UV-Patternable Polymer Blends for Organic Thin-Film Transistors

Abstract

A polymer blend comprises an organic semiconductor polymer blended with a spacer polymer; at least one photoinitiator for generating reactive radicals; and at least one crosslinking agent comprising C═C bonds, thiols, or a combination thereof, such that the organic semiconductor polymer is a diketopyrrolopyrrole-fused thiophene polymeric material, the fused thiophene is β-substituted, and the spacer polymer has a non-conjugated backbone. A method of forming an organic semiconductor device having the polymer blend is also provided.

Description

Background 1. Technical Field

[0002] The present disclosure relates to a UV - patterable organic semiconductor / isolation polymer blend as a semiconductor layer in an organic thin - film transistor (OTFT). 2. Background Art

[0004] Organic thin - film transistors (OTFTs) have attracted wide attention as an alternative to conventional silicon - based technologies, which require high - temperature and high - vacuum deposition processes, as well as complex lithographic patterning methods. The semiconductor (i.e., organic semiconductor, OSC) layer is an important component in an OTFT, which can effectively affect the performance of the device.

[0005] Traditional inorganic TFT device array manufacturing techniques often rely on lithography as the patterning process. However, lithography often involves harsh oxygen (O2) plasma during pattern transfer or photoresist removal, as well as erosive developing solvents, which can severely damage the OSC layer and lead to a significant decline in device performance.

[0006] The present disclosure presents an improved UV - patterable organic semiconductor / isolation polymer blend and its use for the OSC layer of an organic thin - film transistor. Summary of the Invention

[0007] In some embodiments, a polymer blend comprises: an organic semiconductor polymer blended with an isolation polymer; at least one photoinitiator configured to generate reactive free radicals; and at least one cross - linker comprising C═C bonds, thiols, or a combination thereof, wherein the organic semiconductor polymer is a diketopyrrolopyrrole - fused thiophene polymeric material, wherein the fused thiophene is β - substituted, and wherein the isolation polymer has a non - conjugated backbone.

[0008] In one aspect combinable with any other aspect or embodiment, the amount of the organic semiconductor polymer present is in the range of 1 wt% to 99 wt%; the amount of the isolation polymer present is in the range of 1 wt% to 99 wt%; the amount of the at least one photoinitiator present is in the range of 0.1 wt% to 5 wt%; and the amount of the at least one cross - linker present is in the range of 0.05 wt% to 10 wt%.

[0009] In one aspect combinable with any other aspect or embodiment, the amount of the organic semiconductor polymer present is in the range of 10 wt% to 50 wt%.

[0010] In one aspect, which can be combined with any other aspect or embodiment, the at least one photoinitiator is present in an amount in the range of 0.1% to 2.0% by weight; and the at least one crosslinking agent is present in an amount in the range of 0.3% to 5.0% by weight.

[0011] In one aspect, which can be combined with any other aspect or embodiment, the polymer blend further comprises at least one of an antioxidant, a lubricant, a compatibilizer, or a leveling agent, present in an amount in the range of 0.05% to 5% by weight.

[0012] In one aspect, which can be combined with any other aspect or embodiment, the organic semiconductor polymer comprises a repeating unit of Formula 1 or Formula 2, or a salt, isomer, or analog thereof:

[0013]

[0014] wherein, in Formula 1 and Formula 2: m is an integer greater than or equal to 1; n is 0, 1, or 2; R1, R2, R3, R4, R5, R6, R7, and R8 can each independently be hydrogen, a substituted or unsubstituted C4 or higher alkyl, a substituted or unsubstituted C4 or higher alkenyl, a substituted or unsubstituted C4 or higher alkynyl, or a C5 or higher cycloalkyl; a, b, c, and d are each independently integers greater than or equal to 3; e and f are integers greater than or equal to zero; X and Y are each independently a covalent bond, an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted fused aryl or fused heteroaryl, an alkyne, or an alkene; and A and B can each independently be either S or O, provided that: (i) at least one of R1 or R2; one of R3 or R4; one of R5 or R6; and one of R7 or R8 is a substituted or unsubstituted alkyl, a substituted or unsubstituted alkenyl, a substituted or unsubstituted alkynyl, or a cycloalkyl; (ii) if any one of R1, R2, R3, or R4 is hydrogen, then none of R5, R6, R7, or R8 is hydrogen; (iii) if any one of R5, R6, R7, or R8 is hydrogen, then none of R1, R2, R3, or R4 is hydrogen; (iv) e and f cannot both be 0; (v) if either e or f is 0, then c and d are each independently integers greater than or equal to 5; and (vi) the polymer has a molecular weight, wherein the molecular weight of the polymer is greater than 10,000.

[0015] In one aspect, which can be combined with any other aspect or embodiment, the isolating polymer is at least one of the following: polyacrylonitrile (PAN), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), alkyl-substituted polyacrylonitrile (R-PAN), polyethylene (PE), polystyrene, styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-butadiene-styrene rubber (SBR), polystyrene-co-acrylonitrile, acrylonitrile-butadiene-styrene (ABS), styrene-ethylene-butylene-styrene (SEBS), polydimethylsiloxane (PDMS), polysulfonate, polyvinyl acetate, polycarbonate, polypropylene, poly(methyl methacrylate) (PMMA), polyamide, polyphenylene sulfide, poly(methyl methacrylate)-block-poly(butyl acrylate) (PMMA-b-PBA), or derivatives thereof, copolymers thereof, and mixtures thereof.

[0016] In one aspect, which can be combined with any other aspect or embodiment, the isolating polymer comprises an unsaturated C═C backbone.

[0017] In one aspect, which can be combined with any other aspect or embodiment, the at least one photoinitiator includes: 1-hydroxy-cyclohexyl-phenyl-ketone (184); 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one (369); diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO); 2-isopropylthioxanthone (ITX); 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyl oxime) (HRCURE-OXE01); 2,2-dimethoxy-1,2-diphenylethan-1-one (BDK); benzoyl peroxide (BPO); hydroxyacetophenone (HAP); 2-hydroxy-2-methylphenylpropanone (1173); 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (907); 2-benzyl-2-(dimethylamino)-4'-morpholinopropyl phenyl ketone (IHT-PI 910); ethyl 4-(dimethylamino)benzoate (EDB); methyl O-benzoylbenzoate (OMBB); bis-(2,6-dimethoxybenzoyl)-phenylphosphine oxide (BAPO); 4-benzoyl-4'-methyldiphenyl sulfide (BMS); benzophenone (BP); 1-chloro-4-propoxythioxanthone (CPTX); chlorothioxanthone (CTX); 2,2-diethoxyacetophenone (DEAP); diethylthioxanthone (DETX); 2-dimethylaminoethyl benzoate (DMB); 2,2-dimethoxy-2-phenylacetophenone (DMPA); 2-ethylanthraquinone (2-EA); ethyl p-N,N-dimethyl-dimethylaminobenzoate (EDAB); 2-ethylhexyl dimethylaminobenzoate (EHA); 4,4-bis-(diethylamino)-benzophenone (EMK); methylbenzophenone (MBF); 4-methylbenzophenone (MBP); Michler's ketone (MK); 2-methyl-1-[4(methylthio)phenyl]-2-morpholinopropanone (1) (MMMP); 4-phenylbenzophenone (PBZ); 2,4,6-trimethyl-benzoyl-ethoxyphenylphosphine oxide (TEPO); or a combination thereof.

