Synaptic device array and method of fabricating the same

Abstract

This invention discloses a synaptic device array and its fabrication method. The synaptic device array comprises a photodetector and an electrochromic device disposed on the photodetector. The photodetector includes a substrate, an arrayed electrode, and a photosensitive layer. The arrayed electrode is located on the substrate and includes several interdigital electrodes and a metal electrode pad. The photosensitive layer is composed of several perovskite thin films, with any one perovskite thin film completely covering the interdigital electrode. The electrochromic device comprises, from bottom to top, an Al2O3 insulating layer, an ITO electrode, a NiO electrode, an electrochromic layer, and an encapsulation layer. The electrochromic layer is composed of several electrochromic thin films, with the vertical projection surface of any one electrochromic film completely covering the vertical projection surface of the interdigital electrode. This invention achieves the coexistence of detection, storage, and computing capabilities within a single unit.

Description

Technical Field

[0001] This invention relates to a synaptic device array based on an electrochromic photodetector integrated system and its fabrication method, belonging to the field of bio-device fabrication technology. Background Technology

[0002] Electrochromic devices and perovskite photodetectors are both hot research topics in the fields of information display and sensing. Electrochromic devices have advantages such as good color rendering, fast response speed, and low power consumption, and have been widely used in optical switches, information displays, and storage devices. Meanwhile, perovskite photodetectors have characteristics such as high sensitivity and multi-band response range, and can be used as receivers of optical signals to achieve high-quality image acquisition.

[0003] Electrochromism refers to the stable and reversible transformation of the transmittance, absorptivity, and reflectivity of a color-changing material within the visible and infrared spectral regions under the stimulation of an external voltage. Macroscopically, this manifests as the material switching between a transparent state and a colored state, or between two or more colored states. This stable and reversible optical phenomenon is due to a reversible redox reaction occurring in the color-changing material under the influence of an applied driving voltage, causing it to dope and dedope with ions in the electrolyte, thus exhibiting changes in the material's color and optical properties.

[0004] With the rapid development of AI technology, advanced robotic systems need to operate under diverse environmental conditions, thus creating an urgent need for advanced intelligent visual perception systems to enhance and ultimately replace human vision in various scientific and industrial scenarios. Traditional biomimetic solid-state neurons are primarily based on complementary metal-oxide-semiconductor (CMOS) technology, simulating neural response dynamics at the hardware level. However, the physical separation of optical sensing, processing, and storage units leads to increased power consumption, slow response time, and difficulties in device miniaturization. To overcome these limitations, it is necessary to integrate optical sensing, memory, and processing functions into a unified device, thereby realizing a new generation of artificial vision devices with inherent optical sensing and neuromorphic computational behavior. Therefore, it is essential to develop a novel optically modulated AV synaptic structure that possesses both excellent information storage capacity and linear synaptic weight update characteristics to improve recognition accuracy. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the first objective of this invention is to provide a synaptic device array based on an electrochromic photodetector integrated system.

[0006] The second objective of this invention is to provide a method for fabricating a synaptic device array. The fabrication method of this invention is simple, controllable, efficient, and highly adaptable.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The present invention provides a synaptic device array, which comprises a photodetector and an electrochromic device disposed on the photodetector; the photodetector includes a substrate, an arrayed electrode, and a photosensitive layer;

[0009] The arrayed electrodes are located on the substrate and include several interdigitated electrodes and metal electrode pads; the photosensitive layer is composed of several perovskite thin films, with any one of the perovskite thin films disposed on the interdigitated electrodes to completely cover them.

[0010] The electrochromic device comprises, from bottom to top, an Al2O3 insulating layer, an ITO electrode, a NiO electrode, an electrochromic layer, and an encapsulation layer;

[0011] The Al2O3 insulating layer is disposed on the surface of the photodetector.

[0012] The electrochromic layer is composed of several electrochromic films, and the vertical projection surface of any one of the electrochromic films completely covers the vertical projection surface of the interdigitated electrode.

[0013] The synaptic device array of this invention integrates a photodetector and an electrochromic device, achieving the coexistence of detection, storage, and computation capabilities in a single unit. Compared to traditional photonic storage, the optical storage portion (storage unit) in the synapse utilizes an electrochromic device to convert signals into color signals for storage. The discoloration state can further adjust the light transmission intensity, enabling the storage, writing, and erasure of light intensity signals. Furthermore, the photodetector portion (readout unit) of the perovskite photodetector can detect the stored content in the storage unit in real time and convert it into a readable electrical signal. Therefore, applying electrical signals with different pulse widths, amplitudes, and frequencies to the storage unit can effectively alter and store information. Then, the readout unit converts the stored information into an electrical signal, simulating the information storage function of an AV synaptic structure. Moreover, compared to previously reported artificial photosynapses, the structure of this invention can further realize biological synaptic functions such as neural facilitation, long-term enhancement, and long-term inhibition by controlling the wavelength and intensity of external light stimulation, and exhibits good linear synaptic weighting.

[0014] In a preferred embodiment, the substrate is glass; the thickness of the substrate is between 1 and 3 mm.

[0015] In a preferred embodiment, the metal electrode pad includes a positive electrode and multiple negative electrodes, with each negative electrode independently connected to an interdigital electrode, and the positive electrode connected to all the interdigital electrodes.

[0016] In this invention, each interdigitated electrode and the photosensitive film on it together form a detection unit or pixel. Each pixel has an independent negative electrode and all pixels have a common positive electrode, i.e., a common positive electrode. The pixels do not interfere with each other, which can realize real-time light tracking detection and light imaging.

