Preparation method of germanene photoelectrode for self-powered broadband photoelectric detector

Abstract

The invention relates to a preparation method of a germanene photoelectrode for a self-powered broadband photoelectric detector, which comprises the following steps: by taking layered two-dimensional germane (GeH) as a raw material, annealing under an argon condition to dehydrogenate the GeH to obtain two-dimensional germanene. And then a solvent-assisted liquid-phase ultrasonic stripping technology is utilized to obtain the germanene nanosheet. The obtained germanene nanosheet has a good absorption characteristic on light in a wide wavelength range from ultraviolet-visible-near infrared to short-wave infrared. The prepared germanium alkene nanosheet is used as a photosensitive material and is spin-coated or dispensed on ITO glass and a flexible polymer ITO to prepare a photoelectrode. Then, the photoelectrode, electrolyte, a counter electrode and a reference electrode are assembled into a three-electrode system photoelectrochemical photoelectric detector; and assembling the photoelectrode, a solid electrolyte and a counter electrode taking a flexible polymer ITO as a substrate into the flexible photoelectrochemical photoelectric detector. The prepared photoelectric detector has the broadband light detection capability from ultraviolet light to short-wave infrared light, is short in response time and high in detection rate, has the characteristic of self power supply, and can work without additionally providing voltage. The preparation method is simple, the manufacturing cost is low, and large-scale preparation is facilitated.

Description

Technical Field

[0001] The invention relates to a method for preparing a germanium photoelectrode for a self-powered wide-band photodetector, which has important application prospects in photoelectric detection and belongs to the field of nanomaterials and the technical field of optical, electrical and semiconductor material preparation. Background Art

[0002] As a Group IVA two-dimensional (2D) material of the same family as graphene, germanene has an extremely high theoretical carrier mobility and unique sp 2 -sp 3 Germanene has become a hot topic in new material research due to its hybrid bond and low-warpage honeycomb structure, and has broad application prospects in electronics, optoelectronics, energy storage and conversion, etc. However, unlike graphene, there is no natural layered bulk material that can be directly peeled off, so it can only be prepared by chemical synthesis.

[0003] In 2013, the successful synthesis of layered germane (GeH) brought an opportunity for the preparation and application of germanene. In recent years, studies on GeH-based electronic devices have shown that H atoms on the surface of GeH will be removed under annealing conditions to form germanene with semi-metallic properties. The high carrier mobility and wide light absorption range of germanene make it promising for use in photodetectors with wide-band response. Photoelectrochemical photodetectors are low-cost photodetectors with self-powered characteristics, and can be easily made into flexible photodetectors, which have broad application prospects.

[0004] Based on the above research background, the present invention obtains two-dimensional germane by annealing layered two-dimensional germane (GeH) to dehydrogenate GeH. Then, solvent-assisted liquid phase ultrasonic exfoliation technology is used to obtain germane nanosheets. The prepared germane nanosheets are used as photosensitive materials and spin-coated or drop-coated on ITO glass and flexible polymer ITO to make photoelectrodes, which are further assembled into photoelectrochemical photodetectors. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing a germanium photoelectrode for a self-powered wide-band photodetector, characterized in that the method for preparing the germanium photoelectrode comprises the following steps:

[0006] (1) The layered two-dimensional germane (GeH) is annealed under argon conditions to dehydrogenate the GeH to obtain the two-dimensional layered germanene.

[0007] (2) Dispersing the annealed layered germanene in a solvent, and ultrasonicating the dispersion for 1-8 hours using a cell crusher or an ultrasonic cleaning machine under argon protection. During the ultrasonication process, the temperature of the dispersion is kept constant at 3-5°C.

[0008] (3) The dispersion after ultrasonic treatment is centrifuged at a speed of 3000-10000 rpm to remove the unpeeled precipitate to obtain a supernatant, and the supernatant is centrifuged at a speed of 11000-12000 rpm to obtain a precipitate of few-layer germanium nanosheets. The precipitate is then ultrasonically dispersed in a solvent, and after repeated washing and centrifugation precipitation three times, it is placed in a vacuum drying oven and vacuum dried at 80° C. for 24 hours to obtain a powder of few-layer germanium nanosheets.

