Flexible weak ultraviolet photoelectric synapse device and manufacturing method thereof

Abstract

The invention relates to a flexible weak ultraviolet photoelectric synapse device and a manufacturing method thereof. The flexible weak ultraviolet photoelectric synapse device is composed of a flexible electrode substrate, a GO thin film, a ZnO nanowire and an electrode. Wherein the GO thin film and the ZnO nanowire of the device form a ZnO / GO heterostructure, and the ZnO / GO heterostructure can capture electrons by utilizing rich oxygen-containing functional groups in the two-dimensional material graphene oxide, so that the recombination of electron holes is inhibited. The advantages of low defect density, high radiation resistance, environment friendliness and the like of the ZnO-based material are combined, so that dark current and noise current are effectively reduced, weak light identification is realized, and continuous photoconduction is enhanced. According to the method, a ZnO / GO heterostructure is independently designed, and the ZnO / GO heterostructure is transferred to the surface of the flexible electrode substrate by using a wet transfer process, so that the flexible weak ultraviolet photoelectric synapse device is prepared at a relatively low temperature. The preparation method is simple and economical, raw materials are easy to obtain, and large-area preparation can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic information materials, and particularly to a flexible weak ultraviolet optoelectronic synaptic device and a manufacturing method thereof. Background Art

[0002] The human brain's neural information activities have advantages such as high efficient energy utilization, large-scale parallelism, distributed storage and processing, autonomous learning, and low power consumption. Research shows that these excellent characteristics of the human brain mainly benefit from the biological synapses in the nervous system, which have computing and storage capabilities. People highly hope to simulate the synaptic function and execute neural network algorithms similar to the human brain with low energy and dense interconnection. And the artificial vision system is a current research focus.

[0003] Currently, an artificial vision system generally includes a digital image sensor for acquiring data, a storage unit for storing visual information, and a processing unit for performing image processing tasks. The current silicon-based CMOS image sensor of the artificial vision system can continuously and real-time monitor images, but this process will generate a large amount of redundant data and occupy a large amount of storage space. In addition, the existing vision system processors cannot directly process optical signals and need to use a sensor array to convert optical signals into electrical signals and transmit them to the processor for the next signal processing.

[0004] By analyzing the human visual system, it can be known that the external visual information is converted into electrical signals through the retina, then transmitted to the brain through the optic nerve, and finally the neural network in the visual cortex processes the data to form vision. On the retina, neurons with different functions are interconnected to form a hierarchical biological structure. The main function of the retina is to perceive and preprocess visual information, and then extract the key features of visual information, which greatly improves the information processing efficiency of the human brain. Therefore, in terms of unstructured image classification and recognition, the imaging and recognition efficiency of the human visual system is much higher than that of the artificial vision system. Therefore, the retina-like chip has become the development direction of the next-generation vision chip in order to solve the challenges faced by traditional chips.

[0005] So far, researchers have proposed various technical solutions to simulate the retina function, integrating the image sensing unit and the processing unit into each pixel to achieve the retina function. However, since the temperature limit that the flexible substrate can withstand is between 150°C and 200°C, the current optoelectronic synaptic devices mainly use sapphire, silicon wafers or quartz as substrates, which are not bendable and not easy to transfer, thus limiting their application scope. Moreover, the dark current of the existing optoelectronic synaptic devices is relatively high, which limits the sensitivity and dynamic range of the optoelectronic synaptic devices. Summary of the Invention

[0006] Based on this, it is necessary to provide a flexible weak ultraviolet photoelectric synaptic device and its manufacturing method for the above problems. By optimizing the device structure, adjusting the preparation method, etc., finally, the flexible weak ultraviolet photoelectric synaptic device can be prepared at a lower temperature, while obtaining a lower dark current, and improving its sensitivity and dynamic range.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A flexible weak ultraviolet photoelectric synaptic device, comprising:

[0009] A flexible electrode substrate;

[0010] A GO thin film, the GO thin film is located on the surface of the flexible electrode substrate;

[0011] ZnO nanowires, the ZnO nanowires are located on the surface of the GO thin film;

[0012] An electrode, the electrode is arrayed on the surface of the ZnO nanowires.

[0013] In one embodiment, the thickness of the ZnO nanowires is 0.5 μm - 1.5 μm.

