A side-gate vertical photoelectrochemical device with a body heterojunction channel and a preparation method thereof

Abstract

The application discloses a kind of body heterojunction channel's side gate vertical photoelectrochemical device and preparation method thereof;The device includes transparent substrate, ITO bottom electrode, body heterojunction organic semiconductor channel layer, Au top electrode, side gate electrode and electrolyte;ITO bottom electrode, body heterojunction organic semiconductor channel layer and Au top electrode are sequentially laminated to form vertical current transmission path;Side gate electrode is through the electrolyte of simultaneously contacting side gate and channel exposure area to control channel ion-electron coupling state;ITO and Au form asymmetric contact structure, light is incident by transparent substrate and ITO side bottom, which is conducive to the separation, extraction and vertical transport of photo-generated carriers;Body heterojunction channel can use PM6:Y6, PM6:L8-BO, P3HT:PCBM and other donor-acceptor system;The structure can reduce the planar area of unit, and is suitable for constructing high-density retinal-like photoelectric sensing array, which can be used for photoelectric detection, bionic vision, optoelectronic synapse, memory resistance and sensory storage calculation integrated system.

Description

Technical Field

[0001] This invention belongs to the fields of organic electronic devices, organic photoelectrochemical transistors, biomimetic visual perception and neuromorphic electronics, and specifically relates to a side-gate vertical photoelectrochemical device with a bulk heterojunction channel and its preparation method. Background Technology

[0002] With the development of intelligent sensing and edge computing technologies, the integrated sensing-memory-computing architecture, which integrates information perception, state storage, and signal processing at the device level, has attracted widespread attention. Biological vision systems can complete light signal reception, preliminary processing, and information transmission at the retina, providing important inspiration for constructing low-power biomimetic sensor devices. Organic electrochemical transistors (OETTs) combine low-voltage gate control, ion-electron coupling, and signal amplification capabilities. When combined with photosensitive organic semiconductors, they can be used to construct retina-like devices with light sensing, state regulation, and memory characteristics. However, existing OETTs mostly employ planar source-drain structures, which suffer from problems such as large channel lateral dimensions, high pixel area, limited array integration density, and light shading by the top electrode. Some vertical devices also lack structural designs that balance efficient light absorption, independent side-gate regulation, and bottom-incident arraying. Therefore, it is necessary to develop an OETT employing a bulk heterojunction photosensitive channel, asymmetric vertical electrodes, and independent side-gate electrolyte regulation to meet the construction requirements of high-density retina-like photosensitive and integrated sensing-memory-computing devices. Summary of the Invention

[0003] The purpose of this invention is to provide a side-gate vertical photoelectrochemical device with a bulk heterojunction channel and its fabrication method. This device combines ITO / bulk heterojunction organic semiconductor / Au asymmetric vertical stack, independent side-gate electrolyte modulation, and bottom incident light path to shorten the carrier transport path, increase the device planar integration density, and be compatible with a variety of bulk heterojunction materials and electrolyte systems.

[0004] To achieve the above objectives, the present invention provides a side-gate vertical photoelectrochemical device with a bulk heterojunction channel, comprising a transparent substrate, an ITO bottom electrode, a bulk heterojunction organic semiconductor channel layer, an Au top electrode, a side-gate electrode, and an electrolyte; the ITO bottom electrode, the bulk heterojunction organic semiconductor channel layer, and the Au top electrode are sequentially arranged along the thickness direction of the device, so that the source and drain currents are transmitted along the thickness direction of the bulk heterojunction organic semiconductor channel layer; thus, the effective channel length is mainly defined by the thickness of the bulk heterojunction organic semiconductor channel layer, rather than by the planar source-drain spacing; the side-gate electrode is spaced apart from the vertical channel structure, preferably using an Au side-gate electrode; the electrolyte simultaneously contacts the effective gate control region of the side-gate electrode and at least a partially exposed region of the bulk heterojunction organic semiconductor channel layer, so that the side-gate voltage can be changed by ion migration, interface polarization, electrical double-layer modulation, or electrochemical doping to alter the channel conductivity.

