Flexible photoelectric memristor based on copper phthalocyanine and preparation method thereof

Abstract

The invention discloses a flexible photoelectric memristor based on copper phthalocyanine and a preparation method of the flexible photoelectric memristor. The flexible photoelectric memristor sequentially comprises a flexible substrate layer PDMS, a transparent bottom electrode ITO, a resistive layer CuPc and a metal top electrode Au from bottom to top. The photoinduced synaptic enhancement behavior of the device is realized by capturing photo-induced electrons by utilizing the defect energy level in the copper phthalocyanine layer under light irradiation. In addition, the flexible device array can be attached to a spherical surface, and the wide-view function of the biological retina and the perception and storage functions of images are simulated. The preparation method disclosed by the invention is simple and convenient in process and low in cost, and provides a new view angle and a solution for the development of an efficient neuromorphic visual system.

Description

Technical Field

[0001] The present invention relates to the field of microelectronics technology, and particularly to a flexible optoelectronic memristor based on copper phthalocyanine and a preparation method thereof. Background Art

[0002] Traditional machine vision systems are based on the von Neumann architecture. Due to the physical separation of the sensor and the processing unit, a large amount of redundancy and delay occur during the data transmission process, which limits the parallel computing and real-time processing capabilities of the system. In contrast, the human visual system directly transmits information to the brain through the retina for processing, achieving a high degree of integration of perception, storage, and calculation, and demonstrating excellent efficiency and low-latency characteristics. Inspired by this, optoelectronic memristors, as a new type of nanodevice with the characteristics of integrated sensing, storage, and computing, are expected to solve the bottleneck problems of traditional machine vision systems. In addition, due to their wearability and deformability, flexible optoelectronic memristors have broad application prospects in fields such as wearable devices and smart skins, and can further promote the development of neuromorphic electronics. Copper phthalocyanine (CuPc), as an organic semiconductor, has excellent light absorption ability, especially showing good performance in the visible and near-infrared regions, and is commonly used in optoelectronic device fields such as solar cells and photodetectors. However, there is still relatively little research on flexible optoelectronic memristors based on copper phthalocyanine, and their applications in simulating biological vision functions have not been fully explored. Summary of the Invention

[0003] The object of the present invention is to provide a flexible optoelectronic memristor based on copper phthalocyanine and a preparation method thereof.

[0004] To achieve the above object, the present invention is implemented according to the following technical solution:

[0005] The flexible optoelectronic memristor based on copper phthalocyanine of the present invention includes, from bottom to top in sequence: a flexible substrate layer, a transparent bottom electrode, a resistive switching layer, and a metal top electrode; the flexible substrate layer is polydimethylsiloxane; the transparent bottom electrode is indium tin oxide doped with tin; the resistive switching layer is copper phthalocyanine; and the metal top electrode is gold.

[0006] Preferably, the thickness of the flexible substrate layer is 0.15 - 0.3 mm; the thickness of the transparent bottom electrode is 200 nm; the thickness of the resistive switching layer is 50 - 70 nm; and the thickness of the metal top electrode is 30 - 40 nm.

[0007] The preparation method of the flexible optoelectronic memristor based on copper phthalocyanine of the present invention includes the following steps:

[0008] S1: Spin-coat polydimethylsiloxane on a cleaned transparent glass to form a flexible substrate layer. Specifically: Mix polydimethylsiloxane and a curing agent at a volume ratio of 10:1, stir, and let stand for more than 1 h. Then spin-coat the mixture on the cleaned transparent glass, rotate at 1000 rpm for 60 s to form a polydimethylsiloxane film, and then transfer it to an oven at 80 °C for curing for 2 h.

[0009] S2: Magnetron sputter indium tin oxide doped with tin on the flexible substrate layer prepared in step S1 to form a transparent bottom electrode. Specifically: In a magnetron sputtering coating machine filled with argon, sputter an indium tin oxide target doped with tin at a power of 80 W for 20 min. The final thickness of the ITO layer is 200 nm.