[0014] In one embodiment, the diameter of the ZnO nanowires is 130 nm to 150 nm, and the length is 5 μm to 7 μm.

[0015] In one embodiment, the thickness of the GO thin film is 80 nm - 120 nm.

[0016] In one embodiment, the electrode is an In electrode.

[0017] In one embodiment, the array pitch of the electrodes is not greater than 2 mm.

[0018] In one embodiment, the flexible electrode substrate is an ITO flexible electrode substrate.

[0019] Another embodiment discloses a manufacturing method of a flexible weak ultraviolet photoelectric synaptic device, comprising:

[0020] Providing a flexible electrode substrate;

[0021] Preparing a GO thin film;

[0022] Preparing ZnO nanowires;

[0023] Transferring the ZnO nanowires to the surface of the GO thin film to form a ZnO / GO heterostructure;

[0024] Using a wet transfer process to transfer the ZnO / GO heterostructure to the surface of the flexible electrode substrate;

[0025] Fabricate electrodes on the surface of the ZnO nanowires.

[0026] In one embodiment, the GO film is fabricated by a vacuum filtration method.

[0027] In one embodiment, the ZnO nanowires are fabricated by a chemical vapor deposition process.

[0028] The flexible weak ultraviolet photoelectric synaptic device and its manufacturing method disclosed by the present invention. The device has a ZnO / GO heterostructure composed of a GO film and ZnO nanowires. The ZnO nanowires, as a light absorption layer, have excellent photosensitivity. Oxygen vacancy defects inside the material result in a strong persistent photoconductivity effect in the device. At the same time, abundant oxygen-containing functional groups in the two-dimensional material GO are used to capture electrons and inhibit the recombination of electron-hole pairs, resulting in a relatively high current in the device even after the light illumination is removed, showing excellent non-volatility. In addition, the high-resistance characteristic of GO effectively reduces the dark current and noise current, making it more suitable for the field of weak light recognition. The method separately designs the ZnO / GO heterostructure and transfers the ZnO / GO heterostructure to the surface of the flexible electrode substrate by a wet transfer process, realizing the fabrication of a flexible weak ultraviolet photoelectric synaptic device at a relatively low temperature. This manufacturing method is simple, economical, the raw materials are easily available, and it can be fabricated on a large scale. Description of the Drawings

[0029] Figure 1 Schematic diagram of the structure of a flexible weak ultraviolet photoelectric synaptic device provided by an embodiment of the present invention;

[0030] Figure 2 Test graph of the I-t characteristic curve of the flexible weak ultraviolet photoelectric synaptic device provided by an embodiment of the present invention;

[0031] Figure 3 Test graph of the paired-pulse facilitation behavior of the flexible weak ultraviolet photoelectric synaptic device provided by an embodiment of the present invention with a pulse time of 1 s;

[0032] Figure 4 Test graph of the paired-pulse facilitation behavior of the flexible weak ultraviolet photoelectric synaptic device provided by an embodiment of the present invention at different pulse time intervals;

[0033] Figure 5 Test graph of the I-V characteristic curve of the flexible weak ultraviolet photoelectric synaptic device provided by an embodiment of the present invention in the dark state;

[0034] Figure 6 Test graph of the I-t characteristic curve of a pure ZnO weak ultraviolet photoelectric synaptic device and the flexible weak ultraviolet photoelectric synaptic device disclosed by an embodiment of the present invention in the dark state.

[0035] In the figure, 1 is a flexible electrode substrate; 2 is a GO thin film; 3 is a ZnO nanowire; 4 is an electrode. Detailed implementation manners

[0036] To facilitate the understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the implementation manners or embodiments described herein. On the contrary, these implementation manners or embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific implementation manners or embodiments and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of the related listed items. The any and all combinations include any two related listed items, any more related listed items, or the combination of all related listed items.

[0038] An embodiment of the present invention discloses a flexible weak ultraviolet photoelectric synaptic device, as Figure 1 shown, including:

[0039] A flexible electrode substrate 1;

[0040] A GO (graphene oxide) thin film 2, and the GO thin film 2 is located on the surface of the flexible electrode substrate 1;

[0041] ZnO nanowires 3, and the ZnO nanowires 3 are located on the surface of the GO thin film 2;

[0042] An electrode 4, and the electrode 4 is distributed in an array on the surface of the ZnO nanowires 3.