[0005] Preferably, the ITO bottom electrode and the Au top electrode have different work functions and interfacial contact characteristics, which can form an asymmetric carrier injection and extraction interface on both sides of the bulk heterojunction organic semiconductor channel layer, and are conducive to the formation of built-in potential difference and directional carrier transport; the specific direction and magnitude of the built-in potential can vary with the energy level, interfacial dipole and ion modulation state of the bulk heterojunction material.

[0006] Preferably, light is incident from the transparent substrate and the ITO bottom electrode side to the bulk heterojunction organic semiconductor channel layer, so as to reduce the blocking of incident light by the Au top electrode and make the device suitable for constructing an array of photoelectric sensing units.

[0007] Preferably, the bulk heterojunction organic semiconductor channel layer comprises at least one electron donor material and at least one electron acceptor material. The electron donor material may be selected from PM6, P3HT, PBDB-T, PTB7-Th, D18, DPP polymers and their derivatives; the electron acceptor material may be selected from Y6, L8-BO, ITIC, PCBM, PC71BM, NDI materials, PDI materials and their derivatives. Preferred combinations include PM6:Y6, PM6:L8-BO, PBDB-T:Y6, P3HT:PCBM, PTB7-Th:PCBM, D18:Y6, and all-polymer bulk heterojunction systems.

[0008] Preferably, the bulk heterojunction organic semiconductor channel layer is not limited to the traditional photovoltaic bulk heterojunction system, but can also be a donor-acceptor blend system that can simultaneously support light absorption, electron transport, and hole transport, and allow electrolyte ions to enter, adsorb, or regulate the interfacial charge state.

[0009] Preferably, the electrolyte can be an ionic liquid, an ionic gel, a polymer gel electrolyte, a hydrogel electrolyte, a solid or quasi-solid ionic conductor, an aqueous salt solution, or an organic electrolyte.

[0010] The present invention also provides a method for fabricating the above-mentioned device, comprising: patterning an ITO bottom electrode on a transparent substrate; forming a bulk heterojunction organic semiconductor channel layer in a predetermined region of the ITO bottom electrode; forming an Au top electrode on the bulk heterojunction organic semiconductor channel layer; forming an electrically isolated side gate electrode on the side of the vertical stack; insulatingly encapsulating the non-effective region while retaining the channel electrolyte contact region and the side gate effective region; and disposing an electrolyte between the channel and the side gate.

[0011] Multiple devices can be arranged in a two-dimensional array, and each array unit can be addressed independently, in rows and columns, or in groups. Insulating isolation structures, pixel-defining windows, and local electrolyte regions can be incorporated into the array to form a high-density pixel array suitable for retinal-like photoelectric sensing. In the array implementation, patterned gels, local microcavities, or encapsulated electrolytes are preferably used to reduce ion crosstalk between adjacent pixels.

[0012] The beneficial effects of this application are as follows: 1. By using ITO / bulk heterojunction organic semiconductor / Au vertical stack, and using the channel layer thickness as the effective transmission distance, it is beneficial to reduce the device planar size and increase the array integration density.

[0013] 2. Using a transparent ITO bottom electrode to achieve a bottom incident optical path can reduce the light shading of the top metal electrode and improve the compatibility of the device with planar optical arrays.

[0014] 3. The bulk heterojunction channel combines light absorption, exciton dissociation, and carrier transport functions, and can be extended to various donor-acceptor material combinations.

[0015] 4. The asymmetric contact interface between ITO and Au is beneficial for constructing asymmetric injection and extraction conditions, and promotes the directional separation and vertical transport of photogenerated carriers.

[0016] 5. Independent side gates regulate the ion-electron coupling state of the channel through electrolyte modulation, which can adjust the photoelectric response, conductivity state, and maintenance behavior without changing the vertical source-drain structure.