[0018] In one aspect, which can be combined with any other aspect or embodiment, the at least one crosslinking agent includes: triallyl isocyanurate (TAIC), trimethylolpropane trithioglycolate (TRIS),

[0019]

[0020]

[0021]

[0022]

[0023] In some embodiments, a method of forming an organic semiconductor device includes: blending an organic semiconductor polymer with an isolating polymer in an organic solvent to form a polymer blend; depositing a thin film of the polymer blend over a substrate; exposing the thin film to UV light using a photomask to form a patterned thin film; and developing the patterned thin film in a solvent to remove unpatterned regions of the thin film, wherein the organic semiconductor polymer is a diketopyrrolopyrrole-fused thiophene polymeric material, wherein the fused thiophene is β-substituted, and wherein the isolating polymer has a non-conjugated backbone.

[0024] In one aspect, which can be combined with any other aspect or embodiment, the method further includes: between deposition and exposure, heating the thin film at a temperature in the range of 50 °C to 200 °C for a time in the range of 10 seconds to 10 minutes.

[0025] In one aspect, which can be combined with any other aspect or embodiment, the method further includes: after development, heating the patterned thin film at a temperature in the range of 50 °C to 200 °C for a time in the range of 10 seconds to 30 minutes.

[0026] In one aspect, which can be combined with any other aspect or embodiment, the blending includes: dissolving the organic semiconductor polymer in a first organic solvent to form a first solution; dissolving the isolating polymer in a second organic solvent to form a second solution; and combining the first solution and the second solution to form a polymer blend.

[0027] In one aspect, which can be combined with any other aspect or embodiment, the polymer blend further includes: at least one photoinitiator configured to generate reactive free radicals; and at least one crosslinker including C═C bonds, thiols, or a combination thereof.

[0028] In one aspect, which can be combined with any other aspect or embodiment, the amount of the organic semiconductor polymer present is in the range of 1 wt% to 99 wt%; the amount of the isolating polymer present is in the range of 1 wt% to 99 wt%; the amount of the at least one photoinitiator present is in the range of 0.1 wt% to 5 wt%; and the amount of the at least one crosslinker present is in the range of 0.05 wt% to 10 wt%.

[0029] In one aspect, which can be combined with any other aspect or embodiment, the deposition includes at least one of the following: spin coating, dip coating, spraying, electrodeposition, meniscus coating, plasma deposition, and roll coating, curtain coating, and extrusion coating.

[0030] In one aspect, which can be combined with any other aspect or embodiment, the exposure includes: exposing the thin film to energy at 10 mJ / cm 2Up to 600 mJ / cm 2 to UV light within the range, and expose for a time within the range of 1 second to 60 seconds.

[0031] In one aspect, which can be combined with any other aspect or embodiment, the development includes exposing the unpatterned regions of the film to a certain solvent for a time within the range of 10 seconds to 10 minutes, and the solvent includes: chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,2,4-trichlorobenzene, dioxane, p-xylene, m-xylene, toluene, cyclopentanone, cyclohexanone, methyl lactate, 2-butanone, 2-pentanone, 3-pentanone, 2-heptanone, 3-heptanone, anisole, 1,3,5-trimethylbenzene, decalin, butylbenzene, cyclooctane, 1,2,3,4-tetrahydronaphthalene, chloroform, or a combination thereof.

[0032] In one aspect, which can be combined with any other aspect or embodiment, the method further includes: forming a gate electrode above a substrate; forming a gate dielectric layer above the substrate; forming a patterned source and drain layer above the gate dielectric layer; and forming an insulator layer above the patterned source and drain layer.

[0033] In one aspect, which can be combined with any other aspect or embodiment, the isolation polymer contains an unsaturated C═C backbone, or the isolation polymer is configured to generate a C═C backbone before or during UV light exposure. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In conjunction with the accompanying drawings, the present disclosure can be more fully understood through the following detailed description, wherein:

[0035] Figures 1A to 1E Illustrates a conventional patterning technique for an organic semiconductor blend using a photoresist.

[0036] Figures 2A to 2C Illustrates a patterning technique for an organic semiconductor blend according to some embodiments.

[0037] Figure 3 Illustrates an exemplary OTFT device according to some embodiments.

[0038] Figures 4A to 4G Illustrates the patterning of an organic semiconductor blend with different proportions of a photoinitiator according to some embodiments.

[0039] Figures 5A to 5G Illustrates the patterning of an organic semiconductor blend with different proportions of an organic solvent mixture according to some embodiments.

[0040] Figure 6Illustrates the performance of OTFT devices in the case of different proportions of additives and solution concentrations according to some embodiments.

[0041] Figure 7 Illustrates the performance of OTFT devices in the case of different initiators and treatment methods according to some embodiments.

[0042] Figure 8 Illustrates the performance of OTFT devices in the case of different mixed developing solvents according to some embodiments. Detailed Description

[0043] Exemplary embodiments shown in the accompanying drawings will now be described in detail. Whenever possible, the same reference numerals are used in the drawings to denote the same or similar parts. The components in the drawings are not necessarily drawn to scale, but rather the emphasis is on illustrating the principles of the exemplary embodiments. It should be understood that the present application is not limited to the details or methodologies set forth in the specification or illustrated in the drawings. It should also be understood that the terminology is for descriptive purposes only and should not be considered limiting.

[0044] In addition, any examples listed in this specification are illustrative rather than restrictive, and only list some of the many possible embodiments of the claimed invention. Other suitable modifications and adjustments of various conditions and parameters are common in the art and will be apparent to those skilled in the art, which fall within the spirit and scope of the present disclosure.

[0045] Organic semiconductors as functional materials can be used in various applications, for example, including, printed electronic devices, organic transistors [including organic thin-film transistors (OTFTs) and organic field-effect transistors (OFETs)], organic light-emitting diodes (OLEDs), organic integrated circuits, organic solar cells, and disposable sensors. Organic transistors can be used in many applications, including smart cards, security tags, and the substrates of flat panel displays. Compared with inorganic semiconductors (such as silicon), organic semiconductors can significantly reduce costs. Depositing OSCs from solutions can result in fast, large-area manufacturing routes, such as various printing methods and roll-to-roll processes.

[0046] Organic thin-film transistors are of particular interest because their manufacturing processes are not as complex as those of conventional silicon-based technologies. For example, OTFTs generally rely on low-temperature deposition and solution processing and can achieve valuable technical properties when used with semiconductor conjugated polymers, such as compatibility with simple write printing techniques, common low-cost manufacturing methods, and flexible plastic substrates. Other potential applications of OTFTs include flexible electronic paper, sensors, storage devices [e.g., radio frequency identification cards (RFID)], remotely controllable smart tags for supply chain management, large-area flexible displays, and smart cards.

