Photoelectric neural electrode and preparation method and application thereof

Abstract

The invention provides a photoelectric neural electrode and a preparation method and application thereof. The photoelectric neural electrode sequentially comprises a substrate, an electrode layer and a heterostructure photoelectric active layer which are stacked from bottom to top, wherein the heterostructure photoelectric active layer sequentially comprises a p-type light absorption donor layer, a function regulation and control layer and an n-type electron acceptor layer which are stacked from bottom to top; the function regulation and control layer, the p-type light absorption donor layer and the n-type electron acceptor layer form a cascading relation or a bridging relation on an energy band, and the function regulation and control layer is a channel capable of providing in-plane direction charge transmission. The functional regulation and control layer is introduced between the donor layer and the acceptor layer to construct an energy band synergistic heterostructure, so that the photoelectric neural electrode prepared based on the heterostructure can realize higher photocurrent density and charge injection density, has quick response and excellent water phase stability, can realize bidirectional charging and discharging, and has a wide application prospect. The requirements of a nerve interface on sensitivity, time sequence and stability can be met, and the specific biological application prospect is achieved.

Description

Technical Field

[0001] This invention belongs to the field of medical devices and bioelectronics technology, specifically relating to a photoelectric neural electrode, its preparation method, and its application. Background Technology

[0002] Photoelectric nerve electrodes (also known as photocapacitor electrodes) generate charge carriers through light absorption and achieve bidirectional charge and discharge output in an electrolyte environment through interfacial capacitance. This avoids irreversible interfacial changes caused by Faraday reactions and has the advantages of low damage and simple structure.

[0003] Existing research has shown that photoelectric neural electrodes with donor / acceptor organic bilayer structures as their core (such as a stack of H2Pc (phthalocyanine) and PTCDI (3,4,9,10-perylenetetracarboxydiimide)) exhibit fast photoresponse and good aqueous stability, and possess certain absorption and photogenerated charge separation capabilities in the red to near-infrared wavelength range. However, these structures are limited by factors such as the potential difference at the donor / acceptor interface, band docking, and molecular orientation, resulting in problems such as high carrier recombination rate and insufficient in-plane transport channels. This leads to low charge output per unit area and photoelectric conversion efficiency, and the generated photostimulation signal decays rapidly and has poor reproducibility, making it difficult to achieve high-density and stable neural stimulation.

[0004] To improve carrier transport efficiency, some studies have attempted to introduce conductive oxides or graphene between the donor and acceptor layers. However, these materials often face challenges such as poor bandgap matching with the donor / acceptor layers, complex low-temperature transfer processes, and decreased interface reliability under repeated deformation of flexible substrates, making it difficult to achieve long-term stable operation in physiological electrolyte environments and low-modulus flexible device platforms. Other technical approaches, such as those utilizing short-wavelength blue-green light excitation, quantum dot recombination, upconversion particle driving, or pure inorganic heterojunction systems, have significant limitations in terms of tissue penetration, biocompatibility, pump power, and flexibility compatibility.

[0005] Therefore, how to achieve higher photocurrent density and higher charge injection density in physiological electrolytes while maintaining rapid response and aqueous phase stability is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a photoelectric neural electrode, its fabrication method, and its applications. The present invention introduces a functional modulation layer between a p-type light-absorbing donor layer and an n-type electron acceptor layer, constructing a heterostructure photoelectric active layer with band synergistic relationships. This functional modulation layer not only forms band cascades or bridges with adjacent layers, efficiently promoting the directional separation and interface injection of photogenerated carriers and significantly suppressing recombination losses, but also possesses high in-plane mobility, providing a rapid charge transport channel and enhancing charge transport efficiency. Based on this, the photoelectric neural electrode can achieve higher photocurrent density, higher charge injection density, and high photoelectric conversion efficiency in physiological electrolytes while maintaining rapid response and excellent aqueous stability. Furthermore, when operating in aqueous electrolytes, the photoelectric neural electrode can achieve bidirectional charging and discharging by triggering charge separation in the heterogeneous photoactive layer through light incident radiation and coupling via interfacial capacitance. This allows it to be used for phototriggered electrical stimulation modulation of peripheral nerve bundle surfaces, organ surfaces, and the cerebral cortex. The photoelectric neural electrode exhibits strong absorption in the red to near-infrared band, achieving millisecond-level transient photoelectric response and high surface capacitance output. In addition, the electrode maintains excellent performance stability even under long-term aqueous immersion and flexible bending conditions, thus balancing high energy density output, long-term operational reliability, and flexible compatibility with biological tissues. This meets the comprehensive requirements of neural interfaces for sensitivity, timing, and stability, demonstrating feasibility for engineering and biological applications.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a photoelectric neural electrode, which comprises, from bottom to top, a stacked substrate, an electrode layer, and a heterostructured photoelectric active layer.

[0009] The heterostructure photoelectric active layer comprises, from bottom to top, a stacked p-type light-absorbing donor layer, a functional modulation layer, and an n-type electron acceptor layer; the functional modulation layer forms a cascaded or bridged relationship with the p-type light-absorbing donor layer and the n-type electron acceptor layer in the energy band, and the functional modulation layer is a channel that can provide in-plane charge transport.

[0010] This invention introduces a functional modulation layer between a p-type light-absorbing donor layer and an n-type electron acceptor layer to construct a heterostructure photoelectric active layer with band synergy. This functional modulation layer forms a band cascade or bridging structure with the adjacent donor and acceptor layers, effectively promoting the directional separation and interface injection of photogenerated carriers and reducing recombination losses. Simultaneously, the functional modulation layer exhibits high in-plane mobility, providing a fast transport channel for carriers, thereby improving overall charge transport efficiency.

[0011] Based on the aforementioned energy level coupling mechanism, the photoelectric neural electrode of this invention can achieve high photocurrent density and charge injection density in physiological electrolytes, realizing efficient photoelectric conversion while maintaining rapid response and aqueous phase stability. During operation, light incidence triggers charge separation in the heterostructure photoelectric active layer, and the generated charge carriers complete a bidirectional charging and discharging process through interfacial capacitance coupling, thereby achieving non-Radidatic electrical stimulation output.

[0012] This photoelectric neural electrode can be directly applied to peripheral nerve bundles, the heart, or the surface of the cerebral cortex to achieve red or near-infrared light-driven neural stimulation and modulation. It exhibits strong absorption in the red to near-infrared wavelength range, with a response time in the millisecond range, demonstrating high surface capacitance output. Even under conditions of long-term immersion in water and repeated flexible bending, the electrode's photoelectric output performance remains stable, balancing high energy density output, long-term reliability, and biocompatibility.

[0013] In this invention, the electrode layer provides a conductive path and enhances interlayer adhesion; the p-type light-absorbing donor layer absorbs light energy and generates photogenerated holes; the functional modulation layer regulates the band structure, promotes electron transport, and reduces interfacial recombination; and the n-type electron acceptor layer accepts photogenerated electrons and forms a charge separation interface. This multi-layered, synergistic heterostructure photoelectric active layer achieves efficient photogenerated charge separation and interfacial capacitance output through energy level coupling, enabling the device to stably achieve photoelectric conversion and output neural stimulation signals under external illumination.