[0010] S3: Spin-coat copper phthalocyanine on the transparent bottom electrode prepared in step S2 to form a resistive switching layer. Specifically: Dissolve copper phthalocyanine particles in tetrahydrofuran, stir in the dark at room temperature until dissolved to obtain a copper phthalocyanine solution with a concentration of 5 mg / mL. Spin-coat this solution on the transparent bottom electrode layer, rotate at 3000 rpm for 40 s to form a copper phthalocyanine film, and then anneal at 45 °C for 3 min. The final thickness of the copper phthalocyanine layer is 50 - 70 nm. -1 Spin-coat this solution on the transparent bottom electrode layer, rotate at 3000 rpm for 40 s to form a copper phthalocyanine film, and then anneal at 45 °C for 3 min. The final thickness of the copper phthalocyanine layer is 50 - 70 nm.

[0011] S4: Evaporate metal gold on the resistive switching layer prepared in step S3 to form a metal top electrode, and then obtain the flexible optoelectronic memristor based on copper phthalocyanine. Specifically: Use an organic evaporation coating machine in an environment with a pressure less than 6×10 -4 Pa, and evaporate metal gold on copper phthalocyanine at an evaporation rate of to finally form a metal top electrode with a thickness of 30 - 40 nm.

[0012] The beneficial effects of the present invention are:

[0013] The present invention relates to a flexible optoelectronic memristor based on copper phthalocyanine and a preparation method thereof. Compared with the prior art, the present invention has the following technical effects:

[0014] Light-induced synaptic enhancement behavior: Under light irradiation, the defect energy levels inside the copper phthalocyanine layer can capture photo-generated electrons, realizing the light-induced synaptic enhancement behavior of the device, which is similar to the depolarization process of biological synapses, providing a new implementation approach for neuromorphic computing.

[0015] Wide field of view function: The flexible optoelectronic memristor array can be attached to a spherical surface, simulating the hemispherical structure of the biological retina, providing a wider field of view angle, which is close to the visual field range of a human single eye, significantly improving the ability to obtain visual information.

[0016] Image perception and storage function: Utilizing the photosensitive properties of copper phthalocyanine, this device can achieve image perception and storage functions. Through irradiation with an optical mask plate, the device can clearly display images and retain image information for a certain period of time, providing an effective means for the preprocessing of visual information.

[0017] Flexibility and wearability: By using polydimethylsiloxane (PDMS) as the flexible substrate layer, the device has good flexibility and wearability, making it suitable for applications in wearable devices, smart skin, and other fields, expanding the application scope of optoelectronic memristors.

[0018] Simple preparation process: The preparation method of the present invention has a simple process, a concise circuit design, and low production costs, providing a new idea for the preparation of optoelectronic memristors based on biological materials and promoting the development of neuromorphic electronics. Description of the drawings

[0019] Figure 1 It is the structural diagram of the flexible optoelectronic memristive device based on copper phthalocyanine prepared by the present invention.

[0020] Figure 2 It is the energy band structure diagram of the flexible optoelectronic memristive device based on copper phthalocyanine prepared by the present invention;

[0021] Figure 3 It is the light-induced synaptic behavior diagram of the flexible optoelectronic memristive device based on copper phthalocyanine prepared by the present invention;

[0022] Figure 4 It is the schematic diagram of the flexible optoelectronic memristive device based on copper phthalocyanine prepared by the present invention simulating the wide field of view of the human retina;

[0023] Figure 5 It is the current response curve diagram of the flexible optoelectronic memristive device based on copper phthalocyanine prepared by the present invention under different light irradiation times;

[0024] Figure 6 It is the schematic diagram of the synaptic characteristics, wide field of view, and image perception and memory functions of the flexible optoelectronic memristive device based on copper phthalocyanine of the present invention. Detailed implementation manners

[0025] The present invention will be further described below in conjunction with the drawings and specific embodiments. The illustrative embodiments and descriptions of this invention are used to explain the present invention, but do not limit the present invention.

