Organic semiconductor photoresist with hierarchical structure and stable environment, patterning method and organic electronic device

Abstract

The invention belongs to the field of organic electronic manufacturing, and particularly relates to an organic semiconductor photoresist with a hierarchical structure and stable environment, a patterning method and an organic electronic device, and the formula of the photoresist mainly comprises a polymer semiconductor, cross-linkable packaging molecules, a photoinitiator and two or more mixed solvents. The controllable phase separation is realized based on the solubility difference of the polymer semiconductor and the photo-crosslinking packaging molecules in the mixed solvent, and the graded phase distribution forms a hierarchical structure, so that the photo-crosslinking packaging molecules form a self-packaging structure for the polymer semiconductor. Compared with the prior art, the problems that in the prior art, an N-type polymer semiconductor is poor in air stability, and a semiconductor film is prone to being affected by solvent erosion in the solution processing process are solved; according to the method, a controllable gradient separation structure is formed autonomously by utilizing a solvent to drive semiconductor photoresist, and an organic semiconductor film with a compact hierarchical staggered network structure is further prepared through patterning.

Description

Technical Field

[0001] The present invention belongs to the field of organic electronic manufacturing, and in particular relates to an organic semiconductor photoresist with a hierarchical structure and environmental stability, a patterning method and an organic electronic device. Background Art

[0002] Organic field-effect transistors (OFETs) and OFET-based complementary integrated circuits are characterized by low cost, compatibility with flexible substrates, and ease of fabrication. Compared with traditional silicon-based rigid devices, OFETs have great application potential in emerging electronic fields, including implantable medical electronic devices, all-polymer solar cells, and photodetectors. Although P-channel OFETs achieve a satisfactory balance between device performance, reliability, and high-precision manufacturing, for many electronic applications, it is necessary to use N-channel OFETs that conduct electrons and P-channel OFETs that transport holes to fabricate similar complementary metal oxide semiconductor (CMOS) logic circuits. However, the vast majority of N-type polymer semiconductors, including naphthalimides, thiophenes, pyrrolopyrrole diones, and benzimidazole derivatives, cannot exhibit ideal electron transport properties, and the corresponding N-type unit devices also lag behind P-type devices in terms of carrier mobility.

[0003] A key reason for the lack of high-performance n-type organic electronic components is the poor air stability of n-type organic semiconductor polymers. Most n-type organic semiconductor polymers have high LUMO energy levels. When electrons are injected into the organic semiconductor layer of an OFET, the electrons residing in the organic semiconductor are in a high-energy state and easily captured by groups (Si-OH) on the substrate or H₂O and O₂ in the air, thus impairing electron transport. Traditional polymer semiconductor processing techniques, such as spin coating, inkjet printing, screen printing, nanoimprinting, and vacuum evaporation, have fundamental limitations. The processed semiconductor film is significantly exposed to air, inevitably sacrificing the inherent performance of the polymer semiconductor. For example, patents CN117412609A discloses "Organic field-effect transistor memory based on PM series wide-bandgap polymer and Y₆ receptor blend material system and its preparation" and CN116836192A discloses "Bisboron nitrogen bridged bipyridine and its preparation, high-mobility n-type organic semiconductor materials based on it, and their preparation and application." As one of the important components of OFET, high-precision, reliable and stable patterning processing of the organic semiconductor layer is of paramount importance.

[0004] Mixing polymer semiconductors with cross-linked molecules of two or more components and processing the active layer of OFETs through photocrosslinking has attracted increasing interest because this type of patterning method can theoretically provide the highest precision device integration, achieving the goal of reducing manufacturing costs, improving device performance and solution stability of thin films. However, existing photolithographic patterning processes are still insufficient to address the inherent environmental stability issues of N-type polymer semiconductors, such as the paper Nat Commun 11, 1520 (2020)., Angew. Chem. Int. Ed. 2021, 60, 21521.

[0005] Therefore, for polymer semiconductors, especially N-type organic semiconductor polymers, it is necessary to find a patterning process that is compatible with environmental processing to change the performance problems of existing organic electronic devices. Summary of the Invention

[0006] The purpose of the present invention is to solve at least one of the above problems and provide an organic semiconductor photoresist with a hierarchical structure and environmental stability, as well as a patterning method and an organic electronic device, to address the problems in the prior art that N-type polymer semiconductors have poor air stability and the semiconductor film is easily affected by solvent corrosion during solution processing, resulting in the poor performance of the prepared organic electronic devices. The present invention uses solvent-driven photoresist to autonomously form a controllable gradient phase separation structure, and further patterning to form an organic semiconductor film with a dense hierarchical interlaced network structure. The organic semiconductor film exhibits significantly better air stability and electron mobility than previously reported N-type polymer semiconductor photoresists, and is expected to be used in wearable electronics, photodetectors, high-precision flexible complementary logic circuits and other fields.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] The first aspect of the present invention discloses an organic semiconductor photoresist having a hierarchical structure and being environmentally stable, comprising a polymer semiconductor, a photocrosslinking encapsulating molecule and a photoinitiator dissolved in a mixed solvent;

[0009] Based on the solubility difference between polymer semiconductors and photocrosslinking encapsulation molecules in mixed solvents, controllable phase separation of polymer semiconductors and photocrosslinking encapsulation molecules is achieved, and the gradient-changing phase distribution forms a hierarchical structure, so that the photocrosslinking encapsulation molecules form a self-encapsulation structure for the polymer semiconductor.

