Flexible solar-blind ultraviolet detector based on TiO2 / Ga2O3 nano-phase junction and preparation method thereof

Abstract

The application relates to a flexible solar blind ultraviolet detector based on a TiO2 / Ga2O3 nano-phase junction and a preparation method thereof. The detector comprises an Ag upper electrode, a flexible titanium sheet lower electrode, a TiO2 / alpha / beta-Ga2O3 phase junction nanorod array and a graphene / Ag nanowire composite electrode located between the Ag upper electrode and the flexible titanium sheet lower electrode. The flexible titanium sheet serves as a flexible titanium sheet substrate. The TiO2 / alpha / beta-Ga2O3 phase junction nanorod array comprises a TiO2 layer on the flexible titanium sheet substrate, an alpha / beta-Ga2O3 phase junction nanorod array on the TiO2 layer, and the alpha / beta-Ga2O3 phase junction nanorod array comprises a plurality of interval arranged alpha / beta-Ga2O3 phase junction nanorods. The graphene / Ag nanowire composite electrode is located at one end of the alpha / beta-Ga2O3 phase junction nanorod array away from the TiO2 layer, and the Ag upper electrode partially covers the graphene / Ag nanowire composite electrode. The multi-heterojunction structure solar blind ultraviolet detector has stable solar blind characteristics, excellent chemical and thermal stability, and is expected to be widely applied in the field of wearable and portable ultraviolet detectors.

Description

Technical Field

[0001] This invention belongs to the field of ultraviolet photodetector technology, specifically relating to a flexible solar-blind ultraviolet detector based on TiO2 / Ga2O3 nanostructure and its preparation method. Technical Background

[0002] In recent years, the design and fabrication of flexible photodetectors have attracted widespread attention from researchers in order to realize wearable photodetectors. The rapid development of flexible photodetector technology places increasingly higher demands on the sensitivity and flexibility of photosensitive materials. One-dimensional inorganic nanomaterials possess characteristics such as high aspect ratio, fast electron transport speed, and anisotropy. Their unique electron confinement effect is beneficial for maintaining the separation of electron and hole energy states, effectively extending carrier lifetime and exhibiting excellent photoelectric properties. Simultaneously, under external force, their linear geometric structure exhibits good elasticity; when the material deforms, no cracks form on the surface. These characteristics make one-dimensional inorganic nanomaterials very suitable for the design and fabrication of micro-flexible optoelectronic devices.

[0003] Gallium oxide (GaO) is a direct bandgap group III-IV wide-bandgap semiconductor material with a bandgap of 4.2-4.9 eV and a corresponding band-edge emission wavelength of 295-254 nm. It possesses unique advantages in deep ultraviolet photodetection and exhibits good chemical and thermal stability, making it one of the hot research topics in third-generation semiconductor materials in recent years. Compared to thin film materials, GaO nanomaterials, due to their high surface-to-volume ratio, significantly improve their sensitivity to spectral and gas detection. Flexible optoelectronic products are elastic and have a certain curvature surface, while GaO-based photodetectors are typically grown on rigid substrates such as silicon wafers, sapphire, and quartz substrates. These devices cannot be bent, limiting their application range. Although there are reports on the growth of amorphous GaO thin films on PEN polymer flexible substrates and the fabrication of flexible solar-blind ultraviolet detectors, most flexible substrates are currently polymer compounds that cannot withstand high temperatures. Therefore, selecting a high-temperature resistant flexible substrate for preparing single-crystal or polycrystalline GaO materials is crucial for realizing high-performance GaO-based flexible ultraviolet photodetectors.

[0004] To date, there have been reports of solar-blind ultraviolet photodetectors based on flexible gallium oxide nanoribbons (patent number: 201710012296.2). However, such detectors involve transferring pre-synthesized gallium oxide nanoribbons onto a flexible substrate, which has drawbacks such as poor adhesion to the substrate, poor stability, and difficulty in electrode fabrication. Summary of the Invention

[0005] The purpose of this invention is to provide a flexible, bendable, highly sensitive, stable, and fast-responding solar-blind ultraviolet detector based on TiO2 / Ga2O3 nanostructures and its fabrication method.