[0026] The flexible optoelectronic memristor based on copper phthalocyanine of the present invention includes, from bottom to top in sequence: a flexible substrate layer, a transparent bottom electrode, a resistive switching layer, and a metal top electrode; the flexible substrate layer is polydimethylsiloxane (PDMS); the transparent bottom electrode is indium tin oxide doped with tin (ITO); the resistive switching layer is copper phthalocyanine (CuPc); and the metal top electrode is gold (Au).

[0027] The molecular formula structures of PDMS and CuPc are as follows:

[0028]

[0029] Preferably, the thickness of the flexible substrate layer is 0.15 - 0.3 mm; the thickness of the transparent bottom electrode is 200 nm; the thickness of the resistive switching layer is 50 - 70 nm; and the thickness of the metal top electrode is 30 - 40 nm.

[0030] The preparation method of the flexible optoelectronic memristor based on copper phthalocyanine of the present invention includes the following steps:

[0031] S1: Spin-coat polydimethylsiloxane on a cleaned transparent glass to form a flexible substrate layer; specifically: mix polydimethylsiloxane and a curing agent at a volume ratio of 10:1, stir, and let stand for more than 1 h, then spin-coat the mixture on the cleaned transparent glass, rotate at 1000 rpm for 60 s to form a polydimethylsiloxane film, and then transfer it to an oven at 80°C for curing for 2 h.

[0032] S2: Magnetron sputter indium tin oxide doped with tin on the flexible substrate layer prepared in step S1 to form a transparent bottom electrode; specifically: in a magnetron sputtering coating machine filled with argon, sputter an indium tin oxide doped with tin target at a power of 80 W for 20 min, and the finally prepared ITO layer has a thickness of 200 nm.

[0033] S3: Spin-coat copper phthalocyanine on the transparent bottom electrode prepared in step S2 to form a resistive switching layer; specifically: dissolve copper phthalocyanine particles in tetrahydrofuran, stir in the dark at room temperature until dissolved to obtain a copper phthalocyanine solution with a concentration of 5 mg / mL -1 ; spin-coat this solution on the transparent bottom electrode layer, rotate at 3000 rpm for 40 s to form a copper phthalocyanine film, and then anneal at 45°C for 3 min. The finally prepared copper phthalocyanine layer has a thickness of 50 - 70 nm.

[0034] S4: Evaporate metal gold on the resistive switching layer prepared in step S3 to form a metal top electrode, and then obtain the flexible optoelectronic memristor based on copper phthalocyanine. Specifically: use an organic evaporation coating machine in an environment with a pressure less than 6×10 -4 Pa, and evaporate metal gold on copper phthalocyanine at an evaporation rate of , and the finally formed metal top electrode has a thickness of 30 - 40 nm.

[0035] The performance test of the copper phthalocyanine-based flexible optoelectronic memristor of the present invention is as follows:

[0036] 1) The photoinduced synaptic enhancement behavior and double-pulse facilitation (PPF) behavior of the device:

[0037] A positive bias voltage is applied to the metal top electrode of the optoelectronic memristor based on copper phthalocyanine of the present invention, and the ITO bottom electrode is grounded; a 620 nm light is applied to the device, and the resistance state changes before and 100 s after the end of the light illumination are recorded and compared. Under 620 nm light illumination, the device changes from a high resistance state to a low resistance state, and the current slowly decays after the light illumination is removed, and the device exhibits an analog resistive switching behavior. Comparing the resistance state changes before and after, the resistance state of the device decreases, showing a synaptic enhancement behavior; two consecutive 620 nm light pulses are applied to the device, and the current amplitude induced by the second light pulse is greater than that induced by the first light pulse, and the device exhibits a double-pulse facilitation (PPF) behavior.