[0010] Preferably, the polymer semiconductor is an N-type polymer semiconductor, including one or more of naphthalimide, thiophene, diketopyrrolopyrrole, and benzimidazole derivatives;

[0011] The crosslinking groups in the photo-crosslinking encapsulation molecules include one or more of cinnamate groups, azide groups, coumarin groups, acrylate groups, epoxy groups and Si-H groups;

[0012] The photoinitiator includes one or more of an amine photoinitiator, a thioxanthone photoinitiator, a benzophenone photoinitiator, a camphorquinone photoinitiator and a bisimidazole photoinitiator.

[0013] Preferably, the photo-crosslinking encapsulating molecules are photo-crosslinking encapsulating monomer molecules with polar groups, and / or photo-crosslinking encapsulating polymers with a molecular weight greater than 15,000.

[0014] Preferably, the photo-crosslinking encapsulation monomer molecule is a photo-crosslinking monomer with one or more groups selected from benzene, fluorine, naphthalene, biphenyl and Si-O; the skeleton structure of the photo-crosslinking encapsulation polymer is an organosilicon chain, an alkyl chain or an oxygen-containing heterochain.

[0015] Preferably, the mass ratio of the polymer semiconductor to the photocrosslinking encapsulating molecule is 1:2-8, the concentration of the polymer semiconductor is 2-50 mg / mL, and the amount of the photoinitiator is 1-10 wt % of the photocrosslinking encapsulating molecule.

[0016] Preferably, the mixed solvent comprises an aprotic polar solvent and a chloride solvent in a volume ratio of 1:4-20; the solubility of the photocrosslinking encapsulation molecule in the aprotic polar solvent and the chloride solvent is 10-80 mg / mL; the solubility of the polymer semiconductor in the aprotic polar solvent is less than 2 mg / mL, and the solubility of the polymer semiconductor in the chloride solvent is 2-50 mg / mL.

[0017] A second aspect of the present invention discloses a method for patterning an organic semiconductor photoresist having a hierarchical structure and being environmentally stable as described above, comprising the following steps:

[0018] S1: dissolving a polymer semiconductor and a photocrosslinking encapsulating molecule in a mixed solvent, adding a photoinitiator and stirring in the dark before photolithography to obtain an organic semiconductor photoresist having a hierarchical structure and being environmentally stable as described above;

[0019] S2: Spin-coating the photoresist obtained in step S1 on a substrate to obtain a blended film;

[0020] S3: performing patterned exposure on the blended film obtained in step S2 to form a hierarchical interlaced network structure;

[0021] S4: developing the blended film after exposure in step S3 to obtain an organic semiconductor film with a hierarchical interlaced network structure.

[0022] Based on the solubility difference between polymer semiconductors and photocrosslinking encapsulation molecules in mixed solvents, controllable phase separation of polymer semiconductors and photocrosslinking encapsulation molecules in spatial distribution in the blended film is achieved, inducing the film to form a hierarchical structure with gradient changes, so that the photocrosslinking encapsulation molecules form a self-encapsulation structure for the polymer semiconductor. Among them: the photocrosslinking encapsulation molecules are mainly concentrated on the upper surface of the blended film (the surface on the side in contact with the environment), and their content is distributed in an inverted pyramid from the upper surface to the lower surface of the blended film (the surface on the side in contact with the substrate); correspondingly, the polymer semiconductor is mainly concentrated on the lower surface of the blended film, and its content is distributed in a pyramid from the lower surface to the upper surface of the blended film. Therefore, in the blended film, the photocrosslinking encapsulation molecules cover the polymer semiconductor layer by layer, forming a self-encapsulation structure to reduce the area of ​​contact between the polymer semiconductor and the environment.

[0023] Preferably, the substrate is surface-modified so that the surface-modified substrate has a strong adsorption force for the polymer semiconductor and has a regular orientation.

[0024] Preferably, the spin coating is as follows: the standing time before spin coating is 5-60 seconds, the speed during spin coating is 1500-5500 rpm, the pre-bake temperature after spin coating is 75-120°C; the exposure dose of the patterned exposure is 150-3000 mJ cm -2 ; The thickness of the organic semiconductor film is 80-150nm; the developing solution comprises an ester solvent or a non-protonic polar solvent and an aromatic hydrocarbon solvent in a volume ratio of 1:1-9.

[0025] A third aspect of the present invention discloses an organic electronic device, comprising an organic semiconductor thin film having a hierarchical interlaced network structure prepared by any of the above patterning methods.

[0026] The working principle of the present invention is:

[0027] When two or more polymers are physically mixed, phase separation is likely to occur due to differences in compatibility between the polymers. On the one hand, a phase separation size that is too small can only affect the microscopic aggregate structure of the polymer; on the other hand, an overly large phase separation structure makes it difficult to ensure the cross-linking stability of the organic semiconductor film. The present invention uses the principle of solvent induction to orderly divide the spatial distribution of the two phases in the blended film at the micro-nano scale. While ensuring high-precision patterning, cross-linking molecules are used as a sealing encapsulation layer to isolate air from the electron transport in the underlying polymer semiconductor. At the same time, in order to ensure the controllability of the hierarchical interlaced network structure of the semiconductor film and the adequacy of the overall cross-linking of the film, the photo-crosslinkable encapsulation molecules need to have good solubility in chloride solvents and aprotic polar solvents, and need to have a certain adhesion to the substrate or have a molecular weight equivalent to that of the polymer semiconductor. By utilizing the good solubility of the photo-encapsulated cross-linking molecules and having a high solubility in most polar solvents, a suitable mixed solvent is selected to regulate the scale of the hierarchical phase separation to obtain a controllable and well-distributed hierarchical structure and a hierarchical interlaced network structure.