[0006] The technical solution of this invention is as follows: a flexible solar-blind ultraviolet detector based on TiO2 / Ga2O3 nanostructures, comprising an Ag upper electrode, a flexible titanium sheet lower electrode, a TiO2 / α / β-Ga2O3 nanopillar array and a graphene / Ag nanowire composite electrode located between the Ag upper electrode and the flexible titanium sheet lower electrode, wherein the flexible titanium sheet serves as a flexible titanium sheet substrate; the TiO2 / α / β-Ga2O3 nanopillar array includes a TiO2 layer on the flexible titanium sheet substrate, and an α / β-Ga2O3 nanopillar array on the TiO2 layer, the α / β-Ga2O3 nanopillar array comprising a plurality of spaced α / β-Ga2O3 nanopillars; the graphene / Ag nanowire composite electrode is located at one end of the α / β-Ga2O3 nanopillars away from the TiO2 layer, and the Ag upper electrode partially covers the graphene / Ag nanowire composite electrode.

[0007] The TiO2 / α / β-Ga2O3 phase-junction nanopillar array includes a p-type TiO2 layer and an n-type α / β-Ga2O3 nanophase junction.

[0008] The α / β-Ga2O3 nanophase junction comprises an α-Ga2O3 core and a β-Ga2O3 nanophase covering the sidewalls and top of the α-Ga2O3 core; the TiO2 layer is in direct contact with the bottom of the α-Ga2O3 core and the bottom of the β-Ga2O3 nanophase.

[0009] The thickness of the TiO2 layer is 200-300 nm, the diameter of the α / β-Ga2O3 phase nanopillars is 50-100 nm, the length of the α / β-Ga2O3 phase nanopillars is 1 μm-1.3 μm, and the thickness of the β-Ga2O3 is 10-30 nm; the thickness of the flexible titanium substrate is 0.1-0.2 mm.

[0010] The graphene / Ag nanowire composite electrode is composed of graphene sheets and Ag nanowires to form a transparent conductive electrode, and is connected in series with the α / β-Ga2O3 phase-junction nanopillar array.

[0011] Specifically, it is flexible and bendable, with stable performance, and can detect solar-blind ultraviolet light in the 200-280nm range, making it applicable to portable wearable ultraviolet detection devices.

[0012] This invention also includes a second technical solution: a method for fabricating a flexible solar-blind ultraviolet detector based on a TiO2 / Ga2O3 nanostructure, comprising the following steps:

[0013] 1. Immerse the titanium sheet substrate in acetone, ethanol, and deionized water in sequence and sonicate for 10 minutes each. After removing it, rinse it with deionized water and dry it with dry nitrogen gas. Place the cleaned titanium sheet in oxygen plasma to oxidize the surface of the titanium sheet and form a dense TiO2 layer, thus obtaining the TiO2 / Ti sheet substrate.

[0014] Second, place a gallium isopropoxide solution with a concentration of 0.5-1.0 mol / L into the inner liner of the reactor, and then lean the TiO2 / Ti substrate obtained in step one against the inner liner of the reactor and immerse it in the gallium isopropoxide solution, wherein the TiO2 layer faces the side of the inner liner of the reactor that is leaning against it.

[0015] Third, transfer the reaction vessel to an oven and react at 150℃ for 6-8 hours. Then, take out the sample, wash it alternately with deionized water and anhydrous ethanol, dry it, and anneal it in a high-temperature furnace at 400-500℃ for 1.0-2.0 hours to obtain TiO2 / α-Ga2O3 nanopillar array. Then, rapidly heat the high-temperature furnace to 700-800℃ and continue annealing for 10-20 minutes to obtain TiO2 / α / β-Ga2O3 phase-connected nanopillar array.

[0016] Fourth, a layer of graphene and silver nanowire mixed solution is spin-coated onto the TiO2 / α / β-Ga2O3 phase nanopillar array obtained in step three, and dried in a vacuum drying oven at 80°C to fabricate a graphene / Ag nanowire composite electrode.