[0047] Organic semiconductor (OSC) polymers

[0048] Organic semiconductor (OSC) polymers can be used to produce organic semiconductor devices. In some instances, the polymer blend includes an organic semiconductor polymer. In some instances, the OSC polymer has a fully conjugated main backbone. In some instances, the OSC is a diketopyrrolopyrrole (DPP)-fused thiophene polymeric material. In some instances, the fused thiophene is β-substituted. The OSC can contain both fused thiophene and diketopyrrolopyrrole units. In some instances, the OSC is used in OTFT applications. For example, the OSC polymer can include repeating units of Formula 1 or Formula 2, or salts, isomers, or analogs thereof:

[0049]

[0050] Wherein, in Formula 1 and Formula 2: m is an integer greater than or equal to 1; n is 0, 1 or 2; R1, R2, R3, R4, R5, R6, R7 and R8 can independently be hydrogen, substituted or unsubstituted C4 or higher alkyl, substituted or unsubstituted C4 or higher alkenyl, substituted or unsubstituted C4 or higher alkynyl, or C5 or higher cycloalkyl; a, b, c and d are independently integers greater than or equal to 3; e and f are integers greater than or equal to zero; X and Y are independently a covalent bond, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted fused aryl or fused heteroaryl, alkyne or alkene; and A and B can independently be either S or O, provided that: (i) at least one of R1 or R2; one of R3 or R4; one of R5 or R6; and one of R7 or R8 is substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, or cycloalkyl; (ii) if any one of R1, R2, R3 or R4 is hydrogen, then none of R5, R6, R7 or R8 is hydrogen; (iii) if any one of R5, R6, R7 or R8 is hydrogen, then none of R1, R2, R3 or R4 is hydrogen; (iv) e and f cannot both be 0; (v) if either e or f is 0, then c and d are independently integers greater than or equal to 5; and (vi) the polymer has a molecular weight, wherein the molecular weight of the polymer is greater than 10,000.

[0051] In some embodiments, the OSC polymer defined in Formula 1 or Formula 2 can be used for simple transistor fabrication at relatively low temperatures, which is particularly important for obtaining large-area, mechanically flexible electronic devices. The β-substituted OSC polymer can also help improve solubility.

[0052] In some examples, the OSC polymer can comprise repeating units of Formula 3 or Formula 4, or salts, isomers or analogs thereof:

[0053]

[0054]

[0055] In some examples, the solubility of OSC is 0.5 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, or any range defined by any two of these endpoints. In some examples, the solubility of OSC at room temperature is 1 mg / mL or higher.

[0056] In some examples, the hole mobility of OSC is 1 cm 2 V -1 s -1 、2 cm 2 V-1 s -1 、 3 cm 2 V -1 s -1 、 4 cm 2 V -1 s -1 、 5 cm 2 V -1 s -1 、 10 cm 2 V -1 s -1 , or any range defined by any two of these endpoints. The hole mobility can be equal to or greater than any of these values. In some instances, the hole mobility of the OSC is 1 cm 2 V -1 s -1 to 4 cm 2 V -1 s -1 。 In some instances, the hole mobility of the OSC is 2 cm 2 V -1 s -1 。 In some instances, the hole mobility of the OSC is 2 cm 2 V -1 s -1 or higher.

[0057] In some instances, the on / off ratio of the OSC polymer is greater than 10 5 。 In some instances, the on / off ratio of the OSC polymer is greater than 10 6 。

[0058] In some instances, the threshold voltage of the OSC polymer in the thin film transistor device is 1 V, 2 V, 3 V, 4 V, 5 V, 10 V, or any range defined by any two of these endpoints. In some instances, the threshold voltage of the OSC polymer in the thin film transistor device is in the range of 1 V to 3 V. In some instances, the threshold voltage of the OSC polymer in the thin film transistor device is 2 V.

[0059] Isolation polymer

[0060] In some instances, the polymer blend contains an OSC polymer blended with an isolation polymer. In some instances, the isolation polymer is a non-conjugated polymer. In some instances, the isolation polymer has a non-conjugated backbone and conjugated side chains. In some instances, the isolation polymer is not a semiconductor polymer. In some instances, the isolation polymer is blended with the OSC polymer to prevent OSC oxidation.

[0061] In some examples, the isolating polymer is at least one of the following: polyacrylonitrile (PAN), alkyl-substituted polyacrylonitrile (R-PAN), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polyethylene (PE) and its copolymers, polystyrene, styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-butadiene-styrene rubber (SBR), polystyrene-co-acrylonitrile, acrylonitrile-butadiene-styrene (ABS), styrene-ethylene-butene-styrene (SEBS), variants of polydimethylsiloxane (PDMS), polysulfonate, polyvinyl acetate, polycarbonate, polypropylene, poly(methyl methacrylate), polyamide, polyphenylene sulfide, elastomeric block copolymers [e.g., poly(methyl methacrylate)-block-poly(butyl acrylate) (PMMA-b-PBA)], or derivatives thereof, copolymers thereof, and mixtures thereof. In some examples, the isolating polymer is polyacrylonitrile. In some examples, the isolating polymer is polystyrene or a derivative thereof, which enables large-scale production of OSC devices and pre-aggregation and better alignment of semiconductors.

[0062] In some examples, the molecular weight of the isolating polymer is 1,000, 2,000, 3,000, 4,000, 5,000, 10,000, 15,000, 20,000, 25,000, 35,000, 45,000, 50,000, 75,000, 100,000, 125,000, 150,000, 175,000, 200,000, 225,000, 250,000, or any range defined by any two of these endpoints. In some examples, the molecular weight of the isolating polymer is 5,000 or greater. In some examples, the molecular weight of the isolating polymer is 10,000 or greater. In some examples, the molecular weight of the isolating polymer is between 50,000 and 200,000.

[0063] Photoinitiator

[0064] Photoinitiators are key components of photocurable products. Radical-based photoinitiators include reactive radicals that initiate photopolymerization when exposed to UV light. In one example, the mechanism by which photoinitiator TPO initiates thiol-ene radical polymerization is shown below.

[0065]

[0066] In some examples, the polymer blend comprises an OSC polymer blended with an isolating polymer and at least one photoinitiator configured to generate reactive radicals.

[0067] In some instances, the at least one photoinitiator includes: 1-hydroxy-cyclohexyl-phenyl-ketone (184); 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one (369); diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO); 2-isopropylthioxanthone (ITX); 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyloxime) (HRCURE-OXE01); 2,2-dimethoxy-1,2-diphenylethan-1-one (BDK); benzoyl peroxide (BPO); hydroxyacetophenone (HAP); 2-hydroxy-2-methylphenylpropanone (1173); 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (907); 2-benzyl-2-(dimethylamino)-4'-morpholinopropyl phenyl ketone (IHT-PI 910); ethyl 4-(dimethylamino)benzoate (EDB); methyl O-benzoylbenzoate (OMBB); bis-(2,6-dimethoxybenzoyl)-phenylphosphine oxide (BAPO); 4-benzoyl-4'-methyldiphenyl sulfide (BMS); benzophenone (BP); 1-chloro-4-propoxythioxanthone (CPTX); chlorothioxanthone (CTX); 2,2-diethoxyacetophenone (DEAP); diethylthioxanthone (DETX); 2-dimethylaminoethyl benzoate (DMB); 2,2-dimethoxy-2-phenylacetophenone (DMPA); 2-ethylanthraquinone (2-EA); ethyl p-N,N-dimethyl-dimethylaminobenzoate (EDAB); 2-ethylhexyl dimethylaminobenzoate (EHA); 4,4-bis-(diethylamino)-benzophenone (EMK); methylbenzophenone (MBF); 4-methylbenzophenone (MBP); Michler's ketone (MK); 2-methyl-1-[4(methylthio)phenyl]-2-morpholinopropanone (1) (MMMP); 4-phenylbenzophenone (PBZ); 2,4,6-trimethyl-benzoyl-ethoxyphenylphosphine oxide (TEPO); or a combination thereof. Table 1 below shows the structures of representative photoinitiators.

