CN111244201A - A flexible self-supporting ZnO ultraviolet detector and preparation method thereof - Google Patents

Abstract

The invention provides a flexible self-supporting ZnO ultraviolet detector, belonging to the technical field of ultraviolet detection, comprising: a tetrapod-shaped ZnO nanostructure layer, two electrodes arranged on the surface of the tetrapod-shaped ZnO nanostructure layer, and a flexible substrate ; The tetrapod-shaped ZnO nanostructure layer exists independently to realize self-support, and is placed on the flexible substrate by transferring. The invention also provides a preparation method of a flexible self-supporting ZnO ultraviolet detector. The ultraviolet detector of the present invention adopts a tetrapod-shaped ZnO nanostructure layer, which has a special tetrapod-shaped structure. Four nanowires are used as a unit to be stacked into a flocculent self-supporting structure, and a flexible and fast response speed can be obtained simply and efficiently. Ultraviolet detector; the tetrapod-like ZnO nanostructure layer has high crystal quality, excellent performance, high light-dark suppression ratio and fast response speed, which can be used in the manufacture of flexible ultraviolet detectors, effectively solving the existing ZnO micro-nanostructure flexible ultraviolet detectors The problem that the substrate is not resistant to high temperature.

Description

A flexible self-supporting ZnO ultraviolet detector and preparation method thereof

technical field

The invention relates to the technical field of ultraviolet detection, in particular to a flexible self-supporting ZnO ultraviolet detector and a preparation method thereof.

Background technique

Ultraviolet detection technology is another dual-use detection technology after laser and infrared detection technology. detection system. Due to its advantages of low false alarm rate, good concealment and strong anti-electromagnetic interference ability, it has been widely used in many fields such as sewage purification ultraviolet detection, fire monitoring, missile warning, ultraviolet communication and ozone hole detection. In recent years, wide-bandgap semiconductor UV detectors are considered to be the third-generation UV detectors that can replace vacuum photomultiplier tubes and Si photomultiplier tubes due to their small size, light weight, and no need for filters and refrigeration. device. Among many wide-bandgap semiconductor materials, ZnO-based materials have many advantages such as low defect density, strong radiation resistance, and environmental friendliness, and the optical band gap can be continuously adjusted in the range of 3.37-7.78 eV by doping with Mg. At the same time, ZnO has a typical hexagonal-wurtzite crystal structure, which can easily grow different one-dimensional micro-nano structures, and the existence of various defects further makes ZnO nanostructures the most ideal for photodetection and advanced optoelectronic/luminescence technologies one of the materials.

Traditional ZnO UV detectors mainly use sapphire, silicon wafer or quartz as the substrate, which cannot be bent or transferred easily. However, the substrates used in ZnO micro-nano structure flexible UV detectors are not resistant to high temperature, and most of them can withstand a temperature limit of 150-200 °C. Materials cannot be directly prepared on flexible substrates, which limits the preparation of flexible devices. In view of this, there is an urgent need to study a flexible self-supporting ZnO UV detector and its preparation method to solve the technical problem that the flexible substrate of the existing ZnO micro-nano structure flexible UV detector is not resistant to high temperature.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a flexible self-supporting ZnO ultraviolet detector and a preparation method thereof in view of the above-mentioned defects of the prior art, using a tetrapod-shaped ZnO nanostructure layer, which has a special tetrapod-shaped structure, and is composed of four nanowires. As a unit, stacked into a flocculent self-supporting structure, the tetrapod-like ZnO nanostructure layer has high crystal quality, excellent performance, high light-dark suppression ratio, and fast response speed. It can be used in the manufacture of flexible UV detectors, effectively solving existing problems. The substrate is not resistant to high temperature in the ZnO micro-nano structure flexible UV detector.

The purpose of the present invention can be achieved through the following technical measures:

The present invention provides a flexible self-supporting ZnO ultraviolet detector, comprising:

A tetrapod-shaped ZnO nanostructure layer, two electrodes disposed on the surface of the tetrapod-shaped ZnO nanostructure layer, and a flexible substrate;

The tetrapod-shaped ZnO nanostructure layer exists independently to realize self-support, and is placed on the flexible substrate by transferring.