[0017] Fifth, deposit a drop of silver paste on top of the graphene / Ag nanowire composite electrode obtained in step four as the upper electrode, scrape off part of the sample edge surface to expose the metallic titanium surface, which serves as the lower electrode of the flexible detector.

[0018] In step three, the rapid heating time of the high-temperature furnace from 400-500℃ to 700-800℃ is 5-10 minutes.

[0019] In step four, the concentration of the silver nanowire solution is 0.5-1.0 mol / L, and the concentration of graphene is 5-10 g / L.

[0020] Furthermore, in step three, the reaction is carried out at 150°C for 6-8 hours. The sample taken out afterward is a GaOOH nanopillar array grown on a TiO2 / Ti substrate. The GaOOH nanopillar array is transformed into an α / β-Ga2O3 phase junction nanopillar array stepwise at different annealing temperatures, and finally a TiO2 / α / β-Ga2O3 phase junction nanopillar array with multiple heterojunction structure is formed.

[0021] The beneficial effects of this invention are:

[0022] 1. The flexible solar-blind ultraviolet detector based on TiO2 / Ga2O3 nanostructures of the present invention is flexible and bendable, heat-resistant, stable in performance, and highly sensitive, exhibiting solar-blind photoelectric properties. The α / β-Ga2O3 phase-structured nanopillar array used is uniform and ordered, and the nanopillar size is controllable.

[0023] 2. The flexible solar-blind ultraviolet detector based on TiO2 / Ga2O3 nanostructures of the present invention has α / β-Ga2O3 nanopillars with a diameter of 50-100nm, resulting in better photoelectric performance. The composition ratio of the Ga2O3 phase is controllable, and the thickness of β-Ga2O3 is controlled within the range of 10-30nm. The graphene / Ag nanowire composite electrode enhances the conductivity and transmittance of the device, is easy to obtain and process, has good conductivity, and connects to the nanopillar array below the electrode, thereby improving the overall performance of the solar-blind ultraviolet detector.

[0024] 3. The flexible solar-blind ultraviolet detector based on TiO2 / Ga2O3 nanostructure of the present invention has a controllable thickness of 200-300nm for the TiO2 layer, which makes the detector have better photoelectric performance and better flexibility.

[0025] 4. The flexible solar-blind ultraviolet detector based on TiO2 / Ga2O3 nanostructure of the present invention has a three-dimensional multi-heterojunction interface structure, stable solar-blind characteristics, excellent chemical and thermal stability, flexibility and bendability, good repeatability, and can detect ultraviolet light in the solar-blind band of 200-280nm. It can be bent and folded and can be applied to portable wearable ultraviolet detection devices.

[0026] 5. This invention relates to a method for fabricating a flexible solar-blind ultraviolet detector based on TiO2 / Ga2O3 nanostructures. A titanium oxide / gallium oxide nanopillar array is synthesized in situ on a flexible titanium substrate using a hydrothermal method, and then covered with a graphene / silver nanowire composite transparent conductive electrode to create a flexible solar-blind ultraviolet detector with a multi-heterojunction structure. This detector exhibits strong controllability and ease of operation in its fabrication process, strong bonding between the device and the substrate, flexibility, ease of large-area fabrication, good repeatability, and low cost, making it highly promising for applications in wearable devices, ultraviolet detection, and other fields.

[0027] 6. This invention relates to a method for fabricating a flexible solar-blind ultraviolet detector based on a TiO2 / Ga2O3 nanostructure. A TiO2 thin film is generated on the surface of a flexible metallic Ti sheet using an oxygen plasma method, resulting in a dense and uniform film. A GaOOH nanopillar array is then directionally grown on top of the TiO2 film using a hydrothermal method, followed by annealing to form a TiO2 / α / β-Ga2O3 phase-junction nanopillar array. The growth direction, size, and structure are controllable. A graphene / Ag nanowire composite electrode is then spin-coated on top of the α / β-Ga2O3 phase-junction nanopillar array. Finally, a circular silver paste is drop-coated on top as the upper electrode, and an unoxidized Ti metal substrate serves as the lower electrode, thus fabricating a flexible solar-blind ultraviolet detector with a (Ti / TiO2 / α / β-Ga2O3 / C / Ag) multi-heterojunction structure. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of a flexible solar-blind ultraviolet detector based on TiO2 / Ga2O3 nanostructures;

[0029] Figure 2 The XRD pattern is of an α / β-Ga2O3 phase-structured nanopillar array.