[0009] The method for preparing a germanium photoelectrode for a self-powered wide-band photodetector is characterized in that the annealing temperature in step (1) is 150-350° C. and the annealing time is 10-120 min.

[0010] The method for preparing a germanium photoelectrode for a self-powered wide-band photodetector is characterized in that the light absorption wavelength range of the two-dimensional germanium nanosheet obtained in step (1) is from ultraviolet-visible-near infrared to short-wave infrared.

[0012] The method for preparing a germanium photoelectrode for a self-powered wide-band photodetector is characterized in that the solvent in step (2) is ethanol, NMP, DMF, or isopropanol, and the amount of the solvent is 10-50 mg of layered germanium per milliliter of solvent.

[0013] The method for preparing a germanium ene photoelectrode for a self-powered wide-band photodetector is characterized in that in step (2), a cell crusher or an ultrasonic cleaner is used to perform ultrasound for 1-8 hours, argon gas is used to protect the dispersion during the ultrasound process, and the temperature of the dispersion is kept constant at 3-5°C by a circulating cooling device.

[0014] The method for preparing a germanium photoelectrode for a self-powered wide-band photodetector is characterized in that the dispersion after ultrasonic treatment in step (3) is centrifuged at a speed of 1000-10000 rpm, and the supernatant obtained by centrifugation is further centrifuged at a speed of 11000-12000 rpm to obtain a precipitate of few-layer germanium nanosheets.

[0015] The method for preparing a germanium photoelectrode for a self-powered wide-band photodetector is characterized in that the germanium photoelectrode is used for the self-powered wide-band photodetector by the following steps:

[0016] (1) 20 mg of germanium nanosheets were ultrasonically dispersed in 2 mL of ethanol, 200 μL of 0.5 wt% Nafion solution was added, mixed evenly, and then drop-coated or spin-coated onto ITO glass and flexible polymer ITO, and then vacuum-dried in a vacuum drying oven at 60° C. for 24 h to obtain a germanium photoelectrode.

[0017] (2) The prepared germanium photoelectrode is used as the working electrode, the platinum electrode is used as the counter electrode, the calomel electrode is used as the reference electrode, and the KOH solution is used as the electrolyte to assemble a photoelectrochemical photodetector through a three-electrode system.

[0018] (3) Weigh 1-3 mg of conductive carbon black and place it in 1 mL of NMP for 30 min of ultrasonic dispersion to form a uniform solution, then drop-coat or spin-coat it on the flexible polymer ITO, and dry it in a vacuum oven at 60 ° C for 24 h to obtain a conductive carbon black flexible counter electrode. The prepared germanium photoelectrode is used as a working electrode and assembled with a KOH-containing PVA solid electrolyte and a conductive carbon black flexible counter electrode into a flexible photoelectrochemical photodetector. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Scanning electron microscope (SEM) image of germanium nanosheets

[0021] Figure 2 UV-visible-near infrared absorption spectrum of germanium nanosheets

[0022] Figure 3 The photoelectrochemical photodetector based on the three-electrode germanene photoelectrode has a power of 23.3 mW cm at a bias voltage of 0.6 V. -2 Photocurrent density response curves in different KOH electrolyte concentrations under 365nm wavelength illumination with different optical power density

[0023] Figure 4 The photocurrent response curve of the germanium-based three-electrode photodetector under different wavelengths of light at different power densities with 1.0M KOH solution as the electrolyte and 0.6V bias voltage applied. DETAILED DESCRIPTION

[0024] The following is a further description of the present invention, but does not limit the scope of the present invention.

[0025] Embodiment 1:

[0026] Preparation method of germanium nanosheet material:

[0027] (1) 500 mg of layered germane was placed in a tube furnace and protected by argon. The tube furnace was then heated to 250°C at a rate of 1°C / min, kept at that temperature for 10 min, and then naturally cooled to room temperature to obtain layered germanene.