Further, the thickness of the tetrapod-shaped ZnO nanostructure layer is 50-1000 μm; wherein, the tetrapod diameter of the tetrapod-shaped ZnO nanostructure is 50-100 nm, and the tetrapod length is 2-5 μm.

Further, the two electrodes are independently designed and independently selected from any one of In electrodes, Au electrodes, Ag electrodes or Al electrodes, and the thickness of the electrodes is 30-50 nm.

Further, the two electrodes are circular electrodes with a diameter of 1-2 mm; the distance between the two electrodes is less than or equal to 1 mm.

Further, the flexible substrate is a polyethylene terephthalate substrate or a woven cloth substrate.

The present invention also provides a preparation method of the above-mentioned flexible self-supporting ZnO UV detector, comprising the following steps:

S1: preparing the tetrapod-shaped ZnO nanostructure layer;

S2: fixing the two electrodes on the tetrapod-shaped ZnO nanostructure layer by means of bonding;

S3: Transfer the tetrapod-shaped ZnO nanostructure layer bonded with the two electrodes to the flexible substrate, and compact and fix it, and lay sulfuric acid paper before compaction to avoid the tetrapod-shaped ZnO nanostructure layer. The structural layer was damaged and stained during the compaction process, and a flexible self-supporting ZnO UV detector was obtained.

Further, the method for preparing the tetrapod-shaped ZnO nanostructure layer in the step S1 is any one of a flame transmission method, a chemical vapor deposition method, and a hydrothermal method.

Further, in the step S1, chemical vapor deposition method is used to prepare the tetrapod-shaped ZnO nanostructure layer, and the preparation steps are as follows:

S10: The ZnO powder and the graphite powder are ground and mixed uniformly according to the mass ratio of 1:1, and then placed in a chemical vapor deposition device as a growth source;

S11: Heat up the chemical vapor deposition equipment under the protection of inert gas. The temperature control parameters are: (50±1)min from room temperature to 1000℃, (30±1)min from 1000℃ to 1130℃～1150℃ ; When the temperature rises to 1000°C, oxygen is introduced, and the oxygen flow rate is controlled to be 15-20sccm;

S12: keep the temperature at 1130℃～1150℃ for (60±1)min to grow and deposit tetrapod-like ZnO nanostructures;

S13: After the deposition is completed, the temperature is lowered to room temperature, and the tetrapod-shaped ZnO nanostructure layer is obtained by directly separating and taking out with tweezers.

Further, the inert gas is argon or nitrogen.

Further, the inert gas is argon, and the flow rate of argon is 90-110 sccm.

The flexible self-supporting ZnO ultraviolet detector of the present invention adopts a tetrapod-shaped ZnO nanostructure layer and has a special tetrapod-shaped structure. Four nanowires are used as a unit, each structural unit is closely connected, and the structure is relatively firm. When it is large enough, it can exist independently from the substrate, and can be stacked into a floc-like self-supporting structure, which provides more possibilities for the substrate selection of flexible UV detectors, and effectively solves the problem of substrate intolerance in the existing ZnO micro-nano structure flexible UV detectors. The problem of high temperature; the tetrapod-like ZnO nanostructure layer has high crystal quality, excellent performance, high light-dark suppression ratio, and fast response speed, which can be transferred to flexible substrates, and a flexible UV detector with fast response speed can be obtained simply and efficiently. The preparation method of the flexible self-supporting ZnO ultraviolet detector of the present invention is simple and efficient, the preparation process of the tetrapod ZnO nanostructure layer is controllable and can be designed, and the thickness of the tetrapod ZnO nanostructure layer can be designed.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

Fig. 1 is the structural representation of the flexible self-supporting ZnO ultraviolet detector of the present invention;

2 is a schematic structural diagram of the flexible self-supporting ZnO ultraviolet detector of the present invention in a bent state;

3 is a scanning electron microscope (SEM) photograph of a tetrapod-shaped ZnO nanostructure in an embodiment of the present invention;

4 is a voltage-current (I-V) characteristic curve of a flexible self-supporting ZnO UV detector in a dark state and 365 nm illumination according to an embodiment of the present invention;

Fig. 5 is the voltage-current (I-V) characteristic curve of the flexible self-supporting ZnO ultraviolet detector in the dark state and 365nm illumination when the flexible self-supporting ZnO ultraviolet detector according to an embodiment of the present invention is in a bent state;

FIG. 6 is a comparison diagram of FIGS. 4 and 5 .