[0017] 6. The device structure is compatible with ionic liquids, gel electrolytes and solid ionic conductors, and array crosstalk can be reduced by local electrolyte limitation.

[0018] 7. The device can be used to construct a retina-like photoelectric sensor array and further applied to photoelectric detection, bionic vision, photoelectric synapses, memristors, and integrated sensing-memory-computing systems. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the side-gate vertical organic photochemical transistor of the present invention; The attached figures are labeled as follows: 1-Au top electrode; 2-Bulk heterojunction organic semiconductor channel layer; 3-ITO bottom electrode; 4-Electrolyte layer; 5-Side gate electrode; 6-Transparent substrate. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Equivalent substitutions made for material types, film thicknesses, electrode sizes, electrolyte types, and array arrangements without departing from the concept of the present invention should be included within the scope of protection of the present invention.

[0021] Example 1: A side-gate vertical photoelectrochemical device based on a PM6:Y6 channel, such as Figure 1 As shown, the structure, from bottom to top, consists of a transparent glass substrate 6 (1.5 mm thick), an ITO bottom electrode 3 (150 nm thick), a side gate electrode 5 (Au, 80 nm thick), a bulk heterojunction channel layer 2 (100 nm thick), an Au top electrode 1 (80 nm thick), and an electrolyte layer 4 (EMIMTFSI, 20 μL). The fabrication method of the side-gate vertical photoelectrochemical device based on a PM6:Y6 channel includes the following steps: 1. Substrate cleaning: Select a transparent glass substrate 6 with patterned ITO bottom electrode 3, clean it sequentially with deionized water, acetone and isopropanol, bake it in an oven at 80 degrees for 1 hour until dry, and then perform ultraviolet ozone or oxygen plasma treatment for 20 minutes.

[0022] 2. Preparation of active layer solution: PM6 and Y6 were dissolved separately in chloroform solvent and mixed at a predetermined mass ratio of 1:1.2 to form a three-dimensional heterojunction solution with a total concentration of 16 mg / ml. The solution was then placed on a magnetically heated stirring table and stirred overnight at 45 degrees Celsius for later use.

[0023] 3. Preparation of Micro-90 solution: Mix Micro-90 surfactant with deionized water at a concentration of 1:49, stir overnight on a stirring table and set aside.

[0024] 4. Sacrificial layer construction: Micro-90 solution was pre-coated onto the ITO bottom electrode 3 by spin-coating, followed by deposition of a 3µm layer using a parylene coating machine. Subsequently, RIE etching was performed using a mask for 1.5 hours to form patterned channel regions.

[0025] 5. Construction of bulk heterojunction channel layer 2: 25 μL of active layer material was spin-coated onto a transparent glass substrate 6 on which the sacrificial layer was constructed using a dynamic spin-coating method to form a thin film with a thickness of 100 nm. Subsequently, the sacrificial layer was peeled off by a peeling method, leaving patterned channels.

[0026] 6. Top Electrode Construction: On the transparent glass substrate 6 where the bulk heterojunction channel layer 2 has been formed, an Au top electrode 1 with a thickness of 80 nm is deposited by metal mask alignment, so that the ITO bottom electrode 3, the heterojunction channel layer 2 and the Au top electrode 1 form a vertical stack. At the same time, an Au-side gate electrode 5 electrically isolated from the source and drain electrodes is formed on the side of the vertical stack.

[0027] 7. Electrolyte layer 4 construction: 20 μL of EMIMTFSI ionic liquid was directly added by pipette as electrolyte layer 4. Electrolyte layer 4 needs to cover the entire channel and gate region.

[0028] When the device is working, light is incident from the transparent glass substrate 6 and the ITO bottom electrode 3. Photogenerated carriers are generated and separated inside the bulk heterojunction. The side gate modulates the ion distribution and charge state of the electrolyte in the channel through voltage. The source and drain currents are transmitted vertically along the ITO / BHJ / Au direction.

