Polarization-aware optoelectronic synapse device and preparation method and application thereof

Abstract

The present application relates to the field of organic crystal photoelectric device, especially to a polarization sensing type photoelectric synaptic device and its preparation method and application. The present application selects fused ring aromatic hydrocarbon and thiophene with pi conjugated structure and electron donating ability as electron donor, selects aromatic hydrocarbon containing cyano and benzoquinone molecule with strong electron affinity as electron acceptor, adds good organic solvent to dissolve, synthesizes organic charge transfer co-crystal material through solvent evaporation; the mother liquor is added into glycerol, the co-crystal is transferred to the modified silicon wafer, and the bottom top contact type photoelectric detection device is constructed by adopting the mode of transferring gold electrode. The present application designs and develops novel organic charge transfer co-crystal material with excellent photoelectric performance by using cheap and easily obtained commercial materials as raw materials, designs and synthesizes polarization sensitive photoelectric synaptic device with high sensitivity and wide spectral response through simple and low cost solution self-assembly, transfer and device composite process, and can be used for polarization sensitive neural morphological visual imaging and recognition system.

Description

Technical Field

[0001] This invention relates to the field of organic crystal optoelectronic devices, and in particular to a polarization-sensing opto-synaptic device, its fabrication method, and its application. Background Technology

[0002] Faced with the explosive growth of future computing demands, information processing and sensing systems are gradually transforming from traditional computing architectures centered on silicon-based electronic devices to novel device architectures with neuromorphic computing and intelligent sensing capabilities. On the one hand, devices are evolving from simple electronic synapses to opto-electrical coupling synapses to achieve integrated sensing and front-end processing. On the other hand, polarization information, as a high-value dimension of optical signals, can reveal the multidimensional "invisibility" of information to improve target recognition and tracking performance (Adv. Mater. 2025, 37, 2416073). However, integrating functions such as polarization sensitivity, photoelectric detection, and synaptic manipulation into a single device has proven challenging (Adv. Mater. 2024, 2409550).

[0003] Organic low-dimensional materials, with their customizable molecular structure, tunable optoelectronic properties, low-cost large-area fabrication, and biocompatibility, are gradually becoming important candidate materials for next-generation flexible neural synapse devices (Nat. Mater. 2024, 23, 1268). Through molecular crystal engineering and directional growth strategies, highly ordered stacked low-dimensional organic crystal structures can be obtained. These materials not only possess excellent charge transport capabilities but can also introduce strong optical anisotropy at the molecular level, exhibiting sensitive response characteristics to polarized light. This provides a unique material basis for constructing biomimetic devices that combine visual perception and neural synaptic functions.

[0004] Therefore, organic low-dimensional materials with polarization response characteristics provide an ideal material basis for capturing and selectively recognizing light signals in nature. Furthermore, novel biomimetic visual neural synapse devices can be constructed to simulate the direction sensitivity and polarization recognition function of the human visual system, ultimately realizing their application in polarization-sensitive neuromorphic visual imaging. Summary of the Invention

[0005] This invention proposes a method for fabricating polarization-sensing opto-synaptic devices based on organic charge transfer eutectic. Using inexpensive and readily available commercial materials as raw materials, and through simple and low-cost solution self-assembly, transfer printing, and device composite processes, polarization-sensitive synaptic devices with excellent opto-electric properties are designed and synthesized, which can be used for polarization-sensitive neuromorphic visual imaging and recognition.

[0006] To address the aforementioned technical problems, this invention provides a method for fabricating a polarization-sensing photoelectric synapse device, comprising the following steps: S11: Dissolve the electron donor and electron acceptor in a good organic solution to obtain a stock solution; the electron donor is a polycyclic aromatic hydrocarbon, thiophene or a derivative of thiophene, and the electron acceptor is a cyano-containing aromatic hydrocarbon or a derivative of benzoquinone. S12: The stock solution is coated onto the surface of the growth base solution, and the good organic solution is evaporated to obtain an organic charge transfer eutectic material; the growth base solution is one or more of glycerol, water and 9,10-diphenylanthracene. S13: The organic charge transfer eutectic material is transferred onto the surface of a silicon wafer covered with an interface modification layer. Then, the silicon wafer with the eutectic material is inverted on the surface of deionized water to remove the growth substrate solution attached to the crystal surface, thereby obtaining a clean silicon wafer with crystals. S14: Transfer the vapor-deposited metal electrode to the surface of a silicon wafer with crystals to obtain the polarization-sensing photoelectric synapse device.