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to illustrate the present invention, but not to limit the present invention.

In order to make the description of the present disclosure more detailed and complete, the following provides an illustrative description of the embodiments and specific embodiments of the present invention; but this is not the only form of implementing or using the specific embodiments of the present invention. The features of various specific embodiments as well as method steps and sequences for constructing and operating these specific embodiments are encompassed in the detailed description. However, other embodiments may also be utilized to achieve the same or equivalent function and sequence of steps.

The present invention provides a flexible self-supporting ZnO UV detector, as shown in Figures 1 and 2, comprising:

A tetrapod-shaped ZnO nanostructure layer, two electrodes disposed on the surface of the tetrapod-shaped ZnO nanostructure layer, and a flexible substrate;

The tetrapod-shaped ZnO nanostructure layer exists independently to realize self-support, and is placed on the flexible substrate by transferring.

Among them, the tetrapod-shaped ZnO nanostructure has a special tetrapod-shaped structure, with four nanowires as a structural unit, the diameter of the tetrapods is 50-100 nm, and the length of the tetrapods is 2-5 μm. Each structural unit is closely connected, and the structure is relatively firm. When the thickness is large enough, it can exist independently from the substrate and stack into a floc-like self-supporting structure, that is, a tetrapod-like ZnO nanostructure layer with a thickness of 50-1000 μm.

Wherein, the two electrodes are designed independently, and electrodes for ultraviolet detectors well known to those skilled in the art may be used. Preferably, the two electrodes are independently selected from any of In electrodes, Au electrodes, Ag electrodes or Al electrodes; the thickness of the electrodes is preferably 30-50 nm, more preferably 35-45 nm, and most preferably 40 nm. The shape of the two electrodes is preferably a circular electrode, and the diameter is preferably 1 to 2 mm, more preferably 1.2 to 1.8 mm, and most preferably 1.5 mm. The distance between the two electrodes is preferably ≤ 1 mm, more preferably 0.2 to 1 mm, and most preferably 0.5 mm.

Since the tetrapod-shaped ZnO nanostructure layer can be self-supporting, it can be directly picked up and transferred to any substrate, which provides more possibilities for the substrate selection of flexible UV detectors. Preferably, the flexible substrate is polyparaphenylene Ethylene diformate backing or woven backing.

The present invention also provides a method for preparing the above flexible self-supporting ZnO UV detector, comprising the following steps:

S1: preparing the tetrapod-shaped ZnO nanostructure layer;

S2: fixing the two electrodes on the tetrapod-shaped ZnO nanostructure layer by means of bonding;

S3: Transfer the tetrapod-shaped ZnO nanostructure layer bonded with the two electrodes to the flexible substrate, and compact and fix it, and lay sulfuric acid paper before compaction to avoid the tetrapod-shaped ZnO nanostructure layer. The structural layer was damaged and stained during the compaction process, and a flexible self-supporting ZnO UV detector was obtained.

Wherein, the method for preparing the tetrapod-shaped ZnO nanostructure layer in the step S1 is any one of a flame transmission method, a chemical vapor deposition method, and a hydrothermal method. When using chemical vapor deposition to prepare the tetrapod-shaped ZnO nanostructure layer, the preparation steps are as follows:

S10: The ZnO powder and the graphite powder are ground and mixed uniformly according to the mass ratio of 1:1, and then placed in a chemical vapor deposition device as a growth source;

S11: Heat up the chemical vapor deposition equipment under the protection of inert gas. The temperature control parameters are: (50±1)min from room temperature to 1000℃, (30±1)min from 1000℃ to 1130℃～1150℃ ; When the temperature rises to 1000°C, oxygen is introduced, and the oxygen flow rate is controlled to be 15-20sccm;

S12: keep the temperature at 1130℃～1150℃ for (60±1)min to grow and deposit tetrapod-like ZnO nanostructures;

S13: After the deposition is completed, the temperature is lowered to room temperature, and the tetrapod-shaped ZnO nanostructure layer is obtained by directly separating and taking out with tweezers.

Wherein, the inert gas can be selected as argon or nitrogen. When the inert gas is argon, the flow rate of argon is preferably 90-110 sccm.

