Preparation method of transverse photoelectrochemical solar blind ultraviolet photoelectric detector

Abstract

The invention discloses a preparation method of a transverse photoelectrochemical solar blind ultraviolet photoelectric detector, and belongs to the technical field of detector preparation. The method comprises the following steps: covering a part of a conductive substrate by using a mask, and preparing a photosensitive material on the uncovered part; taking down the mask, preparing a counter electrode on the exposed part of the conductive substrate, and punching at the position of the counter electrode to penetrate through the electrode and the substrate for injecting electrolyte; and preparing a high-transmittance quartz plate, bonding the high-transmittance quartz plate with the above structure by using a sarin film with the thickness of 50-60 [mu] m, then injecting an electrolyte through the hole in the electrode, and then sealing the small hole to form the transverse PEC type photoelectric detector. According to the PEC photoelectric detector, the photo-anode and the counter electrode are arranged on the same side, namely, the photo-anode and the counter electrode are transversely arranged, the incident surface is made of high-transmittance quartz, compared with a detector with FTO as an electrode, a solar-blind ultraviolet detector can be achieved, and compared with an inverted structure with platinum on quartz as the counter electrode, the solar-blind ultraviolet detector has a larger incident surface and is high in light absorption efficiency and detection efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of detector preparation, and in particular relates to a method for preparing a lateral photoelectrochemical solar-blind ultraviolet photoelectric detector. Background Art

[0002] Photodetectors are widely used in the national economy and military fields. At present, many different types of photodetectors have been developed. According to the wavelength, they can be divided into ultraviolet, visible, infrared detectors, etc.; they can also be divided into photovoltaic and photoconductive detectors according to the device type. Photovoltaic detectors are divided into Schottky junction and pn junction detectors. Photovoltaic photodetectors can work in self-powered mode due to the built-in electric field, that is, they can work normally without external voltage.

[0003] Photoelectrochemical (PEC) photodetector is a special photovoltaic detector that can work in self-powered mode. It has the advantages of simple preparation, low cost, fast response speed and high responsiveness. The reported PEC photodetectors are generally divided into two categories. One is a three-electrode system and the entire device is placed in an electrolytic cell, such as the invention patent "A photoelectrochemical solar-blind ultraviolet detector based on a gallium oxide nanocolumn array" and the invention patent "Photoelectrochemical self-powered solar-blind deep ultraviolet photodetector and its preparation method". The other is a packaged photoelectrochemical detector, which does not require an electrolytic cell, is smaller in size, more portable, and more conducive to practical application. Both types of detectors are longitudinal structures, including two opposing electrodes, with photosensitive materials and electrolytes between the two electrodes. In the packaged photoelectrochemical detector, the material prepared on the transparent conductive film FTO (or ITO) is called the photoanode and the platinum-plated FTO (or ITO) is located at the upper and lower ends of the device as the counter electrode. The two electrodes are longitudinally opposite, and the electrolyte is filled in the middle. The detection light is incident on the semiconductor from one end of the photoanode. The semiconductor absorbs the light to generate photogenerated electrons and holes, and transports them to the external circuit through the electrodes at both ends to form a path. The packaged photoelectrochemical (PEC) detector with a longitudinal structure has realized photodetectors of various materials and heterojunctions such as ultraviolet and visible. However, due to the bandgap width of the FTO material, light with a wavelength less than 300nm is absorbed by FTO, making the detector unable to detect day-blind ultraviolet detectors below 300nm. Previously, the inventor developed a packaged PEC detector in which a portion of the highly transparent quartz is replaced by the FTO electrode by evaporating Pt (J.Mater.Chem.C, 2019, 7, 6867-6871). Although such a structure avoids the light absorption problem of FTO, it increases the complexity and cost of the process.

[0004] Among the packaged PEC detectors reported, for example, Journal of Alloys and Compounds, Volume 928, 20 December 2022, 167128 reported Large-area hierarchical Bi 2 O 2 S flowers composed of 2D ultrathin nanosheets for high performance self-powered IRphotodetector, in which Bi 2 O 2 The FTO film of S material is used as the photoanode, that is, the light is incident from this side, and the counter electrode is a FTO film plated with platinum (Pt). There is an electrolyte between the two electrodes, and the electrolyte is sealed to prevent leakage. ACS Appl. Nano Mater. 2022, 5, 8, 11003–1101 reported NaBiS with the same structure. 2 Photodetector. In this type of packaged PEC photodetector, due to Bi 2 O 2 S and NaBiS 2 Or other similar materials, the bandgap width is small, and the long-wave limit of light absorption is greater than 300nm, so using FTO as an electrode does not affect the incidence and absorption of light. 2 O 3 The bandgap of the material is 4.9-5.2eV, and the light absorption is around 248nm. If the same structure is used, the incident light is absorbed by FTO and cannot enter Ga 2 O 3 That is, it is impossible to achieve Ga 2 O 3 Photodetector. In previous work, in order to avoid this problem, the inventor designed an inverted packaged PEC detector (J. Mater. Chem. C, 2019, 7, 6867-6871). In this detector, the counter electrode no longer uses platinum-plated FTO, but platinum-plated high-transparent quartz (half of the quartz area is evaporated with platinum metal, and half is not evaporated). The detection light is no longer incident from the FTO side with the material, but from the high-transparent quartz side, thus realizing a solar-blind ultraviolet detector. However, this structure also has certain disadvantages. The light is incident from one side of the quartz, and part of the quartz is plated with platinum electrodes, which blocks part of the incident light, reduces the light absorption rate, and thus reduces the efficiency of the photodetector. Summary of the invention