[0007] Preferably, the electron donor is naphthalene, anthracene, phenanthrene, naphtho[1,2-b:5,6-b']dithiophene, dinaphtho[1,2-b:1',2'-d]thiophene, dithiophene[3,2-b:2',3'-d]thiophene, or dinaphtho[2,3-b:2',3'-f]thiophene[3,2-b]thiophene, such as... Figure 1 As shown; the electron acceptor is 7,7,8,8-tetracyano-p-benzodiquinone dimethane (TCNQ), monofluoro-substituted-7,7,8,8-tetracyano-p-benzodiquinone dimethane (F1-TCNQ), 2,5-difluoro-7,7,8,8-tetracyano-p-benzodiquinone dimethane (F2-TCNQ), tetrafluoro-7,7,8,8-tetracyano-p-benzodiquinone dimethane (F4-TCNQ), tetrafluoro-p-benzoquinone, tetrachloro-p-benzoquinone, 1,2,4,5-tetracyanobenzene, or 9,10-dicyanoanthracene, such as Figure 2 As shown.

[0008] Preferably, the molar ratio of the electron donor to the electron acceptor is 1-3:1-3. Controlling the molar ratio can regulate the phase separation scale of the blended film, forming a sufficient exciton dissociation interface; balance the hole and electron transport channels, reduce carrier recombination; adapt to the charge capture requirements of photoelectric synapses, optimize photoresponse and synaptic plasticity, have high tolerance for range ratios, and facilitate the fabrication of high-performance devices.

[0009] Preferably, the good organic solvent is one or more selected from chloroform, dichloromethane, acetonitrile, tetrahydrofuran, and toluene. This type of solvent has strong dissolving power, capable of fully dissolving fused-ring thiophene donors and TCNQ-type cyano acceptors; it has a moderate evaporation rate, resulting in uniform film formation without obvious pinholes; it has a wide polarity range, adaptable to blending systems with different ratios; it has low residue and is easily removed by annealing, making it suitable for organic thin film spin-coating processes and enabling stable preparation of photoelectric synaptic active layers.

[0010] Preferably, a silicon oxide dielectric layer with a thickness of 100-300 nm is provided between the silicon wafer and the interface modification layer, and the silicon wafer has a thickness of 450-550 nm. Silicon oxide has excellent insulation properties, which can isolate gate leakage current and stably regulate channel carriers; the thickness range balances high dielectric control capability and low surface roughness, which is conducive to the uniform spreading of the interface modification layer; the film is dense and defect-free, suitable for optoelectronic synaptic devices, ensuring stable synaptic response and device repeatability.

[0011] Preferably, the volume ratio of glycerol to the stock solution is 1:800-1200.

[0012] Preferably, the method for preparing the silicon wafer covered with the interface modification layer is as follows: S21: Dissolve polymer molecules in toluene to obtain a polymer solution; the polymer molecules are one or more of polystyrene, polyvinyl cinnamate, and polymethyl methacrylate. S22: Under a protective atmosphere, the polymer solution is coated onto the surface of the silicon wafer and annealed at 80-120°C for 10-30 minutes to form the interface modification layer.

[0013] Preferably, the molecular weight of the polymer molecules ranges from 4000 to 250000 g / mol.

[0014] Preferably, in step S21, the dissolution time is 10-15 h and the concentration of polystyrene is 3-5 mg / mL.

[0015] Preferably, in step S22, the protective atmosphere is nitrogen or argon.

[0016] Preferably, in step S22, the coating method is spin coating, with a spin coating speed of 2000-4000 r / min and a time of 1-5 min.

[0017] Preferably, the thickness of the interface modification layer is 10-20 nm, and the thickness of the organic charge transfer eutectic material after transfer is 20-80 nm.