[0029] Example 2: The device structure in this embodiment is the same as that in Embodiment 1, except that the bulk heterojunction channel layer 2 uses a P3HT:PCBM system and chlorobenzene is used as the solvent. The specific preparation steps are as follows: 1. Substrate cleaning: Select a transparent glass substrate 6 with patterned ITO bottom electrode 3, clean it sequentially with deionized water, acetone and isopropanol, bake it in an oven at 80 degrees for 1 hour until dry, and then perform ultraviolet ozone or oxygen plasma treatment for 20 minutes.

[0030] 2. Preparation of active layer solution: P3HT and PCBM were dissolved separately in chlorobenzene solvent and mixed at a predetermined mass ratio of 1:1.2 to form a three-dimensional heterojunction solution with a total concentration of 16 mg / ml. The solution was then placed on a magnetically heated stirring table and stirred overnight at 45 degrees Celsius for later use.

[0031] 3. Preparation of Micro-90 solution: Mix Micro-90 surfactant with deionized water at a concentration of 1:49, stir overnight on a stirring table and set aside.

[0032] 4. Sacrificial layer construction: Micro-90 solution was pre-coated onto the ITO bottom electrode 3 by spin-coating, followed by deposition of a 3µm layer using a parylene coating machine. Subsequently, RIE etching was performed using a mask for 1.5 hours to form patterned channel regions.

[0033] 5. Construction of bulk heterojunction channel layer 2: 25 μL of active layer material was spin-coated onto a transparent glass substrate 6 on which the sacrificial layer was constructed using a dynamic spin-coating method to form a thin film with a thickness of 120 nm. Subsequently, the sacrificial layer was peeled off by a peeling method, leaving patterned channels.

[0034] 6. Top Electrode Construction: On the transparent glass substrate 6 where the bulk heterojunction channel layer 2 has been formed, an Au top electrode 1 with a thickness of 80 nm is deposited by metal mask alignment, forming a vertical stack of the ITO bottom electrode 3, the PM6:Y6 bulk heterojunction channel layer 2, and the Au top electrode 1. Simultaneously, an Au-side gate electrode 5, electrically isolated from the source and drain electrodes, is formed on the side of the vertical stack.

[0035] 7. Electrolyte layer 4 construction: 20 μL of EMIMTFSI ionic liquid was directly added by pipette as electrolyte layer 4. Electrolyte layer 4 needs to cover the entire channel and gate region.

[0036] Example 3: The device structure in this embodiment is the same as that in Embodiment 1, except that the bulk heterojunction channel uses a D18:L8-BO system and chlorobenzene is used as the solvent. The specific preparation steps are as follows: 1. Substrate cleaning: Select a transparent glass substrate 6 with patterned ITO bottom electrode 3, clean it sequentially with deionized water, acetone and isopropanol, bake it in an oven at 80 degrees for 1 hour until dry, and then perform ultraviolet ozone or oxygen plasma treatment for 20 minutes.

[0037] 2. Preparation of active layer solution: Dissolve D18 and L8-BO separately in chlorobenzene solvent, and mix them at a predetermined mass ratio of 1:1.2 to form a three-dimensional heterojunction solution with a total concentration of 16 mg / ml. Then place it on a magnetically heated stirring table at 45 degrees Celsius and stir overnight for later use.

[0038] 3. Preparation of Micro-90 solution: Mix Micro-90 surfactant with deionized water at a concentration of 1:49, stir overnight on a stirring table and set aside.

[0039] 4. Sacrificial layer construction: Micro-90 solution was pre-coated onto the ITO bottom electrode 3 by spin-coating, followed by deposition of a 3µm layer using a parylene coating machine. Subsequently, RIE etching was performed using a mask for 1.5 hours to form patterned channel regions.

[0040] 5. Construction of bulk heterojunction channel layer 2: 25 μL of active layer material was spin-coated onto a transparent glass substrate 6 on which the sacrificial layer was constructed using a dynamic spin-coating method to form a thin film with a thickness of 120 nm. Subsequently, the sacrificial layer was peeled off by a peeling method, leaving patterned channels.