[0028] The aforementioned statement that "the photocrosslinkable encapsulating molecules need to have good solubility in chloride solvents and aprotic polar solvents and need to have a certain degree of adhesion to the substrate or have a molecular weight comparable to that of the polymer semiconductor" is because: substances with lower solubility will preferentially precipitate from the solution, while substances with higher molecular weight will aggregate toward the substrate under the action of gravity; therefore, it is necessary to control the photocrosslinking encapsulating molecules to have a certain amount of deposition at the bottom of the film to ensure sufficient crosslinking of the entire film. If the molecular weight of the photocrosslinking encapsulating molecules themselves is too small (the molecular weight difference is extremely large), the photocrosslinking encapsulating molecules in the prepared film will only aggregate on the upper surface of the film, resulting in the inability to crosslink the lower layer of the film. At this time, it is necessary to further utilize the adhesion of the photocrosslinking encapsulating molecules themselves to the substrate to ensure that there are a certain number of crosslinking molecules in the lower layer of the film, thereby ensuring sufficient crosslinking of the entire film.

[0029] Therefore, in this scheme, the difference in solubility of polymer semiconductors and photocrosslinked encapsulation molecules in the mixed solvent is the main reason for the formation of phase separation structure and hierarchical interlaced network structure, while the difference in molecular weight between polymer semiconductors and photocrosslinked encapsulation molecules, and the photocrosslinked encapsulation molecules having a certain adhesion to the substrate are supplementary restrictions to ensure that the blended film can form overall crosslinking and sufficient crosslinking, so as to avoid complete stratification and inability to complete the patterning of the polymer semiconductor film.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] Compared with traditional organic semiconductor photoresists, the organic semiconductor photoresist prepared by the present invention has a gradient-changing, layer-by-layer dense cross-linked network structure; excellent dense self-encapsulation and water and oxygen barrier capabilities; large patterning resolution and high integration; the crystallinity and carrier mobility of the organic semiconductor film are no significantly different from or even better than those of the original polymer semiconductor film.

[0032] The photoresist of the present invention is an N-type polymer semiconductor photoresist, which can meet the requirements of direct photolithographic processing, compatibility with the manufacture of organic electronic devices (OFETs, CMOS, etc.), high resolution, high electron mobility and high stability.

[0033] The environmentally stable organic semiconductor photoresist prepared by this method has submicron resolution and excellent environmental stability. The hierarchical interlaced network formed autonomously after patterning isolates the organic semiconductor phase (i.e., polymer semiconductor) from air intrusion, providing a patterning strategy for the active layer of N-type organic electronic components with high electron mobility, high integration, and high stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the process of patterning the organic semiconductor photoresist of the present invention;

[0035] Figure 2 This is an optical microscope image of the organic semiconductor photoresist of Example 2 after patterned exposure;

[0036] Figure 3 Schematic diagram of the structure of the organic semiconductor photoresist with a hierarchical structure in Example 3;

[0037] Figure 4 (a) Schematic diagram of the structure of the OFET device and (b) a photo of the flexible device prepared by the full photolithography process in Example 4;

[0038] Figure 5 The transfer characteristic curve of the organic field effect transistor prepared in Example 6;

[0039] Figure 6 This is the output characteristic curve of the organic field effect transistor prepared in Example 7;

[0040] Figure 7 This is an EDS energy spectrum line scan (along the film cross section) of the polymer semiconductor in the organic semiconductor film prepared in Example 2;

[0041] Figure 8 Comparison of the air stability performance of OFETs prepared in Example 2 and Comparative Example 1 tested under ambient conditions;

[0042] Figure 9This is the output characteristic curve of the organic complementary inverter prepared in Example 5. DETAILED DESCRIPTION

[0043] In the following description, unless otherwise specified, the reagents used are conventional commercial products, and the methods used are well known in the art.

[0044] Unless otherwise specified, all processes described below are carried out at room temperature and atmospheric conditions.

[0045] An environmentally stable organic semiconductor photoresist with a hierarchical interlaced network structure and a patterning method, such as Figure 1 As shown, the following steps are included:

[0046] S1: physically mixing a polymer semiconductor, a photocrosslinkable encapsulating molecule, a photoinitiator, and two or more solvents (mixed solvents) to obtain a precursor solution (i.e., photoresist);

[0047] S2: Surface modification and modification of organic field-effect transistors prepared by standard microelectronics processes to obtain substrates with strong adsorption and regular orientation for polymer semiconductors;

[0048] S3: Spin-coating the precursor solution on the substrate in an orderly manner, and obtaining a multi-dimensional structured blend film by controlling the spin-coating process;

[0049] S4: exposing and curing the obtained blended film, wherein the multidimensional micro-dispersed phase film structure is further interconnected to form a dense hierarchical interlaced network structure;

[0050] S5: Controllably developing the exposed blended film to obtain a patterned, hierarchically interlaced network structured, environmentally stable organic semiconductor film.

[0051] Among them, the polymer semiconductor adopts an N-type polymer semiconductor with high electron deficiency and good electron transmission ability, including one or any combination of naphthalene imide, thiophene, pyrrolopyrrole dione, and benzimidazole derivatives; the cross-linking group carried by the photocrosslinking encapsulation molecule can be one or any combination of cinnamate, azide, coumarin, acrylate, epoxy, Si-H; the photocrosslinking encapsulation molecule can be a monomer molecule with a polar group and a polymer with a molecular weight greater than 15,000 and a complex of the two; the photocrosslinking encapsulation monomer molecule can be a photocrosslinking monomer containing benzene, fluorine, naphthalene, biphenyl, Si-O group; the skeleton structure of the photocrosslinking encapsulation polymer can be an organic silicon chain, an alkyl chain, or an oxygen-containing heterochain; the photoinitiator includes at least one of benzophenone and amine compounds, thioxanthone photoinitiator, camphorquinone and biimidazole.

