A flexible oriented nanoporous organic semiconductor aerogel, its preparation method and application

Abstract

This invention relates to a flexible, oriented nanoporous organic semiconductor aerogel, its preparation method, and its applications, aiming to achieve high orientation and flexibility compatibility in porous structures. The method includes the following steps: injecting a liquid crystal precursor solution into an orientation mold, polymerizing and curing it under ultraviolet light to form a liquid crystal polymer gel film; obtaining an ordered liquid crystal aerogel template after washing and drying; then spin-coating an organic semiconductor solution into the template; and finally obtaining a flexible organic semiconductor aerogel film with a highly oriented nanoporous structure after solvent replacement and further drying. Compared with existing technologies, this invention, through precise control of the liquid crystal template structure and optimization of the drying / transfer process, yields a film with strong orientation, high porosity, and good flexibility, significantly improving its structural adaptability and application potential in flexible electronic devices, especially high-sensitivity organic electrochemical transistor biosensors.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aerogels, in particular to a flexible oriented nanoporous organic semiconductor aerogel and a preparation method and application thereof. BACKGROUND

[0002] Organic semiconductors have become one of the key materials for constructing flexible electronics, biosensing and wearable devices due to their adjustable structure, excellent flexibility and solution processability. In order to improve the mass transfer efficiency and response sensitivity of the active layer in the device, it has become an important development direction to construct porous organic semiconductor materials. Aerogels, as a kind of material with three-dimensional network structure, high porosity and large specific surface area, have been gradually introduced into the system of flexible electronic materials. The multi-level pore structure of aerogels helps to enhance the ion / electron transport capacity and interface interaction of the material, thereby improving the performance of the device. However, most of the existing organic semiconductor aerogels have disordered pore structures, and the pore arrangement lacks directionality, which leads to unstable transport path and low efficiency, limiting their application in high-performance electronic devices.

[0003] Therefore, it has become an important challenge in the current integrated design of porous materials and flexible devices to construct flexible organic semiconductor aerogels with highly ordered and oriented nanoporous structures. Liquid crystal-induced polymerization as a controllable molecular orientation strategy has been used to construct ordered porous materials. It is worth noting that some reactive liquid crystal monomers can form liquid crystal polymer structures with high orientation and flexible mechanical properties after polymerization, which are suitable as template materials for preparing bendable and deformable aerogel systems. However, there are still many challenges in transferring the ordered structure formed in the liquid crystal polymer to the organic semiconductor with high fidelity. For example, the filling efficiency of the organic semiconductor material in the template pore is low, or the template structure is easily damaged during the transfer process, leading to pore collapse and loss of orientation. In addition, there is currently a lack of a set of preparation strategies suitable for various orientation types (such as horizontal, vertical and composite orientation) and with wide adaptability, which limits the application expansion of flexible electronic devices.

[0004] Patent CN115220267A discloses a kind of liquid crystal injection liquid porous smooth surface construction method and its microfluidic application, by the selection of substrate, box thickness control, the selection of orientation material, orientation design prepares the orientation control liquid crystal box;By changing the kind of liquid crystal and liquid crystal polymer monomer, ratio realizes the pre-control of liquid crystal injection liquid porous system;Liquid crystal material mixed well is filled into liquid crystal box, temperature control, under specific phase, form polymer network by exposure wavelength, dose control, and small molecule liquid crystal is not influenced by exposure step, therefore naturally forms liquid crystal injection liquid porous polymer network film, completes the preparation of liquid crystal injection liquid porous material;Then open box, scrape coating small molecule liquid crystal, and injection liquid porous liquid crystal functional surface is obtained.The liquid crystal injection liquid porous smooth surface proposed by the application has smooth characteristics, controllability and self-repairing, and can be used in microfluidic, anti-pollution, super-smooth surface, biosensing and bioengineering, and has wide application prospect.However, the liquid crystal injection liquid porous structure constructed by the application is mainly positioned at surface function regulation, and the obtained material has surface smoothness and controllable wettability as core features, and does not involve the construction of aerogel three-dimensional network structure, nor introduces organic semiconductor material to give electronic function.At the same time, the porous structure depends on the migration and precipitation process of small molecule liquid crystal, lacks structural continuity and orientation control, and it is difficult to realize the functional channel with good penetration and clear direction, and the comprehensive requirements of mechanical stability and electrochemical performance of flexible electronic devices are not considered.Therefore, the method is difficult to be applied to the structure foundation construction of high-performance organic electronic devices. SUMMARY

[0005] The purpose of the present application is to provide a flexible oriented nanoporous organic semiconductor aerogel and its preparation method and application, which can form a flexible organic semiconductor aerogel film with high orientation and nanoporous structure.

