All-light-control synaptic device and modulation method and preparation method thereof

Abstract

The invention discloses a full-light-control synaptic device and a modulation method and a preparation method thereof, and relates to the field of semiconductors, and the full-light-control synaptic device comprises a substrate layer, an active layer and an electrode layer which are sequentially arranged from bottom to top; the electrode layer comprises a source electrode and a drain electrode which are arranged on the active layer at an interval, and an organic photosensitive layer is arranged on the active layer between the source electrode and the drain electrode; wherein the active layer is made of indium gallium zinc oxide, and the organic photosensitive layer is made of PDVT-10. The all-optical control synaptic device can realize an all-optical reversible conductivity regulation and control function under the light stimulation of different light intensities of single-wavelength light or the light stimulation of dual-wavelength combined light.

Description

Technical Field

[0001] This invention relates to the field of fully optically controlled synaptic device technology, and in particular to a fully optically controlled synaptic device and its modulation and fabrication methods. Background Technology

[0002] Machine vision is a data-intensive technology, and the demand for hardware capable of processing visual information with high parallelism, high integration, high energy efficiency, and high stability is constantly increasing. Neuromorphic photonic devices, especially photoelectric synaptic devices, utilize light as an information carrier and modulation signal, providing unique advantages for visual information processing.

[0003] However, a key limitation remains in most reported optosynaptic devices: reversible synaptic weight updates (boosting and suppressing) typically rely on hybrid optoelectronic signals. This necessity not only complicates system architecture and integration but also introduces inherent drawbacks of instability and high power consumption, as the electrical signals can induce parasitic effects, crosstalk, and irreversible damage to the device's microstructure over time.

[0004] In biological vision systems, the retina plays a central role in detecting light signals and efficiently converting them into neural impulses. It comprises photoreceptors (cones and rods), horizontal cells, bipolar cells, aneurysms, and ganglion cells. Among these, bipolar cells in the retina exhibit opposing responses to light stimuli, with different "ON" and "OFF" pathways being activated. This bidirectional signal processing mechanism not only enables efficient contrast encoding but also lays the structural and functional foundation for subsequent visual information integration. This inherent ability to achieve bidirectional plasticity using purely optical cues provides powerful inspiration for designing more efficient and biomimetic artificial visual synapses.

[0005] Current research focuses on advancing the development of all-optically controlled synaptic devices. For example, CsPbBr3-based devices can operate in self-powered mode, and CsPbBr3 / solvent / carbon nitride multilayer structures show promise for all-optical modulation. Furthermore, recent studies have demonstrated that perovskite / ZnO-based heterojunction devices can generate excitation and inhibition responses under ultraviolet (365 nm) and green (525 nm) light, respectively. Nevertheless, many reported "all-optical" devices still require auxiliary electric fields for functional control. Moreover, most existing all-optical devices rely on two beams of light of different wavelengths to modulate signals; research using only light intensity as a control parameter to achieve single-wavelength signal modulation is still limited. Additionally, most existing reports lack stability of reversible conductance under purely optical programming, which is a key metric for reliable neuromorphic computing. Summary of the Invention

[0006] To address the technical problems existing in the background art, this invention proposes a fully optically controlled synaptic device and its modulation and fabrication methods.

[0007] In a first aspect, the present invention proposes a fully optically controlled synaptic device, comprising: a substrate layer, an active layer, and an electrode layer arranged sequentially from bottom to top, wherein the electrode layer includes a source electrode and a drain electrode spaced apart on the active layer, and an organic photosensitive layer is provided on the active layer between the source electrode and the drain electrode; wherein the active layer is made of indium gallium zinc oxide, and the organic photosensitive layer is made of PDVT-10.

[0008] Preferably, the fully optically controlled synaptic device is used to achieve a cyclical reversible change in synaptic weight by changing the intensity of the light stimulation when a single wavelength of light stimulation with a wavelength range within a preset range is applied, or when light stimulation from a preset dual-wavelength combination is applied alternately.

[0009] Preferably, the thickness of the substrate is 0.4-0.6 mm, the thickness of the active layer is 22-78 nm, the thickness of the electrode layer is 60-80 nm, and the thickness of the organic photosensitive layer is 40-59 nm. Preferably, the substrate has a thickness of 0.52 mm, the active layer has a thickness of 53 nm, the electrode layer has a thickness of 60 nm, and the organic photosensitive layer has a thickness of 49 nm.

[0010] In a second aspect, the present invention also proposes a modulation method for a fully optically controlled synaptic device, which is applied to any of the fully optically controlled synaptic devices described in the first aspect, comprising: applying a single wavelength light stimulus with a wavelength range of a preset range to the fully optically controlled synaptic device in the form of a pulse, and by changing the light intensity of the light stimulus, enabling the synaptic weight of the fully optically controlled synaptic device to achieve a cyclic reversible change of enhancement and inhibition.

[0011] Preferably, under single-wavelength light stimulation, when the light power density of the light stimulation is greater than the preset light power density, the fully optically controlled synaptic device exhibits a synaptic weight enhancement effect, the photoconductivity of the fully optically controlled synaptic device is enhanced, and the higher the light power density, the greater the photoconductivity value; When the optical power density of the light stimulus is less than or equal to the preset optical power density, the fully optically controlled synaptic device exhibits a synaptic weight suppression effect, resulting in a decrease in photoconductivity. The higher the optical power density, the weaker the synaptic weight suppression effect becomes. When the optical power density increases to the preset optical power density, it transforms into a synaptic weight enhancement effect.