[0017] In the preferred embodiment, the interdigitated electrodes and the metal electrode pads are made of Cr / Au material.

[0018] In this invention, the thickness of the selected Cr / Au metal electrode is typically 10nm-Cr / 50nm-Au. The chromium metal is usually used as an adhesion layer to enhance the adhesion performance between the gold electrode and the material and substrate, and can also enhance the overall hardness of the metal electrode to increase its test life.

[0019] In a preferred embodiment, the length of each array unit in the arrayed electrode is between 10 and 100 μm, and the gap between two adjacent array units is between 20 and 300 μm.

[0020] In a preferred embodiment, the thickness of the perovskite thin film is 200–300 nm.

[0021] The inventors discovered that the performance of the final device is optimal when the thickness of the perovskite thin film is 200-300 nm. If the thickness is too thick, the light transmittance will be reduced, leading to an increase in photoresponse.

[0022] In a preferred embodiment, the perovskite thin film is square in shape.

[0023] In a preferred embodiment, the perovskite material in the perovskite thin film is selected from CH3NH3PbI3, CH3NH3Pb(I 1-x Br)3、CH3NH3Pb(I 1-x At least one of Cl)3.

[0024] Perovskite materials are semiconductor thin film materials. Due to their large light absorption coefficient, ultra-long carrier lifetime and diffusion length in the visible wavelength range, perovskite materials can be used to assemble high-performance photodetector arrays. Therefore, perovskite materials with excellent performance are preferred for photosensitive layer materials.

[0025] In a preferred embodiment, the Al2O3 insulating layer has a thickness of 50–60 nm. In this invention, the photodetector and the electrochromic device are integrated together via the Al2O3 insulating layer, achieving integrated storage and retrieval, reducing device power consumption, and improving device performance.

[0026] In a preferred embodiment, the thickness of the ITO electrode is 20–100 nm. In this invention, the ITO transparent electrode serves as the counter electrode of the electrochromic device.

[0027] In a preferred embodiment, the thickness of the NiO electrode is 20–100 nm. The NiO electrode, as an ion storage layer, primarily functions to reduce the operating voltage of the electrochromic device and improve its cycle stability.

[0028] In a preferred embodiment, the electrochromic material in the electrochromic film is one of WO3 and TTT-EDOT.

[0029] Electrochromic films can achieve a change in physical color from deep blue to transparent under external stimulation, and this change process is reversible. In addition, they have high optical contrast and good cycling stability in the discolored state.

[0030] In this invention, by having the electrochromic film and the photosensitive film arranged in the same position, the vertical projection surface of the upper electrochromic film completely covers the vertical projection surface of the lower interdigital electrode, thus avoiding signal crosstalk between the upper electrochromic device and the lower perovskite photodetector.

[0031] Each interdigitated electrode, together with the photosensitive layer and electrochromic layer located on it, forms a storage-read unit or pixel, enabling the coexistence of detection, storage, and computing capabilities in a single unit.

[0032] In a preferred embodiment, the encapsulation layer is ITO glass.

[0033] This invention discloses a method for fabricating a synaptic device array. Following an array electrode design, an array electrode is fabricated on a substrate. A photolithography auxiliary layer A is then deposited on the array electrode. The photolithography auxiliary layer A contains a hollow region C corresponding to and larger than the interdigital electrodes, exposing the interdigital electrodes. A perovskite thin film is then fabricated on the hollow region C. The photolithography auxiliary layer A is then peeled off to form a photosensitive layer, thus obtaining a photodetector. An Al2O3 insulating layer, an ITO electrode, and a NiO electrode are then sequentially deposited on the surface of the photodetector. A photolithography auxiliary layer B is then deposited on the surface of the NiO electrode. The photolithography auxiliary layer B contains a hollow region D corresponding to and larger than the perovskite thin film. An electrochromic material is then sprayed onto the hollow region D to obtain an electrochromic thin film. The photolithography auxiliary layer B is then peeled off to form an electrochromic layer. Finally, an electrolyte is cast onto the surface of the electrochromic thin film, and ITO glass is bonded to obtain the synaptic device array.

[0034] In a preferred embodiment, according to the design of the arrayed electrodes, the arrayed electrode pattern is exposed on the substrate using photolithography, and then Cr and Au are deposited sequentially on the arrayed electrode pattern to obtain the arrayed electrodes.

[0035] In this invention, an array of electrode patterns is designed using CleWin, which is then fabricated into a 4-inch glass mask. The electrode patterns are then exposed onto the sample using photolithography-UV exposure technology. The photoresist used is NR9-3000PY.

[0036] In the actual operation, the transparent glass substrate is cut into 5cm×5cm pieces. The cut substrate is then ultrasonically cleaned in acetone, isopropanol and anhydrous ethanol for 15 minutes, rinsed with deionized water, ultrasonically cleaned again for 15 minutes, rinsed with deionized water, and finally dried with nitrogen (N2). A layer of photoresist is then uniformly coated on the substrate surface by spin coating at low speed of 400 rpm for 6 seconds and high speed of 3500 rpm for 30 seconds. After that, the substrate is pre-baked (110℃, 60s), exposed to ultraviolet light, post-baked (100℃, 60s), and developed (RD6, 6s) to complete the preparation of the arrayed electrodes of the sample. Then, Cr / Au metal electrodes are deposited by thermal evaporation coating process, and finally the photoresist is stripped to obtain the arrayed electrodes.