[0006] The purpose of the present application can be realized by the following technical scheme: a preparation method of a flexible oriented nanoporous organic semiconductor aerogel, comprising the following steps:

[0007] (1) inject liquid crystal precursor solution into an oriented liquid crystal mold, polymerize under ultraviolet light irradiation, and solidify to form a liquid crystal polymer gel film;

[0008] (2) wash the liquid crystal polymer gel film, and then freeze-dry or supercritical dry to obtain a flexible liquid crystal polymer aerogel template;

[0009] (3) spin-coat an organic semiconductor-solvent mixed solution into the aerogel template;

[0010] (4) solvent displacement treatment, and freeze-drying or supercritical drying treatment again to obtain a flexible oriented nanoporous organic semiconductor aerogel film;

[0011] The liquid crystal precursor solution comprises the following components by weight: 15-20 parts of reactive liquid crystal monomer, 70-80 parts of non-reactive nematic liquid crystal, 1-2 parts of photoinitiator, 0.5-2 parts of alkenyl crosslinking agent.

[0012] Preferably, the reactive liquid crystal monomer comprises RM105, RM82.

[0013] Preferably, the non-reactive nematic liquid crystal comprises E7, 8CB.

[0014] Preferably, the photoinitiator comprises Irgacure-907, DMPA.

[0015] Preferably, the alkenyl crosslinking agent comprises PEGDA, GDA.

[0016] Preferably, the oriented liquid crystal mold comprises a horizontal orientation mold, a vertical orientation mold, and a composite orientation mold, all of which are constructed from a flexible substrate.

[0017] Further preferably, the oriented liquid crystal mold substrate is a flexible polyimide (PI) film, the surface of which is deposited with an aluminum oxide (Al2O3) layer of about 50 nm by atomic layer deposition (ALD) method.

[0018] Further preferably, the construction method of the horizontal orientation mold comprises sequentially subjecting the PI substrate to plasma cleaning, PVA coating, and directional rubbing treatment, and using two substrates with consistent rubbing direction to construct a sandwich structure.

[0019] More preferably, the method of PVA coating comprises dissolving PVA in deionized water to obtain a PVA solution, and then converting it into a PVA film by spin coating.

[0020] Further preferably, the construction method of the vertical orientation mold comprises surface modification treatment of the upper and lower substrates, the upper substrate is modified by TDTA aqueous solution, and the lower substrate is modified by a mixed solution of Z-6036 and TDTA, and the vertical orientation structure is assembled.

[0021] More preferably, the concentration of the TDTA aqueous solution is 0.5-1.5% v / v, preferably 1% v / v.

[0022] More preferably, the mixed solution of Z-6036 and TDTA is a mixed isopropanol / water solution of Z-6036 and TDTA (volume ratio preferably 1:1), and the concentration of Z-6036 and TDTA is both 0.5-1.5% v / v, preferably 1% v / v. Further preferably, the construction method of the composite orientation mold is to assemble the horizontally oriented substrate treated by friction and the vertically oriented substrate treated by the mixed solution of Z-6036 and TDTA to form a mold structure with horizontally-vertical composite channels.

[0023] In the present application, TDTA and Z-6036 are used synergistically for PI film surface modification, which respectively play the roles of orientation induction of liquid crystal molecules and anchoring fixation of polymers.

[0024] Preferably, the interlayer spacing of the oriented liquid crystal mold is 5-10 μm.

[0025] Preferably, in the oriented liquid crystal mold, a polytetrafluoroethylene spacer is used to assemble the interlayer between the substrates.

[0026] Preferably, step (1) is polymerized for 30-60 minutes under 365 nm ultraviolet light irradiation to form a liquid crystal polymer gel thin film.

[0027] Further preferably, step (1) is polymerized for 40 minutes under 365 nm ultraviolet light irradiation.

[0028] Preferably, after removing the upper substrate of the oriented liquid crystal mold in step (2), the liquid crystal polymer gel thin film is washed with tert-butyl alcohol for 6-16 hours, followed by freeze-drying to obtain a flexible liquid crystal polymer aerogel template; or the liquid crystal polymer gel thin film is washed with ethanol for 6-16 hours, followed by supercritical drying to obtain a flexible liquid crystal polymer aerogel template.

[0029] Further preferably, the liquid crystal polymer gel thin film is washed with tert-butyl alcohol for 6-12 hours.

[0030] Preferably, the freeze-drying condition in step (2) is to dry in a vacuum freeze-drying machine at -65 to -55°C for 5-7 hours.

[0031] Further preferably, the freeze-drying condition in step (2) is to dry in a vacuum freeze-drying machine at -60°C for 6 hours.

[0032] Preferably, the supercritical drying condition in step (2) is to use CO2 as the drying solvent, and to dry at 30-40°C and 7-9 MPa for 14-16 hours.

[0033] Further preferably, the supercritical drying condition of step (2) is drying for 15 hours at 35℃ under 8MPa with CO2 as the drying solvent.