[0018] Preferably, the metal electrode is made of gold and has a thickness of 40-60 nm. The interface modification layer can optimize interface compatibility, reduce interface defects, and lower carrier trapping; the gold electrode has excellent conductivity and strong adhesion, and its thickness range balances low resistance and light transmittance. The combination of the two can improve carrier transport efficiency and stabilize the photoelectric synaptic performance of the device.

[0019] Specifically, the fabrication method for the polarization-sensing photoelectric synapse device includes the following steps: (1) Select condensed ring aromatic hydrocarbons, thiophene and their derivatives with π conjugated structure and strong electron-donating ability as electron donors, and select cyano-containing aromatic hydrocarbons and benzoquinone molecules with strong electron affinity as electron acceptors. (2) Weigh electron donor and acceptor molecules accurately according to the proportion, add a good organic solvent and sonicate for several minutes to dissolve them. Design and synthesize organic charge transfer eutectic materials by solvent evaporation method; (3) Select an oxide silicon wafer as a substrate, cut the silicon wafer into 1cm×1cm small squares, and ultrasonically clean it with acetone, ethanol and isopropanol for 15 min respectively; after cleaning, blow it dry quickly with a nitrogen gun to obtain the dielectric layer. (4) Prepare a polystyrene solution according to a certain mass ratio; (5) Under a protective atmosphere, spin-coat polystyrene solution onto the cleaned silicon wafer and then anneal it to obtain an interface modification layer; (6) Add an appropriate amount of mother liquor to the surface of glycerol and allow it to grow an organic eutectic by solution evaporation; (7) The above crystals are transferred onto the modified silicon wafer by a transfer method; (8) The bottom and top contact devices are constructed by transferring gold electrodes.

[0020] The present invention also provides a polarization-sensing photoelectric synapse device prepared by the above-described preparation method.

[0021] The present invention also provides a polarization-sensitive neuromorphic visual device, including the above-mentioned polarization-sensing photoelectric synapse device.

[0022] Compared with the prior art, the above-described technical solution of the present invention has the following advantages: This invention provides a method for fabricating polarization-sensitive optoelectronic synaptic devices based on organic charge-transfer eutectic low-dimensional materials, as well as a polarization-sensitive neural visual imaging system and recognition application. The beneficial effects are that this invention utilizes charge transfer and eutectic crystal engineering to simply and quickly prepare high-quality organic micron-sized crystals via a solution method, providing a new approach for the controllable fabrication of micro / nano crystals. Simultaneously, based on the prepared organic low-dimensional crystal material, this invention designs and constructs biomimetic visual neural synapses that can simulate the structure and function of biological nerves, receiving, converting, and responding to light, further realizing the integration of visual information perception, storage, and processing. Attached Figure Description

[0023] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0024] Figure 1 This refers to the electron donor structure of fused-ring aromatic hydrocarbons or thiophene molecules and their derivatives with π-conjugated structures in this invention.

[0025] Figure 2 This is the electron acceptor structure of the cyano-containing aromatic hydrocarbon and benzoquinone in this invention.

[0026] Figure 3 This is the X-ray diffraction (XRD) pattern of the organic eutectic material in Example 1 of the present invention.

[0027] Figure 4 This is a graph showing the test results of the transport characteristic curve of the organic eutectic material in Example 1 of the present invention.

[0028] Figure 5 This is a current response diagram of the photoelectric synaptic device in Embodiment 1 of the present invention under light pulse modulation, showing synaptic-like behavior (EPSC).

[0029] Figure 6 The diagram shows the EPSC behavior of the photoelectric synaptic device in Embodiment 1 of the present invention under linearly polarized (520 nm) irradiation with different optical powers and the corresponding polar coordinate diagram.

[0030] Figure 7 This is a demonstration diagram of the use of the photoelectric synapse device of the present invention.