[0012] Preferably, the preset range is 400 ~ 480 nm.

[0013] Preferably, the preset range is 420 ~ 440 nm.

[0014] Preferably, the preset range is 429 ~ 431 nm.

[0015] Thirdly, the present invention also proposes a modulation method for a fully optically controlled synaptic device, applied to any of the fully optically controlled synaptic devices described in the first aspect, comprising: alternately applying light stimulation from a preset dual-wavelength combination to the fully optically controlled synaptic device in the form of pulses, so that the synaptic weight of the fully optically controlled synaptic device achieves a cyclic reversible change of enhancement and inhibition.

[0016] Preferably, the preset dual-wavelength combination is a combination of 340 nm and 625 nm, a combination of 340 nm and 530 nm, a combination of 430 nm and 530 nm, or a combination of 430 nm and 625 nm.

[0017] Fourthly, this invention also proposes a method for fabricating a fully optically controlled synaptic device, comprising: Pretreatment of the substrate; An active layer is formed on the pretreated substrate; wherein the active layer is made of indium gallium zinc oxide. An electrode layer is formed on the active layer; wherein the electrode layer includes source electrodes and drain electrodes spaced apart on the active layer; An organic photosensitive layer is formed on the active layer between the source electrode and the drain electrode; wherein the material of the organic photosensitive layer is PDVT-10.

[0018] Preferably, the fully optically controlled synaptic device is used to achieve a cyclical reversible change in synaptic weight by changing the intensity of a single wavelength of light stimulation within a preset wavelength range, or by alternating light stimulation from a preset dual-wavelength combination.

[0019] The proposed fully optically controlled synaptic device, its modulation method, and its fabrication method form a heterojunction interface through the contact between the active layer and the organic photosensitive layer. This allows the fully optically controlled synaptic device to precisely control the oxygen vacancy concentration in the channel of the IGZO active layer under light stimulation alone, ensuring reversible and stable control of synaptic weights. It completely eliminates the dependence on electrical signals and can achieve both dual-wavelength modulation and single-wavelength modulation, thus being compatible with both light intensity and wavelength modulation paradigms on the same hardware system. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a fully optically controlled synaptic device in one embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the photoresponse conductivity of a fully photocontrolled synaptic device illuminated by 340 nm light under different light intensities, according to one embodiment of the present invention.

[0022] Figure 3This is a schematic diagram of the photoresponse conductivity of a fully photocontrolled synaptic device illuminated by 430 nm light under different light intensities, according to one embodiment of the present invention.

[0023] Figure 4 This is a schematic diagram of the photoresponse conductivity of a fully photocontrolled synaptic device illuminated by 530 nm light under different light intensities, according to one embodiment of the present invention.

[0024] Figure 5 This is a schematic diagram of the photoresponse conductivity of a fully photocontrolled synaptic device illuminated by 625 nm light under different light intensities, according to one embodiment of the present invention.

[0025] Figure 6 This is a schematic diagram showing the test results of the dual-wavelength reversible conductivity modulation performance of the all-optically controlled synaptic device in one embodiment of the present invention; wherein, (a) is the reversible conductivity modulation performance of the combination of 340 nm and 530 nm, (b) is the reversible conductivity modulation performance of the combination of 340 nm and 625 nm, (c) is the reversible conductivity modulation performance of the combination of 430 nm and 530 nm, and (d) is the reversible conductivity modulation performance of the combination of 430 nm and 625 nm.

[0026] Figure 7 This is a schematic diagram showing the test results of the single-wavelength reversible conductivity modulation performance of the all-optically controlled synaptic device in one embodiment of the present invention; wherein, (a) shows the results of different light intensities (5.27 mW·cm) at a wavelength of 430 nm. -2 Strong light, 0.47 mW·cm -2 Under weak light conditions, the synaptic weight exhibits a periodic cyclical modulation characteristic of alternating growth and inhibition with the number of pulses. (b) shows the fully optically controlled synaptic device under strong light intensity (5.27 mW·cm²) at a wavelength of 430 nm. -2 (c) shows the retention performance of the fully optically controlled synaptic device under different conductance states under weak light intensity (0.47 mW·cm) at a wavelength of 430 nm. -2 The retention performance of different conductance states under different conditions.

[0027] Figure 8 This is a schematic diagram showing the results of environmental stability testing of the light suppression response of a fully optically controlled synaptic device in one embodiment of the present invention.

[0028] Figure 9 This is a schematic diagram of the photoresponse conductivity of a pair of monolayer IGZO and PDVT-10 devices proposed in this invention under a weak light intensity of 430 nm; wherein, (a) is a monolayer PDVT-10 device and (b) is a monolayer IGZO device.

[0029] Figure 10This is a schematic diagram of the photoresponse conductivity of a pair of monolayer IGZO and PDVT-10 devices proposed in this invention under a strong light intensity of 430 nm; wherein, (a) is a monolayer PDVT-10 device and (b) is a monolayer IGZO device.