Example 1

A method for preparing a flexible self-supporting ZnO UV detector according to an embodiment of the present invention includes the following steps:

S1: preparing the tetrapod-shaped ZnO nanostructure layer, the specific steps are:

S10: The ZnO powder and the graphite powder are ground and mixed uniformly according to the mass ratio of 1:1, and then placed in a chemical vapor deposition device as a growth source;

S11: The chemical vapor deposition equipment is heated under the protection of argon gas. The temperature control parameters are: from room temperature to 1000 °C in 50 minutes, and from 1000 °C to 1150 °C in 30 minutes; when the temperature rises to about 1000 °C, oxygen is introduced , control the oxygen flow to 16sccm;

S12: Incubate at 1150°C for 60min for growing and depositing tetrapod-like ZnO nanostructures;

S13: After the deposition is completed, the temperature is lowered to room temperature, and the tetrapod-shaped ZnO nanostructure layer is obtained by directly separating and taking out with tweezers, and the thickness is 50 μm.

S2: The two electrodes are fixed on the tetrapod-shaped ZnO nanostructure layer by means of bonding; the two electrodes are circular In particle electrodes, the circular diameter is 1.5 mm, and the thickness is 40 nm, The spacing between the two electrodes is 0.5 mm.

S3: Transfer the tetrapod-shaped ZnO nanostructure layer with the two electrodes bonded to the polyethylene terephthalate flexible substrate, and compact and fix it. Before compaction, cover with sulfuric acid paper to avoid any The tetrapod-shaped ZnO nanostructure layer was damaged and stained during the compaction process, and a flexible self-supporting ZnO UV detector was obtained.

The scanning electron microscope (SEM) photo of the tetrapod-shaped ZnO nanostructure layer prepared in this example is shown in FIG. 3 , the diameter of the tetrapod is 50 nm, and the length of the tetrapod is 3 μm.

Performance Testing:

1) For the flexible self-supporting ZnO UV detector prepared by the present embodiment in a flat state, carry out the voltage-current (I-V) characteristic curve test under dark state and under 365nm illumination, and the specific test method is:

The voltage-current performance test of the flexible self-supporting ZnO ultraviolet detector of this embodiment was carried out in the dark state and the light state by using the Agilent B1500 semiconductor analyzer equipment. First, use a probe station to connect the two electrodes of the flexible self-supporting ZnO UV detector prepared in this example to the semiconductor analyzer. After the connection between the instrument and the device is completed, the device and the whole system are left in a dark state for 30 minutes, and then the test. The voltage output is set from -15V to +15V, and the sampling interval is 100mV, and the obtained data is the I-V characteristic diagram of the device in the dark state. Then, a UV LED with a central wavelength of 365 nm was used to irradiate the surface of the flexible self-supporting ZnO UV detector prepared in this example, and the I-V characteristic diagram of the device under the optical state was obtained by testing again under the same voltage parameters.

The results are shown in Fig. 4. It can be seen that the flexible self-supporting ZnO UV detector prepared in this example has a relatively low dark current in the flat state, and the light-dark suppression ratio can reach three orders of magnitude.

2) For the flexible self-supporting ZnO UV detector prepared in the present embodiment in a bent state, a voltage-current (I-V) characteristic curve test in a dark state and under 365nm illumination is performed. The test process is the same as the above test, with the exception of At this time, the flexible self-supporting ZnO UV detector is in a bent state.

The results are shown in Fig. 5. It can be seen that the flexible self-supporting ZnO UV detector prepared in this example also has a relatively low dark current in the bending state, and the light-dark suppression ratio can reach three orders of magnitude.

As shown in FIG. 6 , the voltage-current (I-V) characteristic curves of the flexible self-supporting ZnO UV detector of the present embodiment in the straight state and the bent state, under the dark state and under 365 nm illumination are compared. It can be seen that the flexible self-supporting ZnO UV detector of this embodiment has the potential to fabricate flexible devices.