[0034] Preferably, the concentration of the organic semiconductor in the organic semiconductor-solvent mixed solution of step (3) is 5-10mg / mL.

[0035] Preferably, the solvent in the organic semiconductor-solvent mixed solution of step (3) comprises chloroform, chlorobenzene, water.

[0036] Preferably, the organic semiconductor of step (3) comprises p(g2T-TT), DPPDTT, PEDOT:PSS.

[0037] Further preferably, when the organic semiconductor is p(g2T-TT), DPPDTT or p(g2T-TT), the solvent is chloroform or chlorobenzene, preferably chloroform, and the concentration of the organic semiconductor is preferably 7mg / mL.

[0038] Further preferably, when the organic semiconductor is PEDOT:PSS, the solvent is water, and the concentration of the organic semiconductor is preferably 7mg / mL.

[0039] Preferably, the solvent of step (4) comprises tert-butyl alcohol, ethanol.

[0040] Preferably, the solvent replacement time of step (4) is 6-12 hours.

[0041] Preferably, the freeze-drying condition of step (4) is drying for 5-7 hours in a vacuum freeze dryer at -65℃ to -55℃.

[0042] Further preferably, the freeze-drying condition of step (4) is drying for 6 hours in a vacuum freeze dryer at -60℃.

[0043] Preferably, the supercritical drying condition of step (4) is drying for 14-16 hours at 30-40℃ under 7-9MPa with CO2 as the drying solvent.

[0044] Further preferably, the supercritical drying condition of step (4) is drying for 15 hours at 35℃ under 8MPa with CO2 as the drying solvent.

[0045] A flexible oriented nanoporous organic semiconductor aerogel is prepared by the above method, wherein the nanoporous channels of the aerogel are horizontally, vertically or complexly oriented, the average pore size is 20-200nm, the overall porosity is not less than 70%, and the specific surface area retention rate after being filled with an organic semiconductor material is not less than 85%.

[0046] Preferably, the composite orientation is arranged as a horizontal and vertical pore three-dimensional interwoven interconnected network.

[0047] An application of the above flexible oriented nanoporous organic semiconductor aerogel, the flexible oriented nanoporous organic semiconductor aerogel is used for an organic electrochemical transistor (OECT) device.

[0048] In the present application, the aerogel is used as an OECT active layer, and the oriented nanoporous channel structure, especially the vertical through-pore, helps to realize fast ion transmission, thereby improving the transconductance performance of the device, and provides new material support for high-sensitivity flexible sensors.

[0049] The present application proposes a high-orientation aerogel template constructed based on liquid crystal-induced polymerization, and realizes high-fidelity transfer of the template structure to an organic semiconductor through a solvent replacement and drying process, to prepare a flexible nanoporous organic semiconductor aerogel film with a three-dimensional network structure and clear orientation. The method has controllability of pore direction (horizontal, vertical, and composite structure) and strong material adaptability, and provides stable structural support and functional basis for high-performance flexible organic electronic devices.

[0050] Compared with the prior art, the present application has the following beneficial effects:

[0051] 1. The present application provides a preparation method based on an oriented liquid crystal template, which can effectively transfer the ordered structure to an organic semiconductor material to form a flexible organic semiconductor aerogel film with high orientation and nanoporous structure.

[0052] 2. The present application provides a general method for preparing a flexible oriented nanoporous organic semiconductor aerogel film by a liquid crystal template, especially a nanoporous structure construction process that can realize horizontal, vertical and composite orientation. The method prepares a flexible ordered nanoporous organic semiconductor aerogel film with different spatial orientation structures by surface chemical modification and physical template synergistic effect, combined with solvent replacement and freeze-drying process, effectively solving the problems of uncontrollable pore structure and limited ion permeation in traditional organic semiconductor films.

[0053] 3. The present application realizes the steps of first regularly and orderly oriented nanoporous skeleton, then introducing semiconductor material by spin coating, and finally realizing high-efficiency structure transfer through solvent replacement and freeze-drying / supercritical drying process, to successfully obtain an oriented organic semiconductor aerogel structure. The process ensures the integrity, directional order and film continuity of the pore structure of the film layer, effectively avoiding problems such as pore collapse or orientation disorder in conventional template transfer.

[0054] 4. The application can realize the orientation induction of liquid crystal molecules and the anchoring fixation of polymer network by the selection of surface modification agent in the orientation mold construction process, significantly improving the accuracy and stability of orientation control. At the same time, the systematic regulation of parameters such as interlayer spacing and friction direction in mold design enables the construction of templates with horizontal, vertical or composite channel structures, laying a structural foundation for realizing multi-dimensional ion / charge cooperative transport.

[0055] 5. The structure of the application has good scalability and can be further used for the construction of various OECT biosensors, suitable for early diagnosis of diseases and high-sensitivity detection in frontier fields.

