel foil together into a cold-wall CVD furnace. Clean the furnace with high-purity argon gas at a flow rate of 500 sccm for 30 min. Heat the CVD furnace to 980℃ at a heating rate of 5℃ / min, using high-purity Ar gas as a protective gas during this period. Use a H2 / Ar mixed gas (volume ratio of 1:10) as a carrier gas to send the carbon source CH4 into the CVD furnace chamber at a flow rate of 60 sccm for a reaction time of 30 min. After the reaction is completed, stop the loading of the reaction gas, use Ar as a protective gas, stop heating, and allow the furnace to cool naturally to room temperature (25℃). After the reaction is completed, a nickel foil film with graphene grown on it is obtained.

[0073] S3. The specific implementation method is the same as step S4 of Example 1;

[0074] S4. Cut the Au quantum dot-modified graphene-nickel foil film to obtain a strip with a length of 10cm, a width of 1cm, and a thickness of 10μm. Transfer the strip in the same way as step S5 of Example 1, and establish contact electrodes at positions 1cm away from the middle of the strip using the same method and conditions as in step S5 of Example 1.

[0075] Comparative Example 2

[0076] A method for preparing a two-dimensional graphene-based photoelectric conversion device is described, with the specific implementation method being the same as in Example 1, except that the gold sputtering time in step S4 is set to 15 seconds.

[0077] Comparative Example 3

[0078] A method for preparing a two-dimensional graphene-based photoelectric conversion device is described, with the specific implementation method being the same as in Example 1, except that the temperature inside the CVD furnace in step S3 is 800℃.

[0079] Comparative Example 4

[0080] A method for preparing a two-dimensional graphene-based photoelectric conversion device is described, with the specific implementation method being the same as in Example 1, except that the temperature inside the CVD furnace in step S4 is 1020℃.

[0081] Comparative Example 5

[0082] A method for preparing a two-dimensional graphene-based photoelectric conversion device is described, with the specific implementation method being the same as in Example 1, except that the thickness of the graphene film supporting the cover in step S3 is 120 μm.

[0083] Performance testing

[0084] The photoelectric conversion devices prepared in the examples and comparative examples were used as samples for the following tests:

[0085] Photoresponse test: Xenon lamps were used to simulate sunlight, with the distance between the light source and the sample being 10 cm. The light source was intermittently blocked with opaque black cardboard. The photoresponse voltage across the electrodes of the electrochemical workstation was tested, as detailed in Table 1.

[0086] Table 1

[0087]

[0088] As shown in Table 1, the graphene-based photoelectric conversion device prepared in Example 1 has stable photoelectric conversion efficiency. In Example 2, without gold quantum dot modification, the voltage under light source irradiation decreased significantly, indicating that gold quantum dot modification enhances the photoelectric conversion efficiency of the graphene-based photoelectric conversion device. In Example 4, without the use of the adhesive-free transfer process of the present invention, the graphene film was damaged and residual adhesive appeared on the surface, which seriously affected the photoelectric conversion efficiency of the graphene device, and the voltage under light source irradiation decreased significantly, indicating that the surface cleanliness of the graphene film is the main factor affecting the photoelectric conversion efficiency of the graphene photoelectric conversion device. In Example 4, using the traditional liquid phase transfer process, the voltage under light source irradiation decreased significantly, indicating that the adhesive-free transfer process... The transfer technology can further enhance the photoelectric conversion of graphene-based photoelectric conversion devices. In Example 5, no graphene plate was used for shielding, and the graphene film did not exhibit photoelectric conversion, indicating that without the graphene plate covering for segmented growth, a normal PN junction cannot be obtained, and photoelectric response cannot be achieved. In Comparative Example 1, the graphene prepared by the transfer CVD method was used as the functional material for the photoelectric conversion device, and the graphene film did not exhibit photoelectric conversion, indicating that pure graphene film does not have the effect of photoelectric conversion. In Comparative Examples 2-5, the relevant process parameters were adjusted, and the photoresponse voltage decreased significantly or could not produce photoelectric conversion, indicating that the relevant parameters defined in this invention are beneficial to the photoelectric conversion of graphene-based photoelectric conversion devices.