[0014] Preferably, the functional control layer is a two-dimensional semiconductor layer, and the material of the two-dimensional semiconductor layer includes any one or a combination of at least two of transition metal dichalcogenides, graphene-like materials or conductive oxides, preferably a few-layer transition metal dichalcogenide.

[0015] In this invention, the functional regulation layer is preferably a two-dimensional semiconductor material with high in-plane mobility and compatibility with the energy levels of the donor / acceptor layer, which can provide cascade transport in the conduction band or valence band direction and suppress interfacial recombination.

[0016] It should be noted that in few-layer transition metal dichalcogenides, "few-layer" means that there are 2 to 10 layers of atoms stacked by van der Waals forces.

[0017] Preferably, the thickness of the functional control layer is ≤5nm, for example, it can be 1nm, 2nm, 3nm, 4nm or 5nm, etc.

[0018] Preferably, the transition metal dichalcogenide includes any one or a combination of at least two of MoS2, WS2, MoSe2 or WSe2.

[0019] This invention preferably uses transition metal dichalcogenides (TMDs) as the functional control layer. On the one hand, they have tunable band gaps and work functions, which can form ideal band cascades or bridging structures between the donor and acceptor layers, thereby significantly promoting the directional separation and cross-interface injection of photogenerated carriers and reducing interfacial recombination losses. On the other hand, these materials have high in-plane electron mobility and excellent van der Waals interlayer bonding characteristics, which can construct stable, low-defect electron transport channels without destroying the organic layer lattice structure, thereby improving the interfacial charge transport rate.

[0020] Preferably, the thickness of the functional control layer is 1-3 nm, for example, it can be 1 nm, 2 nm or 3 nm.

[0021] This invention limits the thickness of the functional modulation layer to 1-3 nm. This thickness range ensures continuous interlayer coverage while maintaining the few-layer structure of the two-dimensional semiconductor, positioning its energy band between the donor and acceptor layers to form a stable band cascade relationship, thereby achieving efficient photogenerated carrier separation and cross-interface injection. When the thickness is less than 1 nm, the functional modulation layer is prone to sheet discontinuities or pinhole defects, leading to increased interfacial barriers and aggravated recombination losses. When the thickness exceeds 3 nm, interlayer energy level coupling weakens, electron transport channels lengthen, and interfacial resistance increases, resulting in decreased response speed and increased energy loss. Therefore, controlling the thickness within 1-3 nm balances carrier transport efficiency, band matching accuracy, and flexible structure stability, representing a preferred range for achieving high photoelectric conversion efficiency and long-term aqueous phase stability.

[0022] Preferably, the thickness ratio of the p-type light-absorbing donor layer, the functional modulation layer, and the n-type electron acceptor layer is (40-60):(1-3):(30-50), wherein the selection range of the p-type light-absorbing donor layer "40-60" can be, for example, 40, 50, or 60, the selection range of the functional modulation layer "1-3" can be, for example, 1, 2, or 3, and the selection range of the n-type electron acceptor layer "30-50" can be, for example, 30, 40, or 50.

[0023] In this invention, the synergistic thickness coordination among the p-type light-absorbing donor layer, the functional modulation layer, and the n-type electron acceptor layer facilitates the precise construction of the band gradient and the optimization of the charge transport path. By controlling the thickness of the donor layer to be 40-60 nm, the functional modulation layer to be 1-3 nm, and the acceptor layer to be 30-50 nm, the migration balance of electrons and holes can be maintained while ensuring sufficient light absorption. This allows photogenerated carriers to achieve rapid separation and efficient injection among the donor, modulation, and acceptor layers, thereby significantly improving photoelectric conversion efficiency and capacitive charge-discharge response. This thickness ratio also avoids the increase in series resistance and recombination loss caused by excessively thick layers, while improving interface adhesion and the stability of the flexible structure, enabling the device to maintain high output performance even after repeated bending or long-term aqueous environments.

[0024] Preferably, the material of the p-type light-absorbing donor layer is an organic semiconductor material, which includes any one or a combination of at least two of phthalocyanine compounds, pentanebenzene compounds, or thiophene-dithiophene compounds, preferably phthalocyanine compounds.

[0025] Preferably, the phthalocyanine compounds include H2Pc (Pigment Blue 16), F 16 H2Pc, metal phthalocyanine compounds, naphthalene phthalocyanine compounds, or functionalized phthalocyanine derivatives with substituents, or a combination of at least two of these.

[0026] Preferably, the metal phthalocyanine compound includes any one or a combination of at least two of CuPc, ZnPc, CoPc, NiPc, or MgPc.

[0027] Preferably, the naphthalene phthalocyanine compound comprises H₂Nc and / or CuNc. It should be noted that the naphthalene phthalocyanine compound is of the extended absorption wavelength type.

[0028] Preferably, the functionalized phthalocyanine derivative with substituents includes Pc-NH2 and / or Pc-COOH. It should be noted that the functionalized phthalocyanine derivative with substituents can achieve photoelectric response matching across different wavelength bands.

[0029] Preferably, the thickness of the p-type light-absorbing donor layer is 40-60 nm, for example, it can be 40 nm, 50 nm or 60 nm.

[0030] Preferably, the material of the n-type electron acceptor layer is an organic semiconductor material, which includes any one or a combination of at least two of pentane compounds, perylene diimide compounds, or fullerene derivatives, preferably perylene diimide compounds. For example, pentane compounds may be pentanebenzene, 6,13-dimethylpentanebenzene, or 6,13-diphenylacetylenepentane, etc.; for example, perylene diimide compounds may be N,N′-dicyclohexyl-3,4,9,10-perylenedicarboximide (PTCDI-C1, Pigment Red 179), N,N′-di-n-butyl-3,4,9,10-perylenedicarboximide (PTCDI-C4), N,N′-di(1-hexyl)perylenedicarboximide (PTCDI-C6) or their halogenated derivatives (such as fluorinated or chlorinated PTCDI), etc.; for example, fullerene derivatives may be C 60 C 70 [6,6]-phenyl-C 61 methyl butyrate (PCBM), [6,6]-phenyl-C 71 methyl butyrate (PC) 71 BM) or its substituted derivatives, etc.

[0031] Preferably, the perylene diimide compound includes N,N′-dicyclohexyl-3,4,9,10-perylene dicarboximide.

[0032] Preferably, the thickness of the n-type electron acceptor layer is 30-50 nm, for example, it can be 30 nm, 40 nm or 50 nm.

[0033] Preferably, the total thickness of the heterostructure photoelectric active layer is ≤100nm, for example, it can be 100nm, 90nm, 85nm, 80nm, 75nm or 70nm, etc.

[0034] Preferably, the electrode layer comprises any one of a metal layer, a transparent conductive oxide layer, or a conductive polymer layer. For example, the metal layer may be at least one of an Au layer, a Pt layer, or a Cr layer; the transparent conductive oxide layer may be, for example, an ITO layer; and the conductive polymer layer may be, for example, a PEDOT:PSS transparent conductive layer.