[0056] 6. The method of the application has good universality, structure controllability and device application adaptability, and is suitable for flexible electronics, biosensing and new organic electronic devices and other fields.

[0057] 7. The method of the application has good universality and adaptability, which can realize the construction of different orientation structures (such as horizontal and vertical) and ensure the complete preservation of the template structure in the transcription process, thereby improving the structural controllability and functional performance of the obtained thin film in ion transport and charge conduction. Such preparation strategy will provide a foundation support for the development of new high-performance organic electronic devices, especially in the fields of organic electrochemical transistors and biosensing.

[0058] 8. The application can realize the high orientation and flexibility compatibility of the porous structure. Through accurate regulation of the liquid crystal template structure and optimization of the drying / transcription process, the obtained thin film has the characteristics of strong orientation, high porosity and good flexibility, which significantly improves its structural adaptability and application potential in flexible electronic devices, especially high-sensitivity organic electrochemical transistor biosensors.

[0059] 9. The application breaks through the limitations of the prior art in terms of pore orientation, flexibility and device application, and proposes a flexible organic semiconductor aerogel construction strategy with highly oriented pore structure. The application uses an oriented liquid crystal template to induce the construction of a three-dimensional porous skeleton, combines freeze-drying and solvent replacement process, and stably transcribes the directional nanopore structure into various organic semiconductor materials to construct a functional layer with good structural integrity and directional consistency. This structure not only improves the ion / charge cooperative transport performance of the material, but also shows good balance in specific surface area retention, porosity control and film continuity, significantly enhancing the electrical response stability and device adaptability of the obtained aerogel film in OECT devices. In addition, the feasibility of the application on flexible PI substrate and the good transcription compatibility of hydrophilic and hydrophobic organic semiconductor materials (such as PEDOT:PSS, p(g2T-TT), DPPDTT, etc.) further verify the universality and promotion potential of the strategy. BRIEF DESCRIPTION OF DRAWINGS

[0060] Figure 1 Flowchart of the method for preparing flexible aligned nanoporous organic semiconductor aerogel for liquid crystal template;

[0061] Figure 2 Preparation of PI substrate alignment layer for inducing liquid crystal horizontal alignment;

[0062] Figure 3 Cross-sectional SEM image and top surface SEM image of horizontally aligned nanoporous p(g2T-TT) organic semiconductor aerogel film;

[0063] Figure 4 Preparation of PI substrate alignment layer for inducing liquid crystal vertical alignment;

[0064] Figure 5 Cross-sectional SEM image and top surface SEM image of vertically aligned nanoporous p(g2T-TT) organic semiconductor aerogel film;

[0065] Figure 6 Cross-sectional SEM image and top surface SEM image of composite aligned nanoporous p(g2T-TT) organic semiconductor aerogel film;

[0066] Figure 7 SEM image of vertically aligned nanoporous DPPDTT organic semiconductor aerogel film;

[0067] Figure 8 Structure of vertical gate structure OECT based on vertically aligned nanoporous p(g2T-TT) organic semiconductor aerogel film;

[0068] Figure 9 Output curve of OECT device based on vertically aligned nanoporous p(g2T-TT) organic semiconductor aerogel film;

[0069] Figure 10 SEM image of the film obtained after the vertically aligned liquid crystal porous polymer film composite p(g2T-TT) without solvent replacement and freeze-drying treatment;

[0070] Figure 11 SEM image of the p(g2T-TT) organic semiconductor aerogel film obtained after the lower substrate surface modifier was replaced by APTES from Z-6036. DETAILED DESCRIPTION

[0071] The application will be described in detail below with reference to the drawings and specific embodiments. The embodiments are implemented on the premise of the technical solutions of the application, and detailed implementation modes and specific operation processes are given, but the protection scope of the application is not limited to the following examples.

[0072] The application provides a general method for preparing a flexible orientation nanoporous organic semiconductor aerogel film based on a liquid crystal template, as shown in Figure 1 The liquid crystal aerogel template with specific orientation (such as horizontal, vertical or composite orientation) is constructed, and an organic semiconductor material is introduced, combined with solvent replacement and freeze-drying and other steps, to obtain a flexible organic semiconductor aerogel film with highly oriented three-dimensional interconnected nanoporous structure. The method is suitable for various polymer organic semiconductor materials (such as p(g2T-TT), DPPDTT, PEDOT:PSS, etc.), has the advantages of adjustable structure, strong adaptability, simple process and the like. The prepared film can be applied in the field of organic electrochemical transistor (OECT) devices and the like, and exhibits excellent ion transport characteristics, and has important application prospects in the direction of biosensing and the like.