[0005] The purpose of the present invention is to solve the problem of absorption of short-wave ultraviolet light by FTO material in traditional encapsulated longitudinal PEC detectors, and to provide a method for preparing a transverse photoelectrochemical solar-blind ultraviolet photodetector.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a lateral photoelectrochemical solar-blind ultraviolet photodetector, the method comprising:

[0008] Step 1: Use a mask to cover a portion of the conductive substrate, and prepare a photosensitive material on the unmasked portion;

[0009] Step 2: Remove the mask, prepare a counter electrode on the exposed portion of the conductive substrate, and drill a hole through the electrode and the substrate at the counter electrode position for injecting electrolyte. During the electrode preparation process, the mask can be used to cover the prepared photosensitive material to avoid being affected by the electrode preparation process;

[0010] Step 3: Prepare a high-transmittance quartz sheet, use a 50-60μm thick sarling film to bond the high-transmittance quartz sheet to the above structure, then inject electrolyte through the hole on the counter electrode, and then seal the small hole with sealing tape to form a lateral PEC type photodetector. The electrolyte is injected from the bottom of the conductive substrate and sealed with sealing tape after injection.

[0011] Furthermore, in step one, the conductive substrate is one of FTO, ITO or silicon.

[0012] Furthermore, in step 1, the photosensitive material is Ga 2 O 3 Thin film, Ga 2 O 3 One of nanomaterials, AlGaN, BN or MgZnO.

[0013] Furthermore, in step one, the preparation method is one of magnetron sputtering, hydrothermal method, chemical bath method or suspension coating method.

[0014] Furthermore, in step 2, the counter electrode is a platinum electrode or a gold electrode, depending on the photosensitive material and the electrolyte, including liquid NaOH, Na 2 SO 4 , polysulfide or solid electrolyte, etc.

[0015] Furthermore, in step 2, the platinum electrode is obtained by evaporation or heating annealing with chloroplatinic acid.

[0016] The beneficial effects of the present invention compared to the prior art are as follows: the present invention designs a lateral PEC photodetector, in which the photoanode and the counter electrode are on the same side, that is, arranged horizontally, and the light incident surface is highly transparent quartz. Compared with the detector with FTO as the electrode mentioned above, it can realize a day-blind ultraviolet detector. Compared with the inverted structure with platinum on quartz as the counter electrode, it has a larger incident surface, high light absorption efficiency and high detection efficiency.

[0017] The present invention provides a method for preparing a transversely packaged PEC photodetector for materials such as gallium oxide with an absorption band below 300nm. The PEC detector is different from the previous longitudinal structure. The photosensitive material and the platinum electrode are evaporated on the same FTO surface to form a transverse structure. In the transverse structure, the light irradiation surface is highly transparent quartz, which can transmit day-blind ultraviolet light, but since there is no need to evaporate the electrode on the quartz, the light-transmitting surface is enlarged, the light absorption efficiency is increased, and the detector performance is further improved, which is convenient for the future design of PEC detectors with more functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the arrangement of photosensitive materials and Pt electrodes on a conductive substrate;

[0019] Figure 2 Schematic diagram of the lateral PEC photodetector structure;

[0020] Figure 3 is α-Ga 2 O 3 Response diagram of the nanopillar array lateral PEC solar-blind UV detector;

[0021] Figure 4 for β-Ga 2 O 3 Response diagram of thin-film lateral PEC solar-blind UV detector.

[0022] Among them, 1-substrate material, 2-gallium oxide, 3-platinum electrode, 4-highly transparent quartz. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] In the present invention, Ga 2 O 3 Thin film or Ga 2 O 3 The nanomaterial is grown on a conductive film, which can be a commonly used transparent conductive film FTO, ITO, or a conductive material such as a traditional silicon material. A portion of the conductive film is used to grow Ga2 O 3 Materials, part of which is used for evaporation of platinum electrodes, namely Ga 2 O 3 The material and the platinum electrode are located on the same conductive film, and highly transparent quartz is used as the incident surface. The electrolyte is filled between the conductive film and the quartz and packaged to obtain a packaged lateral PEC day-blind ultraviolet photodetector.