[0031] Figure 8 The graph shows the test results of the transport characteristic curve of the organic eutectic material in Comparative Example 1 of this invention. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0033] Example 1: Fabrication of photoelectric synaptic devices Preparation of organic low-dimensional materials: 0.0006 g of naphtho[1,2-b:5,6-b']dithiophene and 0.0005 g of 7,7,8,8-tetracyano-p-benzodiquinone dimethane were added to 7.5 mL of toluene and sonicated for 20 min to obtain an electron donor-acceptor organic solvent stock solution; 100 μL of the stock solution was dropped into a glass jar containing glycerol and left to stand for 1 day until the solvent completely evaporated to obtain an organic charge-transfer eutectic material.

[0034] Preparation of the organic active layer: A silicon wafer with a 100 nm oxide layer and a thickness of 500 nm was selected as the substrate and cut into 1 cm × 1 cm cubes. The cubes were ultrasonically cleaned with acetone, ethanol, and isopropanol for 15 minutes each, and then quickly dried with a nitrogen gun. 9 mg of polystyrene (average molecular weight 50,000 g / mol) was added to 3 mL of toluene solution and stirred at room temperature (25 °C) for 7 h to ensure that the polystyrene was fully dispersed in the toluene solution.

[0035] Take 50 μL of the above-mentioned polystyrene solution and spin-coat it onto a silicon wafer at a speed of 2000 r / min for 60 s. Then, anneal it under a nitrogen atmosphere at a temperature of 100℃ for 15 minutes to obtain an organic active layer with a thickness of 10 nm. Holding the cleaned substrate, slowly and vertically insert it at a 45° angle below the surface of a liquid containing glycerol. Move the substrate directly below the eutectic material and then smoothly lift it upwards. Use the surface tension of the glycerol liquid itself to lift the eutectic material completely, allowing the crystal to naturally adhere to the substrate surface. Finally, invert the substrate with the attached crystal in a beaker containing deionized water to dissolve and remove the glycerol. Then, place it in a low-temperature vacuum oven at 30-40 ℃ to slowly dry it, preventing rapid solvent evaporation from causing crystal wrinkling and cracking. Finally, a eutectic material transfer with complete morphology and no damage is achieved (the thickness of the eutectic material after transfer is 50 nm).

[0036] Fabrication of transfer electrodes: A photomask etched with source and drain electrode patterns was attached to a cleaned silicon wafer using high-temperature conductive tape. Gold was then deposited at a rate of 0.1 A / s, with the gold thickness controlled at 50 nm. After deposition, a robotic arm and probe were used to electrostatically transfer the deposited electrodes to a silicon wafer with crystals, thus completing the fabrication of the photoelectric synapse device.

[0037] Example 2: Fabrication of photoelectric synaptic devices The method is the same as in Example 1, except that: Preparation of organic low-dimensional materials: 0.00284 g of dinaphtho[2,1-b:1',2'-d]thiophene and 0.0024 g of 2,5-difluoro-7,7,8,8-tetracyano-p-benzoquinone dimethane (TCNQ) were added to 3 mL of acetonitrile and sonicated for 30 min to obtain an electron donor-acceptor organic solvent stock solution; 100 μL of the stock solution was dropped into a glass jar containing glycerol and allowed to stand for 1 day until the solvent completely evaporated to obtain an organic charge-transfer eutectic material.

[0038] Preparation of the organic active layer: A silicon wafer with a 100 nm oxide layer and a thickness of 500 nm was selected as the substrate and cut into 1 cm × 1 cm cubes. The cubes were ultrasonically cleaned for 15 minutes each with acetone, ethanol, and isopropanol, and then rapidly dried with a nitrogen gun. 9 mg of polystyrene was added to 3 mL of toluene solution and stirred at room temperature for 7 h to ensure complete dispersion of the polystyrene. 50 μL of the polystyrene solution was spin-coated onto the silicon wafer at 2000 r / min for 60 s, and then annealed under a nitrogen atmosphere at 100 °C for 15 minutes to obtain an organic active layer with a thickness of 10 nm. The crystal was then transferred onto the modified silicon wafer using a transfer method.

[0039] Fabrication of transfer electrodes: A photomask etched with source and drain electrode patterns is attached to a cleaned silicon wafer using high-temperature conductive tape. Gold is then deposited at a rate of 0.1 A / s, with the gold thickness controlled at 50 nm. After deposition, a robotic arm and probe are used to transfer the deposited electrodes onto a silicon wafer with crystals, completing the fabrication of the photoelectric synapse device.