[0043] The flexible weak ultraviolet photoelectric synaptic device disclosed in this embodiment has a ZnO / GO heterostructure composed of a GO thin film and ZnO nanowires. The ZnO nanowires, as a light absorption layer, have excellent photosensitivity. The oxygen vacancy defects inside the material capture holes, making the device have a strong persistent photoconductivity effect. At the same time, the rich oxygen-containing functional groups in the two-dimensional material GO capture electrons, inhibiting the recombination of electrons and holes, resulting in the device still having a high current after the light is removed, showing excellent non-volatility. In addition, the high-resistance characteristic of GO effectively reduces the dark current and noise current, making it more suitable for the field of weak light recognition.

[0044] In addition, graphene oxide, as a layered two-dimensional material, can adjust its resistance and material properties according to oxygen-containing functional groups. Meanwhile, ZnO has a typical hexagonal-wurtzite crystal structure and can very easily grow into different one-dimensional micro-nano structures. The existence of various defects further makes the ZnO nano-structures more adaptable to the characteristics of optoelectronic synaptic devices.

[0045] In another embodiment, the thickness of the ZnO nanowires is 0.5 μm - 1.5 μm. Specifically, the thickness of the ZnO nanowires is 0.5 μm or 1.5 μm or 0.7 μm or 1.2 μm or 1 μm, etc.

[0046] In another embodiment, the diameter of the ZnO nanowires is 130 nm - 150 nm and the length is 5 μm - 7 μm. Specifically, the diameter of the ZnO nanowires is 130 nm or 140 nm or 150 nm, and the length is 5 μm or 6 μm or 7 μm.

[0047] As a key wide-bandgap semiconductor material, zinc oxide exhibits extensive application potential in multiple fields such as ultraviolet detectors due to its various excellent properties. Its bandgap width is approximately 3.37 eV and it has a high exciton binding energy of 60 meV, making it an important representative of n-type semiconductor materials. When irradiated with light whose energy is equal to or exceeds its bandgap, electrons in the valence band of zinc oxide can absorb photons and jump to the conduction band. This process will lead to the generation of photo-generated carriers (i.e., electron-hole pairs) under continuous illumination. Research shows that the carrier mobility of zinc oxide thin films at room temperature can be as high as 100 cm 2 / Vs or even higher, which enables zinc oxide to efficiently convert the captured light energy into electrical signals and is very suitable for optoelectronic devices such as ultraviolet detectors.

[0048] In addition, nanostructured zinc oxide has a significant impact on electron transport properties due to its large specific surface area. Specifically, an increase in the specific surface area will lead to an increase in surface defects of the metal oxide. These defects will scatter or capture carriers, thereby reducing the carrier mobility. It should be noted that both oxygen vacancies on the surface and those inside are regarded as the main factors triggering the persistent photoconductivity (PPC) effect in zinc oxide. The persistent photoconductivity phenomenon refers to the fact that the photo-generated current can maintain a relatively high level for a period of time without disappearing immediately after the excitation light source is turned off. For non-volatile optoelectronic synaptic devices, the PPC effect is the main mechanism.

[0049] In this embodiment, the ZnO nanowires have a high specific surface area, which is beneficial to light absorption and improves their photosensitive performance. Meanwhile, during the growth process of ZnO nanowires, the oxygen vacancy concentration of the material can be controlled by adjusting the oxygen ratio.

[0050] In another embodiment, the thickness of the GO film is 80 nm - 120 nm. Specifically, the thickness of the GO film is 80 nm or 90 nm or 100 nm or 110 nm or 120 nm.

[0051] Compared with graphene, graphene oxide is a single atomic layer and can be extended to dozens of micrometers in lateral dimension at any time. Therefore, its structure spans the typical scales of general chemistry and materials science. Although the oxidation process destroys the highly conjugated structure of graphene, it still maintains special surface properties and layered structure. The introduction of oxygen-containing groups not only makes graphene oxide chemically stable, but also provides a large specific surface area to effectively disperse and adhere materials during the composite process with materials such as metals, metal oxides, and polymer polymers, preventing agglomeration. In addition, its conductivity and bandgap can be modulated by controlling the type and quantity of the contained oxygen-containing functional groups, and the material has a wide range of applications. Graphene oxide composites, including polymer composites and inorganic composites, have even broader application fields. Therefore, the ZnO / GO heterostructure in the present invention has multiple advantages.