The flexible self-supporting ZnO ultraviolet detector of the present invention adopts a tetrapod-shaped ZnO nanostructure layer and has a special tetrapod-shaped structure. Four nanowires are used as a unit, each structural unit is closely connected, and the structure is relatively firm. When it is large enough, it can exist independently from the substrate, and can be stacked into a floc-like self-supporting structure, which provides more possibilities for the substrate selection of flexible UV detectors, and effectively solves the problem of substrate intolerance in the existing ZnO micro-nano structure flexible UV detectors. The problem of high temperature; the tetrapod-like ZnO nanostructure layer has high crystal quality, excellent performance, high light-dark suppression ratio, and fast response speed, which can be transferred to flexible substrates, and a flexible UV detector with fast response speed can be obtained simply and efficiently. The preparation method of the flexible self-supporting ZnO ultraviolet detector of the present invention is simple and efficient, the preparation process of the tetrapod ZnO nanostructure layer is controllable and can be designed, and the thickness of the tetrapod ZnO nanostructure layer can be designed.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.

Claims (10)

1. a flexible self-supporting ZnO ultraviolet detector, is characterized in that, comprises: A tetrapod-shaped ZnO nanostructure layer, two electrodes disposed on the surface of the tetrapod-shaped ZnO nanostructure layer, and a flexible substrate; The tetrapod-shaped ZnO nanostructure layer exists independently to realize self-support, and is placed on the flexible substrate by transferring. 2 . The flexible self-supporting ZnO ultraviolet detector according to claim 1 , wherein the thickness of the tetrapod-shaped ZnO nanostructure layer is 50-1000 μm; wherein, the tetrapod diameter of the tetrapod-shaped ZnO nanostructure is 50 to 100 nm, and the length of the quadrupeds is 2 to 5 μm. 3. The flexible self-supporting ZnO UV detector according to claim 1, wherein the two electrodes are independently designed and independently selected from any one of In electrodes, Au electrodes, Ag electrodes or Al electrodes, The electrode thickness is 30 to 50 nm. 4 . The flexible self-supporting ZnO UV detector according to claim 3 , wherein the two electrodes are both circular electrodes with a diameter of 1-2 mm; the distance between the two electrodes is ≤ 1 mm. 5 . 5 . The flexible self-supporting ZnO ultraviolet detector according to claim 1 , wherein the flexible substrate is a polyethylene terephthalate substrate or a woven cloth substrate. 6 . 6. A method for preparing the flexible self-supporting ZnO ultraviolet detector according to any one of claims 1-5, characterized in that, comprising the following steps: S1: preparing the tetrapod-shaped ZnO nanostructure layer; S2: fixing the two electrodes on the tetrapod-shaped ZnO nanostructure layer by means of bonding; S3: Transfer the tetrapod-shaped ZnO nanostructure layer bonded with the two electrodes to the flexible substrate, and compact and fix it, and lay sulfuric acid paper before compaction to avoid the tetrapod-shaped ZnO nanostructure layer. The structural layer was damaged and stained during the compaction process, and a flexible self-supporting ZnO UV detector was obtained. 7. The preparation method of the flexible self-supporting ZnO ultraviolet detector according to claim 6, wherein the method for preparing the tetrapod-shaped ZnO nanostructure layer in the step S1 is a flame transmission method, a chemical vapor deposition method , any of the hydrothermal methods. 8. The method for preparing a flexible self-supporting ZnO UV detector according to claim 7, wherein in the step S1, chemical vapor deposition is used to prepare the tetrapod-shaped ZnO nanostructure layer, and the preparation steps are as follows: S10: The ZnO powder and the graphite powder are ground and mixed uniformly according to the mass ratio of 1:1, and then placed in a chemical vapor deposition device as a growth source; S11: Heat up the chemical vapor deposition equipment under the protection of inert gas. The temperature control parameters are: (50±1)min from room temperature to 1000℃, (30±1)min from 1000℃ to 1130℃～1150℃ ; When the temperature rises to 1000°C, oxygen is introduced, and the oxygen flow rate is controlled to be 15-20sccm; S12: keep the temperature at 1130℃～1150℃ for (60±1)min to grow and deposit tetrapod-like ZnO nanostructures; S13: After the deposition is completed, the temperature is lowered to room temperature, and the tetrapod-shaped ZnO nanostructure layer is obtained by directly separating and taking out with tweezers. 9 . The method for preparing a flexible self-supporting ZnO ultraviolet detector according to claim 8 , wherein the inert gas is argon or nitrogen. 10 . 10 . The method for preparing a flexible self-supporting ZnO ultraviolet detector according to claim 9 , wherein the inert gas is argon, and the flow rate of argon is 90-110 sccm. 11 .

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