[0038] 2) The photo-enhanced / electricity-suppressed conductance reversible cycling operation of the device:

[0039] A bias voltage is applied to the metal top electrode of the copper phthalocyanine-based optoelectronic memristor of the present invention, and the ITO bottom electrode is grounded; the device is stimulated with 620 nm light pulses and reverse -2V voltage pulses multiple times. During each cycle, the device changes from a high resistance state to a low resistance state and then to a high resistance state, demonstrating the ability of continuous reversible conductance change.

[0040] 3) The wide field of view function of the device:

[0041] The hemispherical structure of the retina can provide a wider field of view angle and more visual information for the human eye in a three-dimensional environment. One 20×20 array of copper phthalocyanine-based flexible optoelectronic memristors is attached to a plane and a sphere respectively, and the spatial position of each pixel point and the corresponding field of view angle are calculated. According to the calculation, the field of view angle of the planar optoelectronic memristor array is 48.2°, while that of the hemispherical optoelectronic memristor array is 53.2°, and it can increase to 127.2° as the radius of curvature decreases, which is close to the field of view range of a human single eye (100 - 120°).

[0042] 4) The sensing and storage functions of the device:

[0043] The letter "X" is irradiated onto a 5×5 optoelectronic memristor array through an optical mask. As the decay time increases, the current gradually decreases, but the letter "X" can still be observed from the output image of the device, and as the irradiation time increases, the letter "X" can be shown more clearly.

[0044] The basic principle for the copper phthalocyanine-based flexible optoelectronic memristor provided by the present invention to achieve photoinduced synaptic enhancement behavior is as follows:

[0045] Under illumination at 620 nm, electrons in the valence band of the copper phthalocyanine layer are excited and jump to the conduction band, causing the current in the device to increase. During the transition process, due to the trapping effect of defects inside the copper phthalocyanine on the photo-generated electrons, after the illumination ends, the recombination rate of electrons and holes slows down, and the current gradually decays. Such current response behavior is similar to the depolarization behavior exhibited by biological synapses after external stimulation. See Figure 6 , Figure 6 This is the synaptic characteristic, wide field of view, and image perception and memory function schematic diagram of the flexible optoelectronic memristive device based on copper phthalocyanine of the present invention. It is the principle of the photo-induced synaptic characteristic of the flexible optoelectronic memristor based on copper phthalocyanine of the present invention and the schematic diagram of the wide field of view and image perception and memory function. The present invention provides a new perspective for promoting the development of efficient neuromorphic vision.

[0046] Example: Preparation of a flexible optoelectronic memristor based on copper phthalocyanine:

[0047] 1) Preparation of the flexible substrate layer:

[0048] Mix PDMS and the curing agent at a volume ratio of 10:1, stir, and let stand for more than 1 h for use. Place the cleaned transparent glass on a spin coater and spin coat the PDMS colloid. The spin coating process is to rotate at 1000 rpm for 60 s to form a PDMS thin film, and then immediately transfer it to an oven at 80 °C for curing for 2 h;

[0049] 2) Preparation of the transparent bottom electrode:

[0050] Transfer the flexible substrate treated in step 1) together with the glass to a magnetron sputtering coating machine filled with argon, and sputter the ITO target at a power of 80 W for 20 min. The thickness of the finally prepared ITO layer of the transparent bottom electrode is 200 nm;

[0051] 3) Preparation of the resistive switching layer:

[0052] The preparation process of the CuPc solution is as follows:

[0053] Dissolve the CuPc particles in tetrahydrofuran, stir in the dark at room temperature until dissolved, and obtain a solution of CuPc with a concentration of 5 mg mL -1 ;

[0054] Transfer the film treated in step 2) to a glove box filled with nitrogen and place it on a spin coater to spin coat the CuPc layer solution. The spin coating process is to rotate at 3000 rpm for 40 s to form a CuPc thin film, and then immediately place it on a hot stage for annealing treatment. The annealing temperature and time are 45 °C for 3 min; the thickness of the CuPc layer is about 30 nm;

[0055] 4) Preparation of the metal top electrode:

[0056] Using an organic evaporation coating machine, a metal top electrode Au is evaporated on the CuPc layer at a pressure less than 6×10 -4 Pa, and its evaporation rate is The thickness of the finally formed metal top electrode Au is 35 nm, and the flexible optoelectronic memristor based on copper phthalocyanine is prepared. Figure 1 The structure schematic diagram and energy band structure schematic diagram of the optoelectronic memristor of the present invention. Figure 2 (a) is the energy band structure diagram of the flexible optoelectronic memristor device based on copper phthalocyanine prepared by the present invention, Figure 2 (b) is a schematic diagram of the capture behavior of photo-generated electrons by defects inside the CuPc layer under illumination with a wavelength of 620 nm;

[0057] Performance test of the flexible optoelectronic memristor based on copper phthalocyanine prepared in the embodiment:

[0058] 1) Photo-induced synaptic enhancement behavior of the device:

[0059] A positive bias voltage is applied to the metal top electrode of the optoelectronic memristor based on copper phthalocyanine prepared in Example 1 and the ITO bottom electrode is grounded; the device is respectively irradiated with 620 nm light, and the resistance state changes before and 100 s after the end of illumination are recorded and compared. Under 620 nm illumination, the device changes from a high resistance state to a low resistance state, and the current slowly decays after the illumination is removed, and the device exhibits analog resistive switching behavior. Comparing the resistance state changes before and after, the resistance state of the device decreases, showing synaptic enhancement behavior; two consecutive 620 nm light pulses are applied to the device, and the current amplitude induced by the second light pulse is greater than that induced by the first light pulse, and the device exhibits paired-pulse facilitation (PPF) behavior, see Figure 3 (a) and Figure 3 (b). Figure 3 (a) is the photo-induced synaptic behavior of the flexible optoelectronic memristor device based on copper phthalocyanine prepared by the present invention; Figure 3 (b) is paired-pulse facilitation (PPF) behavior; Figure 3 (c) is a cyclic diagram of reversible regulation of the device conductance of light enhancement / electrical inhibition;

[0060] 2) Reversible cyclic operation of light enhancement / electrical inhibition conductance of the device:

[0061] A bias voltage is applied to the metal top electrode of the optoelectronic memristor based on copper phthalocyanine prepared in Example 1 and the ITO bottom electrode is grounded; the device is respectively stimulated with 620 nm light pulses and reverse -2 V voltage pulses for multiple times. During each cycle, the device changes from a high resistance state to a low resistance state and then to a high resistance state, showing the ability of continuous and reversible change of conductance, see Figure 3 (c).

[0062] 3) Wide field of view function of the device:

[0063] One copper phthalocyanine-based flexible optoelectronic memristor of a 20×20 array is respectively attached to a plane and a spherical surface, and the spatial position of each pixel and the corresponding viewing angle are calculated. According to the calculation, the viewing angle of the planar optoelectronic memristor array is 48.2°, while that of the hemispherical optoelectronic memristor array is 53.2°, and it can increase to 127.2° as the radius of curvature decreases, which is close to the viewing range of a human single eye (100 - 120°), see Figure 4 (a)-(d). Figure 4 (a) is a schematic diagram of the copper phthalocyanine-based flexible optoelectronic memristor device prepared by the present invention simulating the wide field of view of the human retina, Figure 4 (a) is a schematic diagram of attachment to a spherical surface, Figure 4 (c) is the viewing angle of the calculated plane and hemispherical arrays; Figure 4 (d) is the viewing angle corresponding to the device attached to spheres with different curvatures calculated.