[0052] In the embodiment of the present invention, the hydrophilicity of graphene oxide is utilized, and the ZnO / GO heterostructure can be transferred to any substrate by a wet transfer method.

[0053] The ZnO / GO heterojunction combines the advantages of zinc oxide and graphene oxide. The ZnO nanowire, as a light absorption layer, has excellent photosensitivity. The oxygen vacancy defects inside the material capture holes, making the device have a strong persistent photoconductivity effect. At the same time, the rich oxygen-containing functional groups in the two-dimensional material GO capture electrons, inhibiting the recombination of electron holes, resulting in a relatively high current in the device even after the light is removed, showing excellent non-volatility. In addition, the high-resistance characteristic of GO effectively reduces the dark current and noise current, making it more suitable for the field of weak light recognition.

[0054] In another embodiment, the electrode is an In electrode. In the present invention, the electrode can be an electrode for optoelectronic devices well-known to those skilled in the art. In this embodiment, in addition to the In electrode, the electrode can also be an Au electrode, an Ag electrode, or an Al electrode, or can also be an electrode of other metals or doped semiconductor materials.

[0055] In another embodiment, the thickness of the electrode is preferably 30 nm - 50 nm, more preferably 35 nm - 45 nm, and most preferably 40 nm.

[0056] In another embodiment, the electrode is preferably a circular electrode. In addition, the electrode can also be a square electrode, an oval electrode, or other shaped electrodes. In this embodiment, the diameter of the circular electrode is preferably 1 mm - 2 mm, more preferably 1.2 mm - 1.8 mm, and most preferably 1.5 mm.

[0057] In another embodiment, the array pitch of the electrodes is not greater than 2 mm. Specifically, the array pitch of the electrodes is 0.5 mm to 1.5 mm. More specifically, the array pitch of the electrodes is 0.5 mm or 0.8 mm or 1 mm or 1.1 mm or 1.2 mm or 1.5 mm, etc. In addition, the array pitch of the electrodes can also be adjusted according to actual requirements, which will not be elaborated one by one in this embodiment.

[0058] In another embodiment, the flexible electrode substrate is an ITO flexible electrode substrate. It can also be adjusted to other types of flexible electrode substrates according to requirements.

[0059] Another embodiment of the present invention discloses a method for fabricating a flexible weak ultraviolet photoelectric synaptic device, including:

[0060] Providing a flexible electrode substrate;

[0061] Preparing a GO film;

[0062] Preparing ZnO nanowires;

[0063] Transferring the ZnO nanowires to the surface of the GO film to form a ZnO / GO heterostructure;

[0064] Transferring the ZnO / GO heterostructure to the surface of the flexible electrode substrate by using a wet transfer process;

[0065] Preparing electrodes on the surface of the ZnO nanowires.

[0066] The method for fabricating the flexible weak ultraviolet photoelectric synaptic device disclosed in this embodiment separately designs a ZnO / GO heterostructure and uses a wet transfer process to transfer the ZnO / GO heterostructure to the surface of the flexible electrode substrate, realizing the fabrication of a flexible weak ultraviolet photoelectric synaptic device at a lower temperature. This fabrication method is simple and economical, the raw materials are easily available, and it can be fabricated on a large scale.

[0067] In another embodiment, the GO film is prepared by using a vacuum filtration method.

[0068] In another embodiment, the ZnO nanowires are prepared by using a chemical vapor deposition process.

[0069] In another embodiment, the method for fabricating the flexible weak ultraviolet photoelectric synaptic device specifically includes:

[0070] Preparation of GO film by vacuum filtration method: Add 1 ml of GO aqueous original slurry to 40 ml of deionized water to uniformly disperse GO flakes in water. Perform accelerated centrifugation at a speed of 3000 rpm for 15 min, take the supernatant and centrifuge it for another 15 min, then take the supernatant to obtain a GO aqueous dispersion. Take 10 ml of the above dispersion for vacuum filtration to obtain a GO film. Among them, the pressure for preparing the GO film is 30 Pa and the time is 3 h.