[0035] It should be noted that the material selection for the electrode layer must meet the comprehensive requirements of light incidence, low impedance, and flexibility.

[0036] Preferably, the thickness of the electrode layer is 5-50 nm, for example, it can be 5 nm, 10 nm, 20 nm, 30 nm, 40 nm or 50 nm.

[0037] Preferably, the surface roughness Ra of the electrode layer is ≤5nm, for example, it can be 5nm, 4nm, 3nm, 2nm or 1nm, etc.

[0038] In this invention, the low surface roughness of the electrode layer facilitates the formation of a dense, uniform, and continuous thin film interface during the deposition of the p-type light-absorbing donor layer, thereby reducing the density of interface trap states and local electric field distortion, and preventing carrier recombination or leakage at rough protrusions. Simultaneously, the smooth electrode surface improves the adhesion and interfacial contact area between the donor layer and the electrode, reduces contact resistance, and promotes efficient charge injection and extraction. Furthermore, the lower surface roughness reduces stress concentration during bending of the flexible substrate, preventing cracking or peeling of the organic layer, thus significantly improving the structural integrity and photoelectric stability of the device under repeated bending and long-term aqueous environments.

[0039] It should be noted that the choice of electrode material must ensure that the overall optical path and electrode layout meet the synchronous requirements of light incidence and capacitive coupling.

[0040] Preferably, the substrate is a flexible substrate, and the material of the flexible substrate includes any one or a combination of at least two of the following: pyrene-C, polyimide, or polyethylene terephthalate.

[0041] Preferably, the thickness of the substrate is 1-5 μm, for example, it can be 1 μm, 2 μm, 3 μm, 4 μm or 5 μm.

[0042] Preferably, the photoelectric neural electrode further includes an edge encapsulation layer, which encapsulates the circumferential edge region of the entire photoelectric neural electrode. The purpose of introducing the edge encapsulation layer is to facilitate the implantation operation, and it should be noted that the functional area for electrical stimulation is not encapsulated.

[0043] Preferably, the total thickness of the photoelectric nerve electrode is ≤6μm, for example, it can be 6μm, 5μm, 4μm, 3μm, 2μm, 1.5μm or 1μm, etc.

[0044] The total thickness of the photoelectric nerve electrode of this invention is ≤6μm to obtain good bending durability and compliance, and to maintain the stability of output performance.

[0045] In a second aspect, the present invention provides a method for preparing a photoelectric neural electrode as described in the first aspect, the method comprising the following steps:

[0046] Provide a base.

[0047] An electrode layer and a heterostructure photoactive layer are sequentially fabricated on the substrate; wherein, the heterostructure photoactive layer comprises, from bottom to top, a stacked p-type light-absorbing donor layer, a functional modulation layer, and an n-type electron acceptor layer; the functional modulation layer forms a cascaded or bridged relationship with the p-type light-absorbing donor layer and the n-type electron acceptor layer in the energy band, and the functional modulation layer is capable of providing a channel for in-plane charge transport.

[0048] Preferably, the preparation steps of the heterostructure photoelectric active layer include:

[0049] (a) Deposit a p-type light-absorbing donor layer on the electrode layer.

[0050] (b) A functional modulation layer is prepared on the p-type light-absorbing donor layer.

[0051] (c) Deposit an n-type electron acceptor layer on the functional regulation layer.

[0052] Preferably, the preparation method of the functional regulation layer in step (b) is an in-situ growth method or an indirect growth method.

[0053] It should be noted that the in-situ growth method refers to the direct in-situ formation of a functional control layer on a p-type light-absorbing donor layer. A continuous two-dimensional semiconductor layer is generated at the interface through gas-phase or solution chemical reaction, achieving no intermediate layer contamination and precise thickness control.

[0054] Preferably, the indirect growth method includes: preparing an independent functional regulation layer, and then transferring the independent functional regulation layer onto a p-type light-absorbing donor layer.

[0055] In this invention, the indirect growth method can avoid high-temperature or reactive treatment on the p-type light-absorbing donor layer, ensuring that the donor layer structure and energy level are not damaged. At the same time, a uniform, continuous functional control layer with a few layers of controllable thickness can be obtained through selective transfer.

[0056] Preferably, the preparation method of the independent functional regulation layer includes any one of chemical vapor deposition, liquid phase exfoliation, or sol-gel method.

[0057] Preferably, the transfer method includes any one of solution spin coating, van der Waals transfer, or surface activation transfer.

[0058] In this invention, the van der Waals transfer method refers to the use of van der Waals forces between the functional control layer and the target substrate (i.e., the p-type light-absorbing donor layer) to transfer a two-dimensional semiconductor material prefabricated on a temporary carrier substrate to the surface of the p-type light-absorbing donor layer. Its advantage is that a smooth interface can be formed without chemical bonding reactions, making it suitable for flexible organic systems. The surface activation transfer method refers to activating the target surface through plasma, ultraviolet ozone, or chemical activators to increase its surface energy, thereby achieving low-temperature adhesion and transfer of the functional control layer.

[0059] Preferably, in the van der Waals transfer method, the functional modulation layer is attached to the surface of the p-type light-absorbing donor layer by van der Waals forces, forming a band-coupled heterojunction interface.

[0060] Preferably, in the surface activation transfer method, before the functional modulation layer and the p-type light-absorbing donor layer are bonded, the interface between them is pre-activated by ultraviolet ozone or plasma. The purpose of the pre-activation treatment is to improve the cleanliness and adhesion between the layers.

[0061] Preferably, the preparation method includes the following steps:

[0062] (1) Provide a flexible substrate with a thickness of 1-5 μm, wherein the material of the flexible substrate includes any one or a combination of at least two of the following: Pyrene-C, polyimide or polyethylene terephthalate.

[0063] (2) An electrode layer with a thickness of 5-50 nm is deposited on the flexible substrate by thermal evaporation or sputtering; the electrode layer includes any one of a metal layer, a transparent conductive oxide layer or a conductive polymer layer.

[0064] A patterned mask layer (exemplary, such as a stainless steel mask or a mask formed by photolithography) is provided on the electrode layer.

[0065] (3) A p-type light-absorbing donor layer with a thickness of 40-60 nm is deposited on the patterned mask layer using a thermal evaporation method; the material of the p-type light-absorbing donor layer is an organic semiconductor material, the organic semiconductor material is a phthalocyanine compound, and the phthalocyanine compound is H2Pc, CuPc or F 16 Any one or at least two combinations of H2Pc.

[0066] (4) Prepare an independent two-dimensional semiconductor layer, and then transfer the independent two-dimensional semiconductor layer onto a p-type light-absorbing donor layer; wherein, the preparation method of the independent two-dimensional semiconductor layer includes any one of chemical vapor deposition, liquid phase exfoliation or sol-gel method; the transfer method includes any one of solution spin coating, van der Waals transfer or surface activation transfer method; the material of the two-dimensional semiconductor layer includes any one or a combination of at least two of MoS2, WS2 or WSe2.