[0040] Example 3: Fabrication of photoelectric synaptic devices The method is the same as in Example 1, except that: Preparation of organic low-dimensional materials: 0.0012 g of naphtho[1,2-b:5,6-b']dithiophene and 0.0012 g of 2,5-difluoro-7,7,8,8-tetracyano-p-benzodiquinone dimethane were added to 4 mL of dichloromethane and sonicated for 5 min to obtain an electron donor-acceptor organic solvent stock solution; 100 μL of the stock solution was dropped into a glass jar containing glycerol and left to stand for 1 day until the solvent completely evaporated to obtain an organic charge-transfer eutectic material.

[0041] Preparation of the organic active layer: A silicon wafer with a 100 nm oxide layer and a thickness of 500 nm was selected as the substrate and cut into 1 cm × 1 cm cubes. The cubes were ultrasonically cleaned for 15 minutes each with acetone, ethanol, and isopropanol, and then rapidly dried with a nitrogen gun. 9 mg of polystyrene was added to 3 mL of toluene solution and stirred at room temperature for 7 h to ensure complete dispersion of the polystyrene in the toluene solution. 50 μL of the polystyrene solution was spin-coated onto the silicon wafer at 2000 rpm for 60 s, and then annealed under a nitrogen atmosphere at 100 °C for 15 minutes to obtain an organic active layer with a thickness of 10 nm. The crystal was then transferred onto the modified silicon wafer using a transfer method.

[0042] Fabrication of transfer electrodes: A photomask etched with source and drain electrode patterns is attached to a cleaned silicon wafer using high-temperature conductive tape. Gold is then deposited at a rate of 0.1 A / s, with the gold thickness controlled at 50 nm. After deposition, a robotic arm and probe are used to transfer the deposited electrodes onto a silicon wafer with crystals, completing the fabrication of the photoelectric synapse device.

[0043] Comparative Example 1: Fabrication of photoelectric synaptic devices The method is the same as in Example 1, except that: Preparation of organic low-dimensional materials: 0.0006 g of naphtho[1,2-b:5,6-b']dithiophene was added to 7.5 mL of toluene and sonicated for 20 min to obtain an electron donor-acceptor organic solvent stock solution; 100 μL of the stock solution was dropped into a glass jar containing glycerol and left to stand for 1 day until the solvent was completely evaporated to obtain an organic charge transfer eutectic material.

[0044] Preparation of the organic active layer: A silicon wafer with a 100 nm oxide layer and a thickness of 500 nm was selected as the substrate and cut into 1 cm × 1 cm cubes. The cubes were ultrasonically cleaned for 15 minutes each with acetone, ethanol, and isopropanol, and then rapidly dried with a nitrogen gun. 9 mg of polystyrene was added to 3 mL of toluene solution and stirred at room temperature for 7 h to ensure complete dispersion of the polystyrene. 50 μL of the polystyrene solution was spin-coated onto the silicon wafer at 2000 r / min for 60 s, and then annealed under a nitrogen atmosphere at 100 °C for 15 minutes to obtain an organic active layer with a thickness of 10 nm. The crystal was then transferred onto the modified silicon wafer using a transfer method.

[0045] Fabrication of transfer electrodes: A photomask etched with source and drain electrode patterns is attached to a cleaned silicon wafer using high-temperature conductive tape. Gold is then deposited at a rate of 0.1 A / s, with the gold thickness controlled at 50 nm. After deposition, a robotic arm and probe are used to transfer the deposited electrodes onto a silicon wafer with crystals, completing the fabrication of the photoelectric synapse device.