[0028] (2) 400 mg of layered germanene was dispersed in ethanol, and the dispersion was placed in an ultrasonic cleaner under argon protection and ultrasonicated at a constant temperature of 3° C. for 8 h.

[0029] (3) The dispersion after ultrasonic treatment was centrifuged at 3000 rpm to remove the unpeeled precipitate to obtain a supernatant, and then the supernatant was centrifuged at 11000 rpm to obtain a precipitate of few-layer germanium nanosheets. The precipitate was then placed in a vacuum drying oven and vacuum dried at 80° C. for 24 hours to obtain a powder of few-layer germanium nanosheets.

[0030] Figure 1 The SEM image of the germanium nanosheet material prepared under the present conditions is given, and it can be seen that the lateral size of the germanium nanosheet is in the range of tens of nanometers to hundreds of nanometers. Figure 2 The UV-Vis-NIR absorption spectrum of the germanium nanosheet material prepared under these conditions is given, and it can be seen that the obtained two-dimensional germanium nanosheet has good absorption characteristics for light in a wide range of wavelengths from UV-Vis-NIR to short-wave infrared.

[0031] Embodiment 2:

[0032] Preparation of Germanene Photoelectrode and Application of Three-electrode Photodetector:

[0033] (1) 20 mg of germanium nanosheet powder was ultrasonically dispersed in 2 mL of ethanol, 200 μL of 0.5 wt% Nafion solution was added, mixed evenly, and then drop-coated on ITO glass, and then vacuum dried in a vacuum oven at 60 ° C for 24 h to obtain a photoelectrode based on germanium nanosheets. The prepared photoelectrode was then used as a working electrode, a platinum electrode as a counter electrode, a calomel electrode as a reference electrode, and KOH solutions of different concentrations as electrolytes to assemble a photoelectrochemical photodetector through a three-electrode system.

[0034] (2) The photoelectric performance of the photodetector was tested using a Chenhua CHI660D electrochemical workstation. Under a bias voltage of 0.6 V, the photoelectrode was irradiated with monochromatic light of different power densities to test its photocurrent response.

[0035] Figure 3 The photoelectrochemical detection based on germanene photoelectrode at 0.6V bias and 23.3mW cm -2 The photocurrent response diagram under 365nm wavelength light with high power density. It can be seen that with the increase of KOH electrolyte concentration, the photocurrent density of photoelectrochemical photoelectric detection based on germanene photoelectrode gradually increases. Therefore, at the three KOH electrolyte concentrations of 0.1, 0.5 and 1.0M, 1.0M KOH is the best concentration for germanene-based photodetectors. Figure 4The photocurrent response curves of the germanium-based photodetector under different wavelengths of light at different power densities under the conditions of 1.0M KOH electrolyte concentration and 0.6V bias voltage are shown. It can be seen that the photodetector has a good response to all test light sources in the range of 365-980nm, showing excellent self-powered wide-band response characteristics.

[0036] Embodiment 3:

[0037] Application of flexible photoelectrochemical photodetectors based on germanene photoelectrodes:

[0038] (1) 20 mg of germanium nanosheet powder was ultrasonically dispersed in 2 mL of ethanol, 200 μL of 0.5 wt% Nafion solution was added, mixed evenly and then drop-coated on a flexible PET-ITO, and then vacuum dried in a vacuum drying oven at 60 °C for 24 h to obtain a flexible photoelectrode based on germanium nanosheets.

[0039] (2) Weigh 2 mg of conductive carbon black and place it in 1 mL of NMP for 30 min to disperse it into a uniform solution, then drop-coat or spin-coat it on the flexible polymer ITO, and dry it in a vacuum oven at 60° C. for 24 h to obtain a conductive carbon black flexible counter electrode. The prepared germanium photoelectrode is used as a working electrode and assembled with a PVA solid electrolyte containing 0.1 M KOH and a conductive carbon black flexible counter electrode into a flexible photoelectrochemical photodetector.