[0067] (5) Using thermal evaporation, an n-type electron acceptor layer with a thickness of 30-50 nm is deposited on the two-dimensional semiconductor layer after transfer in step (4); the material of the n-type electron acceptor layer is an organic semiconductor material, which includes any one or a combination of at least two of pentadiene compounds, perylene diimide compounds or fullerene derivatives.

[0068] Thirdly, the present invention provides an application of the photoelectric nerve electrode as described in the first aspect in the photoelectric modulation of nerve tissue.

[0069] Preferably, the photoelectric nerve electrode is used for wireless light stimulation of the surface of peripheral nerve bundles or the brain surface, and the charge density and time constant generated under predetermined light intensity and pulse conditions meet the requirements of the nerve excitation threshold.

[0070] It should be noted that those skilled in the art will understand that, without departing from the basic concept of this invention, the material type, thickness, and crystal orientation of the functional regulation layer can be optimized and adjusted according to the target spectral band and carrier transport requirements; the materials of the donor layer and acceptor layer can also be selected from organic field-effect transistors or high-mobility organic semiconductors commonly found in organic photovoltaic systems, such as phthalocyanines, perylene diimides, thiophene-dithiophenes, or fullerene derivatives. The electrode layer and encapsulation system can be selected based on light flux, tissue compatibility, and long-term stability to balance conductivity, mechanical flexibility, and physiological environmental adaptability. Furthermore, the device shape, layer structure, and array layout can be structurally designed and sized according to the type of nerve tissue, implantation path, and application site to achieve adaptation to different nerve or organ surfaces. In addition to neural modulation, the photoelectric nerve electrode proposed in this invention can be extended to applications such as micro-light energy conversion, in vivo micro-sensing, low-power implantable energy, and flexible bioelectronic systems.

[0071] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0072] Compared with the prior art, the present invention has the following beneficial effects:

[0073] (1) In this invention, a functional regulation layer is introduced between the p-type light-absorbing donor layer and the n-type electron acceptor layer to construct a heterostructure photoelectric active layer with band synergy. This functional regulation layer forms a band cascade or bridging structure with the adjacent donor and acceptor layers, which can effectively promote the directional separation and interface injection of photogenerated carriers and reduce recombination losses. At the same time, the functional regulation layer has a high in-plane mobility, providing a fast transport channel for carriers, thereby improving the overall charge transport efficiency.

[0074] Based on the aforementioned energy level coupling mechanism, the photoelectric neural electrode of this invention can achieve high photocurrent density and charge injection density in physiological electrolytes, realizing efficient photoelectric conversion while maintaining rapid response and aqueous phase stability. During operation, light incidence triggers charge separation in the heterostructure photoelectric active layer, and the generated charge carriers complete a bidirectional charging and discharging process through interfacial capacitance coupling, thereby achieving non-Radidatic electrical stimulation output.

[0075] (2) This photoelectric neural electrode can be directly applied to the peripheral nerve bundles, the heart, or the surface of the cerebral cortex to achieve nerve stimulation and modulation driven by red or near-infrared light. It has strong absorption capacity in the red to near-infrared band, and the response time can reach the millisecond level, exhibiting high surface capacitance output. Even under long-term aqueous immersion and repeated flexible bending conditions, the photoelectric output performance of the electrode remains stable, taking into account high energy density output, long-term reliability, and bio-flexibility matching.

[0076] (3) In this invention, the electrode layer provides a conductive path and enhances interlayer adhesion; the p-type light-absorbing donor layer is responsible for absorbing light energy and generating photogenerated holes; the functional regulation layer is used to adjust the band structure, promote electron transport, and reduce interfacial recombination; and the n-type electron acceptor layer is used to accept photogenerated electrons and form a charge separation interface. The above-mentioned multilayer synergistic heterostructure photoelectric active layer achieves efficient photogenerated charge separation and interfacial capacitance output through energy level coupling, enabling the device to stably achieve photoelectric conversion and nerve stimulation signal output under external illumination. Attached Figure Description

[0077] Figure 1 This is a partial structural schematic diagram of the photoelectric nerve electrode provided in Embodiment 1 of the present invention.

[0078] Figure 2This is a schematic diagram of the energy band structure of the heterostructure photoelectric active layer in the photoelectric nerve electrode provided in Embodiment 1 of the present invention.

[0079] Figure 3 This is a process flow diagram provided in Embodiment 1 of the present invention.

[0080] Figure 4 This is a comparison chart of the charge-discharge curves of the photoelectric nerve electrodes provided in Example 1 and Comparative Example 1 of this invention.

[0081] Figure 5 This is a schematic diagram of the application of the photoelectric nerve electrode provided in Embodiment 1 of the present invention in cardiac tissue.

[0082] Figure 6 This is a schematic diagram of the application of the photoelectric neural electrode provided in Embodiment 1 of the present invention in brain tissue.

[0083] Figure 7 This is a schematic diagram illustrating the application of the photoelectric nerve electrode provided in Embodiment 1 of the present invention in peripheral nerve tissue.

[0084] Among them, 1-flexible substrate; 2-electrode layer; 3-p-type light-absorbing donor layer; 4-two-dimensional semiconductor layer; 5-n-type electron acceptor layer; 6-heart; 7-photoelectric nerve electrode; 8-laser source; 9-brain; 10-peripheral nerve. Detailed Implementation

[0085] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0086] It should be understood that in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0087] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0088] Example 1

[0089] This embodiment provides a photoelectric neural electrode, and a partial structural schematic diagram is shown below. Figure 1 As shown, the photoelectric neural electrode comprises, from bottom to top, a layered flexible substrate 1, an electrode layer 2, and a heterogeneous photoelectric active layer.

[0090] The heterostructure photoelectric active layer comprises, from bottom to top, a stacked p-type light-absorbing donor layer 3, a two-dimensional semiconductor layer 4, and an n-type electron acceptor layer 5; the two-dimensional semiconductor layer 4 is made of MoS2 and has a thickness of 2 nm; the p-type light-absorbing donor layer 3 is made of H2Pc and has a thickness of 50 nm; the n-type electron acceptor layer 5 is made of PTCDI-C1 and has a thickness of 40 nm; the thickness ratio of the p-type light-absorbing donor layer 3, the two-dimensional semiconductor layer 4, and the n-type electron acceptor layer 5 is 50:2:40; and the total thickness of the heterostructure photoelectric active layer is 92 nm.

[0091] The electrode layer 2 comprises an Au layer with a thickness of 5 nm and a Cr layer with a thickness of 3 nm, and the surface roughness Ra of the electrode layer 2 is 3 nm; the flexible substrate 1 is made of Pyrelin-C and has a thickness of 3 μm; the photoelectric nerve electrode also includes an edge encapsulation layer, which is used to encapsulate the circumferential edge region of the entire photoelectric nerve electrode; the total thickness of the photoelectric nerve electrode is 3.1 μm.

[0092] This embodiment also provides a method for preparing the above-mentioned photoelectric neural electrode, the process flow diagram of which is shown below. Figure 3 As shown, the preparation method includes the following steps:

[0093] (1) Provide a flexible substrate with a thickness of 3μm and a material of Pyrene-C, and subject the flexible substrate to ultrasonic cleaning of acetone and isopropanol for 10 min in sequence, and dry it at 60°C.