[0037] In a preferred embodiment, photoresist is spin-coated onto the arrayed electrodes, and then a hollow square region C corresponding to and larger than the interdigitated electrodes is etched out to obtain the photolithography auxiliary layer A.

[0038] In actual operation, photoresist (NPR-3000PY) is spin-coated again on the surface of the arrayed metal electrode and baked at 110℃ for 1 min. Then, the hollow area above the arrayed electrode is etched on the sample surface using photolithography and baked at 100℃ for 1 min. After development in developer (RD6) for 6 s, it is rinsed with deionized water and the remaining deionized water solution is dried with a nitrogen gun. This completes the calibration of the hollow area above the arrayed electrode.

[0039] In a preferred embodiment, the perovskite thin film is prepared by: depositing a perovskite thin film precursor in the hollow region C using a thermal evaporation coating process to obtain a perovskite precursor thin film; and then spin-coating a CH3NH3I3 solution onto the surface of the perovskite precursor thin film to convert the perovskite precursor material into a perovskite thin film.

[0040] The perovskite film precursor is selected from PbI3, PbBr3, and Pb 1-x Br x PbCl3, Pb 1-x ICl x At least one of them.

[0041] In a further preferred embodiment, the evaporation rate of the perovskite thin film precursor is 0.2–0.5 nm / s.

[0042] In a further preferred embodiment, the CH3NH3I3 solution is obtained by dissolving CH3NH3I3 in isopropanol, wherein the mass-to-volume ratio of CH3NH3I3 to isopropanol is 15-45 mg:1 L.

[0043] With the rapid development of information technology, the research of photodetectors is moving towards faster response speeds, higher detectivity, lower signal-to-noise ratios, miniaturization, and array-based designs. Currently, although the basic performance parameters of perovskite-based photodetectors have been greatly improved, the incompatibility of perovskite materials with traditional photolithography processes makes the assembly of array-integrated photodetectors a challenge. This invention combines the characteristics of perovskite materials with a method that integrates with traditional photolithography processes. The gas-liquid hybrid method combines gas-phase and liquid-phase methods in the perovskite synthesis process, thus employing a two-step method for synthesizing perovskite thin films. The gas-phase method uses a thermal evaporation device to prepare the perovskite precursor film. This device has two heatable sources to evaporate the raw materials for synthesizing the perovskite precursor. A substrate is placed on a rotating device above, and the device rotates at a constant speed during deposition to ensure uniform deposition of the perovskite precursor film. During the perovskite precursor film synthesis process, the entire cavity must be in a vacuum environment to avoid the influence of water vapor and oxygen in the air on the perovskite precursor film during deposition. Then, the perovskite precursor film was converted into a perovskite film using a liquid-phase method.

[0044] The perovskite thin film array prepared by this invention is a regular square, neatly arranged, with no superfluous crystals outside the pixels. The shape of the perovskite thin film is consistent with the shape and position of the hollow region surface after arraying, indicating that the shape, size, and position of the synthesized material can be controlled by photolithography. Furthermore, the perovskite thin precursor material (PbI3) film is uniformly covered on the arrayed interdigitated electrodes, with numerous gaps between the crystals, facilitating the full reaction between solid PbI3 and liquid methylammonium iodide. The transformed perovskite thin film material retains the morphology and position of the perovskite thin precursor material (PbI3) array synthesized in the first step. The synthesized perovskite thin film has a regular and uniform shape, a dense surface, and almost no pinhole defects. Since perovskite thin films are easily soluble in organic solvents, if the preparation method of this invention is not followed, the perovskite thin film prepared in the previous step may be destroyed by some organic solvents during the later assembly of the photodetector, thereby affecting the performance of the photodetector or causing the device to completely fail to detect photoelectric signals.

[0045] The preferred method involves depositing an Al2O3 insulating layer on the surface of the photodetector using physical vapor deposition (PVD). The deposition parameters are: power: 100W; deposition time: 8–10 min; pressure: 2 × 10⁻⁶. -2 ~2.5×10 -2Pa; the protective gas used during deposition is a mixture of N2 and O2, with N2 and O2 flow rates of 0.2–0.4 NL / min.

[0046] The preferred embodiment involves depositing an ITO electrode on the surface of an Al2O3 insulating layer using physical vapor deposition (PVD). The deposition parameters are: power: 60W, deposition time: 8–10 min, and pressure: 2 × 10⁻⁶. -2 ~2.5×10 -2 Pa, the gas used is a mixture of N2 and O2, and the gas flow rate is 0.2 to 0.4 NL / min.

[0047] The preferred embodiment uses physical vapor deposition to deposit a NiO electrode on the surface of an ITO electrode. The deposition parameters are: power: 90W, deposition time: 8–10 min, and pressure: 2 × 10⁻⁶. -2 ~2.5×10 -2 Pa, the gas used is a mixture of N2 and O2, and the gas flow rate is 0.2 to 0.4 NL / min.

[0048] In actual operation, a magnetron sputtering thin film apparatus is used for deposition.

[0049] In a preferred embodiment, the electrolyte is selected from at least one of solid polymer electrolytes (SPE), gel polymer electrolytes (GPE), composite polymer electrolytes, and ionic liquid mixed polymer electrolytes.

[0050] In a further preferred embodiment, the ionic liquid mixed polymer electrolyte is obtained by mixing a photocurable resin with an ionic liquid, wherein the ionic liquid is BMIMTFSI.