[0071] In this embodiment, the thickness of the GO film is 80 nm - 120 nm. Specifically, the thickness of the GO film is 80 nm or 90 nm or 100 nm or 110 nm or 120 nm.

[0072] Compared with graphene, graphene oxide is a single atomic layer and can be extended to dozens of micrometers in the lateral dimension at any time. Therefore, its structure spans the typical scales of general chemistry and materials science. Although the oxidation process destroys the highly conjugated structure of graphene, it still maintains special surface properties and layered structure. The introduction of oxygen-containing groups not only endows graphene oxide with chemical stability, but also provides a large specific surface area to effectively disperse and adhere materials during the composite process with materials such as metals, metal oxides, and polymer polymers, preventing agglomeration. In addition, its conductivity and bandgap can be modulated by controlling the type and quantity of the contained oxygen-containing functional groups, and the material has a wide range of applications. Graphene oxide composites, including polymer composites and inorganic composites, have even more extensive application fields. Therefore, the ZnO / GO heterostructure in the present invention has multiple advantages.

[0073] Meanwhile, graphene oxide is a hydrophilic substance and has excellent dispersibility in water. In this embodiment, the hydrophilicity of graphene oxide is utilized to easily achieve the large-area preparation of two-dimensional materials (GO film) by vacuum filtration.

[0074] Preparation of ZnO nanowires by chemical vapor deposition (CVD) technology: Grind and mix ZnO powder and graphite powder evenly according to a mass ratio of 1:1. The heating process is divided into three stages. The first stage is 30 min, heating to 1000 °C; the second stage is 10 min, heating to 1030 °C; the third stage is at 1030 °C for 60 min. During these three stages, argon is always used as the protective gas, and the argon flow rate is 100 sccm. When the temperature rises to about 1000 °C, open oxygen (the oxygen is the growth gas) by observing the gas mass, and the oxygen flow rate is 10 sccm.

[0075] In this embodiment, the thickness of the ZnO nanowires is 0.5 μm - 1.5 μm. Specifically, the thickness of the ZnO nanowires is 0.5 μm or 1.5 μm or 0.7 μm or 1.2 μm or 1 μm, etc.

[0076] In one embodiment, the diameter of the ZnO nanowires is 130 nm to 150 nm and the length is 5 μm to 7 μm. Specifically, the diameter of the ZnO nanowires is 130 nm or 140 nm or 150 nm, and the length is 5 μm or 6 μm or 7 μm.

[0077] As a key wide-bandgap semiconductor material, zinc oxide exhibits extensive application potential in multiple fields such as ultraviolet detectors due to its various excellent properties. Its bandgap width is approximately 3.37 eV, and it has a high exciton binding energy of 60 meV, making it an important representative of n-type semiconductor materials. When irradiated with light whose energy is equal to or exceeds its bandgap, electrons in the valence band of zinc oxide can absorb photons and jump to the conduction band, and this process will lead to the generation of photo-generated carriers (i.e., electron-hole pairs) under continuous illumination. Research shows that the carrier mobility of zinc oxide thin films at room temperature can be as high as 100 cm 2 / Vs or even higher, which enables zinc oxide to efficiently convert the captured light energy into electrical signals and is very suitable for optoelectronic devices such as ultraviolet detectors.

[0078] In addition, nanostructured zinc oxide has a significant impact on electron transport properties due to its large specific surface area. Specifically, an increase in the specific surface area will lead to an increase in surface defects of the metal oxide, and these defects will scatter or capture carriers, thereby reducing the carrier mobility. It should be noted that both surface oxygen vacancies and internal oxygen vacancies are regarded as the main factors triggering the persistent photoconductivity (PPC) effect in zinc oxide. The persistent photoconductivity phenomenon refers to the fact that the photo-generated current can still maintain a relatively high level for a period of time without disappearing immediately after the excitation light source is turned off. For non-volatile optoelectronic synaptic devices, the PPC effect is the main mechanism.

[0079] In this embodiment, the ZnO nanowires have a high specific surface area, which is beneficial to light absorption and improves their photosensitive performance. At the same time, the oxygen vacancy concentration of the material can be controlled by adjusting the oxygen ratio during the growth of ZnO nanowires.