[0030] Figure 11 This is a schematic diagram of the photoresponse conductivity of a pair of monolayer IGZO and PDVT-10 devices proposed in this invention under 340 nm illumination; wherein, (a) is a monolayer PDVT-10 device and (b) is a monolayer IGZO device.

[0031] Figure 12 This is a schematic diagram of the photoresponse conductivity of a pair of monolayer IGZO and PDVT-10 devices proposed in this invention under 530 nm illumination; wherein, (a) is a monolayer PDVT-10 device and (b) is a monolayer IGZO device.

[0032] Figure 13 This is a schematic diagram of the photoresponse conductivity of a pair of monolayer IGZO and PDVT-10 devices proposed in this invention under 625 nm illumination; wherein, (a) is a monolayer PDVT-10 device and (b) is a monolayer IGZO device.

[0033] Figure 14 This is an energy band diagram of the IGZO active layer and the PDVT-10 organic photosensitive layer before contact in one embodiment of the present invention; wherein, (a) is the PDVT-10 organic photosensitive layer, and (b) is the IGZO active layer.

[0034] Figure 15 This is a schematic diagram illustrating the working mechanism of the all-optical reversible conductivity modulation of the all-optical controlled synaptic device in one embodiment of the present invention. Detailed Implementation

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] Firstly, such as Figure 1 As shown, the present invention proposes a fully optically controlled synaptic device, comprising: a base layer, an active layer and an electrode layer arranged sequentially from bottom to top, wherein the electrode layer includes a source electrode and a drain electrode, the source electrode and the drain electrode are disposed alternately on the active layer, and an organic photosensitive layer is provided on the active layer between the source electrode and the drain electrode.

[0037] In one embodiment, the active layer is made of indium gallium zinc oxide (IGZO). That is, the active layer in this embodiment is an indium gallium zinc oxide (IGZO) active layer.

[0038] In one embodiment, the organic photosensitive layer is made of PDVT-10. That is, the organic photosensitive layer is a PDVT-10 organic photosensitive layer.

[0039] It is important to understand that the full name of PDVT-10 in this embodiment is poly[[2,5-bis(2-decyltetradecyl)-2,3,5,6-tetrahydro-3,6-dioxopyrrolo[3,4-c]pyrrolo-1,4-diyl][2,2'-bithiophene]-5,5'-diyl-(1E)-1,2-vinyldiyl][2,2'-bithiophene]-5,5'-diyl], which is a polymer material with organic conductivity and CAS number 1403959-02-3.

[0040] In this embodiment, the thickness of the substrate is 0.4-0.6 mm, the thickness of the active layer is 22-78 nm, the thickness of the electrode layer is 60-80 nm, and the thickness of the organic photosensitive layer is 40-59 nm.

[0041] In a further embodiment, the substrate has a thickness of 0.52 mm, the active layer has a thickness of 53 nm, the electrode layer has a thickness of 60 nm, and the organic photosensitive layer has a thickness of 49 nm.

[0042] It should be understood that the actual thickness values ​​in this embodiment are all within the preset error range of the set values.

[0043] In this embodiment, both the source electrode and the drain electrode are gold (Au) electrodes.

[0044] The substrate in this embodiment is a SiO2 / Si substrate.

[0045] In one specific embodiment, the substrate is a P-type heavily doped silicon wafer. A 200 nm thick SiO2 insulating layer is grown on the surface of the P-type heavily doped silicon wafer.

[0046] In this embodiment, the active layer and the organic photosensitive layer form a heterojunction interface, enabling the fully optically controlled synaptic device to achieve fully optically reversible conductivity modulation under light stimulation of different intensities of a single wavelength or under light stimulation of different intensities of two wavelengths.

[0047] The fully optically controlled synaptic device in this embodiment is used to achieve a cyclical reversible change in synaptic weight by changing the intensity of the light stimulation when a single wavelength of light stimulation with a wavelength range within a preset range is applied, or when light stimulation from a preset dual-wavelength combination is applied alternately.

[0048] The single-wavelength light used in this embodiment is blue light, such as light with a wavelength of 400 to 480 nm.

[0049] This embodiment uses a combination of two wavelengths of light, such as a combination of 340 nm and 625 nm or a combination of 430 nm and 530 nm. Of course, other dual-wavelength light combinations that can realize the fully optically reversible conductivity modulation function of this fully optically controlled synaptic device are also included.

[0050] In one specific embodiment, by irradiating the fully optically controlled synaptic device with light of different intensities at a wavelength of 430 nm, or irradiating the fully optically controlled synaptic device with light of dual wavelengths of 340 nm and 625 nm, or irradiating the fully optically controlled synaptic device with light of dual wavelengths of 430 nm and 530 nm, the fully optically controlled synaptic device can achieve synaptic weight suppression or enhancement effects under different light intensities or different wavelengths, thereby realizing the fully optically reversible conductivity control function.

[0051] It's important to understand that among metal-oxide-semiconductor (MOS) materials, amorphous indium gallium zinc oxide (IGZO) stands out due to its wide application in optoelectronics and high compatibility with CMOS processes. This compatibility is a necessary prerequisite for integrating large-scale neuromorphic systems. Amorphous IGZO films possess abundant and uniformly distributed oxygen vacancy defects, which can serve as effective trapping / releasing centers for photoexcited carriers, thus laying a solid foundation for stable all-photoconductive modulation. Furthermore, the long-range disordered structure of amorphous IGZO eliminates grain boundary barriers and reduces carrier transport resistance, contributing to low-energy operation. PDVT-10, on the other hand, is a narrow-bandgap conjugated polymer. Its large π-conjugated molecular structure endows it with broad-spectrum absorption characteristics, stably responding to the ultraviolet and visible light bands from 340 nm to 625 nm, meeting the requirements for wavelength modulation.