[0073] Specifically, the following steps are included:

[0074] (1) Liquid crystal template system construction: reactive liquid crystal monomers are mixed with non-reactive liquid crystal materials at an addition amount of 15-20wt%, a photoinitiator and a crosslinking agent are added, and a liquid crystal mixture is uniformly mixed by a vortex mixer;

[0075] (2) Preparation of oriented template sandwich structure:

[0076] a) Preparation step of horizontal orientation template sandwich: flexible polyimide (PI) film is used as a substrate, and an aluminum oxide (Al2O3) layer with a thickness of about 50 nm is deposited on the surface of the substrate by atomic layer deposition (ALD) method to enhance the interface stability. Then the PI film is subjected to plasma cleaning, polyvinyl alcohol (PVA) coating and directional rubbing treatment in sequence, and two substrates with consistent rubbing direction are used to construct the sandwich structure;

[0077] b) Preparation step of vertical orientation template sandwich: the same ALD modified flexible PI film is used as a substrate, the upper substrate is subjected to surface treatment in TDTA aqueous solution, and the lower substrate is subjected to silanization treatment in Z-6036 / TDTA mixed solution to construct a vertical orientation sandwich structure;

[0078] c) Preparation step of composite orientation template sandwich: the horizontally oriented substrate subjected to PVA coating and directional rubbing treatment is combined with the vertically oriented substrate subjected to Z-6036 / TDTA mixed solution treatment to form a horizontal-vertical composite channel structure;

[0079] The spacing between the sandwich layers of each orientation template is 5-10 μm.

[0080] (3) Liquid crystal mixture filling and curing: The liquid crystal mixture is injected into the sandwich structure by capillary action, and a liquid crystal polymer gel film is formed by polymerization under UV irradiation for 30-60 minutes;

[0081] (4) Preparation of liquid crystal polymer aerogel template: After removing the upper substrate, the non-polymerized components are removed by washing with tert-butyl alcohol solvent for 6-16 hours, and the liquid crystal polymer aerogel template is obtained by freeze-drying;

[0082] (5) Organic semiconductor material compounding: The organic semiconductor material is dissolved in a solvent (such as chloroform) and stirred at 60°C to dissolve, and then spin coating is performed to fill the template to complete the filling;

[0083] (6) Preparation of organic semiconductor aerogel film: After replacement with tert-butyl alcohol and freeze-drying, a flexible nanoporous organic semiconductor aerogel film with specific orientation structure is obtained.

[0084] As a preferred technical solution, the reactive liquid crystal monomer in step (1) is RM82 and RM105, and the addition amounts are 15wt% and 5wt%, respectively; the non-reactive liquid crystal material is E7, and the addition amount is 76wt%; the photoinitiator is DMPA, and the addition amount is 2wt%; and the crosslinking agent is PEGDA, and the addition amount is 2wt%.

[0085] As a preferred technical solution, the interlayer structure distance of the horizontal orientation template in step (2)a) is 7μm; the concentration of the TDTA aqueous solution in step (2)b) is 1% v / v, and the concentrations of Z-6036 and TDTA in the mixed solution of Z-6036 and TDTA are both 1% v / v.

[0086] As a preferred technical solution, the wavelength of the UV light in step (3) is 365nm, and the polymerization time is 40 minutes.

[0087] As a preferred technical solution, the tert-butyl alcohol washing time in step (4) is 6-12 hours.

[0088] As a preferred technical solution, the organic semiconductor material in step (5) is selected from p(g2T-TT), DPPDTT or PEDOT:PSS, and the concentration of the organic semiconductor solution is 7mg / mL.

[0089] In the present application, RM105 is 4-[[6-[(1-oxo-2-propenyl)oxy]hexyl]oxy]benzoic acid 4-methoxyphenyl ester, RM82 is 1,4-bis(4-(6-acryloyloxyhexyloxy)benzoyloxy)-2-methylbenzene, E7 is mixed liquid crystal, 8CB is 4'-n-octyl-4-cyanobiphenyl, Irgacure-907 is 2-methyl-1-(4-methylthiophenyl)-2-morpholin-1-propanone, DMPA is 2,2-dimethylol propionic acid, PEDOT:PSS is poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, p(g2T-TT) is poly[thiophene-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene], DPPDTT is polydithiophene-pyrrolopyrrolidone, PVA is polyvinyl alcohol, TDTA is tetradecyldimethyl(3-trimethoxysilylpropyl)ammonium chloride, Z-6036 is methacryloyloxypropyl triethoxysilane, PEGDA is polyethylene glycol diacrylate, and GDA is tetraallyloxyethane.

[0090] The present application will be described in detail below with specific examples.

[0091] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present application are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0092] Example 1

[0093] Preparation of flexible horizontally aligned nanoporous organic semiconductor aerogel (using p(g2T-TT) as the organic semiconductor material)

[0094] This example provides a specific method for constructing a nanoporous channel structure using a horizontally aligned liquid crystal template and compounding an organic semiconductor polymer p(g2T-TT) to form an aerogel film, with the following steps:

[0095] Step 1: Preparation of liquid crystal precursor solution

[0096] After weighing the reactive liquid crystal monomers RM82 (15 wt%) and RM105 (5 wt%), the non-reactive liquid crystal E7 (76 wt%), the photoinitiator DMPA (2 wt%) and the crosslinking agent PEGDA (2 wt%), they are mixed well using a vortex shaker to form a homogeneous precursor solution.