[0041] 6. Top Electrode Construction: On the transparent glass substrate 6 where the bulk heterojunction channel layer 2 has been formed, an Au top electrode 1 with a thickness of 80 nm is deposited by metal mask alignment, forming a vertical stack of the ITO bottom electrode 3, the PM6:Y6 bulk heterojunction channel layer 2, and the Au top electrode 1. Simultaneously, an Au-side gate electrode 5, electrically isolated from the source and drain electrodes, is formed on the side of the vertical stack.

[0042] 7. Electrolyte layer 4 construction: 20 μL of EMIMTFSI ionic liquid was directly added by pipette as electrolyte layer 4. Electrolyte layer 4 needs to cover the entire channel and gate region.

[0043] Example 4: The device structure in this embodiment is the same as that in Embodiment 1, except that the electrolyte layer uses an ionic liquid gel electrolyte system. The specific preparation steps are as follows: 1. Substrate cleaning: Select a transparent glass substrate 6 with patterned ITO bottom electrode 3, clean it sequentially with deionized water, acetone and isopropanol, bake it in an oven at 80 degrees for 1 hour until dry, and then perform ultraviolet ozone or oxygen plasma treatment for 20 minutes.

[0044] 2. Preparation of active layer solution: PM6 and Y6 were dissolved separately in chloroform solvent and mixed at a predetermined mass ratio of 1:1.2 to form a three-dimensional heterojunction solution with a total concentration of 16 mg / ml. The solution was then placed on a magnetically heated stirring table and stirred overnight at 45 degrees Celsius for later use.

[0045] 3. Preparation of Micro-90 solution: Mix Micro-90 surfactant with deionized water at a concentration of 1:49, stir overnight on a stirring table and set aside.

[0046] 4. Sacrificial layer construction: Micro-90 solution was pre-coated onto the ITO bottom electrode 3 by spin-coating, followed by deposition of a 3µm layer using a parylene coating machine. Subsequently, RIE etching was performed using a mask for 1.5 hours to form patterned channel regions.

[0047] 5. Construction of bulk heterojunction channel layer 2: 25 μL of active layer material was spin-coated onto a transparent glass substrate 6 on which the sacrificial layer was constructed using a dynamic spin-coating method to form a thin film with a thickness of 100 nm. Subsequently, the sacrificial layer was peeled off by a peeling method, leaving patterned channels.

[0048] 6. Top Electrode Construction: On the transparent glass substrate 6 where the bulk heterojunction channel layer 2 has been formed, an Au top electrode 1 with a thickness of 80 nm is deposited by metal mask alignment, forming a vertical stack of the ITO bottom electrode 3, the PM6:Y6 bulk heterojunction channel layer 2, and the Au top electrode 1. Simultaneously, an Au-side gate electrode 5, electrically isolated from the source and drain electrodes, is formed on the side of the vertical stack.

[0049] 7. Electrolyte Layer 4 Construction: Prepare an electrolyte solution according to the ratio of EMIMTFSI:PVDF-HFP:70:30, using acetone as the solvent, with a total solute concentration of 200 mg / ml. Add 20 μL of gel directly using a pipette as electrolyte layer 4, ensuring that electrolyte layer 4 covers the entire channel and gate region.

Claims

1. A side-gate vertical photoelectrochemical device with a bulk heterojunction channel, characterized in that, The device includes a transparent substrate, an ITO bottom electrode, a bulk heterojunction organic semiconductor channel layer, an Au top electrode, a side gate electrode, and an electrolyte. The ITO bottom electrode, the bulk heterojunction organic semiconductor channel layer, and the Au top electrode are sequentially disposed on the transparent substrate along the thickness direction of the device to form a vertical current transport path along the thickness direction of the bulk heterojunction organic semiconductor channel layer. The side gate electrode is disposed on the transparent substrate at a distance from the vertical current transport path. The electrolyte is in contact with at least a partially exposed area of ​​the side gate electrode and the bulk heterojunction organic semiconductor channel layer, so that the side gate electrode can regulate the conductivity state of the bulk heterojunction organic semiconductor channel layer through ion migration, interface polarization, or electrochemical doping in the electrolyte. The ITO bottom electrode and the Au top electrode form an asymmetric contact structure with the bulk heterojunction organic semiconductor channel layer, allowing light to enter from the transparent substrate and the ITO bottom electrode side.