[0052] In this embodiment, an amorphous IGZO oxide semiconductor / PDVT-10 organic semiconductor heterostructure is selected as the core functional layer. The IGZO active layer provides oxygen vacancy carrier regulation center, and the PDVT-10 organic photosensitive layer realizes a wide spectrum response. The two form an effective heterojunction through interfacial interaction, which can precisely control the oxygen vacancy concentration in the IGZO channel under light stimulation, ensuring reversible and stable control of synaptic weights and completely eliminating dependence on electrical signals. It can not only realize dual-wavelength modulation, but also single-wavelength modulation, and is compatible with dual modulation paradigms of light intensity and wavelength on the same hardware system.

[0053] In a second aspect, the present invention also proposes a modulation method for a fully optically controlled synaptic device, which is applied to any of the fully optically controlled synaptic devices described in the first aspect, comprising: applying a single wavelength light stimulus of a preset wavelength range to the fully optically controlled synaptic device in the form of a pulse, and by changing the light intensity of the light stimulus, enabling the synaptic weight of the fully optically controlled synaptic device to achieve a cyclical reversible change of enhancement and inhibition.

[0054] Under single-wavelength light stimulation, when the light power density of the light stimulation is greater than the preset light power density, the fully optically controlled synaptic device exhibits a synaptic weight enhancement effect, and the photoconductivity of the fully optically controlled synaptic device is enhanced. The higher the light power density, the greater the photoconductivity value. When the optical power density of the light stimulus is less than or equal to the preset optical power density, the fully optically controlled synaptic device exhibits a synaptic weight suppression effect, resulting in a decrease in photoconductivity. The higher the optical power density, the weaker the synaptic weight suppression effect becomes. When the optical power density increases to the preset optical power density, it transforms into a synaptic weight enhancement effect.

[0055] In this embodiment, the preset range is 400 ~ 480 nm.

[0056] In a further embodiment, the preset range is 420 ~ 440 nm.

[0057] In a further embodiment, the preset range is 429 ~ 431 nm.

[0058] Thirdly, the present invention also proposes a modulation method for a fully optically controlled synaptic device, applied to any of the fully optically controlled synaptic devices described in the first aspect, comprising: alternately applying light stimulation from a preset dual-wavelength combination to the fully optically controlled synaptic device in the form of pulses, so that the synaptic weight of the fully optically controlled synaptic device achieves a cyclic reversible change of enhancement and inhibition.

[0059] In this embodiment, the preset dual-wavelength combinations are 340 nm and 625 nm, 340 nm and 530 nm, 430 nm and 530 nm, or 430 nm and 625 nm.

[0060] Fourthly, the present invention provides a method for fabricating a fully optically controlled synaptic device, comprising: Pretreatment of the substrate; An active layer is formed on the pretreated substrate; An electrode layer is formed on the active layer; An organic photosensitive layer is formed on the active layer between the source electrode and the drain electrode.

[0061] In this embodiment, the substrate is a SiO2 / Si substrate with a thickness of 0.52 mm.

[0062] Specifically, in this embodiment, a P-type heavily doped silicon wafer (with a 200 nm thick SiO2 insulating layer grown on its surface) is selected as the substrate.

[0063] During the pretreatment of the substrate, ultrasonic cleaning was performed sequentially using ethanol, a 70°C mixed cleaning solution, and deionized water, with each cleaning session lasting 10 minutes, to remove oil and impurities from the substrate surface. The mixed cleaning solution was prepared by mixing deionized water, ammonia, and hydrogen peroxide in a volume ratio of 7:2:1. After cleaning, the surface was purged with nitrogen until it was completely dry and ready for use.

[0064] In this embodiment, an active layer is formed on the pretreated substrate, specifically including: An active layer was formed on a pretreated substrate using a magnetron sputtering deposition method.

[0065] In one specific embodiment, the active layer is an IGZO active layer, and the material of the IGZO active layer is indium gallium zinc oxide.

[0066] In a further specific embodiment, the thickness of the IGZO active layer is 53 nm.

[0067] During the magnetron sputtering deposition of the IGZO active layer, the pretreated substrate is loaded into the magnetron sputtering chamber. After the chamber is closed, a vacuum of 5 × 10⁻⁶ is first applied. -4 The pressure was increased to Pa to remove interfering impurities such as air and water vapor in the chamber. Then, argon gas was introduced at a flow rate of 20 sccm to adjust the chamber deposition pressure to 0.6-0.8 Pa. The sputtering power was set to 50 W, and magnetron sputtering deposition was performed at room temperature until an amorphous IGZO film with a thickness of 53 nm was formed. After deposition, the substrate with the IGZO film was placed in an annealing furnace and annealed at 450°C for 2 hours.

[0068] In this embodiment, forming an electrode layer on the active layer specifically includes: An electrode layer is formed on the active layer using a vacuum thermal evaporation method.

[0069] In this embodiment, the electrodes in the electrode layer are Au electrodes.