[0030] Figure 3 This is a SEM image of an α / β-Ga2O3 phase-structured nanopillar array;

[0031] Figure 4 This is the It image of a flexible solar-blind ultraviolet detector based on TiO2 / Ga2O3 nanopillar arrays with different structures under 254nm ultraviolet light illumination. Detailed Implementation

[0032] The present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Other embodiments obtained by those skilled in the art within the scope of the embodiments of the present invention without inventive effort are all within the protection scope of the present invention.

[0033] Example 1

[0034] The fabrication method of a flexible solar-blind ultraviolet detector based on TiO2 / Ga2O3 nanostructures includes the following steps:

[0035] (1) Soak the flexible titanium sheet substrate in acetone, ethanol and deionized water in sequence and sonicate for 10 minutes each. After taking it out, rinse it with deionized water and blow it dry with dry nitrogen. Place the cleaned titanium sheet in oxygen plasma to oxidize the surface of the titanium sheet and form a dense TiO2 layer to obtain the TiO2 / Ti sheet substrate. (2) Take 30 mL of 0.5 mol / L gallium isopropoxide solution and place it in the inner liner of the reactor. Then, lean the TiO2 / Ti sheet substrate obtained in step (1) against the inner liner of the reactor and immerse it in the gallium isopropoxide solution, with the TiO2 side facing down (i.e., facing the side of the inner liner of the reactor that is leaning against). (3) Transfer the reactor to an oven and react at 150°C for 6 hours. Then take out the sample, wash it with deionized water and anhydrous ethanol alternately 3 times, dry it and then heat it in a high-temperature furnace at 400°C. First, anneal for 1.0 hour to obtain TiO2 / α-Ga2O3 nanopillar array, then rapidly heat the high temperature furnace to 750℃ and continue annealing for 10 minutes to obtain TiO2 / α / β-Ga2O3 phase-connected nanopillar array; (4) spin-coat a layer of graphene and silver nanowire mixed solution on the TiO2 / α / β-Ga2O3 phase-connected nanopillar array obtained in step (3), and dry it in a vacuum drying oven at 80℃ to make graphene / Ag nanowire composite transparent conductive electrode;

[0036] (5) Deposit a drop of silver paste on top of the graphene / Ag nanowire composite electrode obtained in step (4) as the upper electrode, scrape off part of the sample edge surface to expose the metal titanium surface, and use it as the lower electrode of the flexible detector.

[0037] Specifically, in step (1), the cleaned titanium sheet is placed in oxygen plasma. The discharge power of the oxygen plasma treatment is 50W, the oxygen flow rate is 30Sccm, the treatment time is 20 minutes, and the thickness of the TiO2 layer formed is 300nm.

[0038] In this embodiment, the thickness of the flexible titanium substrate is 0.2 mm. In other embodiments, the thickness of the flexible titanium substrate can be in the range of 0.1-0.2 mm, such as 0.1 mm, 0.12 mm, 0.15 mm, or 0.18 mm. These are not exhaustive examples here.

[0039] In step (3), the rapid heating time for the high-temperature furnace from 400℃ to 750℃ is 10 minutes. In other embodiments, the rapid heating time only needs to be controlled within 5-10 minutes, such as 5 minutes, 6 minutes, 7 minutes, 8 minutes, or 9 minutes. The phase transition from αβ-Ga2O3 to β-Ga2O3 is controlled by controlling the rapid heating time.