[0052] In the precursor solution, the content of N-type polymer semiconductor is 2 mg / mL to 50 mg / mL; the mass ratio of N-type polymer semiconductor and photocrosslinkable encapsulating molecules is 1:2 to 1:8; the doping amount of photoinitiator is 1-10% of the mass of photocrosslinkable encapsulating molecules; the mixed solvent used includes a mixture of two or more of aprotic polar solvents and chloride solvents, with a volume ratio of 1:4 to 1:20; the developer used includes an ester solvent or a mixture of two or more of aprotic polar solvents and aromatic hydrocarbon solvents, with a volume ratio of ester solvent to aromatic hydrocarbon solvent of 1:1 to 1:9.

[0053] The photocrosslinking encapsulation molecules need to have good solubility in both aprotic polar solvents and chloride solvents to form a controllable solubility difference with the organic semiconductor in the mixed solution, ensuring the controllable hierarchical interlaced network structure of the semiconductor film. Therefore, in this scheme, the solubility of the photocrosslinking encapsulation molecules in aprotic polar solvents and chloride solvents is controlled to 10-80 mg / mL; the solubility of the polymer semiconductor in aprotic polar solvents is less than 2 mg / mL, and the solubility of the polymer semiconductor in chloride solvents is 2-50 mg / mL.

[0054] The ordered spin coating process for patterning environmentally stable organic semiconductor thin films with hierarchical interlaced network structures includes selecting the volume of photoresist droplets according to the substrate size, the rest time before spin coating (5-60 seconds), the spin coating speed (1500-5500 rpm), and the pre-bake temperature after spin coating (75-120°C). The exposure process includes timely adjustment of the exposure dose according to the photoresist formula, substrate, photoresist film thickness, and pattern size, with the exposure dose range of 150-3000 mJ cm -2 .

[0055] By controlling the spin coating process, under the action of solvent induction force (main effect), gravity and substrate adhesion force, components with lower solubility and higher molecular weight (polymer semiconductors) tend to precipitate and solidify preferentially on the base material (substrate), while components with higher solubility and lower molecular weight (photo-crosslinked encapsulation molecules) tend to aggregate on the surface of the film, and the gradient phase distribution forms a blended film with a multidimensional structure.

[0056] Surface modification and modification of organic field-effect transistors, including surface modification of gate dielectrics, source and drain electrodes.

[0057] The gate dielectric (gate insulating layer) is an inorganic, organic, or organic / inorganic hybrid material, including but not limited to: silicon dioxide, hafnium dioxide, aluminum oxide, zirconium oxide, epoxy resin, cinnamate and other photocurable polymers, and polymers such as polyvinyl alcohol, polyacrylonitrile, and polyvinylidene fluoride.

[0058] The modifiers for the source and drain electrodes include some organic small molecules and inorganic compounds that can be adsorbed on the electrodes to change the metal work function, and the modifiers for the gate dielectric use some organic compounds that are super-hydrophobic and can bond to the dielectric layer.

[0059] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. However, it should be emphasized that the specific details of these embodiments are intended only to illustrate the present invention and do not represent all the technical solutions of the present invention. Therefore, these details should not be construed as limiting the technical solutions of the present invention. In the opinion of some skilled persons, non-substantial additions and modifications that do not deviate from the concept of the present invention should also be included in the scope of protection of the present invention.

[0060] Example 1:

[0061] A hierarchical interlaced network-dominated, environmentally stable organic semiconductor photoresist, wherein a patterning method thereof comprises the following steps:

[0062] 1) Poly{[N,N'-bis(2-hexyldecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)}[P(NDI2HD-T2), CAS: 145168-70-7] and photocrosslinkable encapsulating molecule acrylic-cage polysilsesquioxane (POSS, CAS: 1620202-27-8) were mixed at a mass ratio of 2:1 and dissolved in chlorobenzene (CB, CAS: 108-90-7) and 1,4-dioxane (D-1) at a volume ratio of 19:1. The invention relates to a method for preparing a semiconductor photoresist comprising: adding a first-line product of claim 1 to a mixed solvent of POSS and stirring at 25° C. and 300 rpm to dissolve the first-line product; then adding a free radical initiator, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO, CAS: 75980-60-8) and a thiol additive, trimethylolpropane tris (3-mercaptopropionate) (TRIS, CAS: 33007-83-9), in an amount of 5 wt % based on the POSS; and stirring at 25° C. and 250 rpm in the dark for 5 minutes; and obtaining a semiconductor photoresist having a P(NDI2HD-T2) content of 10 mg / mL.

[0063] 2) Patterned electrodes were prepared on a silicon substrate with a 300-nanometer oxide layer using laser direct write lithography, and 5-nanometer chromium and 45-nanometer gold were then deposited as source and drain electrodes using thermal evaporation. The prepared source and drain electrodes were immersed in an organic solvent (such as toluene) containing octadecyltrichlorosilane for 12 hours. The modified device was then removed and washed with chloroform and ethanol to remove excess octadecyltrichlorosilane from the device surface.

[0064] 3) Under yellow light, select the appropriate glue drop volume according to the size of the device. Wait 20 seconds after glue drop to allow physical phase separation of the precursor solution on the substrate. Then, spin coat at 2000 rpm for 30 seconds to prepare a multi-dimensional blend film with uniform layers. Then, spin coat at 385 nm wavelength and 800 mJ cm -2 The laser direct writing lithography machine is used for maskless patterning, and the cross-linked and dispersed multi-dimensional structure further forms an interconnected and dense hierarchical interlaced network structure, effectively isolating water and oxygen;

[0065] 4) Immerse in a developer with a volume ratio of CB to DI of 9:1 for 45 seconds. The pattern in the exposed area does not dissolve, while the unexposed area falls off the silicon substrate after vigorous shaking in the developer, forming a patterned active layer with a thickness of about 100 nm.