[0070] In a further embodiment, the Au electrode has a thickness of 60 nm.

[0071] During the formation of the Au electrode, the substrate with the active layer is transferred to the chamber of a vacuum thermal evaporation apparatus, and the vacuum is evacuated to ≤5×10⁻⁶. -4 Pa; Au electrodes were deposited on the surface of the IGZO active layer using a vacuum thermal evaporation method, with the evaporation rate controlled at 0.06 nm / s, until the electrode thickness reached 60 nm, thus completing the electrode fabrication.

[0072] In one specific embodiment, the organic photosensitive layer is a PDVT-10 organic photosensitive layer.

[0073] In a further specific embodiment, the thickness of the PDVT-10 organic photosensitive layer is 49 nm.

[0074] During the formation of the PDVT-10 organic photosensitive layer, a pre-prepared PDVT-10 solution was coated onto the surface of the active layer between the source and drain electrodes using a spin coating method. The spin coating speed was set to 1000 rpm and the spin coating time was 60 seconds. After spin coating, the fully photocontrolled synaptic device was placed in an oven at 150°C for annealing for 15 minutes to form a PDVT-10 organic photosensitive layer with a thickness of 49 nm, thus completing the fabrication of the fully photocontrolled synaptic device.

[0075] The preparation process of the PDVT-10 solution in this embodiment includes: dissolving the PDVT-10 organic conjugated polymer in chloroform solvent to prepare a PDVT-10 solution with a concentration of 5 mg / mL, and heating it in a 50°C water bath for 4 hours for later use.

[0076] The present invention will now be described in conjunction with specific embodiments.

[0077] Example 1 This invention proposes a fully optically controlled synaptic device, comprising: a substrate layer, an active layer, and an electrode layer arranged sequentially from bottom to top. The electrode layer includes a source electrode and a drain electrode, which are spaced apart on the active layer. An organic photosensitive layer is disposed on the active layer between the source electrode and the drain electrode. The substrate is a SiO2 / Si substrate with a thickness of 0.52 mm; the active layer is an indium gallium zinc oxide (IGZO) active layer with a thickness of 53 nm; the organic photosensitive layer is a PDVT-10 organic photosensitive layer with a thickness of 49 nm; and both the source electrode and the drain electrode in the electrode layer are gold (Au) electrodes with a thickness of 60 nm.

[0078] Example 2 This invention proposes a method for fabricating a fully optically controlled synaptic device, comprising: A heavily doped P-type silicon wafer is provided as the substrate; The substrate is pretreated; the pretreatment process includes: ultrasonic cleaning with ethanol, 70℃ mixed cleaning solution, and deionized water in sequence, each cleaning lasting 10 minutes; the mixed cleaning solution is prepared by deionized water, ammonia, and hydrogen peroxide in a volume ratio of 7:2:1; after cleaning, nitrogen gas is used to purge until the surface is completely dry, and it is ready for use. An IGZO active layer with a thickness of 53 nm was formed on the pretreated substrate by magnetron sputtering. An electrode layer is formed on the IGZO active layer by vacuum thermal evaporation; wherein the electrode layer includes two Au electrodes with a thickness of 60 nm; The PDVT-10 solution was coated onto the surface of the active layer between the source and drain electrodes using a spin coating method. The spin coating speed was 1000 rpm and the spin coating time was 60 seconds. After spin coating, the fully photocontrolled synaptic device was placed in an oven at 150°C for annealing for 15 minutes to form a PDVT-10 organic photosensitive layer with a thickness of 49 nm, thus completing the fabrication of the fully photocontrolled synaptic device.

[0079] During the magnetron sputtering deposition of the IGZO active layer, the pretreated substrate is loaded into the magnetron sputtering chamber. After the chamber is closed, a vacuum of 5 × 10⁻⁶ is first applied. -4 The pressure was increased to Pa to remove interfering impurities such as air and water vapor in the chamber. Then, argon gas was introduced at a flow rate of 20 sccm to adjust the chamber deposition pressure to 0.6-0.8 Pa. The sputtering power was set to 50 W, and magnetron sputtering deposition was performed at room temperature until an amorphous IGZO film with a thickness of 53 nm was formed. After deposition, the substrate with the IGZO film was placed in an annealing furnace and annealed at 450°C for 2 hours.

[0080] During the formation of the Au electrode, the substrate with the IGZO active layer is transferred to the chamber of a vacuum thermal evaporation apparatus, and the vacuum is evacuated to ≤5×10⁻⁶. -4 Pa; Au electrodes were deposited on the surface of the IGZO active layer using a vacuum thermal evaporation method, with the evaporation rate controlled at 0.06 nm / s, until the electrode thickness reached 60 nm, thus completing the electrode fabrication.

[0081] The preparation process of the PDVT-10 solution in this embodiment includes: dissolving the PDVT-10 organic conjugated polymer in chloroform solvent to prepare a PDVT-10 solution with a concentration of 5 mg / mL, and heating it in a 50°C water bath for 4 hours for later use.

[0082] Example 3 The photoresponse conductivity of the fully optically controlled synaptic device in Example 1 was tested under different light intensities with a single wavelength of light. The test results are as follows: Figures 2-5 As shown, this fully optically controlled synaptic device was illuminated by light at 340 nm, 430 nm, 530 nm, and 625 nm, with light intensity ranging from 0.46 to 67.4 mW·cm⁻¹. -2 .