[0064] 4) Perception and storage functions of the device:

[0065] The letter "X" is irradiated onto a 5×5 optoelectronic memristor array through an optical mask. As the decay time increases, the current gradually decreases, but the letter "X" can still be observed from the output image of the device. Moreover, as the irradiation time increases, the letter "X" can be shown more clearly, see Figure 5 (a) and Figure 5 (b). Figure 5 (a) is the current response curve of the copper phthalocyanine-based flexible optoelectronic memristor device prepared by the present invention under different light irradiation times; Figure 5 (b) is to simulate the image perception and memory functions of the human retina;

[0066] In summary, for the copper phthalocyanine-based flexible optoelectronic memristor of the present invention, by utilizing the capture of photo-generated electrons by the defect energy levels inside the copper phthalocyanine layer under light irradiation, the light-induced synaptic enhancement behavior of the device is realized. In addition, this flexible device array can be attached to a spherical surface, can simulate the wide field of view function of the retina, as well as the perception and storage of images.

[0067] The technical solution of the present invention is not limited to the limitations of the above specific embodiments. Any technical deformation made according to the technical solution of the present invention falls within the protection scope of the present invention.

Claims

1. A flexible photoelectric memristor based on copper phthalocyanine, characterized in that: From bottom to top, it includes: a flexible substrate layer, a transparent bottom electrode, a resistive layer, and a metal top electrode; the flexible substrate layer is polydimethylsiloxane; the transparent bottom electrode is tin-doped indium tin oxide; the resistive layer is copper phthalocyanine; and the metal top electrode is gold.

2. The flexible photoelectric memristor based on copper phthalocyanine according to claim 1, characterized in that: The thickness of the flexible substrate layer is 0.15-0.3 mm; the thickness of the transparent bottom electrode is 200 nm; the thickness of the resistive layer is 50-70 nm; and the thickness of the metal top electrode is 30-40 nm.

3. A method for preparing a flexible photoelectric memristor based on copper phthalocyanine as claimed in claim 2, characterized in that: The following steps are involved: S1: Spin-coat polydimethylsiloxane on clean transparent glass to make a flexible base layer; S2: magnetron sputtering tin-doped indium tin oxide on the flexible substrate layer prepared in step S1 to form a transparent bottom electrode; S3: Spin-coating copper phthalocyanine on the transparent bottom electrode prepared in step S2 to form a resistive switching layer; S4: Vapor-depositing metal gold on the resistive layer prepared in step S3 to form a metal top electrode, and then obtaining the copper phthalocyanine-based flexible photoelectric memristor.

4. The method for preparing a flexible photoelectric memristor based on copper phthalocyanine according to claim 3, characterized in that: The step S1 is specifically as follows: polydimethylsiloxane and a curing agent are mixed and stirred at a volume ratio of 10:1, and then allowed to stand for more than 1 hour, and then the mixture is spin-coated on a clean transparent glass, and rotated at 1000 rpm for 60 seconds to form a polydimethylsiloxane film, and then transferred to an oven at 80° C. for curing for 2 hours.

5. The method for preparing a flexible photoelectric memristor based on copper phthalocyanine according to claim 4, characterized in that: The step S2 specifically includes: sputtering a tin-doped indium tin oxide target material at a power of 80 W for 20 minutes in a magnetron sputtering coating machine filled with argon gas, and finally preparing an ITO layer with a thickness of 200 nm.

6. The method for preparing a flexible photoelectric memristor based on copper phthalocyanine according to claim 5, characterized in that: The step S3 specifically comprises: dissolving the copper phthalocyanine particles in tetrahydrofuran, stirring at room temperature in the dark until dissolved, and obtaining a concentration of 5 mg / mL -1 The copper phthalocyanine solution is spin-coated on the transparent bottom electrode layer, and the copper phthalocyanine film is formed by rotating at 3000 rpm for 40 seconds, and then annealing at 45° C. for 3 minutes. The thickness of the copper phthalocyanine layer finally prepared is 50-70 nm.

7. The method for preparing a flexible photoelectric memristor based on copper phthalocyanine according to claim 6, characterized in that: The step S4 is specifically as follows: using an organic evaporation coating machine at a pressure less than 6×10 -4 Under the Pa environment, Metal gold is evaporated on copper phthalocyanine at an evaporation rate of, and the thickness of the final metal top electrode is 30-40nm.

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