[0066] 5) Annealing at 190°C for 10 minutes to form an environmentally stable organic semiconductor film dominated by a hierarchical staggered network, and construct a bottom-gate bottom-contact organic field-effect transistor device. The preparation process is shown in the following figure: Figure 1 shown.

[0067] Example 2:

[0068] A hierarchical interlaced network-dominated, environmentally stable organic semiconductor photoresist, wherein the patterning method thereof is different from that of Example 1 in that:

[0069] In step 1), poly (2,7-bis (2-octyldodecyl) benzo [LMN] [3,8] phenanthroline-1,3,6,8 (2H,7H) -tetraketone-4,9-diyl) ([2,2'] dithienyl -5,5'-diyl) (N2200, CAS: 1100243-40-0) and photo-crosslinkable encapsulating molecule polyvinyl cinnamate (PVCN, CAS: 9050-06-0) were mixed at a mass ratio of 1:4 and dissolved in a trifluoroacetic acid solution with a volume ratio of 17:3. The mixture was heated and stirred at 45°C and 300 rpm to dissolve in a mixed solvent of methyl chloride (CF, CAS: 67-66-3) and N,N-dimethylformamide (DMF, CAS: 68-12-2). 2-isopropylthioxanthone (ITX, CAS: 5495-84-1) was then added as a free radical initiator at an amount of 3 wt% based on the weight of the PVCN. The mixture was stirred at 25°C and 250 rpm in the dark for 5 minutes. The resulting semiconductor photoresist precursor solution had an N2200 content of 4 mg / mL.

[0070] In step 2), a monolayer of octadecyltrichlorosilane was self-assembled on a silicon wafer having a 300-nanometer oxide layer by vacuum solvent annealing to obtain a flat, hydrophobic substrate; the device was then immersed in a solution of 1-thiodecane and ethanol at a volume ratio of 1:1000 for 2 minutes to modify the source / drain electrodes. After removal, excess 1-thiodecane was washed off with ethanol, followed by annealing at 130° C. for 10 minutes;

[0071] In step 3), under yellow light, the appropriate glue drop volume was selected according to the size of the substrate. After glue drop, waited for 12 seconds to construct the physical phase separation of the precursor solution on the substrate. Then, spin coating was performed at 3000 rpm for 30 seconds to prepare a multi-dimensional blend film with uniform layers. Then, the film was sprayed at a wavelength of 385 nm and a power of 200 mJ cm -2 Laser direct writing lithography machine for maskless patterning, Figure 2 This is an optical microscope image of the high-precision pattern of the organic semiconductor photoresist prepared in Example 2;

[0072] In step 4), the substrate is immersed in a developer solution of ethyl acetate and toluene (TL, CAS: 108-88-3) in a volume ratio of 2:8 for 15 seconds. The pattern in the exposed area is not dissolved, and the unexposed area is vigorously shaken in the developer and falls off from the silicon substrate, forming a patterned polymer semiconductor film with a thickness of about 80 nm.

[0073] In step 5), annealing is performed at 170° C. for 10 minutes, and the rest is the same as in Example 1.

[0074] Comparative Example 1:

[0075] A hierarchical interlaced network-dominated, environmentally stable organic semiconductor photoresist, wherein the patterning method thereof is different from that of Example 2 in that:

[0076] In step 1), poly(2,7-bis(2-octyldodecyl)benzo[LMN][3,8]phenanthroline-1,3,6,8(2H,7H)-tetraone-4,9-diyl)([2,2']dithienyl-5,5'-diyl) (N2200, CAS: 1100243-40-0) and photocrosslinkable encapsulating molecule PVCN are mixed in a mass ratio of 1:4 and dissolved in a single solvent of chloroform. The rest of the steps are the same as in Example 2.

[0077] Example 3:

[0078] A hierarchical interlaced network-dominated, environmentally stable organic semiconductor photoresist, wherein the patterning method thereof is different from that of Example 1 in that:

[0079] In step 1), poly[N,N'-bis(2-octyldodecyl)-pyrrolopyrroledione-alt-benzothiadiazole] (P(NDI2OD-BDT)) and a photocrosslinkable encapsulating molecule PVCN are mixed in a mass ratio of 1:5 and dissolved in a mixed solvent of CB, o-dichlorobenzene (DCB, CAS: 95-50-1), and ethyl acetate (EA, CAS: 141-78-6) in a volume ratio of 89:1:10, and heated and stirred at 25°C and 300 rpm to dissolve; then, a free radical initiator ITX is added in an amount of 3wt% of PVCN, and stirred in the dark at 25°C and 250 rpm for 5 minutes; the resulting semiconductor photoresist has a precursor solution with a P(NDI2OD-BDT) content of 6 mg / mL;

[0080] In step 3), under yellow light, the appropriate glue drop volume was selected according to the size of the substrate. After glue drop, waited for 15 seconds to construct the physical phase separation of the precursor solution on the substrate. Then, spin coating was performed at 1800 rpm for 45 seconds to prepare a multi-dimensional blend film with uniform layers. Then, the film was sprayed at a wavelength of 385 nm and a power of 450 mJ cm -2 Laser direct writing lithography machine for maskless patterning, Figure 3 Schematic diagram of the hierarchical interlaced network-dominated environmentally stable organic semiconductor film prepared in Example 4;

[0081] In step 5), vacuum annealing is performed at 180° C. for 30 minutes, and the rest is the same as in Example 1.