[0068]

[0069] Table 1

[0070] Crosslinker

[0071] In some instances, the polymer blend comprises an OSC polymer blended with a spacer polymer, at least one photoinitiator configured to generate reactive radicals, and at least one crosslinker comprising C═C bonds, thiols, or a combination thereof.

[0072] In some instances, the crosslinker can be a small molecule or polymer having two or more thiol groups, and the thiol groups react with double bonds in the spacer polymer through thiol-ene click chemistry. In some instances, the crosslinker can be a small molecule or polymer having two or more acrylate groups, and the acrylate groups react with double bonds in the spacer polymer through an addition reaction. In some instances, the crosslinker can be a small molecule or polymer having two or more vinyl groups, and the vinyl groups react with double bonds in the spacer polymer through an addition reaction.

[0073] In some instances, the at least one crosslinker includes: triallyl isocyanurate (TAIC), trimethylolpropane trithioglycolate (TRIS),

[0074]

[0075]

[0076]

[0077]

[0078] Table 2 below shows representative crosslinker structures.

[0079]

[0080] Table 2

[0081] Polymer blend

[0082] In some instances, the performance of a device comprising an OSC polymer can be improved by blending the OSC polymer with another polymer. In some instances, the OSC polymer and the spacer polymer are blended in a solvent. One advantage of the OSC polymers disclosed herein is that they are easy to process in non-halogenated solvents. In some instances, the non-halogenated solvent is used to dissolve the mixture of the OSC polymer and the spacer polymer. In some instances, the non-halogenated solvent is m-xylene, o-xylene, p-xylene, toluene, 1,2,3,4-tetrahydronaphthalene, cis-decalin, trans-decalin, 1,3,5-trimethylbenzene, cyclooctane, dicyclohexane, or a combination thereof. In some instances, a mixture of more than one solvent can be used.

[0083] In some instances, the isolating polymer is polystyrene, and polystyrene plus a non-halogenated solvent can pre-aggregate and better align the semiconductor. In some instances, the isolating polymer can be a copolymer of styrene and other monomers [e.g., styrene-butadiene-styrene (SBS), acrylonitrile-butadiene-styrene (ABS), styrene-ethylene-butylene-styrene (SEBS), styrene-butadiene rubber (SBR), styrene-acrylate, etc.].

[0084] In some instances, the weight ratio of the OSC polymer to the isolating polymer is 95:5, 90:10, 85:15, 80:20, 75:25, 70:30, 65:35, 60:40, 55:45, 50:50, 45:55, 60:40, 65:35, 70:30, 75:25, 80:20, 85:15, 90:10, 95:5, or any range defined by any two of these endpoints.

[0085] In some instances, the blend includes at least one of the following: an OSC polymer, an isolating polymer, a photoinitiator, a crosslinker, and an additive. The OSC polymer is in the range of 1 wt% to 99 wt%, or 5 wt% to 95 wt%, or 10 wt% to 90 wt%. The OSC polymer is, for example, a donor-acceptor type OSC polymer, where DPP is the acceptor and the fused thiophene is the donor. The isolating polymer is in the range of 1 wt% to 99 wt%, or 5 wt% to 95 wt%, or 10 wt% to 90 wt%. For example, the isolating polymer has free-radical curable sites from the main chain or side chain, or it is prone to generate or in-situ generate curable sites before the UV patterning process (e.g., polymers containing C═C, such as SBS, SIS, SBR, certain acrylic polymers, etc.). The photoinitiator is in the range of 0.1 wt% to 5 wt%, and it is, for example, a substance that generates active radicals under UV exposure (e.g., 184, 369, TPO, BPO, BDK, etc.). The crosslinker is in the range of 0.05 wt% to 5 wt%, and it is, for example, a substance having a C═C bond or thiol as a curing site. And the additive is in the range of 0.05 wt% to 5 wt%, and it is, for example, an antioxidant, a lubricant, a compatibilizer, a leveling agent, etc.

[0086] In some instances, the blend includes at least two of the following: the above OSC polymer, isolating polymer, photoinitiator, crosslinker, and additive. In some instances, the blend includes at least three of the following: the above OSC polymer, isolating polymer, photoinitiator, crosslinker, and additive. In some instances, the blend includes at least four of the following: the above OSC polymer, isolating polymer, photoinitiator, crosslinker, and additive.

[0087] OTFT Device Fabrication

[0088] Applications using OTFT devices require patterning of the organic semiconductor material to prevent undesired high off-currents and crosstalk between adjacent devices. As described above, photolithography is a common patterning technique in semiconductor device fabrication. However, photolithography often involves harsh oxygen (O2) plasma during pattern transfer or photoresist removal, and involves aggressive developing solvents, which can severely damage the OSC layer and result in a significant degradation of the OTFT device performance. In other words, when conjugated organic materials are exposed to light, these materials tend to degrade, and the chemicals used in photolithography can have an adverse effect on organic thin film transistors. Therefore, it is not practical to pattern organic semiconductor materials using photolithography. Additionally, currently available patterning semiconductor polymers with photosensitive side groups require time-consuming molecular design and synthesis. Since there is a reduction in effective conjugation in the crosslinked backbone of these crosslinked polymers, these crosslinked polymers can also have an adverse effect on OTFT devices.

[0089] This application discloses a photo-patternable spacer polymer containing C═C double bonds blended with an OSC polymer to enable UV patterning of an OSC / spacer polymer blend for OTFT fabrication.

[0090] Thiol-ene polymerization is an organic reaction that occurs between a thiol (e.g., an OSC polymer) and an ene (e.g., a spacer polymer) to form an alkyl sulfide. When exposed to UV light, a radical-based photoinitiator forms reactive radicals that initiate photopolymerization. This type of reaction generally proceeds via a step-growth mechanism of radicals, which involves two steps (Reaction 1) in forming an intermediate (e.g., a carbon-centered radical) after initiation:

[0091]

[0092] R1· + RSH → RS· + R1H

[0093] Reaction 1: Formation of a carbon-centered radical intermediate

[0094] Subsequently, in the first growth step, a thiol radical is added to the carbon of the ene functional group (Reaction 2):

[0095]

[0096] Reaction 2: Reaction of a thiol radical with a C═C double bond

[0097] And in the second growth step, the carbon-centered radical abstracts a hydrogen from the thiol group, thereby forming a sulfur radical (Reaction 3):

[0098]

[0099] Reaction 3: Hydrogen abstraction

[0100] Termination occurs by radical-radical coupling (Reactions 4A to 4C):

[0101] RS· + RS· → RS-SR

[0102] Reaction 4A

[0103]

[0104] Reaction 4B

[0105]

[0106] Reaction 4C

[0107] UV crosslinking of the thiol-ene reaction can be carried out effectively in air because the peroxy radicals formed by O2 scavenging of alkyl groups abstract hydrogen atoms from the thiol. Thus, after the initial step - Reaction 1 and the first propagation step - Reaction 2, O2 scavenging of alkyl groups can form peroxy radicals (Reaction 5):

[0108]

[0109] Reaction 5: O2 scavenging of alkyl groups

[0110] And the peroxy radicals then abstract hydrogen atoms from the thiol (Reaction 6):

[0111]

[0112] Reaction 6: Hydrogen abstraction

[0113] In particular, the photoinduced thiol-ene reaction promotes the formation of a uniform network structure, which ensures that the engraved pattern has high resolution and allows the formation of nanostructured polymer networks, which are strong candidates for electronic components containing resistors or wires.