[0051] The ionic liquid mixed polymer electrolyte selected in this invention is obtained by mixing a light-curing resin with an ionic liquid, and the ionic liquid is BMIMTFSI (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonate)imine salt).

[0052] The ionic liquid mixed polymer electrolyte used in this invention has the advantages of being easy to prepare and having excellent film-forming properties, which helps to reduce the preparation time of electrochromic devices, make the contact between device layers more compact, and enable ECDs to have higher safety, higher optical contrast, good memory effect, excellent cycle stability and mechanical deformation.

[0053] Principles and advantages

[0054] This invention provides a synaptic device array based on an integrated electrochromic and photodetector system and its fabrication method. The integrated electrochromic and photodetector system comprises two main components: an electrochromic device and a perovskite photodetector. The perovskite array device includes: a substrate; a metal circuit containing arrayed electrodes, located on the substrate; a photosensitive layer located in a hollow region of a photolithographically defined auxiliary layer, having a hollow region corresponding to the location of the arrayed electrodes, and located on the arrayed electrodes; the synaptic device array, using the perovskite array device as the substrate, including an Al2O3 insulating layer, ITO and NiO electrodes, located on the substrate; an electrochromic layer defined by photolithography, having an array region corresponding to the photosensitive layer, located on the ITO and NiO electrodes; and an encapsulation layer, tightly bonding an electrolyte titrated onto the electrochromic layer and ITO glass. This synaptic device array exhibits good pixel uniformity and visible light detection characteristics; and achieves highly linear weight updates of light modulation through the synergistic effect of photoelectric stimulation, with high accuracy and good fault tolerance, showing promising application prospects in future AI systems.

[0055] This invention proposes a synaptic device array based on an integrated electrochromic and photodetector system and its fabrication method. Combining the advantages of electrochromic devices and perovskite photodetectors, it proposes an AV synaptic structure integrating electrochromic devices and perovskite photodetectors, achieving the coexistence of detection, storage, and computing capabilities in a single unit. More importantly, by designing the device structure and integrating the two devices together, it ensures the electrical performance of the individual device while obtaining a large-area array of materials. The electrochromic device, as the optical storage unit in the device structure, can convert electrical signals into color signals for storage. The perovskite photodetector, as the readout unit, can detect the stored content in the storage unit and convert it into a readable electrical signal, greatly enhancing its application value in future AI systems. This invention focuses on utilizing suitable material preparation techniques. Through device structure design, it develops a technology for preparing two-dimensional materials that is compatible with practical applications and applicable to most gas-liquid bonding methods. It also proposes a method for constructing standard arrayed devices using photolithography, avoiding the incompatibility between photoresist and polar solvents and perovskite materials involved in traditional photolithography processes, greatly improving the fabrication efficiency and yield of arrayed devices. In summary, the synaptic device array and its fabrication method based on an electrochromic photodetector integrated system proposed in this invention have good pixel uniformity and visible light detection characteristics; and through the synergistic effect of photoelectric stimulation, highly linear weight update of light modulation is achieved, with high accuracy and good fault tolerance, showing good application prospects in future AI systems.

[0056] The method for fabricating synaptic device arrays using photolithography provided by this invention has the following advantages:

[0057] 1) The gas-liquid combined growth method has low cost, high yield and high cleanliness. Moreover, by controlling factors such as growth temperature, it is possible to controllably obtain micron-sized or even millimeter-sized large-area materials, which lays the material foundation for realizing the arraying and integration of optoelectronic devices.

[0058] 2) The device fabrication process is compatible with traditional processes, saving on micro-nano processing costs;

[0059] 3) The device arraying process is simple, and the array pattern and size can be freely designed according to requirements;

[0060] 4) The design of the device structure and fabrication process of this invention can effectively integrate two independent devices together, improve device performance, and ensure the possibility of storage-reading integration. The key is that: first, the perovskite material is used as a photosensitive layer. Due to its advantages such as large light absorption coefficient, ultra-long carrier lifetime and diffusion length in the visible wavelength range, it can be used to assemble high-performance photodetector arrays; second, it can be combined with micro-nano fabrication technology to integrate two independent devices together.

[0061] 6) The device fabrication fully utilizes the advantages of materials and processes, controlling experimental costs while ensuring that the fabrication process is not complicated, and also achieving the experimental objectives. Attached Figure Description

[0062] Figure 1 This is a schematic diagram of the synaptic device array structure of the electrochromic and photodetector integrated system of the present invention. (a) Schematic diagram of the synaptic device array structure; (b) Storage unit (electrochromic device); (c) Readout unit (photodetector device).

[0063] Figure 2 The performance characterization of the electrochromic device in Example 1 is shown in the following figures: (a) Schematic diagram of the layered structure of the electrochromic device; (b) Grayscale image of the "H" in the colored state of the electrochromic device.

[0064] Figure 3 The performance of the photodetector device shown in Example 1 is characterized as follows: (a) Schematic diagram of a single photodetector structure; (b) Optical and SEM images of the perovskite photodetector array; (c) Incident light power density of 0–10 mW / cm² under darkness and 633 nm illumination. 2 (d) The logarithmic current-voltage (IV) curve of the measuring device; the transient light response characteristics of a single pixel under different light intensities.