[0083] Here, the conductance response represents the synaptic weight. All photoconductance responses are acquired at a fixed reading voltage of 0.1 V. This voltage is only used for conductance signal acquisition and does not participate in photoconductance regulation.

[0084] Example 4 The dual-wavelength reversible conductivity modulation performance of the all-optically controlled synaptic device in Example 1 was tested, and the test results are as follows: Figure 6As shown. Among them, the 340 nm light exhibiting the synaptic weight enhancement effect (intensity 2.75 mW·cm²) -2 ), respectively compared with 530 nm light (intensity 6.19 mW·cm) which exhibits a suppressive effect. -2 ), 625 nm (light intensity 6.36 mW·cm) -2 ) combination; 430 nm light (intensity 5.27 mW·cm) exhibiting synaptic weight enhancement effect. -2 ), respectively compared with 530 nm light (intensity 39.2 mW·cm) exhibiting a suppression effect. -2 ), 625 nm (light intensity 67.4 mW·cm) -2 )combination.

[0085] Example 5 The single-wavelength reversible conductivity modulation performance of the all-optically controlled synaptic device in Example 1 was tested, and the test results are as follows: Figure 7 As shown. The wavelength is 430 nm, and the light intensities are 0.47 and 5.27 mW·cm⁻¹, respectively. -2 .

[0086] Example 6 The environmental stability test of the light suppression response of the all-optical synaptic device in Example 1 was conducted, and the test results are as follows: Figure 8 As shown.

[0087] Comparative Example 1 The optical response of monolayer PDVT-10 devices and monolayer IGZO devices under weak light intensity at 430 nm was tested, and the test results are as follows: Figure 9 As shown.

[0088] Comparative Example 2 The optical response of monolayer PDVT-10 devices and monolayer IGZO devices under 430 nm strong light illumination was tested, and the test results are as follows: Figure 10 As shown.

[0089] Comparative Example 3 The optical response of monolayer PDVT-10 devices and monolayer IGZO devices under 340 nm wavelength illumination was tested, and the test results are as follows: Figure 11 As shown.

[0090] Comparative Example 4 The optical response of monolayer PDVT-10 devices and monolayer IGZO devices under 530 nm wavelength illumination was tested, and the test results are as follows: Figure 12 As shown.

[0091] Comparative Example 5 The optical response of monolayer PDVT-10 devices and monolayer IGZO devices under 625 nm wavelength illumination was tested, and the test results are as follows: Figure 13 As shown.

[0092] according to Figure 3 It can be seen that when this fully optically controlled synaptic device is illuminated by light with a wavelength of 430 nm, the power density of the light with a wavelength of 430 nm is ≥2.06 mW·cm⁻¹. -2 At that time, the conductivity of the fully optically controlled synaptic device showed a continuous increasing trend, and after the light was removed, the conductivity of the fully optically controlled synaptic device gradually decreased to a value higher than the initial conductivity (ΔG>0), which showed a synaptic weight enhancement effect. Moreover, the conductivity enhancement was positively correlated with the light intensity, that is, the higher the light intensity, the greater the conductivity value. When the power density of the 430 nm wavelength light was <2.06 mW·cm -2 At that time, the conductivity of the fully optically controlled synaptic device increased instantaneously at the beginning of illumination and then continued to decrease. After the light was removed, the conductivity of the fully optically controlled synaptic device decayed to below the initial conductivity value (ΔG < 0), exhibiting a synaptic weight suppression effect; as the light intensity decreased from 0.47 mW·cm -2 Increased to 5.27 mW·cm -2 The conductivity change ΔG gradually increased from -0.65 nS to 0.54 nS, indicating that the suppression effect gradually weakened with increasing light intensity and eventually turned into an enhancement effect. This result confirms that the fully optically controlled synaptic device of this invention has the potential to achieve fully optically reversible conductivity modulation through light intensity modulation of a single wavelength (430 nm).

[0093] according to Figure 2 , Figure 4 and Figure 5 It can be seen that when this fully optically controlled synaptic device is illuminated by light with a wavelength of 340 nm, as the light intensity increases from 0.46 mW·cm⁻¹, the synaptic device exhibits a certain variability in light intensity. -2 Increased to 6.15 mW·cm -2 The conductivity change ΔG of this fully optically controlled synaptic device increased from 0.54 nS to 15.4 nS, consistently exhibiting a synaptic weight enhancement effect. However, when this fully optically controlled synaptic device was illuminated with light of 530 nm wavelength, the conductivity changed from 6.19 mW·cm⁻¹ to 15.4 nS. -2 Increased to 39.2 mW·cm -2 The conductivity change ΔG of this fully optically controlled synaptic device decreased from -0.16 nS to -3.12 nS, consistently exhibiting a synaptic weight suppression effect. Simultaneously, when this fully optically controlled synaptic device was illuminated with 625 nm wavelength light, as the light intensity increased from 6.36 mW·cm⁻¹… -2 Increased to 67.4 mW·cm -2The conductivity change ΔG of the fully optically controlled synaptic device decreased from -0.25 nS to -1.29 nS, and it always exhibited the synaptic weight suppression effect.