[0097] Step 2: Construction of horizontally aligned template sandwich

[0098] As Figure 2As shown, two pieces of PI film with Al2O3 layer deposited were pre-cleaned, and then plasma cleaning (6 min), PVA orientation layer spin coating (3500 rpm, 2 min) and rubbing treatment with a woolen cloth (one-way rubbing 60 times) were carried out in sequence. A polytetrafluoroethylene spacer (thickness 7 μm) was used to assemble the template sandwich.

[0099] Step 3: Liquid crystal filling and photopolymerization

[0100] The precursor solution was injected into the template sandwich by capillary action, and cured under 365 nm ultraviolet light for 40 min.

[0101] Step 4: Template purification and drying

[0102] The upper substrate was removed, the template was immersed in t-butyl alcohol for 12 h (solvent was replaced every 4 h), and then freeze-drying was carried out (-60°C, 6 h).

[0103] Step 5: Organic semiconductor polymer filling

[0104] p(g2T-TT) was dissolved in chloroform (7 mg / mL, 60°C stirring for 2 h), the template channels were filled by spin coating (1000 rpm, 30 s), and the solvent was replaced with t-butyl alcohol and then freeze-dried again.

[0105] Structural characterization:

[0106] As shown in FIG. 1, the SEM image shows that the structure presents highly consistent horizontal nanochannels, and the pores are arranged along the surface with an average pore size of 20-200 nm. Figure 3

[0107] Example 2

[0108] Preparation of flexible vertically aligned nanochannel organic semiconductor aerogel (using p(g2T-TT) as the organic semiconductor material)

[0109] This example discloses a method for constructing a vertically aligned nanochannel liquid crystal aerogel template and compounding an organic semiconductor material p(g2T-TT) to form an organic semiconductor aerogel film, and the steps are as follows:

[0110] Step 1: Precursor solution and template construction

[0111] The ratio of the liquid crystal precursor solution is the same as in Example 1.

[0112] As shown in FIG. 1, the PI substrate was subjected to the following surface treatment: Figure 4 Upper substrate: 1% TDTA aqueous solution was immersed in the dark for 10 min, washed with deionized water and dried with nitrogen;

[0113]

[0114] ​​Lower substrate: 1% Z-6036 mixed with TDTA solution was soaked for 10 min in dark, and dried before assembling the sandwich template (7 μm interval).

[0115] Steps 2-5

[0116] Liquid crystal filling, polymerization, template purification and p(g2T-TT) filling steps are the same as in Example 1.

[0117] Structural characterization

[0118] As shown in Figure 5 SEM images clearly show the interwoven horizontal-vertical nanochannel network structure, with an average pore size of 20-200 nm.

[0119] Example 3

[0120] Preparation of flexible composite oriented nanoporous organic semiconductor aerogel (using p(g2T-TT) as organic semiconductor material)

[0121] This example discloses a preparation process for preparing a composite oriented nanoporous liquid crystal aerogel template and filling an organic semiconductor material p(g2T-TT) to construct an organic semiconductor aerogel film, with the specific steps as follows:

[0122] Step 1: Construction of composite template sandwich

[0123] Upper substrate: PVA rubbing treatment (horizontal orientation);

[0124] Lower substrate: Z-6036 and TDTA co-modification (vertical orientation);

[0125] Sandwich assembly: composite orientation structure with 7 μm interval.

[0126] Steps 2-5

[0127] Preparation of precursor, filling, photopolymerization and p(g2T-TT) composite according to steps 1, 3-5 of Example 1.

[0128] Structural characterization

[0129] As shown in Figure 6 SEM images clearly show the interwoven horizontal-vertical nanochannel network structure, with an average pore size of 20-200 nm.

[0130] Example 4

[0131] Template compatibility verification of different organic semiconductor materials (using DPPDTT as an example)

[0132] This example verifies the compatibility of different types of organic semiconductor materials under the same template conditions.

[0133] The DPPDTT organic semiconductor aerogel film was prepared according to the process parameters of Example 2, filling the template with DPPDTT solution (concentration of 7 mg / mL, solvent of chloroform), using the same solvent to replace and freeze-drying process.

[0134] As shown in Figure 7 , the structural characterization results show that the DPPDTT film maintains the vertical orientation nano-pore structure, the average pore size is about 20-200 nm, the pore channel has good throughness, the overall structure is consistent with the film obtained by filling p(g2T-TT), and there is no obvious pore blockage or collapse phenomenon.