[0046] Effect evaluation: In Example 1, by Figure 3 The XRD pattern of the eutectic showed characteristic diffraction peaks distinctly different from those of the donor and acceptor, indicating the formation of the organic eutectic. Figure 4 The transfer characteristic curve was obtained, which shows typical N-channel characteristics. At a drain-source voltage of 20 V, the field-effect mobility reaches 1.76 × 10⁻⁶. -3 cm 2 ·V -1 ·s -1 This indicates a significant electrical response. Figure 5 The device exhibits typical excitatory postsynaptic current (EPCS) behavior. Upon light stimulation, the current instantaneously rises to approximately 1.6 nA, then slowly decays to slightly above the initial state within 20 seconds after the light pulse stops. Figure 6This study investigated the synaptic behavior triggered by linearly polarized light spikes under different illumination intensities. Due to the anisotropy of the crystal, the polarization-sensing EPSC exhibited a periodic intensity variation with increasing polarization angle. Furthermore, for a specific polarization angle, the EPSC significantly increased with increasing input light intensity, which is a direct result of the photoinduced carrier effect.

[0047] The structure of the low-gate oxide-driven organic field-effect light-emitting transistor prepared in Comparative Example 1 is the same as that in Example 1, as follows: Figure 7 As shown. Electrical performance testing, the transfer characteristic curve is as follows. Figure 8 As shown. By Figure 4 It can be seen that the electrical performance of the photoelectric synaptic device prepared in this comparison is poor, with a carrier mobility of 1.08 × 10⁻⁶ in its N-channel. -3 cm 2 ·V -1 ·s -1 .

[0048] As can be seen from the above comparative examples and embodiments, the channel carrier mobility of the eutectic photosynaptic device provided by this invention, under the same process and fabrication conditions, is increased from approximately 1.08 × 10⁻⁶ in the original single-crystal structure. -3 cm 2 ·V -1 ·s -1 Significantly improved to 1.76×10 -3 cm 2 ·V -1 ·s -1 The device's conduction performance is significantly enhanced, and it has higher current drive capability and response speed.

[0049] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for fabricating a polarization-sensing photoelectric synaptic device, characterized in that, Includes the following steps: S11: Add an electron donor and an electron acceptor to a good organic solution to obtain a stock solution; wherein the electron donor is a polycyclic aromatic hydrocarbon, thiophene or a derivative of thiophene, and the electron acceptor is a cyano-containing aromatic hydrocarbon or a derivative of benzoquinone; S12: After coating the stock solution onto the surface of the growth substrate solution, the good organic solution is volatilized to obtain an organic charge transfer eutectic material; the growth substrate solution is one or more of glycerol, water, and 9,10-diphenylanthracene. S13: The organic charge transfer eutectic material is transferred onto the surface of a silicon wafer covered with an interface modification layer to obtain a silicon wafer with crystals; S14: Transfer the vapor-deposited metal electrode to the surface of a silicon wafer with crystals to obtain the polarization-sensing photoelectric synapse device.

2. The preparation method according to claim 1, characterized in that: The electron donor is one of the following structural formulas: ； The electron acceptor is one of the following structural formulas: 。 3. The preparation method according to claim 1, characterized in that: The molar ratio of the electron donor to the electron acceptor is 1-3:1-3.

4. The preparation method according to claim 1, characterized in that: The good organic solvent is one or more of chloroform, dichloromethane, acetonitrile, tetrahydrofuran, and toluene.

5. The preparation method according to claim 1, characterized in that: A silicon oxide dielectric layer with a thickness of 100-300 nm is provided between the silicon wafer and the interface modification layer.

6. The preparation method according to claim 1, characterized in that: The method for preparing the silicon wafer covered with the interface modification layer is as follows: S21: Dissolve polymer molecules in toluene to obtain a polymer solution; the polymer molecules are one or more of polystyrene, polyvinyl cinnamate, and polymethyl methacrylate. S22: Under a protective atmosphere, the polymer solution is coated onto the surface of the silicon wafer and annealed at 80-120°C for 10-30 min to form the interface modification layer.

7. The preparation method according to claim 1, characterized in that: The thickness of the interface modification layer is 10-20 nm.

8. The preparation method according to claim 1, characterized in that: The metal electrode is made of gold and has a thickness of 40-60 nm.

9. A polarization-sensing photoelectric synapse device prepared by the preparation method according to any one of claims 1-8.

10. A polarization-sensitive neuromorphic visual device, characterized in that, Includes the polarization-sensing photosynaptic device as described in claim 9.

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