[0040] In step (4), the concentration of the silver nanowire solution is 0.5 mol / L, and the concentration of the graphene dispersion is 5 g / L. The mixing ratio of the silver nanowire solution and graphene can be 1:1 by volume, and other ratios can also be used in other embodiments, without specific limitation. A mixed solution is formed by mixing the silver nanowire solution and the graphene dispersion, and this mixed solution is spin-coated onto an α / β-Ga2O3 phase nanopillar array.

[0041] Further, step (3) involves preparing an α / β-Ga2O3 phase-junction nanopillar array using a hydrothermal method. A GaOOH nanopillar array is grown on a TiO2 / Ti substrate and then further annealed. The GaOOH nanopillar array is transformed stepwise into an α / β-Ga2O3 phase-junction nanopillar array at different annealing temperatures, ultimately forming a TiO2 / α / β-Ga2O3 phase-junction nanopillar array with a multi-heterojunction structure.

[0042] The samples obtained before and after annealing in step (3) were subjected to XRD analysis. Figure 2 As can be seen from the data, the diffraction peaks (021), (002), and (070) are characteristic peaks of the GaOOH phase, indicating that the product generated by the hydrothermal method is GaOOH. The diffraction peaks (110) and (300) are characteristic peaks of the α-Ga2O3 phase, indicating that α-Ga2O3 is obtained after annealing at 400℃. The diffraction peaks (002), (111), and (401) are characteristic peaks of the β-Ga2O3 phase. Figure 2 No characteristic peaks of other impurities were found, indicating that the material obtained after annealing at 750℃ is β-Ga2O3. Therefore, under appropriate annealing time, α / β-Ga2O3 phase junction material can be obtained, and with the increase of annealing time, the α-Ga2O3 phase will be completely transformed into the β-Ga2O3 phase. The sample obtained in step (3) was observed under a scanning electron microscope, and it was found that the nanopillars grew uniformly, such as Figure 3 As shown, Figure (a) is a scanning electron microscope image of the end face of the α / β-Ga2O3 heterojunction nanopillar array, showing that the diameter of the α / β-Ga2O3 heterojunction nanopillars is 100-200 nm. Figure (b) is a side scan image of the heterojunction nanopillar array, showing that the height of the α / β-Ga2O3 heterojunction nanopillars is 1.0-1.3 μm and the thickness of TiO2 is 300 nm.

[0043] The photoelectric performance of the flexible solar-blind ultraviolet detector based on TiO2 / Ga2O3 nanostructure obtained in step (5) was tested. Figure 4 Flexible solar-blind ultraviolet detectors based on TiO2 / Ga2O3 nanopillar arrays with different structures are presented at a light intensity of 5 mW / cm². 2The It curves, obtained by continuously switching the light source on and off under 254nm illumination, showed excellent repeatability after four It cycles. The maximum photocurrent for the TiO2 / α-Ga2O3 nanopillar array was 25nA, and for the TiO2 / β-Ga2O3 nanopillar array it was 80nA. The maximum photocurrent for the TiO2 / α / β-Ga2O3 phase junction nanopillar array was significantly better at 230nA. This is because the Ga2O3 heterojunction can form a second type of band arrangement at the interface, where the conduction and valence bands of one phase are higher than those of the other. For optoelectronic devices, this allows electron-hole pairs generated under illumination to separate at the interface, with electrons flowing to the lower energy side and holes transferring to the higher energy side. This enables rapid and efficient separation of photogenerated carriers, improving the performance of optoelectronic devices. While TiO2 / β-Ga2O3 and TiO2 / α-Ga2O3 only have a single pn junction structure, their efficiency in separating electron-hole pairs is relatively lower compared to the multiple heterojunctions of TiO2 / α / β-Ga2O3. Gallium oxide nanopillar arrays, however, exhibit excellent optoelectronic properties due to their high aspect ratio and fast electron transport speed. Furthermore, their linear geometry provides good elasticity under external forces; no cracks form on the surface after material deformation. Combined with a flexible titanium substrate, this makes them ideal for the design and fabrication of flexible optoelectronic devices, with the potential for widespread application in fields such as mobile wearable devices and ultraviolet detection.