[0114] Figures 1A to 1E Illustrates a conventional patterning technique 100 using a photoresist-based organic semiconductor blend. In the first step ( Figure 1A ), the blended OSC polymer film 104 is deposited above the substrate 102, and subsequently in Figure 1BIn this case, a photoresist layer 106 is deposited on a thin film 104. Optionally, the thin film 104 can be thermally annealed. Photoresist deposition can be carried out by methods known in the art (e.g., spin coating). For example, the photoresist is converted into a liquid form by dissolving solid components in a solvent, the liquid-form photoresist is poured onto a substrate, and then it is rotated at high speed on a turntable to produce a desired film. Subsequently, the resulting resist film can be subjected to a post-application baking process (i.e., soft baking or pre-baking) to dry the photoresist when removing the excess solvent.

[0115] In Figure 1C this step, the photoresist layer 106 is exposed to UV light 112 passing through a mother pattern, which is called a photomask 108 and is positioned at a certain distance from the photoresist layer 106, thereby forming a portion 110 of the photoresist layer 106 with a higher degree of crosslinking. The exposure to UV light serves to change the solubility of the photoresist in a subsequent developer solvent solution to form a pattern on top of the substrate. Before development, the resist layer can be subjected to a post-exposure bake. In Figure 1D this step, the pattern 116 of the photoresist layer is transferred into the thin film 104 by subtractive etching 114 (i.e., O2 plasma dry etching). The patterned photoresist layer 116 "resists" etching and protects the material covered by the photoresist. When the etching is completed, the photoresist is stripped [e.g., using an organic solution or an inorganic solution and dry (plasma) stripping], thereby leaving the desired pattern 118 etched into the thin film layer.

[0116] However, as described above, various aspects of traditional lithography processes (e.g., the harsh O2 plasma during pattern transfer and the aggressive photoresist developer solvents and / or stripping solvents) can severely damage the OSC layer and result in a significant decrease in device performance.

[0117] Figures 2A to 2C Illustrates a patterning technique 200 for an organic semiconductor blend according to some embodiments. In the first step ( Figure 2A ), a blended OSC polymer thin film 204 is deposited above a substrate 202. Optionally, the thin film 204 can be thermally annealed. In some instances, the deposition includes at least one of the following: spin coating, dip coating, spray coating, electrodeposition, meniscus coating, plasma deposition, and roll coating, curtain coating, and extrusion coating.

[0118] The thin film 204 is prepared from the above polymer blend, which comprises: an organic semiconductor (OSC) polymer blended with a spacer polymer; at least one photoinitiator configured to generate reactive free radicals; and at least one crosslinker comprising C═C bonds, thiols, or a combination thereof, wherein the organic semiconductor polymer is a diketopyrrolopyrrole-fused thiophene polymeric material, wherein the fused thiophene is β-substituted, and wherein the spacer polymer has a non-conjugated backbone. In some instances, blending comprises: dissolving the organic semiconductor polymer in a first organic solvent to form a first solution; dissolving the spacer polymer in a second organic solvent to form a second solution; and combining the first solution and the second solution to form a polymer blend. The organic semiconductor polymer can be dissolved in the first solution overnight at a high temperature (e.g., 120° C.); however, the spacer polymer may decompose at this high temperature during prolonged stirring. Thus, the first solution and the second solution are prepared separately and then combined. After combining, the crosslinker and the photoinitiator are added to the combined solution as a solid or as a third solution containing both components.

[0119] In some instances, the amount of the OSC polymer present ranges from 1 wt % to 99 wt %, or from 5 wt % to 95 wt %, or from 10 wt % to 90 wt %; the amount of the spacer polymer present ranges from 1 wt % to 99 wt %, or from 5 wt % to 95 wt %, or from 10 wt % to 90 wt %; the amount of the at least one photoinitiator present ranges from 0.1 wt % to 5 wt %; and the amount of the at least one crosslinker present ranges from 0.05 wt % to 10 wt %. In some instances, the amount of the OSC polymer present ranges from 10 wt % to 50 wt % or from 10 wt % to 30 wt %. In some instances, the amount of the at least one photoinitiator present ranges from 0.1 wt % to 2.0 wt % or from 0.1 wt % to 1.0 wt %; and the amount of the at least one crosslinker present ranges from 0.3 wt % to 5.0 wt %. In some instances, the amount of at least one of an antioxidant, a lubricant, a compatibilizer, or a leveling agent present ranges from 0.05 wt % to 5 wt %.

[0120] In some instances, after the blended OSC polymer thin film is deposited over a substrate and before the film is exposed to UV light, the film can be heated at a temperature in the range of 50° C. to 200° C. for a time in the range of 10 seconds to 10 minutes to remove excess solvent.

[0121] In a second step ( Figure 2B) wherein, the thin film 204 is exposed to UV light 208 passing through a photomask 206 to form a portion 210 of the thin film 204 with a higher degree of crosslinking. In some instances, the exposure includes: exposing the thin film to UV light having an energy in the range of 10 mJ / cm 2 to 600 mJ / cm 2 (e.g., 400 mJ / cm 2 ), for a time in the range of 1 second to 60 seconds (e.g., 10 seconds). In some instances, the energy of the UV light can be in the range of 300 mJ / cm 2 to 500 mJ / cm 2 , and the operating time can be in the range of 5 seconds to 20 seconds.

[0122] Similar to Figures 1A to 1E the function of the photoresist described above, the exposure to UV light serves to change the solubility of the thin film in a subsequent developer solvent solution to form a pattern on top of the substrate. As described in Reactions 1 to 6, the internal photocuring mechanism of the thin film is based on a radical initiator and C═C double bonds / thiols as curing sites. Different from cationic crosslinking initiated by a photoacid generator (PAG), the radical initiator is compatible with a small amount of moisture and water from the surrounding environment.

[0123] In Figure 2C the step of, when the light exposure is completed, a portion of the thin film 204 that is not exposed to UV light 208 is stripped using a predetermined solvent 212, thereby leaving the desired pattern 214 in the thin film layer. In other words, the portion 210 with a higher degree of crosslinking is developed in a solvent to remove the unpatterned area of the thin film 204. In some instances, the development includes: exposing the unpatterned area of the thin film to a certain solvent for a time in the range of 10 seconds to 10 minutes, and the solvent includes: chlorobenzene, 1,2 - dichlorobenzene, 1,3 - dichlorobenzene, 1,2,4 - trichlorobenzene, dioxane, p - xylene, m - xylene, toluene, cyclopentanone, cyclohexanone, methyl lactate, 2 - butanone, 2 - pentanone, 3 - pentanone, 2 - heptanone, 3 - heptanone, anisole, 1,3,5 - trimethylbenzene, decalin, styrene - butadiene, cyclooctane, 1,2,3,4 - tetrahydronaphthalene, chloroform, or a combination thereof. In some instances, the developer solution includes chlorobenzene, p - xylene, dioxane, or a combination thereof.

[0124] In some instances, after developing the patterned thin film in a solvent to remove the unpatterned area of the thin film, the thin film can be heated at a temperature in the range of 50 °C to 200 °C for a time in the range of 10 seconds to 30 minutes.

[0125] Subsequently, the OTFT device can be completed through the following steps: forming a patterned gate electrode above the substrate; forming a patterned gate dielectric layer above the substrate; forming patterned source and drain electrodes above the gate dielectric layer; forming a patterned organic semiconductor active layer above the source and drain electrodes; and forming an insulator layer above the patterned organic semiconductor active layer.( Figure 3 )。

[0126] Example

[0127] The embodiments described herein are further illustrated by the following examples.