[0065] Figure 4 For performance characterization of the synaptic device array in Example 1, (a) optical power is 10 mW / cm 2(a) Postsynaptic current (ΔPSC) of an artificial synapse with a pulse voltage of 2V and a pulse width of 2s, illustration: good performance after 300s; (b) Optical power of 10mW cm -2 Artificial postsynaptic current (ΔPSC) at different pulse widths when the pulse voltage is 2V and 1V; (c) in the range of 0.34–32.5 mW / cm 2 Within the laser power range, linear LTP and LTD characteristics were trained using 100 consecutive enhancement pulses and 100 suppression pulses. Enhancement process: electrical pulse, 2V; pulse width, uniformly increased from 0.02 to 2s. De-voltage process: electrical pulse, -2V; pulse width, uniformly increased from 0.02 to 2s; (d) Image mapping of artificial postsynaptic current (ΔPSC) of the synaptic device array at optical power intensities of 2.04, 10, and 32.5 mW. Detailed Implementation

[0066] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can more clearly understand the present invention.

[0067] The following explanation uses a synaptic device array based on an electrochromic photodetector integrated system and its fabrication method as an example. This method utilizes photolithography for controlled growth, adding an insulating layer (Al2O3) between the perovskite photodetector and the electrochromic device to integrate the two independent devices, achieving integrated storage and retrieval, reducing power consumption, and improving device performance. The array structure is constructed using photolithography, and its basic structure is shown below. Figure 1 As shown.

[0068] The working principle of the improved device performance is as follows: Compared with traditional photonic storage devices, the optical storage unit (storage section) in the synapse utilizes electrochromic materials as a light intensity modulation system to convert electrical signals into color signals for storage. The discoloration state can further adjust and switch the transmission intensity of light, realizing the storage, writing, and erasure of light intensity signals. Furthermore, the perovskite photodetector detection section (readout unit) can detect the stored content in the storage unit and convert it into a readable electrical signal. Therefore, by applying electrical stimulation with different pulse widths, amplitudes, and frequencies to the storage unit, the transmitted information can be effectively altered and stored. The readout unit then converts the remembered transmitted information back into an electrical signal, simulating the information storage function of the AV synaptic structure. Moreover, compared with previously reported artificial photosynapses, this device structure can further realize biological synaptic functions such as neural facilitation, long-term enhancement (LTP), and long-term inhibition (LTD) through the wavelength and intensity of external light stimulation, and exhibits good linear synaptic weighting.

[0069] The synaptic device array fabrication method of the present invention is highly controllable and efficient. While improving the performance of individual devices, it realizes the construction of array devices, providing a new approach for the future construction of two-dimensional integrated devices.

[0070] The following section further presents a method for controllable fabrication of synaptic device arrays in an electrochromic and photodetector integrated system, including the following steps:

[0071] Step 1: Use an organic solvent to ultrasonically clean the transparent substrate in the following order: acetone (5-15 min) → isopropanol (10-15 min) → deionized water (10-20 min). Finally, use a nitrogen gun to blow away the remaining deionized water on the substrate to obtain a clean transparent glass substrate.

[0072] Step 2: Deposit arrayed metal electrodes on the transparent substrate obtained in the previous step. A transparent glass substrate is placed on a spin coater. Using a plastic dropper, an appropriate amount of photoresist (NPR-3000PY) is spin-coated onto the transparent glass substrate (low speed 400 rpm, 6 s; high speed 3500 rpm, 30 s). Pre-baking is then performed (110°C, 60 s). The baked transparent glass substrate is placed on the substrate tray of the lithography machine. The arrayed metal electrodes defined by the glass mask are then exposed onto the transparent glass substrate using ultraviolet light. Post-baking is then performed (100°C, 60 s), followed by development in a developer (RD6) for 6 s. The substrate is then rinsed with deionized water and the remaining deionized water is removed using a nitrogen gun to obtain the arrayed electrodes. Metal (Cr-Au) is deposited on the lithographic substrate using a thermal evaporation process. Excess photoresist is removed to obtain the arrayed metal electrodes. The arrayed metal electrodes include several interdigitated electrodes and metal electrode pads. Each metal electrode pad includes a positive electrode and multiple negative electrodes. Each negative electrode is independently connected to an interdigitated electrode, and the positive electrode is connected to all interdigitated electrodes.

[0073] Step 3: Spin-coat the surface of the arrayed metal electrode obtained in Step 2 with photoresist (NPR-3000PY) and bake at 110°C for 1 min. Then, use photolithography to etch the hollow area above the arrayed electrode on the sample surface and bake at 100°C for 1 min. Develop in developer (RD6) for 6 s. Rinse with deionized water and blow dry the remaining deionized water solution with a nitrogen gun to complete the calibration of the hollow area above the arrayed electrode.

[0074] Step 4: On the sample obtained in Step 3, a perovskite precursor thin film is grown using a gas-liquid hybrid method. The perovskite precursor thin film is deposited via thermal evaporation at a rate of 0.4 nm / s. Afterwards, photoresist is removed to obtain an array of perovskite precursor thin films corresponding to the hollow regions. Finally, the perovskite precursor material is converted into a perovskite thin film using a one-step spin-coating method, thus obtaining the perovskite photodetector, the structure of which is shown below. Figure 3 As shown.

[0075] Step 5: Using physical vapor deposition, deposit an Al2O3 insulating layer on the device surface of the sample obtained in Step 4. The deposition parameters are: power: 100W; deposition time: 8–10 min; pressure: 2 × 10⁻⁶. -2 ~2.5×10 -2 Pa; the gas used is a mixture of N2 and O2; the gas flow rate is 0.2 to 0.4 NL / min.