[0044] Example 2

[0045] Steps (1), (4), and (5) are the same as in Example 1. In step (2), the concentration of the gallium isopropoxide solution is 0.5 mol / L. In step (3), the reaction is carried out at 150 °C for 7 h to hydrothermally grow gallium hydroxyl oxide. Then, GaOOH is transferred to a high-temperature furnace for annealing. First, it is annealed at 400 °C for 1.5 h to obtain a TiO2 / α-Ga2O3 nanopillar array. Then, the high-temperature furnace is rapidly heated to 700 °C and annealed for another 20 minutes to obtain a TiO2 / α / β-Ga2O3 phase-junction nanopillar array. The crystal structure, chemical composition, and photoelectric properties of the obtained TiO2 / α / β-Ga2O3 phase-junction nanopillar array, as well as the photoelectric properties of the flexible solar-blind ultraviolet detector based on the TiO2 / Ga2O3 nanostructure, are similar to those in Example 1.

[0046] Example 3

[0047] Steps (1), (4), and (5) are the same as in Example 1. In step (2), the concentration of the gallium isopropoxide solution is 1.0 mol / L. In step (3), the reaction is carried out at 150 °C for 8 h to hydrothermally grow gallium hydroxyl oxide. Then, GaOOH is transferred to a high-temperature furnace for annealing. First, it is annealed at 500 °C for 2.0 h to obtain a TiO2 / α-Ga2O3 nanopillar array. Then, the high-temperature furnace is rapidly heated to 800 °C and annealed for another 10 minutes to obtain a TiO2 / α / β-Ga2O3 phase-junction nanopillar array. The crystal structure, chemical composition, and photoelectric properties of the obtained TiO2 / α / β-Ga2O3 phase-junction nanopillar array are similar to those of Example 1.

[0048] Example 4

[0049] Steps (1), (4), and (5) are the same as in Example 1. In step (2), the concentration of the gallium isopropoxide solution is 1.0 mol / L. In step (3), the reaction is carried out at 150°C for 7 hours to hydrothermally grow gallium hydroxyl oxide. Subsequently, GaOOH is transferred to a high-temperature furnace for annealing at 500°C for 2.0 hours to obtain a TiO2 / α-Ga2O3 nanopillar array. The crystal structure and chemical composition of the obtained TiO2 / α-Ga2O3 nanopillar array are similar to those of the sample obtained after the first annealing in Example 1. The photoelectric performance of the flexible solar-blind ultraviolet detector based on the TiO2 / α-Ga2O3 nanopillar array is significantly lower than that of the TiO2 / Ga2O3 nanostructure. Figure 4 ).

[0050] Example 5

[0051] Steps (1), (4), and (5) are the same as in Example 1. In step (2), the concentration of the gallium isopropoxide solution is 1.0 mol / L. In step (3), the reaction is carried out at 150°C for 7 hours to hydrothermally grow gallium hydroxyl oxide. Subsequently, GaOOH is transferred to a high-temperature furnace for annealing at 800°C for 2.0 hours to obtain a TiO2 / β-Ga2O3 nanopillar array. The crystal structure and chemical composition of the obtained TiO2 / β-Ga2O3 nanopillar array are similar to those of the sample obtained after the second annealing in Example 1. The photoelectric performance of the flexible solar-blind ultraviolet detector based on the TiO2 / β-Ga2O3 nanopillar array is slightly lower than that of the TiO2 / Ga2O3 nanostructure. Figure 4 ).