[0082] Example 4:

[0083] A hierarchical interlaced network-dominated, environmentally stable organic semiconductor photoresist, wherein the patterning method thereof is different from that of Example 1 in that:

[0084] In step 2), a patterned electrode was prepared on a clean polyethylene terephthalate (PET) flexible substrate using laser direct write lithography, and a 30-nm gold gate was deposited by thermal evaporation. A gate insulating layer was then formed on the gate, and an epoxy-based negative photoresist (SU-8) was used to photolithography at a wavelength of 385 nm and a power of 1600 mJ cm. -2 The film was patterned without a mask using a laser direct write lithography machine, and then immersed in a propylene glycol methyl ether acetate developer for 8 seconds. The pattern in the exposed area did not dissolve, and the unexposed area fell off the PET substrate after vigorous shaking in the developer. It was then annealed at 170°C for 30 minutes to form a gate insulating layer with a thickness of about 450 nanometers.

[0085] The rest is the same as in Example 1.

[0086] Figure 4(a) is a schematic diagram of the fully photolithographic OFET device structure in this embodiment; (b) is a fully photolithographically processed flexible device;

[0087] Example 5:

[0088] A hierarchical interlaced network-dominated, environmentally stable organic semiconductor photoresist, wherein the patterning method thereof is different from that of Example 1 in that:

[0089] In step 1), poly[[1,2,3,6,7,8-hexahydro-2,7-bis(2-octyldodecyl)-1,3,6,8-tetraoxybenzo[lmn][3,8]phenanthroline-4,9-diyl]-2,5-thiophenediyl]]PNDI(2OD)-T, CAS: 1236111-76-4] and a photocrosslinkable encapsulating molecule POSS are mixed in a mass ratio of 1:2 and dissolved in a mixed solvent of 1-chloronaphthalene (CAS: 90-13-1), DCB, and DI in a volume ratio of 1:9:1, and heated and stirred at 25°C and 350 rpm to dissolve; then, a free radical initiator ITX is added in an amount of 5wt% of PVCN, and stirred at 25°C and 250 rpm in the dark for 5 minutes; the obtained semiconductor photoresist contains an N-type precursor solution with a PNDI(2OD)-T content of 4 mg / mL;

[0090] A p-type semiconductor polymer poly(tetrathienopyrroledione) (PTDPPTFT4) and a photocrosslinkable encapsulating molecule POSS were mixed in a mass ratio of 1:2 and dissolved in a mixed solvent of 1-chloronaphthalene (CAS: 90-13-1), DCB, and DI in a volume ratio of 1:20:1. The mixture was heated and stirred at 25°C and 350 rpm to dissolve. A free radical initiator ITX was then added at a concentration of 5 wt% of the PVCN and stirred at 25°C and 250 rpm in the dark for 5 minutes. The resulting semiconductor photoresist contained a p-type precursor solution containing 4 mg / mL of PTDPPTFT4.

[0091] In step 2), the patterned electrodes of the inverter were prepared on a clean polyethylene terephthalate (PET) flexible substrate using laser direct write lithography. 30 nm gold was then deposited as a gate electrode by thermal evaporation. A gate insulating layer was then formed on the gate electrode using an epoxy resin-based negative photoresist (SU-8) at a wavelength of 385 nm and a power of 1600 mJ cm -2The film was patterned without a mask using a laser direct write lithography machine, and then immersed in propylene glycol methyl ether acetate developer for 8 seconds. The pattern in the exposed area did not dissolve, and the unexposed area fell off the PET substrate after vigorous shaking in the developer. It was then annealed at 170°C for 30 minutes to form a gate insulating layer with a thickness of approximately 450 nanometers. Laser direct write lithography was then used to prepare patterned electrodes for the inverter on a substrate with a 450-nanometer organic dielectric layer, and 5 nanometers of chromium and 45 nanometers of gold were deposited as source and drain electrodes using thermal evaporation technology.

[0092] In step 3), the active layer of the P-type transistor is first patterned under yellow light. The appropriate glue volume is selected according to the size of the device. After glue application, wait for 60 seconds to construct the physical phase separation of the P-type precursor solution on the substrate. Then, spin coating is performed at 2000 rpm for 30 seconds to prepare a multi-dimensional blended film with uniform layers. Then, the film is heated at a wavelength of 385 nm and a power of 1200 mJ cm -2 The laser direct write lithography machine was used for maskless patterning. Then, the N-type transistor semiconductor thin film in the complementary inverter was patterned. The appropriate glue drop volume was selected according to the size of the device. After glue drop, it was waited for 20 seconds to construct the physical phase separation of the N-type precursor solution on the substrate. Then, spin coating was performed at 2000 rpm for 30 seconds to prepare a multi-dimensional blended thin film with uniform layers. Then, the laser was sprayed at a wavelength of 385 nm and a power of 800 mJ cm -2 The laser direct writing lithography machine is used for maskless patterning; the formed cross-linked and dispersed multi-dimensional structure further forms an interconnected and dense hierarchical interlaced network structure, effectively isolating water and oxygen;

[0093] The rest is the same as in Example 1.

[0094] Example 6:

[0095] A hierarchical interlaced network-dominated, environmentally stable organic semiconductor photoresist, wherein the patterning method thereof is different from that of Example 1 in that:

[0096] In step 1), PNDIF-T2 (obtained by replacing the alkyl side chain of N2200 with a semifluorinated alkyl side chain) and PVCN are mixed in a mass ratio of 1:2 and dissolved in a mixed solvent of chloroform and 1,4-dioxane in a volume ratio of 16:4, and heated and stirred at 25°C and 300rpm to dissolve; then, a free radical initiator 2-isopropylthioxanthone is added in an amount of 3wt% of PVCN, and stirred at 25°C and 250rpm in the dark for 5 minutes; the resulting semiconductor photoresist has a PNDIF-T2 content of 7mg / mL.