[0094] (2) An electrode layer is formed by depositing an Au layer with a thickness of 5 nm and a Cr layer with a thickness of 3 nm on the flexible substrate by means of thermal evaporation.

[0095] A patterned mask layer is formed on the electrode layer by photolithography.

[0096] (3) A 50 nm thick H2Pc thin film is deposited on the patterned mask layer by thermal evaporation at a rate of 0.1 nm / s to form a p-type light-absorbing donor layer.

[0097] (4) Prepare an independent MoS2 film, and then transfer the independent MoS2 film onto a p-type light-absorbing donor layer to form a two-dimensional semiconductor layer; wherein the preparation method of the independent MoS2 film is liquid phase exfoliation; and the transfer method is solution spin coating.

[0098] (5) A PTCDI-C1 thin film with a thickness of 40 nm is deposited on the two-dimensional semiconductor layer by thermal evaporation to form an n-type electron acceptor layer.

[0099] (6) An edge encapsulation layer is deposited in the circumferential edge region of the device obtained in step (5), and the material of the edge encapsulation layer is Pyrene-C.

[0100] Figure 2 A schematic diagram of the energy band structure of the heterostructure photoactive layer in the photoelectric neural electrode provided in this embodiment is shown. As can be seen from the figure, the heterostructure photoactive layer consists of a p-type light-absorbing donor layer 3, a two-dimensional semiconductor layer 4, and an n-type electron acceptor layer 5. Its energy level distribution forms a continuous energy band cascade structure. The vertical axis represents the energy level, with energy decreasing from top to bottom; the horizontal axis represents the position, indicating the order of the interlayer arrangement. The highest occupied molecular orbital (HOMO) of the p-type light-absorbing donor layer 3 is located at -5.2 eV, and the lowest unoccupied molecular orbital (LUMO) is located at -3.4 eV; the conduction band bottom (CB) of the two-dimensional semiconductor layer 4 is approximately -4.1 eV, and the valence band top (VB) is approximately -5.7 eV; the LUMO of the n-type electron acceptor layer 5 is -4.0 eV, and the HOMO is -6.7 eV. Under illumination, the p-type light-absorbing donor layer 3 absorbs photons, generating photogenerated electrons and holes. Electrons are transferred from the LUMO of H2Pc through the conduction band of MoS2 to the LUMO of PTCDI, achieving layer-by-layer electron transport. Holes migrate from the HOMO of PTCDI to the HOMO of H2Pc, forming hole migration channels. Since the energy level of MoS2 is located between H2Pc and PTCDI, it can effectively reduce the interface barrier and block the back diffusion of holes, thereby improving carrier separation efficiency and photoelectric conversion performance.

[0101] Figure 5This diagram illustrates the application of the photoelectric neural electrode provided in this embodiment in cardiac tissue. As shown in the figure, the photoelectric neural electrode 7 is a flexible attachment structure that can be directly attached to the surface of the heart 6, forming a stable capacitive coupling interface with the cardiac tissue surface through its flexible substrate. When light of a specific wavelength emitted by an external laser source 8 irradiates the surface of the photoelectric neural electrode 7, the heterogeneous photoelectric active layer in the photoelectric neural electrode 7 absorbs the light energy and generates transient charge separation, forming a controllable bidirectional capacitive charging and discharging process. This achieves non-invasive electrical stimulation of the cardiac 6 neural tissue without metal electrode polarization or the absence of a Radial reaction. This scheme utilizes the high tissue penetration of red or near-infrared light to achieve wireless light-driven stimulation of deep tissues. At the same time, the photoelectric neural electrode 7 can adapt to the dynamic movement of the heart 6, ensuring signal stability and biocompatibility under long-term implantation or surface attachment. Therefore, this figure illustrates the potential application scenarios of the photoelectric neural electrode 7 provided by this invention in neural modulation and myocardial function regulation.

[0102] Figure 6 This diagram illustrates the application of the photoelectric neural electrode provided in this embodiment in brain tissue. As shown, the photoelectric neural electrode 7 is a flexible, adhesive structure that conforms to the surface of the brain cortex 9, forming a capacitive coupling interface with the cortical tissue through its flexible base. When light of a specific wavelength emitted by the laser source 8 irradiates the surface of the photoelectric neural electrode 7, the heterogeneous photoelectric active layer absorbs the light energy, resulting in carrier separation, transient charge accumulation, and inducing a controllable electrical stimulation signal at the tissue interface, thereby achieving photoelectric modulation of neurons. This structure can utilize the high tissue penetration of red or near-infrared light to achieve non-contact, wireless neural activation. Simultaneously, the photoelectric neural electrode 7 can adapt to the complex geometry of the brain 9 surface, maintaining excellent mechanical compliance and signal stability, avoiding tissue damage and signal drift caused by traditional metal electrodes. This diagram demonstrates that the photoelectric neural electrode 7 provided by this invention can be applied to brain nerve stimulation, epilepsy intervention, brain-computer interface signal modulation, and other fields.

[0103] Figure 7This diagram illustrates the application of the photoelectric nerve electrode provided in this embodiment in peripheral nerve tissue. As shown, the photoelectric nerve electrode 7 has a flexible ring or sleeve structure that can surround and cover the surface of the peripheral nerve 10 tissue, forming compliant contact with the nerve epineurium, thereby establishing a stable capacitive coupling interface. After an external laser source 8 emits light of a specific wavelength to irradiate the surface of the photoelectric nerve electrode 7, the heterogeneous photoactive layer inside the electrode absorbs the light energy and generates photogenerated carrier separation, thereby inducing a transient electric field at the nerve interface, achieving non-invasive light-driven modulation of the signal of the peripheral nerve 10. This structure can achieve high spatial resolution local stimulation without penetrating the tissue. By adjusting the light intensity, pulse width, and frequency, nerve excitation or inhibition behavior can be precisely controlled. Furthermore, the mechanical compatibility of the photoelectric nerve electrode 7 ensures its attachment stability during dynamic nerve movement, avoiding the mechanical stimulation and inflammatory response caused by traditional rigid electrodes. This diagram demonstrates that the photoelectric nerve electrode provided by this invention can be widely used in peripheral nerve repair, pain control, nerve regeneration, and implantable brain-nerve interfaces.

[0104] Example 2

[0105] This embodiment provides a photoelectric neural electrode, which, from bottom to top, comprises a stacked flexible substrate, an electrode layer, and a heterostructured photoelectric active layer.

[0106] The heterostructure photoelectric active layer comprises, from bottom to top, a stacked p-type light-absorbing donor layer, a two-dimensional semiconductor layer, and an n-type electron acceptor layer; the two-dimensional semiconductor layer is made of WS2 and has a thickness of 1 nm; the p-type light-absorbing donor layer is made of H2Pc and has a thickness of 40 nm; the n-type electron acceptor layer is made of PTCDI-C1 and has a thickness of 30 nm; the thickness ratio of the p-type light-absorbing donor layer, the two-dimensional semiconductor layer, and the n-type electron acceptor layer is 40:1:30; and the total thickness of the heterostructure photoelectric active layer is 71 nm.