[0135] Result analysis: Although DPPDTT is a hydrophobic polymer and p(g2T-TT) has hydrophilicity, the difference between the two is large, but in the template system provided by the application, both of them show good film forming consistency and pore channel retention ability, which shows that the template method has good material universality and expandability.

[0136] Example 5

[0137] Construction and performance verification of vertical OECT device

[0138] The flexible aerogel film was prepared by selecting the vertical orientation template of Example 2 with the content of RM82 and RM105 being 15wt% and 5wt% respectively, and the organic semiconductor used was p(g2T-TT) as the active layer of OECT device.

[0139] As shown in Figure 8 , the source and drain electrodes (Au / Cr, thickness of 35 / 3 nm) were deposited on the surface of the film by metal mask thermal evaporation, the electrode spacing (channel length) was 0.1 mm, the channel width was 2 mm, and W / L=20. An Ag / AgCl electrode was inserted into the liquid drop as the gate electrode of OECT.

[0140] The electrolyte of the device was 0.1M NaCl aqueous solution, which was accurately injected into the channel area by a micro-injection pump to ensure that the film pores were fully contacted with the solution. In order to verify the stability and repeatability of the device, three batches of different preparation batches of vertical orientation films were selected for device assembly and testing. As shown in Figure 9 , the device output characteristics and transfer characteristics both showed stable curve morphology, and the transconductance value g max exceeded 70 mS.

[0141] Comparative Example 1

[0142] In the present comparative example, the precursor ratio, orientation mold construction and organic semiconductor solution concentration are kept consistent with those in Example 2, and the "solvent replacement and freeze-drying" process in the step is omitted, and the organic semiconductor composite is directly dried into a film at room temperature and normal pressure. The obtained film is basically complete in macroscopic appearance, but as shown in FIG. 2B, the nano-porous structure is discontinuous, and there are phenomena such as pore closure and channel collapse, and the overall porosity is reduced. Figure 10 The above results show that the "solvent replacement + freeze-drying" process in step (4) plays a key role in constructing a stable and continuous nano-porous structure, and is an important guarantee for realizing the performance advantages of the device.

[0143] Comparative Example 2

[0144] In the present comparative example, the surface modification of the upper substrate is kept unchanged by using 1% TDTA aqueous solution, the surface modifier of the lower substrate is replaced by a TDTA and APTES (3-aminopropyl triethoxysilane) mixed solution instead of the Z-6036 and TDTA mixed solution used in Example 2, and the liquid crystal ratio, polymerization and drying conditions are kept consistent. The results show that the liquid crystal polymer film prepared in the subsequent drying process has obvious edge warping and local shrinkage, the overall adhesion of the structure is poor, and the final aerogel template channel arrangement direction is not clear, and there are local area collapse and short channel phenomena. Figure 11 The above results show that the methacryloyloxy group in Z-6036 can react with RM82 or RM105, and firmly anchor the liquid crystal polymer film to the surface of the lower substrate during polymerization, avoiding film shrinkage, peeling and orientation loss, which is a key factor to ensure the construction of high-fidelity nano-porous structure. APTES only provides physical adsorption through the aminopropyl group, and lacks sufficient copolymerization ability, making it difficult to form effective chemical anchoring at the polymerization interface, thereby significantly reducing the structural stability and orientation retention ability.

[0145] Although there are studies on the use of liquid crystal templates to construct various ordered structures in the prior art, there is still a lack of a general preparation strategy for organic semiconductor nanostructures with high porosity, strong flexibility and controllable orientation structure. The present application provides a method for preparing a flexible orientation nano-porous structure organic semiconductor aerogel film by liquid crystal template regulation, which has the characteristics of simple process, strong applicability, controllable channel orientation, etc. The obtained film structure is stable and continuous, and is suitable for functional devices with different orientation requirements.

[0146] Compared with the traditional porous organic semiconductor thin film preparation method, the application has the beneficial effects that: under the unified process conditions, through the synergistic effect of template structure design and surface chemical regulation, the horizontal direction, vertical direction and composite orientation of the nano-pore structure can be realized, and the versatility and function expansion ability of the material system are significantly enhanced. The process compatibility is excellent, the material adaptability is wide, the template construction method is suitable for various organic semiconductor materials, has good structure retention and filling compatibility, especially suitable for common high-performance polymer systems such as p(g2T-TT), PEDOT:PSS, DPPDTT, etc. The application potential in flexible electronics and biosensors is great, and the obtained aerogel organic semiconductor thin film has high porosity, high specific surface area and directional ion transmission capacity, especially the vertical orientation structure provides a low impedance, high flux ion diffusion channel in the short channel direction, and is suitable for high-sensitivity organic electrochemical transistor biosensors under low-voltage working conditions.

[0147] The above description of the embodiments is to facilitate the understanding and use of the application by those skilled in the art. Those skilled in the art can easily make various modifications to the embodiments, and apply the general principles described herein to other embodiments without creative labor. Therefore, the application is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art within the scope of the application without departing from the scope of the application should be within the protection scope of the application.