[0097] The rest is the same as in Example 1.

[0098] Figure 5Schematic diagram of the transfer curve of the device tested in this embodiment.

[0099] Example 7:

[0100] A hierarchical interlaced network-dominated, environmentally stable organic semiconductor photoresist, wherein the patterning method thereof is different from that of Example 1 in that:

[0101] In step 1), PNDIBS (selenium with a larger atomic radius is used to replace the sulfur on the N2200 main chain) and PVCN are mixed in a mass ratio of 1:5 and dissolved in a mixed solvent of chloroform and 1,4-dioxane in a volume ratio of 95:5, and heated and stirred at 25°C and 300rpm to dissolve; then a free radical initiator 2-isopropylthioxanthone is added in an amount of 3wt% of PVCN, and stirred at 25°C and 250rpm in the dark for 5 minutes; the resulting semiconductor photoresist has a PNDIBS content of 5 mg / mL precursor solution.

[0102] The rest is the same as in Example 1.

[0103] Figure 6 Schematic diagram of the output curve of the device test processed in this embodiment.

[0104] Performance testing:

[0105] The patterning effect, thin film structure, and performance of the organic field-effect transistors of the organic semiconductor photoresists prepared in the above examples were characterized:

[0106] (1) Patterning accuracy and environmental stability of polymer semiconductor photoresists

[0107] Table 1 Performance test results

[0108]

[0109] Table 1 shows a comparison of the patterning effects and environmental stability of the polymer semiconductor photoresists prepared in Examples 1-7 and Comparative Example 1. The environmental stability is determined by measuring the mobility.

[0110] In Comparative Example 1, since a single-component solvent is used, the conjugated polymer film prepared cannot independently produce a controllable gradient phase separation encapsulation structure. Therefore, the film obtained after spin coating is evenly exposed to the air. After the source electrode injects charges, the electrons are easily captured by water and oxygen in the air, so the test effect in the environment is poor. In the other embodiments, since the photoresist is prepared using a precursor solution prepared with a good solvent and a poor solvent, the overall structure of the prepared film undergoes controllable gradient phase separation. By controlling the spin coating speed and the pre-baking process after spin coating, a multi-dimensional structured blended film is prepared. Then, after exposure and curing, the dispersed multi-dimensional structure further forms an interconnected, dense hierarchical interlaced network structure, effectively isolating water and oxygen. Finally, the unexposed area is removed with a developer, and a patterned hierarchical interlaced network-dominated environmentally stable polymer semiconductor film is obtained.

[0111] like Figure 2 The optical microscope image of the interlaced network encapsulated polymer semiconductor film prepared in Example 2 is shown. Figure 2 The minimum line width is only 0.6μm, showing excellent patterning ability; Figure 3 Schematic diagram of the structure of the polymer semiconductor film after photocrosslinking in Example 3.

[0112] Figure 7 This is a cross-sectional energy spectrum line scan of the photocrosslinked hierarchical interlaced network polymer semiconductor film prepared in Example 2. As can be seen from the figure, the content of the two characteristic elements N Kα1_2 (N element characteristic peak) and S Kα1 (S element characteristic peak) contained in the patterned film increases layer by layer from the top surface to the substrate, indicating that the film exhibits an ideal aggregated structure. Correspondingly, the encapsulated crosslinking molecules exhibit the opposite distribution, forming a layer-by-layer crosslinked network after exposure. This demonstrates that the samples prepared by this method provide excellent encapsulation and protection.

[0113] Figure 5 and Figure 6 The transfer curves and output curves of the OFETs prepared in Examples 6 and 7 are shown respectively. The specific test methods are as follows:

[0114] The tests were performed using commercial semiconductor testers and probe stations.

[0115] The test parameters used for the transfer curve test are as follows: the source voltage is fixed at 60V, the drain end is grounded, and the gate end voltage is swept from 0V to 60V at a sweep rate of 2V / step.

[0116] The test parameters uniformly adopted for the output curve test are: the gate voltage is fixed at 60V, the drain end is grounded, the source end voltage is swept from 0V to 60V, and the sweep speed is 10 / Step, the same below.

[0117] It can be seen from the figure that even when tested under ambient conditions, the organic field-effect transistor prepared in the embodiment can maintain stable electrical characteristics, thereby proving the reliability of the implementation of this solution.

[0118] In the field of OFETs, carrier mobility is an important parameter for measuring the performance of organic semiconductors. In order to verify the reliability of the implementation of this solution, a batch of OFETs devices were prepared using the two processes in Example 2 and Comparative Example 1, and their electrical performance tests (transfer and output curves) were carried out under atmospheric conditions. Figure 8 As shown, the electron mobility of the device prepared in Example 2 is significantly higher than that of the device prepared in Comparative Example 1, thus proving that the semiconductor film formed by solvent-induced dense hierarchical cross-linking network has more stable performance under ambient conditions.

[0119] (2) Performance characterization of organic complementary inverter

[0120] Test Method: A commercial semiconductor tester and probe station were used. The drive voltage was kept constant at 60V, the input voltage was swept from 0V to 60V at a sweep rate of 0.05V / step, and one terminal was grounded. The voltage change at the output electrode was measured.

[0121] The results are as follows Figure 9 As shown in the figure, it can be seen that the organic complementary inverter prepared in Example 5 exhibits typical logic operations within the range of input (0 and 1) and output logic states (1 and 0).