[0094] like Figure 6 As shown, alternating photostimulation tests with different combinations of enhancement-inhibition wavelengths were conducted on this fully optically controlled synaptic device: using pulse on-time of 1 s and off-time of 1 s, 340 nm (2.75 mW·cm⁻¹) light was applied. -2 (enhanced) and 530 nm (6.19 mW·cm) -2 (suppression), 340 nm (2.75 mW·cm -2 (enhanced) and 625 nm (6.36 mW·cm) -2 The conductance of this fully optically controlled synaptic device exhibited a clear and reversible change, first increasing with the enhancement of the wavelength stimulation and then decreasing with the inhibition of the wavelength stimulation, when subjected to a combination of wavelengths of 430 nm (5.27 mW·cm⁻¹) for both enhancement and inhibition. Using pulse on-time of 5 s and off-time of 10 s, the conductance was applied at 430 nm (5.27 mW·cm⁻¹) wavelengths. -2 ) and 530 nm (39.2 mW·cm -2 ), 430 nm (5.27 mW·cm -2 ) and 625 nm (67.4 mW·cm -2 When stimulated with different wavelength combinations, the conductivity of this fully optically controlled synaptic device exhibits cyclical reversible changes of enhancement and inhibition under alternating light stimulation of different combinations. These test results demonstrate that the fully optically controlled synaptic device can achieve fully optically reversible conductivity modulation through combinations of different wavelengths of light stimulation, verifying the practicality of the technical solution.

[0095] like Figure 7 As shown, to demonstrate the single-wavelength reversible photoconductive performance of this fully optically controlled synaptic device, a group of 32 transistors with a higher power density (5.27 mW·cm²) was used. -2 The optical pulses are used to enhance the photoconductivity of the device, while the same number of optical pulses (but with a lower power density of 0.47 mW·cm) are used simultaneously. -2 To reduce its photoconductivity, 10 cycles of cyclic optical write / erase were performed. Minimum and maximum photoconductivity states were collected during each optical modulation cycle, stabilizing at approximately 10.22 nS and 40.02 nS, respectively. The on / off ratio of the optical modulation was approximately 3.92. The on / off ratio was calculated as the ratio of maximum photoconductivity to minimum photoconductivity. Furthermore, the photoconductivity states are non-volatile in both optical write and optical erase modes; the eight enhanced and suppressed photoconductivity states shown here are clearly distinguishable after 1000 s.

[0096] In addition, such as Figure 8 As shown, the photo-suppression response of this invention exhibits long-term stability after 8 months of exposure to atmospheric conditions. The excellent photoconductive tuning performance of this fully optically controlled synaptic device is attributed to its requirement for only a small read voltage (0.1V) and optical signal to perform all operations. Furthermore, the oxide IGZO semiconductor, compatible with existing CMOS processes, typically exhibits excellent chemical and thermal stability, effectively preventing damage to the device's microstructure and the generation of Joule heat, thereby enhancing the stability of the synaptic device.

[0097] from Figure 2 , 3 As can be seen from 1, 2, 3, 4, 5, 9, 10, 11, 12, and 13, only the photoconductivity enhancement effect can be observed in the single-layer IGZO and single-layer PDVT-10 devices, and there is no light-induced suppression behavior. This confirms that the bidirectional modulation characteristics of the present invention originate from the synergistic effect of the heterojunction interface formed by the IGZO active layer and the PDVT-10 organic photosensitive layer.

[0098] The band diagrams of the IGZO active layer and the PDVT-10 organic photosensitive layer before relative contact in this embodiment are as follows: Figure 14 As shown in (a) and (b) in the figure. The working mechanism diagram of the all-optical reversible conductivity modulation of the all-optical controlled synaptic device in this embodiment is shown in the figure. Figure 15 As shown. Among them, Figure 15 The weak blue light mentioned refers to light with a wavelength of 430 nm and an intensity of 0.27 mW·cm. -2 Intense blue light refers to light with a wavelength of 430 nm and an intensity of 5.27 mW·cm⁻¹. -2 The light used in the photo is as follows: green light refers to light with a wavelength of 530 nm, red light refers to light with a wavelength of 625 nm, and violet light refers to light with a wavelength of 340 nm.

[0099] according to Figure 14 and Figure 15 It is known that under dark conditions, the difference in work function between the PDVT-10 organic photosensitive layer and the IGZO active layer causes the heterojunction interface to form a built-in electric field (IEF) pointing from the IGZO active layer to the PDVT-10 organic photosensitive layer. Under illumination, the built-in electric field drives photogenerated electrons in the PDVT-10 organic photosensitive layer to migrate to the channel in the IGZO active layer. The photogenerated electrons interact with ionized oxygen vacancies (V0) in the IGZO active layer. o 2+ Neutralization reaction occurs (V) o 2+ + 2e - →V o The photogenerated carriers in the IGZO active layer itself induce neutral oxygen vacancy ionization (V0). o → V o 2+ + 2e- The competition between oxygen vacancy neutralization and ionization effects dominates the change in conductivity, and the specific excitation is explained below: Under weak light intensity (weak blue light) irradiation at 430 nm, PDVT-10 exhibits higher photosensitivity and light absorption efficiency, with the neutralization effect induced by electron injection being dominant, resulting in suppression. Under high light intensity (strong blue light) irradiation at 430 nm, the oxygen vacancy ionization effect of IGZO is dominant and is enhanced. Under 340 nm light (violet light), the light absorption of IGZO is dominant, and the ionization effect is dominant, which is enhanced. Under 530 nm (green) or 625 nm (red) illumination, PDVT-10 exhibits dominant light absorption and a dominant neutralization effect induced by electron injection, resulting in suppression.