[0040] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a germanium photoelectrode for a self-powered wide-band photodetector, characterized in that: The method for preparing the germanene photoelectrode comprises the following steps: (1) The layered two-dimensional germane (GeH) is annealed under argon conditions to dehydrogenate the GeH to obtain the two-dimensional layered germanene. (2) Dispersing the annealed layered germanene in a solvent, and ultrasonicating the dispersion for 1-8 hours using a cell crusher or an ultrasonic cleaning machine under argon protection. During the ultrasonication process, the temperature of the dispersion is kept constant at 3-5°C. (3) The dispersion after ultrasonic treatment is centrifuged at a speed of 3000-10000 rpm to remove the unpeeled precipitate to obtain a supernatant, and the supernatant is centrifuged at a speed of 11000-12000 rpm to obtain a precipitate of few-layer germanium nanosheets. The precipitate is then ultrasonically dispersed in a solvent, and after repeated washing and centrifugation precipitation three times, it is placed in a vacuum drying oven and vacuum dried at 80° C. for 24 hours to obtain a powder of few-layer germanium nanosheets.

2. A method for preparing a germanium photoelectrode for a self-powered wide-band photodetector as claimed in claim 1, characterized in that In step (1), the annealing temperature is 150-350° C. and the annealing time is 10-120 min.

3. A method for preparing a germanium photoelectrode for a self-powered wide-band photodetector as claimed in claim 1, characterized in that The light absorption wavelength range of the two-dimensional germanium nanosheet obtained in step (1) is from ultraviolet-visible-near infrared to short-wave infrared.

4. A method for preparing a germanium photoelectrode for a self-powered wide-band photodetector as claimed in claim 1, characterized in that The solvent in step (2) is ethanol, NMP, DMF, isopropanol, and the amount of the solvent is 10-50 mg of layered germanene per milliliter of solvent.

5. A method for preparing a germanium photoelectrode for a self-powered wide-band photodetector as claimed in claim 1, characterized in that In step (2), ultrasonic treatment is performed for 1-8 hours using a cell crusher or an ultrasonic cleaning machine. During the ultrasonic treatment, the dispersion is protected by argon gas, and the temperature of the dispersion is kept constant at 3-5° C. using a circulating cooling device.

6. A method for preparing a germanium photoelectrode for a self-powered wide-band photodetector as claimed in claim 1, characterized in that The dispersion after ultrasonic treatment in step (3) is centrifuged at a speed of 1000-10000 rpm, and the supernatant obtained by centrifugation is further centrifuged at a speed of 11000-12000 rpm to obtain a precipitate of few-layer germanium nanosheets.

7. A method for preparing a germanium photoelectrode for a self-powered wide-band photodetector as claimed in claim 1, characterized in that The germanene photoelectrode was used for self-powered broadband photodetector by following the steps below: (1) 20 mg of germanium nanosheets were ultrasonically dispersed in 2 mL of ethanol, 200 μL of 0.5 wt% Nafion solution was added, mixed evenly, and then drop-coated or spin-coated onto ITO glass and flexible polymer ITO, and then vacuum-dried in a vacuum drying oven at 60° C. for 24 h to obtain a germanium photoelectrode. (2) The prepared germanium photoelectrode is used as the working electrode, the platinum electrode is used as the counter electrode, the calomel electrode is used as the reference electrode, and the KOH solution is used as the electrolyte to assemble a photoelectrochemical photodetector through a three-electrode system. (3) Weigh 1-3 mg of conductive carbon black and place it in 1 mL of NMP for 30 min of ultrasonic dispersion to form a uniform solution, then drop-coat or spin-coat it on the flexible polymer ITO, and dry it in a vacuum oven at 60 ° C for 24 h to obtain a conductive carbon black flexible counter electrode. The prepared germanium photoelectrode is used as a working electrode and assembled with a KOH-containing PVA solid electrolyte and a conductive carbon black flexible counter electrode into a flexible photoelectrochemical photodetector.

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