[0052] Example 6

[0053] A flexible solar-blind ultraviolet detector based on TiO2 / Ga2O3 nanostructures, with the structure as follows: Figure 1As shown, the device includes an Ag upper electrode 6, a flexible titanium sheet 1 lower electrode, a TiO2 / α / β-Ga2O3 phase-connected nanopillar array and a graphene / Ag nanowire composite electrode 5 located between the Ag upper electrode 6 and the flexible titanium sheet 1 lower electrode. The flexible titanium sheet 1 serves as the substrate. The TiO2 / α / β-Ga2O3 phase-connected nanopillar array includes a TiO2 layer 2 on the flexible titanium sheet 1 substrate, and an α / β-Ga2O3 phase-connected nanopillar array on the TiO2 layer 2. The α / β-Ga2O3 phase-connected nanopillar array includes several spaced-apart α / β-Ga2O3 phase-connected nanopillars. The graphene / Ag nanowire composite electrode 5 is located at one end of the α / β-Ga2O3 phase-connected nanopillars away from the TiO2 layer 2, and the Ag upper electrode 6 partially covers the graphene / Ag nanowire composite electrode 5.

[0054] The TiO2 / α / β-Ga2O3 phase-junction nanopillar array includes a p-type TiO2 layer 2 and an n-type α / β-Ga2O3 nanophase junction.

[0055] The α / β-Ga2O3 nanophase junction includes an α-Ga2O3 core 3 and a β-Ga2O3 nanophase 4 covering the sidewalls and top of the α-Ga2O3 core 3; the TiO2 layer 2 is in direct contact with the bottom of the α-Ga2O3 core 3 and the bottom of the β-Ga2O3 nanophase 4.

[0056] The TiO2 layer 2 has a thickness of 200–300 nm, the α / β-Ga2O3 phase-connected nanopillars have a diameter of 50–100 nm, a length of 1 μm–1.3 μm, and a thickness of β-Ga2O3 nanophase 4 of 10–30 nm; the flexible titanium sheet 1 substrate has a thickness of 0.1–0.2 mm. The thickness of the β-Ga2O3 nanophase 4 refers to the dimension of the β-Ga2O3 nanophase 4 parallel to the plane of the flexible titanium sheet 1 substrate.

[0057] The graphene / Ag nanowire composite electrode 5 is composed of graphene sheets and Ag nanowires to form a transparent conductive electrode, and is connected in series with the α / β-Ga2O3 phase-junction nanopillar array.

[0058] The present invention provides a flexible solar-blind ultraviolet detector based on TiO2 / Ga2O3 nanostructures. It is flexible and bendable, and can detect solar-blind ultraviolet light in the range of 200-280 nm. It can be applied to portable wearable ultraviolet detection devices.

[0059] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. For those skilled in the art, any modifications, equivalent substitutions, or improvements made based on the above description and within the methods and principles of this invention should be included within the scope of protection of this invention. It is neither necessary nor possible to exhaustively describe all embodiments here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A flexible solar blind ultraviolet detector based on TiO2 / Ga2O3 nano-phase junction, characterized in that, The application relates to a TiO2 / alpha / beta-Ga2O3 phase junction nanorod array electrode, which comprises an Ag upper electrode, a flexible titanium sheet lower electrode, a TiO2 / alpha / beta-Ga2O3 phase junction nanorod array located between the Ag upper electrode and the flexible titanium sheet lower electrode, and a graphene / Ag nanowire composite electrode, wherein the flexible titanium sheet serves as a flexible titanium sheet substrate; the TiO2 / alpha / beta-Ga2O3 phase junction nanorod array comprises a TiO2 layer on the flexible titanium sheet substrate, an alpha / beta-Ga2O3 phase junction nanorod array on the TiO2 layer, and the alpha / beta-Ga2O3 phase junction nanorod array comprises a plurality of interval arranged alpha / beta-Ga2O3 phase junction nanorods; the graphene / Ag nanowire composite electrode is located at one end of the alpha / beta-Ga2O3 phase junction nanorod array which is away from the TiO2 layer, and the Ag upper electrode partially covers the graphene / Ag nanowire composite electrode; the alpha / beta-Ga2O3 phase junction comprises an alpha-Ga2O3 core and a beta-Ga2O3 nanophase which is coated on the sidewall and top of the alpha-Ga2O3 core; and the TiO2 layer is directly in contact with the bottom of the alpha-Ga2O3 core and the bottom of the beta-Ga2O3 nanophase. 2.The flexible solar blind UV detector based on TiO 2 / Ga 2O 3 nano-phase junction according to claim 1, wherein, The TiO2 / alpha / beta-Ga2O3 phase junction nanorod array comprises a p-type TiO2 layer and an n-type alpha / beta-Ga2O3 phase junction. 3.The flexible solar blind UV detector based on TiO 2 / Ga 2 O 3 nano-phase junction according to claim 1, wherein, The thickness of the TiO2 layer is 200-300 nm, the diameter of the alpha / beta-Ga2O3 phase junction nanorod is 50-100 nm, the length of the alpha / beta-Ga2O3 phase junction nanorod is 1 mu m-1.3 mu m, and the thickness of the beta-Ga2O3 nanophase is 10-30 nm; and the thickness of the flexible titanium sheet substrate is 0.1-0.2 mm. 4.The flexible solar blind UV detector based on TiO 2 / Ga 2 O 3 nano-phase junction of claim 1, wherein, The graphene / Ag nanowire composite electrode is formed by compounding graphene sheets and Ag nanowires to form a transparent conductive electrode, and the alpha / beta-Ga2O3 phase junction nanorod array is connected in series.