[0100] Therefore, this invention enables bidirectional (enhancement / suppression) conductivity modulation solely through changes in light intensity at a single wavelength, simplifying the optical hardware structure and system, and improving the conductivity modulation switching speed. Furthermore, the compatibility of conductivity control in both light intensity and wavelength dimensions increases the degree of freedom of control, providing a multi-mode platform to support all-optical signal processing in neuromorphic vision systems. In addition, the all-optical photoconductivity control stability of this invention ensures the repeatability and reliability of device function and guarantees the ability to maintain the state of weight updates, forming the foundation for realizing all-optical neuromorphic computing.

[0101] In summary, the all-optical synaptic device proposed in this invention completely eliminates the dependence on electrical signals. It does not require the introduction of electrical signal modulation and can achieve bidirectional photoconductive modulation using only pure optical signals. It can achieve not only dual-wavelength modulation but also single-wavelength modulation. It is compatible with dual modulation paradigms of light intensity and wavelength on the same hardware system, and achieves a qualitative leap in stability, energy efficiency, integration, modulation accuracy, and the purity of bio-inspiration.

[0102] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A fully optically controlled synaptic device, characterized in that, include: The substrate layer, active layer, and electrode layer are arranged sequentially from bottom to top. The electrode layer includes a source electrode and a drain electrode spaced apart on the active layer. An organic photosensitive layer is provided on the active layer between the source electrode and the drain electrode. The active layer is made of indium gallium zinc oxide, and the organic photosensitive layer is made of PDVT-10. The fully optically controlled synaptic device is used to achieve a cyclical reversible change in synaptic weight by changing the intensity of a single wavelength of light stimulation within a preset wavelength range, or by alternating light stimulation from a preset combination of two wavelengths.

2. The fully optically controlled synaptic device according to claim 1, characterized in that, The substrate has a thickness of 0.4-0.6 mm, the active layer has a thickness of 22-78 nm, the electrode layer has a thickness of 60-80 nm, and the organic photosensitive layer has a thickness of 40-59 nm.

3. The fully optically controlled synaptic device according to claim 2, characterized in that, The substrate has a thickness of 0.52 mm, the active layer has a thickness of 53 nm, the electrode layer has a thickness of 60 nm, and the organic photosensitive layer has a thickness of 49 nm.

4. A modulation method for a fully optically controlled synaptic device, applied to the fully optically controlled synaptic device according to any one of claims 1-3, characterized in that, A single wavelength of light stimulation with a preset wavelength range is applied to the fully optically controlled synaptic device in the form of pulses. By changing the intensity of the light stimulation, the synaptic weight of the fully optically controlled synaptic device exhibits a cyclical reversible change of enhancement and inhibition.

5. The modulation method for the all-optically controlled synaptic device according to claim 4, characterized in that, Under single-wavelength light stimulation, when the light power density of the light stimulation is greater than the preset light power density, the fully optically controlled synaptic device exhibits a synaptic weight enhancement effect, and the photoconductivity of the fully optically controlled synaptic device is enhanced. The higher the light power density, the greater the photoconductivity value. When the optical power density of the light stimulus is less than or equal to the preset optical power density, the fully optically controlled synaptic device exhibits a synaptic weight suppression effect, resulting in a decrease in photoconductivity. The higher the optical power density, the weaker the synaptic weight suppression effect becomes. When the optical power density increases to the preset optical power density, it transforms into a synaptic weight enhancement effect.

6. The modulation method for the all-optically controlled synaptic device according to claim 4, characterized in that, The preset range is 400 ~ 480 nm; Preferably, the preset range is 420 ~ 440 nm; Preferably, the preset range is 429 ~ 431 nm.

7. A modulation method for a fully optically controlled synaptic device, applied to the fully optically controlled synaptic device according to any one of claims 1-3, characterized in that, By alternately applying light stimulation from a preset dual-wavelength combination in the form of pulses to the fully optically controlled synaptic device, the synaptic weight of the fully optically controlled synaptic device can achieve a cyclical and reversible change of enhancement and inhibition.

8. The modulation method for the all-optically controlled synaptic device according to claim 7, characterized in that, The preset dual-wavelength combinations are 340 nm and 625 nm, 340 nm and 530 nm, 430 nm and 530 nm, or 430 nm and 625 nm.

9. A method for fabricating a fully optically controlled synaptic device, characterized in that, include: Pretreatment of the substrate; An active layer is formed on the pretreated substrate; wherein the active layer is made of indium gallium zinc oxide. An electrode layer is formed on the active layer; wherein the electrode layer includes source electrodes and drain electrodes spaced apart on the active layer; An organic photosensitive layer is formed on the active layer between the source electrode and the drain electrode; wherein, the material of the organic photosensitive layer is PDVT-10; The fully optically controlled synaptic device is used to achieve a cyclical reversible change in synaptic weight by changing the intensity of a single wavelength of light stimulation within a preset wavelength range, or by alternating light stimulation from a preset dual-wavelength combination.

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