[0025] Embodiment 1:

[0026] 1. Take a FTO conductive substrate, cover half of the substrate area with a mask, and grow GaOOH nanomaterials on the substrate using a hydrothermal method. After annealing, α-Ga 2 O 3 Nanopillar array, due to the coverage of the mask, only half of the area of ​​the FTO substrate is covered by α-Ga 2 O 3 Nanopillar arrays.

[0027] 2. Prepare α-Ga 2 O 3 The nanopillar array is covered again with a mask, and the remaining exposed part is used for evaporation of Pt electrodes. 2 O 3 The nanocolumn array is partially a Pt electrode, with a gap between the two to avoid leakage or electrical barriers caused by contact between the two.

[0028] 3. Make a small hole at the Pt electrode covering position for subsequent injection of electrolyte from the small hole, such as Figure 1 shown.

[0029] 4. Take a highly transparent quartz and use a 60μm thick sarling film to bond the FTO substrate with the photoanode and the platinum counter electrode to the highly transparent quartz. Then inject electrolyte through the holes on the Pt electrode to fill the gaps, forming a lateral PEC type photodetector such as Figure 2 The photoelectric response of the detector is shown in Figure 3 As shown, the detector's response peak is at 244nm, and there is no response above 280nm, which proves that a solar-blind ultraviolet detector with excellent performance has been obtained.

[0030] Embodiment 2:

[0031] 1. Take a conductive n-type silicon substrate, cover half of the substrate area with a mask, and use magnetron sputtering to prepare Ga on the substrate. 2 O 3 The film was annealed to obtain β-Ga 2 O 3Due to the coverage of the mask, β-Ga is only obtained on half of the silicon substrate area. 2 O 3 film.

[0032] 2. Prepare β-Ga 2 O 3 Part of the film substrate is re-covered with a mask, and the remaining exposed part is used for evaporation of Pt electrodes. After the above steps are completed, part of the silicon substrate is β-Ga 2 O 3 The film is partially Pt electrode, and a gap is left between the two to avoid leakage or electrical barriers caused by contact between the two.

[0033] 3. Make a small hole at the Pt electrode covering position for subsequent injection of electrolyte from the small hole, such as Figure 1 shown.

[0034] 4. Take a high-transparent quartz and use a 60μm thick sarin film to 2 O 3 The thin film photoanode and the silicon substrate of the Pt counter electrode are bonded to highly transparent quartz. Then, electrolyte is injected through the holes on the Pt electrode to fill the gaps, forming a lateral PEC type photodetector such as Figure 2 The photoelectric response of the detector is shown in Figure 4 As shown, the detector's response peak is at 248nm, and there is no response above 280nm, which proves that a solar-blind ultraviolet detector with excellent performance has been obtained.

Claims

1. A method for preparing a lateral photoelectrochemical solar-blind ultraviolet photodetector, characterized in that: The method is: Step 1: Use a mask to cover a portion of the conductive substrate, and prepare a photosensitive material on the unmasked portion; Step 2: Remove the mask, prepare a counter electrode on the exposed portion of the conductive substrate, and drill a hole at the counter electrode position to penetrate the electrode and the substrate for injecting electrolyte during the electrode preparation process; Step 3: Prepare a high-transmittance quartz sheet, use a 50-60μm thick Surlyn film to bond the high-transmittance quartz sheet to the above structure, then inject electrolyte through the hole on the electrode, and then seal the small hole to form a lateral PEC type photodetector.

2. The method for preparing a lateral photoelectrochemical solar-blind ultraviolet photodetector according to claim 1, characterized in that: In step 1, the conductive substrate is one of FTO, ITO or silicon.

3. The method for preparing a lateral photoelectrochemical solar-blind ultraviolet photodetector according to claim 1, characterized in that: In step 1, the photosensitive material is one of Ga2O3 thin film, Ga2O3 nanomaterial, AlGaN, BN or MgZnO.

4. The method for preparing a lateral photoelectrochemical solar-blind ultraviolet photodetector according to claim 1, characterized in that: In step 1, the preparation method is one of magnetron sputtering, hydrothermal method, chemical bath method or suspension coating method.

5. The method for preparing a lateral photoelectrochemical solar-blind ultraviolet photodetector according to claim 1, characterized in that: In step 2, the counter electrode is a platinum electrode or a gold electrode.

6. The method for preparing a lateral photoelectrochemical solar-blind ultraviolet photodetector according to claim 1, characterized in that: In step 2, the platinum electrode is obtained by evaporation or heating annealing with chloroplatinic acid.

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