[0076] Step Six: Using physical vapor deposition, deposit an ITO transparent electrode and a NiO ion storage layer on the insulating layer (Al2O3) of the sample obtained in Step Four. The ITO transparent electrode serves as the counter electrode of the electrochromic device, while the NiO ion storage layer primarily functions to reduce the operating voltage of the electrochromic device and improve its cycle stability. The deposition parameters are: power: 60W, 90W; deposition time: 8–10 min; pressure: 2 × 10⁻⁶. -2 ~2.5×10 -2 Pa, the gas used is a mixture of N2 and O2, and the gas flow rate is 0.2 to 0.4 NL / min.

[0077] Step 7: Spin-coat the sample obtained in Step 6 with NPR-3000PY (low speed 400rpm, 6s; high speed 3500rpm, 30s), bake at 110℃ for 1min. Similarly, mark the device obtained in Step 3 using UV exposure to etch out the excess parts. Then bake at 100℃ for 1min, develop (RD6, 6s), rinse the excess developer with deionized water, and blow dry the remaining deionized water solution with a nitrogen gun to expose the arrayed hollow area. Finally, spray electrochromic material onto the hollow area using a spraying method, and peel off the excess photoresist so that the electrochromic layer and the photosensitive layer (perovskite material) have the same array position, and the upper electrochromic layer completely covers the lower perovskite material, which can avoid signal crosstalk between the upper electrochromic device and the lower perovskite photodetector.

[0078] Step 8: Using a titration method, the electrolyte is titrated onto the electrochromic material to form an encapsulation layer, which is then bonded to ITO glass. This yields the synaptic device array of the electrochromic perovskite photodetector integrated system.

[0079] The following are specific embodiments of the synaptic device array based on the electrochromic photodetector integrated system prepared according to the present invention.

[0080] Example 1

[0081] A method for controllably fabricating a synaptic device array includes the following steps:

[0082] Step 1: Use an organic solvent to ultrasonically clean the transparent substrate in the following order: acetone (15 min) → isopropanol (15 min) → deionized water (15 min). Finally, use a nitrogen gun to blow away the remaining deionized water on the substrate to obtain a clean transparent glass substrate.

[0083] Step 2: Deposit arrayed metal electrodes on the transparent substrate obtained in the previous step. Place the transparent glass substrate on a spin coater, and use a plastic dropper to spin coat an appropriate amount of photoresist (NPR-3000PY) onto the transparent glass substrate (low speed 400rpm, 6s; high speed 3500rpm, 30s). Then perform pre-baking (110°C, 60s). Place the baked transparent glass substrate on the substrate tray of the lithography machine, and expose the arrayed metal electrodes defined by the glass mask onto the transparent glass substrate using ultraviolet light. Then perform post-baking (100°C, 60s), and immerse it in the developer (RD6) for 6s. Afterward, rinse it with deionized water and then rinse off the remaining deionized water with a nitrogen gun to obtain the arrayed electrodes. Deposit metal (Cr-Au) on the photolithographic substrate using a thermal evaporation process, and remove excess photoresist to obtain the arrayed metal electrodes.

[0084] Step 3: Spin-coat the surface of the arrayed metal electrode obtained in Step 2 with photoresist (NPR-3000PY) and bake at 110°C for 1 min. Then, use photolithography to etch the hollow area above the arrayed electrode on the sample surface and bake at 100°C for 1 min. Develop in developer (RD6) for 6 s. Rinse with deionized water and blow dry the remaining deionized water solution with a nitrogen gun to complete the calibration of the hollow area above the arrayed electrode.

[0085] Step 4: On the sample obtained in Step 3, a perovskite precursor thin film is grown using a gas-liquid hybrid method. The perovskite precursor thin film (PbI3 film) is deposited via thermal evaporation at a rate of 0.4 nm / s. Afterwards, photoresist is removed to obtain an array of perovskite precursor thin films corresponding to the hollow regions. Finally, the perovskite precursor (15 mg / L CH3NH3I3) is converted into a perovskite thin film using a one-step spin-coating method, thus obtaining the perovskite photodetector, the structure of which is shown below. Figure 3 As shown.

[0086] Step 5: Using physical vapor deposition, deposit an Al2O3 insulating layer on the device surface of the sample obtained in Step 4. The deposition parameters are: power: 100W; deposition time: 8min; pressure: 2×10⁻⁶. -2 The pressure is around 0.2 Pa; the gas used is a mixture of N2 and O2; the gas flow rate is 0.2 NL / min.

[0087] Step Six: Using physical vapor deposition, deposit an ITO transparent electrode and a NiO ion storage layer on the insulating layer (Al2O3) of the sample obtained in Step Four. The ITO transparent electrode serves as the counter electrode of the electrochromic device. The deposition parameters are: power: 60W, deposition time: 8min, and pressure: 2×10⁻⁶. -2 Pa, the gas used is a mixture of N2 and O2, and the gas flow rate is 0.2 NL / min.

[0088] NiO, as an ion storage layer, primarily functions to reduce the operating voltage of electrochromic devices and improve their cycling stability. The deposition parameters were: power: 90W, deposition time: 8min, and pressure: 2×10⁻⁶. -2 Pa, the gas used is a mixture of N2 and O2, and the gas flow rate is 0.2 NL / min.