5. A method for preparing a flexible solar blind ultraviolet detector based on TiO2 / Ga2O3 nano-phase junction, characterized in that, The application further discloses a preparation method of the TiO2 / alpha / beta-Ga2O3 phase junction nanorod array electrode. Firstly, a flexible titanium sheet substrate is sequentially soaked in acetone, ethanol and deionized water for 10 minutes, and then washed with deionized water and dried with dry nitrogen; the cleaned metal titanium sheet is placed in an oxygen plasma to oxidize the metal titanium surface and form a dense TiO2 layer, thereby obtaining a TiO2 / Ti sheet substrate; Secondly, a gallium isopropyl alcohol solution with a concentration of 0.5-1.0 mol / L is placed in a reaction kettle inner container, and then the TiO2 / Ti sheet substrate obtained in step one is obliquely placed in the reaction kettle inner container and immersed in the gallium isopropyl alcohol solution, wherein the TiO2 layer is directed to the side of the obliquely placed reaction kettle inner container; Thirdly, the reaction kettle is transferred into an oven to react at 150 DEG C for 6-8 hours, and then the sample is taken out and washed with deionized water and anhydrous ethanol alternately; after drying, the sample is annealed at 400-500 DEG C in a high-temperature furnace for 1.0-2.0 hours to obtain a TiO2 / alpha-Ga2O3 nanorod array, and then the high-temperature furnace is rapidly heated to 700-800 DEG C and continuously annealed for 10-20 minutes to obtain a TiO2 / alpha / beta-Ga2O3 phase junction nanorod array. Four, spin coating a layer of graphene and silver nanowire mixed solution on the TiO2 / α / β-Ga2O3 phase junction nanorod array obtained in step three, and drying in a vacuum drying oven at 80℃ to make a graphene / Ag nanowire composite electrode; Five, depositing a drop of silver glue on the graphene / Ag nanowire composite electrode obtained in step four as an upper electrode, scraping off part of the surface of the sample edge to expose the titanium metal surface as a lower electrode of the flexible probe; the rapid heating time of the high-temperature furnace in step three is 5-10 minutes from 400-500℃ to 700-800℃.

6. The method for preparing a flexible solar blind UV detector based on TiO2 / Ga2O3 nano-phase junction according to claim 5, characterized in that, In step one, the discharge power of the oxygen plasma treatment is 50W, the oxygen flow is 30Sccm, and the treatment time is 20-30 minutes.

7. The method for preparing a flexible solar blind UV detector based on TiO2 / Ga2O3 nano-phase junction according to claim 5, characterized in that, In step four, the concentration of the silver nanowire solution is 0.5-1.0mol / L, and the concentration of the graphene dispersion solution is 5-10g / L. 8.The method for preparing a flexible solar blind ultraviolet detector based on TiO 2 / Ga 2 O 3 nano-phase junction according to claim 5, characterized in that, The sample in step three is a TiO2 / Ti sheet substrate growing GaOOH nanorod array.

Images