[0080] 0.2 g of ZnO nanowires were uniformly dispersed in 30 ml of ethanol, and the above solution was poured onto the GO film, and a ZnO / GO heterostructure was obtained by vacuum filtration at a pressure of 40 Pa.

[0081] The ZnO / GO heterojunction prepared by the method disclosed in this embodiment combines the advantages of zinc oxide and graphene oxide. The ZnO nanowires, as the light absorption layer, have excellent photosensitivity. The oxygen vacancy defects inside the material capture holes, enabling the device to have a strong persistent photoconductivity effect. At the same time, the abundant oxygen-containing functional groups in the two-dimensional material GO capture electrons, inhibiting the recombination of electron-hole pairs, resulting in a relatively high current in the device even after the light is removed, showing excellent non-volatility. In addition, the high-resistance characteristic of GO effectively reduces the dark current and noise current, making it more suitable for the field of weak light recognition.

[0082] Transfer the ZnO / GO heterostructure onto the ITO flexible electrode substrate by wet transfer. Specifically, the ZnO / GO heterostructure can be placed on a mesh tray, and then the mesh tray is placed in deionized water. At this time, due to the hydrophilicity of the GO film, the ZnO / GO heterostructure will detach from the mesh tray and float on the water surface. Then, the ITO flexible electrode substrate is lifted from the bottom up to attach the ZnO / GO heterostructure to the surface of the ITO flexible electrode substrate.

[0083] Prepare an In electrode on the surface of the ZnO nanowires of the ZnO / GO heterostructure to obtain a flexible weak ultraviolet photoelectric synaptic device.

[0084] Among them, in this embodiment, the electrode is an In electrode. In the present invention, the electrode can be an electrode for optoelectronic devices well-known to those skilled in the art. In this embodiment, in addition to the In electrode, the electrode can also be an Au electrode, an Ag electrode, or an Al electrode, or an electrode made of other metals or doped semiconductor materials.

[0085] In another embodiment, the thickness of the electrode is preferably 30 nm to 50 nm, more preferably 35 nm to 45 nm, and most preferably 40 nm.

[0086] In another embodiment, the electrode is preferably a circular electrode. In addition, the electrode can also be a square electrode, an oval electrode, or other shaped or irregular electrodes. In this embodiment, the diameter of the circular electrode is preferably 1 mm to 2 mm, more preferably 1.2 mm to 1.8 mm, and most preferably 1.5 mm.

[0087] In another embodiment, the array pitch of the electrodes is not greater than 2 mm. Specifically, the array pitch of the electrodes is 0.5 mm to 1.5 mm. More specifically, the array pitch of the electrodes is 0.5 mm or 0.8 mm or 1 mm or 1.1 mm or 1.2 mm or 1.5 mm, etc. In addition, the array pitch of the electrodes can also be adjusted according to actual needs, which will not be elaborated one by one in this embodiment.

[0088] In this embodiment, the dosage of each material in the manufacturing method of the flexible weak ultraviolet photoelectric synaptic device is only an example, and the dosage can also be enlarged or reduced proportionally on this basis to prepare the flexible weak ultraviolet photoelectric synaptic device.

[0089] In another embodiment, the I-t characteristic curve test (365 nm light illumination stimulates the device) is performed on the flexible weak ultraviolet photoelectric synaptic device disclosed in the above embodiment. The specific test method is as follows:

[0090] The artificial synaptic plasticity performance test is performed on the flexible weak ultraviolet photoelectric synaptic device by using a Keithley 2450 digital source meter. First, connect the upper and lower electrodes of the device to be tested to the digital source meter with a probe station. After the instrument is connected to the device, let the device stand still in the dark state for 30 minutes with the whole set of systems, and then perform the test. The voltage output is set to 1 V, and the 365 nm laser pulse width is 1 s. The obtained data is the I-t characteristic diagram of the device. The detection results are as Figure 2 shown, and the device exhibits a long-lasting persistent photoconductivity phenomenon after illumination.

[0091] The paired-pulse facilitation behavior test is performed on the flexible weak ultraviolet photoelectric synaptic device: Figure 3 Two illuminations with a pulse time of 1 s are used to stimulate the device. From Figure 3 it can be seen that the current of the second pulse is significantly higher than that of the first pulse. By changing the pulse interval time, different PPF indexes are obtained. The experimental and fitting data are as Figure 4 shown.