[0089] Step 7: Spin-coat the sample obtained in Step 6 with NPR-3000PY (low speed 400rpm, 6s; high speed 3500rpm, 30s), bake at 110℃ for 1min. Similarly, mark the device obtained in Step 3 using UV exposure to etch out the excess parts. Then bake at 100℃ for 1min, develop (RD6, 6s), rinse with deionized water to remove excess developer, and dry the remaining deionized water solution with a nitrogen gun to expose the arrayed hollow region. Finally, spray the electrochromic conductive polymer TTT-EDOT onto the hollow region, peel off the excess photoresist, so that the electrochromic layer and the photosensitive layer (perovskite material) in the electrochromic layer have the same array position, and the upper electrochromic layer completely covers the lower perovskite material, which can avoid signal crosstalk between the upper electrochromic device and the lower perovskite photodetector.

[0090] Step 8: Using a titration method, an ionic liquid mixed polymer electrolyte (obtained by mixing UV resin L-8400C and ionic liquid BMIMTFSI at a mass ratio of 3:7, wherein the UV resin was purchased from Lancolu and the ionic liquid from Lande Technology) is titrated onto the electrochromic material to form an encapsulation layer, which is then bonded to ITO glass. This yields the synaptic device array of the electrochromic perovskite photodetector integrated system.

[0091] A schematic diagram of a synaptic device array based on an electrochromic photodetector integrated system is shown below. Figure 1 As shown, Figure 2 This is a physical image corresponding to step four of the specific implementation method. Figure 3 This is a physical diagram corresponding to step eight of the specific implementation method.

[0092] like Figure 1 As shown, from bottom to top, it includes a transparent glass substrate, an arrayed electrode (Cr-Au), a photosensitive layer material (CH3NH3PbI3), an insulating layer (Al2O3), a transparent electrode (ITO), an ion storage layer (NiO), an electrochromic layer, an electrolyte layer, and ITO glass.

[0093] The arrayed electrode includes several interdigital electrodes and a metal electrode pad. The metal electrode pad includes a positive electrode and multiple negative electrodes. Any negative electrode is independently connected to an interdigital electrode, and the positive electrode is connected to all interdigital electrodes.

[0094] The photosensitive layer material completely covers the arrayed interdigital electrodes.

[0095] The electrochromic device is located above the photodetector, with the Al2O3 layer acting as an insulator. An ITO transparent electrode and a NiO ion storage layer are prepared using physical vapor deposition. The electrochromic solution and electrolyte solution are then titrated onto the ITO transparent electrode and NiO ion storage layer. Figure 2 As shown. A 10×10 array was fabricated using photolithography. A CH3NH3PbI3 perovskite photosensitive layer film with a thickness of 300 nm was prepared using a gas-liquid two-step method. A 10 nm Cr / 50 nm Au metal electrode was obtained through thermal evaporation, as shown. Figure 3 As shown in (a).

[0096] like Figure 4 As shown, an optimized light intensity modulation system and a CH3NH3PbI3 photodetector are integrated into a synaptic structure to form a synaptic device array, enabling signal transmission, storage, and retrieval. Figure 4 As shown in (a), when a constant light intensity is applied to the synaptic device, the photoactive postsynaptic current (PSC) read by the photodetector is initially low due to the electrochromic material being in a colored state. When a positive pulse voltage is applied to the signal generator in the synaptic device, the postsynaptic current exhibits a significant increment of 8 nA (ΔPSC), and remains at the 8 nA current level for a long time after the pulse voltage is removed, indicating good long-term enhancement (LTP) behavior. Figure 4 (b) It can be observed that as the pulse width increases from 0.2s to 2s, the peak current value of ΔPSC gradually increases from 10nA to 50nA. Applying a longer pulse width under the same pulse duration effectively enhances the stimulation effect on the artificial synapse. Finally, the linear and symmetric long-term enhancement (LTP) and long-term inhibition (LTD) results under different light power modulations also show that our constructed AV synaptic structure maintains highly linear synaptic weights even under different light power signals, laying the foundation for achieving high image recognition accuracy. The proposed device structure exhibits excellent performance over duration, demonstrating the device's ability to improve visual memory with changes in light intensity, which is also the basis for achieving high image recognition accuracy.

[0097] This invention is the first to integrate electrochromic and photodetector technologies to fabricate synaptic devices. It utilizes photolithography to achieve vertical structure integration, directly fabricating arrayed metal electrodes on the sample and performing multiple photolithography processes to realize an arrayed synaptic device with integrated storage and readout capabilities. Simultaneously, a gas-liquid hybrid method is used to prepare the perovskite photosensitive layer, avoiding the negative impacts of incompatibility between organic solvents and perovskite materials in photolithography. This significantly improves the safety, efficiency, and yield of arrayed synaptic device fabrication. In today's rapidly developing information age with advanced integrated circuit technology, the design of this invention has significant guiding significance for its future development.

[0098] Finally, it should be noted that the purpose of disclosing the embodiments is to help further understand the present invention. Those skilled in the art should understand that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the content disclosed in the embodiments, and the scope of protection of the present invention is defined by the claims.