[0122] In summary, the organic semiconductor photoresist proposed in the present invention has high-precision patterning capability, and the organic semiconductor film obtained by its patterning has a hierarchical interlaced network structure, and has excellent dense self-packaging, water and oxygen barrier capabilities, and strong environmental stability: the packaging structure independently composed of cross-linked molecules achieves good air stability, and at the same time, the dense cross-linked network in the upper layer protects most of the polymer semiconductors in the prepared blended film (because most of them are deposited at the bottom of the blended film) from the influence of the solvent (mainly referring to the development step); the crystallinity and carrier transfer rate of the organic semiconductor film are not significantly different from or even better than those of the original polymer semiconductor film: referring to the same concentration of solution and the same thickness of organic semiconductor film, the organic semiconductor film prepared by the method of the present invention, the dense and intricate polymer semiconductor fibers in the lower layer have better conductivity than the uniform semiconductor film, this is because the charge transfer is mainly in the thickness of a few nanometers on the lower surface of the film.

[0123] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. An organic semiconductor photoresist having a hierarchical structure and being environmentally stable, characterized in that: including a polymer semiconductor, a photocrosslinking encapsulating molecule, and a photoinitiator dissolved in a mixed solvent; Based on the solubility difference between polymer semiconductors and photocrosslinking encapsulation molecules in mixed solvents, controllable phase separation of polymer semiconductors and photocrosslinking encapsulation molecules is achieved, and the gradient-changing phase distribution forms a hierarchical structure, so that the photocrosslinking encapsulation molecules form a self-encapsulation structure for the polymer semiconductor.

2. The organic semiconductor photoresist having a hierarchical structure and being environmentally stable according to claim 1, characterized in that: The polymer semiconductor is an N-type polymer semiconductor, including one or more of naphthalimide, thiophene, diketopyrrolopyrrole, and benzimidazole derivatives; The crosslinking groups in the photo-crosslinking encapsulation molecules include one or more of cinnamate groups, azide groups, coumarin groups, acrylate groups, epoxy groups and Si-H groups; The photoinitiator includes one or more of an amine photoinitiator, a thioxanthone photoinitiator, a benzophenone photoinitiator, a camphorquinone photoinitiator and a bisimidazole photoinitiator.

3. The organic semiconductor photoresist having a hierarchical structure and being environmentally stable according to claim 2, characterized in that: The photo-crosslinking encapsulating molecules are photo-crosslinking encapsulating monomer molecules with polar groups, and / or photo-crosslinking encapsulating polymers with a molecular weight greater than 15,000.

4. The organic semiconductor photoresist having a hierarchical structure and being environmentally stable according to claim 3, characterized in that: The photo-crosslinking encapsulation monomer molecule is a photo-crosslinking monomer with one or more groups selected from benzene, fluorine, naphthalene, biphenyl and Si-O; the skeleton structure of the photo-crosslinking encapsulation polymer is an organic silicon chain, an alkyl chain or an oxygen-containing heterochain.

5. The organic semiconductor photoresist having a hierarchical structure and being environmentally stable according to claim 1, characterized in that: The mass ratio of the polymer semiconductor to the photocrosslinking encapsulating molecule is 1:2-8, the concentration of the polymer semiconductor is 2-50 mg / mL, and the amount of the photoinitiator is 1-10 wt% of the photocrosslinking encapsulating molecule.

6. The organic semiconductor photoresist having a hierarchical structure and being environmentally stable according to claim 1, characterized in that: The mixed solvent comprises an aprotic polar solvent and a chloride solvent in a volume ratio of 1:4-20; the solubility of the photocrosslinked encapsulation molecule in the aprotic polar solvent and the chloride solvent is 10-80 mg / mL; the solubility of the polymer semiconductor in the aprotic polar solvent is less than 2 mg / mL, and the solubility of the polymer semiconductor in the chloride solvent is 2-50 mg / mL.

7. A method for patterning an organic semiconductor photoresist having a hierarchical structure and being environmentally stable according to any one of claims 1 to 6, characterized in that: The steps include: S1: dissolving a polymer semiconductor and a photocrosslinking encapsulating molecule in a mixed solvent, adding a photoinitiator before photolithography, and stirring in the dark to obtain an organic semiconductor photoresist having a hierarchical structure and being environmentally stable as claimed in any one of claims 1 to 6; S2: Spin-coating the photoresist obtained in step S1 on a substrate to obtain a blended film; S3: performing patterned exposure on the blended film obtained in step S2 to form a hierarchical interlaced network structure; S4: developing the blended film after exposure in step S3 to obtain an organic semiconductor film with a hierarchical interlaced network structure.

8. The method for patterning an organic semiconductor photoresist having a hierarchical structure and being environmentally stable according to claim 7, wherein: The substrate is surface-modified so that the surface-modified substrate has a strong adsorption force on the polymer semiconductor and has a regular orientation.

9. The method for patterning an organic semiconductor photoresist having a hierarchical structure and being environmentally stable according to claim 7, wherein: The spin coating process is as follows: the standing time before spin coating is 5-60 seconds, the speed during spin coating is 1500-5500 rpm, and the pre-bake temperature after spin coating is 75-120°C; the exposure dose of the patterned exposure is 150-3000 mJ cm -2 ; The thickness of the organic semiconductor film is 80-150nm; the developing solution comprises an ester solvent or a non-protonic polar solvent and an aromatic hydrocarbon solvent in a volume ratio of 1:1-9.

10. An organic electronic device, characterized in that: An organic semiconductor film having a hierarchical interlaced network structure prepared by the patterning method according to any one of claims 7 to 9.

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