[0092] From Figure 2 , Figure 3 and Figure 4 it can be known that the flexible weak ultraviolet photoelectric synaptic device disclosed in the embodiment of the present invention has obvious synaptic behavior.

[0093] Figure 5 This is the current-voltage (I-V) characteristic curve (dark current) of the flexible weak ultraviolet photoelectric synaptic device with ZnO / GO heterojunction disclosed in the embodiment of the present invention in the dark state and the photocurrent of the device under 365 nm light illumination. From Figure 5 it can be seen that the flexible weak ultraviolet photoelectric synaptic device prepared in the embodiment of the present invention has a relatively low dark current, and the light-to-dark suppression ratio can reach three orders of magnitude.

[0094] Figure 6 This is a comparison of the I-t characteristic curve test diagrams of the weak ultraviolet photoelectric synaptic device of pure ZnO nanowires and the flexible weak ultraviolet photoelectric synaptic device with ZnO / GO heterojunction disclosed in the embodiment of the present invention (365 nm light illumination stimulates the device). From Figure 6It can be seen that under the same light-dark inhibition ratio, the dark current of the flexible weak ultraviolet photoelectric synaptic device prepared in the embodiment of the present invention is significantly lower than that of the weak ultraviolet photoelectric synaptic device in the prior art.

[0095] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it can be directly on the other component or there may also be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in the description of this application are only for the purpose of illustration and do not represent the only implementation manner.

[0096] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of this application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, device, product or equipment that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products or equipment.

[0097] In this application, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may be that the first feature is in direct contact with the second feature, or the first feature is indirectly in contact with the second feature through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or only indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or only indicates that the first feature has a lower horizontal height than the second feature.

[0098] Unless otherwise defined, all technical and scientific terms used in the description of this application have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the description of this application are only for the purpose of describing specific implementation manners and are not intended to limit this application. The term "and / or" used in the description of this application includes any and all combinations of one or more of the related listed items.

[0099] The technical features of the above embodiments can be combined without changing the basic principles of the present application. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0100] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the patent protection scope of the present application shall be subject to the appended claims.

Claims

1. A flexible weak ultraviolet photoelectric synaptic device, characterized in that: include: Flexible electrode substrate; GO film, wherein the GO film is located on the surface of the flexible electrode substrate; ZnO nanowires, wherein the ZnO nanowires are located on the surface of the GO film; Electrodes, wherein the electrode array is distributed on the surface of the ZnO nanowires.

2. The flexible weak ultraviolet photoelectric synaptic device according to claim 1, characterized in that: The thickness of the ZnO nanowire is 0.5 μm-1.5 μm.

3. The flexible weak ultraviolet photoelectric synaptic device according to claim 1, characterized in that: The ZnO nanowire has a diameter of 130nm to 150nm and a length of 5μm to 7μm.

4. The flexible weak ultraviolet photoelectric synaptic device according to claim 1, characterized in that: The thickness of the GO film is 80nm-120nm.

5. The flexible weak ultraviolet photoelectric synaptic device according to claim 1, characterized in that: The electrode is an In electrode.

6. The flexible weak ultraviolet photoelectric synaptic device according to claim 1, characterized in that: The array spacing of the electrodes is no greater than 2 mm.

7. The flexible weak ultraviolet photoelectric synaptic device according to claim 1, characterized in that: The flexible electrode substrate is an ITO flexible electrode substrate.

8. A method for manufacturing a flexible weak ultraviolet photoelectric synaptic device, characterized in that: include: providing a flexible electrode substrate; Preparation of GO thin film; Preparation of ZnO nanowires; Transferring the ZnO nanowires to the surface of the GO film to form a ZnO / GO heterostructure; Transferring the ZnO / GO heterostructure to the surface of the flexible electrode substrate using a wet transfer process; An electrode is prepared on the surface of the ZnO nanowire.

9. The manufacturing method according to claim 8, characterized in that: The GO film was prepared by a vacuum filtration method.

10. The manufacturing method according to claim 8, characterized in that: The ZnO nanowires are prepared by chemical vapor deposition process.

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