Claims

1. A method of preparing a flexible oriented nanoporous organic semiconductor aerogel, characterized in that, The method comprises the following steps: (1) injecting a liquid crystal precursor solution into an oriented liquid crystal mold, and polymerizing and curing under ultraviolet light irradiation to form a liquid crystal polymer gel thin film; (2) washing the liquid crystal polymer gel thin film, and then performing freeze drying or supercritical drying treatment to obtain a liquid crystal polymer aerogel template; (3) spin coating an organic semiconductor-solvent mixed solution into the liquid crystal polymer aerogel template; (4) performing solvent replacement treatment, and then performing freeze drying or supercritical drying again to obtain a flexible oriented nanoporous organic semiconductor aerogel thin film; The liquid crystal precursor solution comprises the following components by weight: 15-20 parts of a reactive liquid crystal monomer, 70-80 parts of a non-reactive nematic liquid crystal, 1-2 parts of a photoinitiator, and 0.5-2 parts of an alkenyl crosslinking agent; The reactive liquid crystal monomer comprises RM105 and RM82; The oriented liquid crystal mold comprises a horizontal orientation mold, a vertical orientation mold, and a composite orientation mold; The oriented liquid crystal mold substrate is a flexible polyimide film, and an aluminum oxide layer with a thickness of 45-55 nm is deposited on the surface of the substrate by atomic layer deposition; The interlayer spacing of the oriented liquid crystal mold is 5-10 μm; The horizontal orientation mold is constructed by performing PVA coating and directional rubbing treatment on two substrates, and then assembling the two substrates into a horizontal orientation structure; The vertical orientation mold is constructed by performing surface modification treatment on the upper and lower substrates, modifying the upper substrate with a TDTA aqueous solution, and modifying the lower substrate with a mixed solution of Z-6036 and TDTA, and then assembling the upper and lower substrates into a vertical orientation structure; The composite orientation mold is constructed by assembling a horizontally oriented substrate subjected to rubbing treatment with a vertically oriented substrate subjected to a mixed solution of Z-6036 and TDTA, to form a mold structure with horizontal-vertical composite channels; The organic semiconductor comprises p(g2T-TT), DPPDTT, and PEDOT:PSS.

2. The method for preparing flexible oriented nanoporous organic semiconductor aerogel according to claim 1, characterized in that, The non-reactive nematic liquid crystal comprises E7 and 8CB; The photoinitiator comprises Irgacure-907 and DMPA; The alkenyl crosslinking agent comprises PEGDA and GDA.

3. The method for preparing flexible oriented nanoporous organic semiconductor aerogel according to claim 1, characterized in that, The concentration of the TDTA aqueous solution is 0.5-1.5 % v / v; The mixed solution of Z-6036 and TDTA is an isopropyl alcohol / water mixed solvent system, and the concentrations of Z-6036 and TDTA in the mixed solution are both 0.5-1.5 % v / v.

4. The method for preparing flexible oriented nanoporous organic semiconductor aerogel according to claim 1, characterized in that, In step (1), the liquid crystal polymer gel thin film is formed by polymerization under 365 nm ultraviolet light irradiation for 30-60 minutes.

5. The method for preparing flexible oriented nanoporous organic semiconductor aerogel according to claim 1, characterized in that, In step (2), after removing the upper mold substrate: the liquid crystal polymer gel thin film is washed with tert-butyl alcohol for 6-16 hours, and then freeze dried to obtain a liquid crystal polymer aerogel template; or the liquid crystal polymer gel thin film is washed with ethanol for 6-16 hours, and then supercritically dried to obtain a liquid crystal polymer aerogel template.

6. The method for preparing flexible oriented nanoporous organic semiconductor aerogel according to claim 1, characterized in that, In step (3), the concentration of the organic semiconductor in the organic semiconductor-solvent mixed solution is 5-10 mg / mL, and the solvent comprises chloroform, chlorobenzene, and water.

7. The method for preparing flexible oriented nanoporous organic semiconductor aerogel according to claim 1, characterized in that, In step (4), the solvent comprises tert-butyl alcohol and ethanol.

8. A flexible oriented nanoporous organic semiconductor aerogel, characterized in that, The aerogel is prepared by the preparation method in any one of claims 1-7, the nanochannel of the aerogel is arranged in horizontal, vertical or composite orientation, the average pore size is 20-200nm, the overall porosity is not less than 70%, and the specific surface area retention rate after filling with an organic semiconductor material is not less than 85%. The composite orientation arrangement is an interconnected network formed by three-dimensional interweaving of horizontal and vertical channels.

9. Use of the flexible oriented nanoporous organic semiconductor aerogel according to claim 8, characterized in that, The flexible orientation nanochannel organic semiconductor aerogel is used for an organic electrochemical transistor device.

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