[0107] The electrode layer is an Au layer with a thickness of 29 nm and a surface roughness Ra of 2.5 nm; the flexible substrate is made of Pyrelin-C and has a thickness of 3 μm; the photoelectric neural electrode also includes an edge encapsulation layer, which is used to encapsulate the circumferential edge region of the entire photoelectric neural electrode; the total thickness of the photoelectric neural electrode is 3.1 μm.

[0108] This embodiment also provides a method for preparing the above-mentioned photoelectric neural electrode, the method comprising the following steps:

[0109] (1) Provide a flexible substrate with a thickness of 3μm and a material of Pyrene-C, and subject the flexible substrate to ultrasonic cleaning of acetone and isopropanol for 10 min in sequence, and dry it at 60°C.

[0110] (2) An Au layer with a thickness of 29 nm is deposited on the flexible substrate by thermal evaporation to form an electrode layer.

[0111] A patterned mask layer is formed on the electrode layer by photolithography.

[0112] (3) A 40 nm thick H2Pc thin film is deposited on the patterned mask layer by thermal evaporation at a rate of 0.1 nm / s to form a p-type light-absorbing donor layer.

[0113] (4) Prepare an independent WS2 film and then transfer the independent WS2 film onto the p-type light-absorbing donor layer to form a two-dimensional semiconductor layer; wherein the preparation method of the independent WS2 film is chemical vapor deposition; the transfer method is van der Waals transfer; in the van der Waals transfer, the two-dimensional semiconductor layer is attached to the surface of the p-type light-absorbing donor layer by van der Waals forces to form a band-coupled heterojunction interface.

[0114] (5) A PTCDI-C1 thin film with a thickness of 30 nm is deposited on the two-dimensional semiconductor layer by thermal evaporation to form an n-type electron acceptor layer.

[0115] (6) An edge encapsulation layer is deposited in the circumferential edge region of the device obtained in step (5), and the material of the edge encapsulation layer is Pyrene-C.

[0116] Example 3

[0117] This embodiment provides a photoelectric neural electrode, which, from bottom to top, comprises a stacked flexible substrate, an electrode layer, and a heterostructured photoelectric active layer.

[0118] The heterostructure photoelectric active layer comprises, from bottom to top, a stacked p-type light-absorbing donor layer, a two-dimensional semiconductor layer, and an n-type electron acceptor layer; the two-dimensional semiconductor layer is made of WSe2 and has a thickness of 3 nm; the p-type light-absorbing donor layer is made of H2Pc and has a thickness of 60 nm; the n-type electron acceptor layer is made of PTCDI-C1 and has a thickness of 50 nm; the thickness ratio of the p-type light-absorbing donor layer, the two-dimensional semiconductor layer, and the n-type electron acceptor layer is 60:3:50; and the total thickness of the heterostructure photoelectric active layer is 113 nm.

[0119] The electrode layer is an Au layer with a thickness of 50 nm and a surface roughness Ra of 3 nm; the flexible substrate is made of Pyrelin-C and has a thickness of 3 μm; the photoelectric neural electrode also includes an edge encapsulation layer, which is used to encapsulate the circumferential edge region of the entire photoelectric neural electrode; the total thickness of the photoelectric neural electrode is 3.163 μm.

[0120] This embodiment also provides a method for preparing the above-mentioned photoelectric neural electrode, the method comprising the following steps:

[0121] (1) Provide a flexible substrate with a thickness of 3μm and a material of Pyrene-C, and subject the flexible substrate to ultrasonic cleaning of acetone and isopropanol for 10 min in sequence, and dry it at 60°C.

[0122] (2) An Au layer with a thickness of 50 nm is deposited on the flexible substrate by thermal evaporation to form an electrode layer.

[0123] A patterned mask layer is formed on the electrode layer by photolithography.

[0124] (3) A 60 nm thick H2Pc thin film is deposited on the patterned mask layer by thermal evaporation at a rate of 0.1 nm / s to form a p-type light-absorbing donor layer.

[0125] (4) Prepare an independent WSe2 film, and then transfer the independent WSe2 film onto the p-type light-absorbing donor layer to form a two-dimensional semiconductor layer; wherein, the preparation method of the independent WSe2 film is the sol-gel method; the transfer method is the surface activation transfer method; in the surface activation transfer method, before the two-dimensional semiconductor layer and the p-type light-absorbing donor layer are combined, the interface between the two is pre-activated by ultraviolet ozone.

[0126] (5) A PTCDI-C1 thin film with a thickness of 50 nm is deposited on the two-dimensional semiconductor layer by thermal evaporation to form an n-type electron acceptor layer.

[0127] (6) An edge encapsulation layer is deposited in the circumferential edge region of the device obtained in step (5), and the material of the edge encapsulation layer is Pyrene-C.

[0128] Example 4

[0129] The difference between this embodiment and embodiment 1 is that step (4) is replaced by the following steps:

[0130] A two-dimensional semiconductor layer was obtained by directly depositing a MoS2 film on the p-type light-absorbing donor layer using chemical vapor deposition.

[0131] The remaining preparation methods and parameters are consistent with those in Example 1.

[0132] Example 5

[0133] The difference between this embodiment and Embodiment 1 is that the thickness of the two-dimensional semiconductor layer is 10 nm.

[0134] The remaining preparation methods and parameters are consistent with those in Example 1.

[0135] Example 6

[0136] The difference between this embodiment and Embodiment 1 is that the material of the two-dimensional semiconductor layer is replaced with graphene.

[0137] The remaining preparation methods and parameters are consistent with those in Example 1.

[0138] Example 7

[0139] The difference between this embodiment and Embodiment 1 is that the material of the two-dimensional semiconductor layer is replaced with indium tin oxide (ITO).

[0140] The remaining preparation methods and parameters are consistent with those in Example 1.

[0141] Comparative Example 1

[0142] The difference between this comparative example and Example 1 is that no two-dimensional semiconductor layer is provided.

[0143] The remaining preparation methods and parameters are consistent with those in Example 1.

[0144] Figure 4 A comparison of the charge-discharge curves of the photoelectric neural electrodes provided in Example 1 and Comparative Example 1 is shown. As can be seen from the figure, the black curve corresponds to the photoresponse curve of the traditional H2Pc / PTCDI bilayer structure, while the red curve corresponds to the photoresponse curve of the heterostructure photoactive layer (H2Pc / MoS2 / PTCDI) introduced in this invention. Under 500ms light pulse irradiation, both structures exhibit typical photocapacitor charge-discharge behavior: the current density rises rapidly when the light is turned on, forming a charging peak; and the current reverses, resulting in a discharge peak, after the light is turned off. In contrast, the peak current density of the structure of this invention is significantly higher (approximately 5 times higher), indicating that it has higher photoelectric conversion and charge injection capabilities. This enhancement effect originates from the introduction of the MoS2 control layer: MoS2 provides conduction band cascade channels and blocks hole reverse migration, thereby achieving more efficient electron transport and interface charge separation. Furthermore, the structure of this invention exhibits a faster response speed and lower residual current during charge-discharge processes, indicating that carrier recombination is effectively suppressed and the interface capacitor charge-discharge process is more stable. Therefore, the photoelectric nerve electrode with a two-dimensional semiconductor layer is superior to the traditional double-layer structure in terms of photocurrent density, response rate and charge retention, which verifies the performance advantages of the present invention in photoelectric response and nerve stimulation applications.