[0128] Example 1 : Photopatterning of an OSC / SBS blend having 369 and / or ITX as a photoinitiator and TRIS as a crosslinker

[0129] Direct photopatterning of an OSC / SBS blend film without using a photoresist. A patterned film is formed by first spin-coating onto a substrate and then exposing to UV light through a photomask. The exposed areas of the film are crosslinked while the unexposed areas (which remain uncrosslinked and soluble) are removed by a developing solvent, thereby transferring the pattern of the photomask to the film in a negative manner.

[0130] In one example, 0.03 grams of the OSC polymer of formula 4 and 0.07 grams of a styrene-butadiene-styrene (SBS) block polymer were separately dissolved in 10 mL of p-xylene, stirred at room temperature for 2 hours, and then mixed to prepare a 10 mg / mL solution. Then, 1 wt% (0.001 grams) of trimethylolpropane trithioglycolate (TRIS) (CAS No. 33007-83-9) crosslinker, 1 wt% (0.001 grams) of 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone (369) (CAS No. 119313-12-1) photoinitiator, and optionally 1 wt% (0.001 grams) of 2-isopropylthioxanthone (ITX) (CAS No. 5495-84-1) photoinitiator were added to the OSC polymer / SBS block polymer solution and stirred for 2 minutes.

[0131] The solution was spin-coated onto a substrate and pre-baked in air, then exposed to 365 nm UV light through a photomask in air. Subsequently, the film was immersed in a p-xylene developer solution and post-baked in air. Due to the above process, a patterned organic semiconductor / block polymer blend as the semiconductor layer of an OTFT was prepared without using a photoresist. Table 1 summarizes the preparation conditions, where Sample 1 includes both 369 and ITX photoinitiators, while Sample 2 includes only the 369 photoinitiator.

[0132]

[0133] Table 1

[0134] Example 2 : Photopatterning of OSC / SBS blends with different photoinitiators and TRIS as crosslinker

[0135] OSC / SBS blend films were prepared and photopatterned in a process similar to that described in Example 1 using different photoinitiators and their concentrations. The preparation conditions are summarized in Table 2. Sample 3 includes the TPO photoinitiator, Samples 4a and 4b include 0.5 wt% and 0.8 wt% of the 369 photoinitiator, respectively, and Samples 5a - 5d include 0.3 wt%, 0.5 wt%, 0.8 wt%, and 1 wt% of the HRCURE - OXEO1 photoinitiator, respectively.

[0136]

[0137]

[0138] Table 2

[0139] In the photopatterning conditions of Table 2, the UV exposure energy was reduced due to the increased efficiency of photoinitiators such as HRCURE - OXEO1 and TPO. It was observed that the uncrosslinked SBS in the unexposed areas selectively dissolved, and a high proportion of crosslinker could induce a higher degree of photocrosslinking in the exposed portions of the blended polymer film. Additionally, as the proportion of HRCURE - OXEO1 and 369 increased, the color contrast of the photopatterned film was higher (see Figures 4B to 4G ). Thus, a patterned organic semiconductor / isolation polymer blend serving as the semiconductor layer of an OTFT was prepared without using a photoresist.

[0140] Example 3 : Photopatterning of OSC / SBS blends using various developers

[0141] OSC / SBS blend films were prepared and photopatterned in a process similar to that described in Example 1 using different OSC polymers and developer solutions. The preparation conditions are summarized in Table 3. Samples 6a and 6b both include a mixture of OSC polymers of Formula 3 and Formula 4, and the developer solutions are chlorobenzene / 1,4 - dioxane and p - xylene / 1,4 - dioxane, respectively. Samples 7a and 7b both include the OSC polymer of Formula 4, and the developer solutions are chlorobenzene / 1,4 - dioxane and p - xylene / 1,4 - dioxane, respectively.

[0142]

[0143]

[0144] Table 3

[0145] Among the optical patterning conditions in Table 3, the solvent mixtures of chlorobenzene / 1,4-dioxane and p-xylene / 1,4-dioxane as developers were investigated. Figures 5A to 5C The color contrast of Samples 6a and 6b using the chlorobenzene / 1,4-dioxane developer [at ratios of 7 / 3 ( Figure 5A ), 8 / 2 ( Figure 5B ), and 9 / 1 ( Figure 5C )] was illustrated, and Figure 5D and 5E the color contrast of Samples 6a and 6b using the p-xylene / 1,4-dioxane developer [at ratios of 7 / 3 ( Figure 5D ), and 8 / 2 ( Figure 5E )] was illustrated. Figure 5F The color contrast of Samples 7a and 7b using the chlorobenzene / 1,4-dioxane developer (at a ratio of 7 / 3) was illustrated, and Figure 5G the color contrast of Samples 7a and 7b using the p-xylene / 1,4-dioxane developer (at a ratio of 7 / 3) was illustrated.

[0146] It was observed that as the proportion of chlorobenzene decreased (i.e., decreased), the color contrast of the optical patterning film was higher (e.g., for comparison Figures 5A to 5C ). It was also observed that as the proportion of p-xylene decreased (i.e., decreased), the color contrast of the optical patterning film was higher (e.g., for comparison Figure 5D and 5E ). Adding 1,4-dioxane reduced the solubility of OSC in the solvent mixture and retained more OSC on the substrate.

[0147] Example 4 : Device performance of the OSC / SBS blend system

[0148] Figure 3 The structure of a general bottom-gate bottom-contact OTFT was illustrated. The photo-crosslinked OSC / SBS blend film described herein was incorporated as the organic semiconductor layer into the bottom-gate bottom-contact OTFT. The gate electrode [e.g., gold (Au)] was patterned. In some examples, an epoxy gate insulator layer was spin-coated and photo-patterned through a photomask. The source / drain [e.g., gold (Au)] was patterned. The OSC / SBS blend solution was spin-coated on the substrate, pre-baked in air, and then exposed to 365 nm UV light passing through a photomask in air. Subsequently, the film was soaked in a p-xylene developer solution and post-baked in air.

[0149] Figure 6 The electrical properties of various OTFT devices prepared according to the above were compared and summarized in Table 4.

[0150]

[0151] Table 4

[0152] Using 2 wt% TRIS and 1 wt% 369, and when the solution concentration was 20 mg / mL (Sample 10), the "on" current was 0.6 nA (V g = -15 V). Using 1 wt% TRIS, 1 wt% 369 and 1 wt% ITX, and when the solution concentration was 10 mg / mL (Sample 8), the "on" current was 9 nA (V g = -15 V). The on-off current ratio was 10 -2 -10 -3 , and the turn-on voltage was in the range of -5 V to 5 V.

[0153] Figure 7 The electrical properties of various OTFT devices prepared according to the above were compared and summarized in Table 5. The manufacturing process of bottom-gate bottom-contact OTFTs is provided herein. Under UV light exposure, the photoinitiator decomposes into reactive free radicals, which can induce photopolymerization / crosslinking. The effects of various photoinitiators on device performance were studied. In air, Samples 12 - 14 (with different photoinitiators) were exposed to 365 nm UV light passing through a photomask. Without using a photomask, in air, Samples 16 and 17 were exposed to 365 nm UV light (Sample 16 was also not soaked in a developing solvent). Sample 15 was neither exposed to UV light nor soaked in a developing solvent.