Claims

1. A method for fabricating a two-dimensional graphene-based photoelectric conversion device, characterized in that, The preparation method includes the following steps: S1. Nickel foil pretreatment; S2. Place the pretreated nickel foil on the surface of a graphite plate, cover the surface of the nickel foil, and then place the graphite plate, nickel foil, and cover material together into a cold-wall CVD furnace. In an inert gas atmosphere, ethyl boric acid is introduced. After the reaction is completed, a P-type graphene-nickel foil film with B doping is obtained. S3. Remove the masking material from the surface of the B-doped P-type graphene-nickel foil film and place it on the area of ​​the B-doped P-type graphene on the nickel foil surface. Place the graphite plate, the B-doped P-type graphene-nickel foil film, and the masking material together into a cold-wall CVD furnace. Under an inert gas atmosphere, introduce pentachloropyridine and a phosphorus source. After the reaction is complete, obtain a P-doped N-type graphene-nickel foil film. Remove the masking material. A graphene-nickel foil film with B, P, and N co-doped surfaces was obtained, in which P-type graphene regions and N-type graphene regions were grown alternately, the P and N co-doped regions were N-type graphene, and the B-doped regions were P-type graphene. A PN junction is formed at the interface between P-type graphene and N-type graphene. S4. Sputter gold onto the surface of the graphene-nickel foil film with B, P, and N co-doped growth to obtain an Au quantum dot-modified B, P, and N co-doped graphene-nickel foil film. S5. Cut Au quantum dot-modified B, P, N co-doped graphene-nickel foil film to obtain a sample strip, ensuring that the PN junction is located at the center of the sample strip. Then, etch the sample strip, transfer it to a silicon wafer, dry it, and establish the electrode to obtain a two-dimensional graphene-based photoelectric conversion device.

2. The preparation method according to claim 1, characterized in that, The covering material is a graphite plate, the same length as the graphite flat plate, and 2-6 cm wide.

3. The preparation method according to claim 1, characterized in that, In S2, the cold-wall CVD furnace is heated to 900-1000℃, and under an inert gas atmosphere, gaseous ethylboric acid is fed into the CVD furnace cavity using an H2 / Ar mixed gas as a carrier gas.

4. The preparation method according to claim 3, characterized in that, The flow rate of the H2 / Ar mixed gas is 20-100 sccm, and the introduction time is 10-60 min.

5. The preparation method according to claim 1, characterized in that, In S3, the cold-wall CVD furnace is heated to 900-1000℃. Under an inert gas atmosphere, Ar gas is used as a carrier gas to send gaseous pentachloropyridine into the CVD furnace cavity. At the same time, a phosphorus source is loaded into the CVD furnace cavity in the form of a PH3 / Ar mixed gas.

6. The preparation method according to claim 5, characterized in that, The flow rate of the Ar mixed gas is 20-100 sccm, the flow rate of the PH3 / Ar mixed gas is 10-50 sccm, and the introduction time is 10-60 min.

7. The preparation method according to claim 1, characterized in that, In S3, after removing the mask and placing it on the area of ​​B-doped P-type graphene on the surface of the nickel foil, a graphene film is used to support the mask at the edge of the mask. The thickness of the graphene film is <100μm, and the gap between the mask and the nickel foil is less than 1mm.

8. The preparation method according to claim 1, characterized in that, In S5, the etching specifically includes: cleaning the sample strip and transferring it to a potassium persulfate aqueous solution, etching until the nickel foil is semi-transparent, immediately injecting deionized water, diluting the potassium persulfate aqueous solution, and stopping the etching.

9. The preparation method according to claim 1, characterized in that, In S5, the silicon wafer transfer specifically includes: picking up the etched sample strip with a cleaned silicon wafer and laying it flat on the surface of the silicon wafer, while continuously adding ethanol to the potassium persulfate aqueous solution during the picking process.

10. A two-dimensional graphene-based photoelectric conversion device, characterized in that, Obtained by the preparation method according to any one of claims 1-9.

Images