Claims

1. A synaptic device array, characterized in that: The synaptic device array consists of a photodetector and an electrochromic device disposed on the photodetector; the photodetector includes a substrate, an arrayed electrode, and a photosensitive layer; The arrayed electrodes are located on the substrate and include several interdigitated electrodes and metal electrode pads; the photosensitive layer is composed of several perovskite thin films, with any one of the perovskite thin films disposed on the interdigitated electrodes to completely cover them. The electrochromic device comprises, from bottom to top, an Al2O3 insulating layer, an ITO electrode, a NiO electrode, an electrochromic layer, and an encapsulation layer; The Al2O3 insulating layer is disposed on the surface of the photodetector. The electrochromic layer is composed of several electrochromic films, and the vertical projection surface of any one of the electrochromic films completely covers the vertical projection surface of the interdigitated electrode.

2. A synaptic device array according to claim 1: characterized in that: The metal electrode pad includes a positive electrode and multiple negative electrodes. Each negative electrode is independently connected to an interdigital electrode, and the positive electrode is connected to all interdigital electrodes. The interdigitated electrodes and the metal electrode pads are made of Cr / Au.

3. A synaptic device array according to claim 1: characterized in that: The length of each array unit in the arrayed electrode is between 10 and 100 μm, and the gap between two adjacent array units is between 20 and 300 μm.

4. A synaptic device array according to any one of claims 1-3, characterized in that: The thickness of the perovskite thin film is 200~300 nm; The perovskite film is square in shape; The perovskite material in the perovskite film is selected from CH3NH3PbI3 and CH3NH3Pb(I 1-x Br)3、CH3NH3Pb(I 1-x At least one of Cl)3.

5. A synaptic device array according to any one of claims 1-3, characterized in that: The thickness of the Al2O3 insulating layer is 50~60 nm; The thickness of the ITO electrode is 20~100 nm; The electrochromic material in the electrochromic film is one of WO3 and TTT-EDOT. The encapsulation layer is ITO glass.

6. A method for fabricating a synaptic device array according to any one of claims 1-5, characterized in that: According to the design of the arrayed electrodes, the arrayed electrodes are fabricated on the substrate, and then a photolithography auxiliary layer A is set on the arrayed electrodes. The photolithography auxiliary layer A has a hollow region C that corresponds to and is larger than the interdigital electrodes, exposing the interdigital electrodes. Then, a perovskite thin film is fabricated on the hollow region C. The photolithography auxiliary layer A is then peeled off to form a photosensitive layer, thus obtaining a photodetector. Then, an Al2O3 insulating layer, an ITO electrode, and a NiO electrode are sequentially deposited on the surface of the photodetector. Then, a photolithography auxiliary layer B is set on the surface of the NiO electrode. The photolithography auxiliary layer B has a hollow region D that corresponds to and is larger than the perovskite thin film. Then, an electrochromic material is sprayed onto the hollow region D to obtain an electrochromic thin film. The photolithography auxiliary layer B is peeled off to form an electrochromic layer. Finally, an electrolyte is cast onto the surface of the electrochromic thin film, and ITO glass is bonded to obtain a synaptic device array.

7. The method for fabricating a synaptic device array according to claim 6, characterized in that: According to the design of the arrayed electrode, the arrayed electrode pattern is exposed on the substrate using photolithography, and then Cr and Au are deposited sequentially on the arrayed electrode pattern to obtain the arrayed electrode. Photoresist is spin-coated onto the arrayed electrodes, and then a hollow square region C corresponding to the interdigitated electrodes and larger than the interdigitated electrodes is etched out to obtain the photolithography auxiliary layer A.

8. The method for fabricating a synaptic device array according to claim 6, characterized in that: The perovskite thin film preparation process is as follows: a perovskite thin film precursor is deposited in the hollow region C by thermal evaporation coating process to obtain a perovskite precursor thin film, and then CH3NH3I3 solution is spin-coated on the surface of the perovskite precursor thin film to convert the perovskite precursor material into a perovskite thin film. The perovskite film precursor is selected from PbI3, PbBr3, and Pb 1-x Br x PbCl3, Pb 1-x ICl x At least one of them; The deposition rate of the perovskite thin film precursor is 0.2~0.5 nm / s; The CH3NH3I3 solution is obtained by dissolving CH3NH3I3 in isopropanol, and the mass-to-volume ratio of CH3NH3I3 to isopropanol is 15~45 mg:1 L.

9. The method for fabricating a synaptic device array according to claim 6, characterized in that: An Al2O3 insulating layer was deposited on the surface of the photodetector using physical vapor deposition (PVD). The deposition parameters were: power: 100 W; deposition time: 8–10 min; pressure: 2 × 10⁻⁶. -2 ~2.5×10 -2 Pa; The protective gas used during deposition is a mixture of N2 and O2, with flow rates of both N2 and O2 ranging from 0.2 to 0.4 NL / min; ITO electrodes were deposited on the surface of an Al2O3 insulating layer using physical vapor deposition. The deposition parameters were: power: 60 W, deposition time: 8-10 min, and pressure: 2 × 10⁻⁶. -2 ~2.5×10 -2 Pa, the gas used is a mixture of N2 and O2, and the gas flow rate is 0.2~0.4 NL / min; A NiO electrode was deposited on the surface of an ITO electrode using physical vapor deposition. The deposition parameters were: power: 90 W, deposition time: 8-10 min, and pressure: 2 × 10⁻⁶. -2 ~2.5×10 -2 Pa, the gas used is a mixture of N2 and O2, and the gas flow rate is 0.2~0.4 NL / min.

10. A method for fabricating a synaptic device array according to claim 6, characterized in that: The electrolyte is selected from at least one of solid polymer electrolytes, gel polymer electrolytes, composite polymer electrolytes, and ionic liquid mixed polymer electrolytes.

Images