[0154]

[0155] Table 5

[0156] Using the same crosslinker (TRIS) and different photoinitiators (TPO for Sample 12; HRCURE - OXEO1 for Samples 13 and 15 - 17; and 369 for Sample 14), the "on" current was 0.079 nA to 24 nA (V g = -15 V). The on-off current ratio was 10 -2 -10 -3 , and the turn-on voltage was in the range of -5 V to 5 V.

[0157] Figure 8The electrical properties of bottom-gate bottom-contact OTFT devices prepared by stripping the OSC polymer layer with a developer mixture were compared. In air, the OSC polymer film was exposed to 365 nm UV light passing through a photomask and then developed by immersion in a solvent mixture containing chlorobenzene and 1,4-dioxane. Table 6 summarizes the preparation procedures.

[0158]

[0159] Table 6

[0160] When developed in the mixed solvent, especially when the “on” current increased to 181 - 438 nA (V g = -15 V), the device performance was significantly improved (as Figure 8 shown). To increase the “on” current (V g = -15 V), the solvent mixture as the developer was studied. Chlorobenzene is an excellent solvent for OSC and SBS, while 1,4-dioxane is an excellent solvent for SBS but a poor solvent for OSC. Therefore, more OSC will be retained in the blend film when compared to using only p-xylene as the developer. At least for this reason, when developed in the mixed solvent [compared to a single solvent (such as chlorobenzene) that is excellent for both OSC and SBS], the device performance was significantly improved. Compared to the previous examples (such as samples 12 - 14), sample 18 showed improved device performance, especially the “on” current. Multiple devices (B1 - 4, B2 - 1, D1 - 1, and D2 - 4) were tested, and the reproducibility was confirmed.

[0161] Example 5 : UV patterning process and OTFT manufacturing procedures

[0162] General UV patterning process for OSC / isolating polymer blends

[0163] In some embodiments, the process includes the following steps: In solution 1, dissolve the OSC polymer in a suitable organic solvent. To ensure complete dissolution, the mixture can be heated at a high temperature. For example, the OSC polymer of formula 4 can be dissolved in p-xylene at 120 °C for 16 hours. In solution 2, dissolve the isolating polymer in the same solvent as the OSC polymer at 20 - 25 °C and stir for several hours to ensure complete dissolution. Then combine solution 1 and solution 2, then add at least one photoinitiator, crosslinker, and other additives, and further stir the combination for several minutes to ensure complete dissolution. Then deposit the combination on a substrate and then spin-coat to obtain a polymer film with a thickness of 10 nm to 200 nm [Schwan Easy Coater (coating machine) 6]. A laser scanning confocal microscope (CLSM) (Keyence VK-X260K) can be used to characterize the morphology of the spin-coated thin film.

[0164] The film can be baked in air at a high temperature for several minutes (e.g., baked at 100 °C for 4 minutes), and then exposed to parallel UV light using a photomask to pattern the film. After exposure, the film is immersed in a suitable developer solvent or solvent mixture to wash away the unpatterned areas. After drying the patterned film with air, the patterned film is baked again in air at a high temperature for several minutes (e.g., baked at 100 °C for 10 minutes).

[0165] General manufacturing procedure of the OTFT device

[0166] In some embodiments, a bottom-gate bottom-contact OTFT device can be formed as follows: A gold (Au) or silver (Ag) gate electrode is patterned onto a substrate, and then a dielectric is spin-coated onto the substrate and processed to obtain a gate dielectric layer. After patterning the Au or Ag source and drain electrodes, an OSC layer can be formed to a thickness of 10 nm to 200 nm by the patterning materials and methods described herein. Finally, an insulator layer is provided. Figure 3 An example of the formed OTFT device is shown.

[0167] Therefore, as proposed herein, an improved UV-patternable organic semiconductor / isolation polymer blend and its use for the OSC layer of an organic thin film transistor, as well as a method for manufacturing an OTFT device comprising the UV-patternable blend, are disclosed.

[0168] Advantages of the UV-patternable organic semiconductor / isolation polymer blend and its manufacturing method include: (1) patterning directly in air, which is highly desirable for industrial applications of manufacturing OTFT devices based on patterned polymer films at low cost; (2) highly efficient patterning under conditions (such as power, time, etc.) enabling micro-patterned films with high resolution (e.g., 10 μm × 10 μm); and (3) directly patterning the UV-curable OSC blend without using a photoresist, resulting in a more efficient and environmentally friendly process. Additional advantages of UV patterning include: (1) a reduced amount of OSC polymer used (e.g., reduced to the range of 10 wt% to 50 wt%, or even 10 wt% to 30 wt%) compared to conventional methods using up to 80 wt% of OSC polymer, thus reducing the material cost of OTFT manufacturing; and (2) a reduced amount of crosslinking agent and photoinitiator used (e.g., reduced to 1 wt% and 0.8 wt% respectively), thus minimizing the adverse side effects of the crosslinking agent and photoinitiator on the performance of OTFT devices.

[0169] Additionally, the UV patterns of the OSC polymer and isolation polymer blend can be customized. For example, the UV patterning formulation can be adjusted such that it (1) has different types of OSCs based on donor-acceptor structures; and (2) has different types and loadings of isolation polymer, photoinitiator, and crosslinking agent. The UV patterning process can also be customized. For example, the process can be adjusted such that it (1) has various UV exposure times, wavelengths, and UV lamp powers; (2) has multiple choices of solvents for spin coating and dipping to obtain the desired UV pattern (e.g., a single solvent or a solvent mixture); and (3) has various times and temperatures for pre-baking and post-baking steps to help obtain optimized OTFT performance.

[0170] As used herein, the terms "about", "approximately", "substantially", and similar terms are intended to have a broad meaning consistent with the ordinary and acceptable usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. Those skilled in the art reviewing this disclosure should understand that these terms are intended to allow for the description of certain features recited and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be construed to mean that non-substantial or minor modifications or variations of the recited and claimed subject matter are considered to be within the scope of the invention as set forth in the appended claims.

[0171] As used herein, terms such as "optional" or "optionally" are intended to mean that the subsequent described event or circumstance may or may not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not occur. Unless otherwise stated, the indefinite articles "a" or "an" and their corresponding definite article "the" as used herein mean at least one, or one or more.

[0172] Element positions referred to herein (e.g., "top", "bottom", "above", "below", etc.) are for describing the orientation of the respective elements in the drawings only. It should be understood that the orientation of each element may vary according to other exemplary embodiments, and such variations are intended to be covered within the scope of the present disclosure.

[0173] For substantially any plural and / or singular terms used herein, those skilled in the art can appropriately convert from the plural to the singular form and / or from the singular to the plural form as long as it is applicable to the context and / or application. For clarity, various singular / plural permutations may be explicitly stated herein.

[0174] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the claimed subject matter. Accordingly, the claimed subject matter is not limited by anything other than the appended claims and their equivalents.

Claims

1. A polymer blend, comprising: An organic semiconductor polymer blended with an isolating polymer; At least one photoinitiator configured to generate reactive free radicals; and At least one crosslinking agent comprising C═C bonds, thiols, or a combination thereof, Among them, The organic semiconductor polymer is a diketopyrrolopyrrole-fused thiophene polymer material, wherein the fused thiophene is β-substituted, Wherein the isolating polymer has a non-conjugated backbone, and Wherein the isolating polymer comprises an unsaturated C═C backbone.