[0145] Performance testing

[0146] The photoelectric neural electrodes provided in the above embodiments and comparative examples were subjected to photoelectric performance testing. The testing method was as follows: the photoelectric neural electrode was placed flat on a probe stage with the heterostructure photoactive layer facing upwards, and contacted with PBS (pH 7.4) buffer to form an electrolyte interface. During the test, no external voltage was applied, and the electrode operated in an open-circuit state. A red pulsed light source (wavelength 638 nm) was used to vertically illuminate the electrode surface, with a circular spot of approximately 1 cm in diameter. The light pulse was generated by TTL signal modulation to produce a rectangular pulse of the required duration (500 ms in the test) to simulate the phototriggered event under neural stimulation conditions. The photogenerated signal was extracted through the contact electrode, amplified by a signal amplifier, and the transient current-time curve was recorded by a high-speed acquisition card or oscilloscope. The obtained signal was integrated to calculate the charge injection per unit area, which was used to characterize the photoelectric response capability and capacitance charge-discharge characteristics of the device. The test conditions were as follows: the photoelectric performance test was conducted under simulated physiological conditions, and the test system was a single-electrode transient photoresponse mode. The photoelectric neural electrode was fixed on a transparent insulating substrate, with its heterostructured photoactive layer in contact with a PBS solution (pH 7.4). No external bias voltage was applied, and the electrode surface was vertically irradiated by a 638nm red pulsed light source with a spot diameter of approximately 1cm and a light intensity of 3mW / cm². 2 The optical pulses are modulated by a TTL signal to form rectangular pulses with a duration of 500ms, used to simulate light-triggered neural stimulation conditions. The device output signal is amplified and the transient current-time curve is recorded at the sampling rate. The test temperature is controlled at 25℃.

[0147] A cyclic bending experiment was conducted on the photoelectric neural electrodes provided in the above embodiments and comparative examples. The specific steps included: fixing the photoelectric neural electrode sample on a controllable bending device, and performing a reciprocating mechanical bending test with a bending radius of 3 mm and a bending angle of 180°. The bending rate was 30 times / min, and the total number of cycles was 500. After every 100 bends, under the same illumination conditions (638 nm, 3 mW / cm²), the samples were subjected to bending. 2 The transient photoelectric response curve of the device (with a pulse width of 100 ms) was measured, and the corresponding charge injection density was calculated. The output retention rate of the device was obtained by comparing the changes in charge injection density before and after bending.

[0148] Long-term immersion experiments were conducted on the photoelectric neural electrodes provided in the above embodiments and comparative examples. The specific steps included: immersing the photoelectric neural electrode samples in PBS solution (pH 7.4) and storing them at a constant temperature of 37°C to simulate long-term operation in a bodily fluid environment. Samples were removed every 24 hours, the surface was gently washed with deionized water, and then the samples were placed under the same light conditions (638 nm, 3 mW / cm²). 2The transient photoelectric response curve of the device was tested with a pulse width of 100ms, and the corresponding charge injection density was calculated. The output retention rate of the device was recorded by comparing the changes in charge injection density at different immersion times (1 day, 3 days, 7 days, 14 days, and 30 days).

[0149] The results are shown in Table 1.

[0150] Table 1

[0151]

[0152] analyze:

[0153] As shown in Table 1, this invention introduces a functional regulation layer between the p-type light-absorbing donor layer and the n-type electron acceptor layer to construct a heterostructure photoelectric active layer with band synergy. This functional regulation layer not only forms band cascades or bridges with adjacent layers, efficiently promoting the directional separation and interface injection of photogenerated carriers and significantly suppressing recombination losses, but also possesses high in-plane mobility, providing a fast charge transport channel and enhancing charge transport efficiency. Based on this, the photoelectric neural electrode can achieve higher photocurrent density, higher charge injection density, and high photoelectric conversion efficiency in physiological electrolytes while maintaining rapid response and excellent aqueous stability. Furthermore, when operating in aqueous electrolytes, the photoelectric neural electrode can achieve bidirectional charging and discharging by triggering charge separation in the heterogeneous photoactive layer through light incident radiation and coupling via interfacial capacitance. This allows it to be used for phototriggered electrical stimulation modulation of peripheral nerve bundle surfaces, organ surfaces, and the cerebral cortex. The photoelectric neural electrode exhibits strong absorption in the red to near-infrared band, achieving millisecond-level transient photoelectric response and high surface capacitance output. In addition, the electrode maintains excellent performance stability even under long-term aqueous immersion and flexible bending conditions, thus balancing high energy density output, long-term operational reliability, and flexible compatibility with biological tissues. This meets the comprehensive requirements of neural interfaces for sensitivity, timing, and stability, demonstrating feasibility for engineering and biological applications.

[0154] As can be seen from the comparison between Example 1 and Example 5, if the thickness of the two-dimensional semiconductor layer is too large, it will lead to a weakening of the interlayer potential gradient, a significant increase in series resistance, and a lengthening of the migration path of photogenerated carriers within the layer, thereby exacerbating recombination loss and causing a significant decrease in both photocurrent density and charge injection amount. At the same time, an excessively thick two-dimensional semiconductor layer is prone to microcracks under bending stress, reducing the device's flexibility, stability, and interface adhesion.

[0155] As can be seen from the comparison between Examples 1 and Examples 6 and 7, if the material of the two-dimensional semiconductor layer is replaced with graphene, although the conductivity is high, its work function has poor matching degree with the energy level of the adjacent organic layer, resulting in a low interface barrier, weakened carrier directional separation ability, easy electron-hole recombination, and reduced photoelectric response amplitude. If the material of the two-dimensional semiconductor layer is replaced with ITO, since ITO is a brittle inorganic oxide, its interface adhesion with the p-type light-absorbing donor layer and the n-type electron acceptor layer is poor. Under bending or long-term immersion conditions, interface delamination or microcracks are easy to occur. At the same time, its surface energy and polarity are too high, which can easily cause ion penetration and chemical degradation, resulting in rapid attenuation of device output.

[0156] As can be seen from the comparison between Example 1 and Comparative Example 1, if a two-dimensional semiconductor layer is not provided, an organic-organic interface is directly formed between the p-type light-absorbing donor layer and the n-type electron acceptor layer. The energy level difference is large and the interface electric field distribution is uneven. Photogenerated carrier recombination is severe, and electron transport is restricted, resulting in a significant decrease in photocurrent density and charge injection capability. As a result, efficient photoelectric conversion and stable capacitor charge-discharge response cannot be achieved.