2. The side-gate vertical photoelectrochemical device according to claim 1, characterized in that, The bulk heterojunction organic semiconductor channel layer comprises at least one electron donor material and at least one electron acceptor material, characterized in that the electron donor material is selected from one or more of PM6, P3HT, PBDB-T, PTB7-Th, D18, DPP polymers and their derivatives, and the electron acceptor material is selected from one or more of Y6, L8-BO, ITIC, PCBM, PC71BM, NDI materials, PDI materials and their derivatives.

3. The side-gate vertical photoelectrochemical device according to claim 1, characterized in that, The thickness of the bulk heterojunction organic semiconductor channel layer is 20 nm to 1000 nm, and the thickness of the Au top electrode is 20 nm to 300 nm.

4. The side-gate vertical photoelectrochemical device according to claim 1, characterized in that, The side gate electrode is an Au side gate electrode, and the side gate electrode is electrically isolated from the ITO bottom electrode and the Au top electrode.

5. The side-gate vertical photoelectrochemical device according to claim 1, characterized in that, The electrolyte is selected from one or more of the following: ionic liquid, ionic gel, polymer gel electrolyte, hydrogel electrolyte, solid ionic conductor, quasi-solid ionic conductor, aqueous salt solution, and organic electrolyte.

6. The side-gate vertical photoelectrochemical device according to claim 5, characterized in that, The electrolyte partially covers the exposed area of ​​the bulk heterojunction organic semiconductor channel layer and the effective gate control area of ​​the side gate electrode.

7. The side-gate vertical photoelectrochemical device according to claim 1, characterized in that, The ITO bottom electrode and the Au top electrode have different work functions or interface energy level matching relationships, which makes an asymmetric carrier injection and extraction interface formed on both sides of the bulk heterojunction organic semiconductor channel layer.

8. A method for fabricating a side-gate vertical photoelectrochemical device according to any one of claims 1 to 7, characterized in that, include: Patterning of the ITO conductive layer on a transparent substrate to form an ITO bottom electrode; A bulk heterojunction organic semiconductor channel layer is formed in a predetermined region of the ITO bottom electrode; An Au top electrode is formed on the bulk heterojunction organic semiconductor channel layer, so that the ITO bottom electrode, the bulk heterojunction organic semiconductor channel layer, and the Au top electrode constitute a vertical stack; a side gate electrode electrically isolated therefrom is formed on a transparent substrate to the side of the vertical stack; the non-effective region is insulated and encapsulated, while retaining the electrolyte contact region of the bulk heterojunction organic semiconductor channel layer and the effective gate control region of the side gate electrode; an electrolyte is disposed between the electrolyte contact region and the effective gate control region.

9. The preparation method according to claim 8, characterized in that, The bulk heterojunction organic semiconductor channel layer is formed by one of the following methods: spin coating, blade coating, inkjet printing, screen printing, spraying, transfer printing, or vacuum deposition. The Au top electrode is formed by vacuum evaporation, magnetron sputtering, electron beam evaporation, transfer printing, or metal ink printing. The electrolyte is set by drop addition, microcavity confinement, patterned gel, microfluidic delivery, in-situ polymerization, or lamination encapsulation.

10. The preparation method according to claim 8, characterized in that, The transparent substrate is a transparent flexible substrate, and the material of the transparent flexible substrate includes, but is not limited to, glass, quartz, polyethylene terephthalate, and polyimide.

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