[0157] It should be noted that the present invention is illustrated through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A photoelectric nerve electrode, characterized in that, The photoelectric neural electrode comprises, from bottom to top, a stacked substrate, an electrode layer, and a heterogeneous photoelectric active layer; The heterostructure photoelectric active layer comprises, from bottom to top, a stacked p-type light-absorbing donor layer, a functional modulation layer, and an n-type electron acceptor layer; the functional modulation layer forms a cascaded or bridged relationship with the p-type light-absorbing donor layer and the n-type electron acceptor layer in the energy band, and the functional modulation layer is a channel that can provide in-plane charge transport.

2. The photoelectric nerve electrode according to claim 1, characterized in that, The functional regulation layer is a two-dimensional semiconductor layer, and the material of the two-dimensional semiconductor layer includes transition metal dichalcogenides, preferably few-layer transition metal dichalcogenides. Preferably, the thickness of the functional control layer is ≤5nm.

3. The photoelectric nerve electrode according to claim 2, characterized in that, The transition metal dichalcogenides include any one or a combination of at least two of MoS2, WS2, MoSe2 or WSe2; Preferably, the thickness of the functional regulation layer is 1-3 nm; Preferably, the thickness ratio of the p-type light-absorbing donor layer, the functional modulation layer and the n-type electron acceptor layer is (40-60):(1-3):(30-50).

4. The photoelectric nerve electrode according to any one of claims 1-3, characterized in that, The material of the p-type light-absorbing donor layer is an organic semiconductor material, which includes any one or a combination of at least two of phthalocyanine compounds, pentacene compounds, or thiophene dithiophene compounds, preferably phthalocyanine compounds; Preferably, the phthalocyanine compounds include H2Pc and F. 16 H2Pc, metal phthalocyanine compounds, naphthalene phthalocyanine compounds, or functionalized phthalocyanine derivatives with substituents, or a combination of at least two of these. Preferably, the metal phthalocyanine compound includes any one or a combination of at least two of CuPc, ZnPc, CoPc, NiPc or MgPc; Preferably, the naphthalene phthalocyanine compound includes H2Nc and / or CuNc; Preferably, the functionalized phthalocyanine derivative with substituents includes Pc-NH2 and / or Pc-COOH; Preferably, the thickness of the p-type light-absorbing donor layer is 40-60 nm; Preferably, the material of the n-type electron acceptor layer is an organic semiconductor material, which includes any one or a combination of at least two of pentacene compounds, perylene diimide compounds, or fullerene derivatives, preferably perylene diimide compounds; Preferably, the perylene diimide compound includes N,N′-dicyclohexyl-3,4,9,10-perylene dicarboximide; Preferably, the thickness of the n-type electron acceptor layer is 30-50 nm; Preferably, the total thickness of the heterostructure photoelectric active layer is ≤100nm.

5. The photoelectric nerve electrode according to any one of claims 1-4, characterized in that, The electrode layer includes any one of a metal layer, a transparent conductive oxide layer, or a conductive polymer layer; Preferably, the thickness of the electrode layer is 5-50 nm; Preferably, the surface roughness Ra of the electrode layer is ≤5 nm; Preferably, the substrate is a flexible substrate, and the material of the flexible substrate includes any one or a combination of at least two of the following: Pyrene-C, polyimide, or polyethylene terephthalate. Preferably, the thickness of the substrate is 1-5 μm; Preferably, the photoelectric neural electrode further includes an edge encapsulation layer, which is used to encapsulate the circumferential edge region of the entire photoelectric neural electrode; Preferably, the total thickness of the photoelectric nerve electrode is ≤6μm.

6. A method for preparing a photoelectric neural electrode as described in any one of claims 1-5, characterized in that, The preparation method includes the following steps: Provide a base; An electrode layer and a heterostructure photoactive layer are sequentially fabricated on the substrate; wherein, the heterostructure photoactive layer comprises, from bottom to top, a stacked p-type light-absorbing donor layer, a functional modulation layer, and an n-type electron acceptor layer; the functional modulation layer forms a cascaded or bridged relationship with the p-type light-absorbing donor layer and the n-type electron acceptor layer in the energy band, and the functional modulation layer is capable of providing a channel for in-plane charge transport.

7. The preparation method according to claim 6, characterized in that, The preparation steps of the heterostructured photoelectric active layer include: (a) Depositing a p-type light-absorbing donor layer on the electrode layer; (b) A functional modulation layer is fabricated on the p-type light-absorbing donor layer; (c) Deposit an n-type electron acceptor layer on the functional regulation layer; Preferably, the preparation method of the functional regulation layer in step (b) is an in-situ growth method or an indirect growth method; Preferably, the indirect growth method includes: preparing an independent functional modulation layer, and then transferring the independent functional modulation layer onto a p-type light-absorbing donor layer; Preferably, the preparation method of the independent functional regulation layer includes any one of chemical vapor deposition, liquid phase exfoliation, or sol-gel method; Preferably, the transfer method includes any one of solution spin coating, van der Waals transfer, or surface activation transfer.

8. The preparation method according to claim 7, characterized in that, In the van der Waals transfer method, the functional modulation layer is attached to the surface of the p-type light-absorbing donor layer by van der Waals forces, forming a band-coupled heterojunction interface. Preferably, in the surface activation transfer method, before the functional regulation layer and the p-type light absorption donor layer are combined, the bonding interface between the two is pre-activated by ultraviolet ozone or plasma.

9. The preparation method according to any one of claims 6-8, characterized in that, The preparation method includes the following steps: (1) Provide a flexible substrate with a thickness of 1-5 μm, wherein the material of the flexible substrate includes any one or a combination of at least two of the following: Pyrene-C, polyimide or polyethylene terephthalate; (2) An electrode layer with a thickness of 5-50 nm is deposited on the flexible substrate by thermal evaporation or sputtering; the electrode layer includes any one of a metal layer, a transparent conductive oxide layer or a conductive polymer layer; A patterned mask layer is disposed on the electrode layer; (3) A p-type light-absorbing donor layer with a thickness of 40-60 nm is deposited on the patterned mask layer using a thermal evaporation method; the material of the p-type light-absorbing donor layer is an organic semiconductor material, the organic semiconductor material is a phthalocyanine compound, and the phthalocyanine compound includes H2Pc, CuPc or F 16 Any one or at least two of the H2Pcs; (4) Prepare an independent two-dimensional semiconductor layer, and then transfer the independent two-dimensional semiconductor layer onto a p-type light-absorbing donor layer; wherein, the preparation method of the independent two-dimensional semiconductor layer includes any one of chemical vapor deposition, liquid phase exfoliation or sol-gel method; the transfer method includes any one of solution spin coating, van der Waals transfer or surface activation transfer method; the material of the two-dimensional semiconductor layer includes any one or a combination of at least two of MoS2, WS2 or WSe2; (5) Using thermal evaporation, an n-type electron acceptor layer with a thickness of 30-50 nm is deposited on the two-dimensional semiconductor layer after transfer in step (4); the material of the n-type electron acceptor layer is an organic semiconductor material, which includes any one or a combination of at least two of pentadiene compounds, perylene diimide compounds or fullerene derivatives.

10. The application of a photoelectric neural electrode as described in any one of claims 1-5 in photoelectric modulation of nerve tissue.

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