2. The polymer blend according to claim 1, wherein: The amount of the organic semiconductor polymer present ranges from 1 wt% to 99 wt%; The amount of the isolating polymer present ranges from 1 wt% to 99 wt%; The amount of the at least one photoinitiator present ranges from 0.1 wt% to 5 wt%; and The amount of the at least one crosslinking agent present ranges from 0.05 wt% to 10 wt%.

3. The polymer blend according to claim 2, wherein: The amount of the organic semiconductor polymer present ranges from 10 wt% to 50 wt%.

4. The polymer blend according to claim 2, wherein: The amount of the at least one photoinitiator present ranges from 0.1 wt% to 2.0 wt%; and The amount of the at least one crosslinking agent present ranges from 0.3 wt% to 5.0 wt%.

5. The polymer blend according to claim 2, further comprising: At least one of an antioxidant, a lubricant, a compatibilizer, or a leveling agent, present in an amount ranging from 0.05 wt% to 5 wt%.

6. The polymer blend according to claim 1, wherein The organic semiconductor polymer comprises repeating units of Formula 1 or Formula 2, or salts, isomers, or analogs thereof: Wherein, in Formula 1 and Formula 2: m is an integer greater than or equal to 1; n is 0, 1, or 2; R1, R2, R3, R4, R5, R6, R7, and R8 can independently be hydrogen, a substituted or unsubstituted C4 or higher alkyl, a substituted or unsubstituted C4 or higher alkenyl, a substituted or unsubstituted C4 or higher alkynyl, or a C5 or higher cycloalkyl; a, b, c, and d are independently integers greater than or equal to 3; e and f are integers greater than or equal to zero; X and Y are independently a covalent bond, an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted fused aryl or fused heteroaryl, an alkyne, or an alkene; and A and B can independently be any one of S or O, provided that: i. At least one of R1 or R2; one of R3 or R4; one of R5 or R6; and one of R7 or R8 is a substituted or unsubstituted alkyl, a substituted or unsubstituted alkenyl, a substituted or unsubstituted alkynyl, or a cycloalkyl; ii. If any one of R1, R2, R3, or R4 is hydrogen, then none of R5, R6, R7, or R8 is hydrogen; iii. If any one of R5, R6, R7, or R8 is hydrogen, then none of R1, R2, R3, or R4 is hydrogen; iv. e and f cannot both be 0; v. If either e or f is 0, then c and d are independently integers greater than or equal to 5; and vi. The polymer has a molecular weight, wherein the molecular weight of the polymer is greater than 10,000.

7. The polymer blend according to claim 1, wherein The isolating polymer is at least one of the following: polyacrylonitrile (PAN), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), alkyl-substituted polyacrylonitrile (R-PAN), polyethylene (PE), polystyrene, styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-butadiene-styrene rubber (SBR), polystyrene-co-acrylonitrile, acrylonitrile-butadiene-styrene (ABS), styrene-ethylene-butene-styrene (SEBS), polydimethylsiloxane (PDMS), polysulfonate, polyvinyl acetate, polycarbonate, polypropylene, poly(methyl methacrylate) (PMMA), polyamide, polyphenylene sulfide, poly(methyl methacrylate)-block-poly(butyl acrylate) (PMMA-b-PBA), or its derivatives, its copolymers, and its mixtures.

8. The polymer blend according to claim 1, wherein, The at least one photoinitiator includes: 1-hydroxy-cyclohexyl-phenyl-ketone (184); 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one (369); diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO); 2-isopropylthioxanthone (ITX); 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyloxime) (HRCURE-OXE01); 2,2-dimethoxy-1,2-diphenylethan-1-one (BDK); benzoyl peroxide (BPO); hydroxyacetophenone (HAP); 2-hydroxy-2-methylphenylpropanone (1173); 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (907); 2-benzyl-2-(dimethylamino)-4'-morpholinopropyl phenyl ketone (IHT-PI 910); ethyl 4-(dimethylamino)benzoate (EDB); methyl O-benzoylbenzoate (OMBB); bis-(2,6-dimethoxybenzoyl)-phenylphosphine oxide (BAPO); 4-benzoyl-4'-methyldiphenyl sulfide (BMS); benzophenone (BP); 1-chloro-4-propoxythioxanthone (CPTX); chlorothioxanthone (CTX); 2,2-diethoxyacetophenone (DEAP); diethylthioxanthone (DETX); 2-dimethylaminoethyl benzoate (DMB); 2,2-dimethoxy-2-phenylacetophenone (DMPA); 2-ethylanthraquinone (2-EA); ethyl p-N,N-dimethyl-dimethylaminobenzoate (EDAB); 2-ethylhexyl dimethylaminobenzoate (EHA); 4,4-bis-(diethylamino)-benzophenone (EMK); methylbenzophenone (MBF); 4-methylbenzophenone (MBP); Michler's ketone (MK); 2-methyl-1-[4(methylthio)phenyl]-2-morpholinopropanone (1) (MMMP); 4-phenylbenzophenone (PBZ); 2,4,6-trimethyl-benzoyl-ethoxyphenylphosphine oxide (TEPO); or a combination thereof.

9. The polymer blend according to claim 1, wherein The at least one crosslinking agent includes: triallyl isocyanurate (TAIC), trimethylolpropane trithioglycolate (TRIS), 10. A method of forming an organic semiconductor device, the method comprising: blending an organic semiconductor polymer with an isolating polymer in an organic solvent to form a polymer blend; depositing a thin film of the polymer blend over a substrate; exposing the thin film to UV light using a photomask to form a patterned thin film; and developing the patterned thin film in a solvent to remove the unpatterned regions of the thin film, wherein the organic semiconductor polymer is a diketopyrrolopyrrole-fused thiophene polymeric material, wherein the fused thiophene is β-substituted, wherein the isolating polymer has a non-conjugated backbone, wherein the polymer blend further comprises: at least one photoinitiator configured to generate reactive free radicals; and at least one crosslinking agent comprising C═C bonds, thiols, or a combination thereof, and Wherein, the spacer polymer comprises an unsaturated C═C backbone, or the spacer polymer is configured to generate a C═C backbone before or during UV light exposure.

11. The method according to claim 10, further comprising: Performing a first heating on the thin film at a temperature in the range of 50°C to 200°C for a time in the range of 10 seconds to 10 minutes between deposition and exposure.

12. The method according to claim 11, further comprising: Performing a second heating on the patterned thin film at a temperature in the range of 50°C to 200°C for a time in the range of 10 seconds to 30 minutes after development.

13. The method according to claim 10, wherein, The blending comprises: Dissolving an organic semiconductor polymer in a first organic solvent to form a first solution; Dissolving a spacer polymer in a second organic solvent to form a second solution; Combining the first solution and the second solution to form a polymer blend.

14. The method according to claim 13, wherein: The amount of the organic semiconductor polymer present is in the range of 1 wt% to 99 wt%; The amount of the spacer polymer present is in the range of 1 wt% to 99 wt%; The amount of the at least one photoinitiator present is in the range of 0.1 wt% to 5 wt%; and The amount of the at least one crosslinking agent present is in the range of 0.05 wt% to 10 wt%.

15. The method according to claim 10, wherein The deposition comprises at least one of: spin coating, dip coating, spray coating, electrodeposition, meniscus coating, plasma deposition, and roll coating, curtain coating, and extrusion coating.

16. The method according to claim 10, wherein The exposure comprises: Expose the film to UV light with energy in the range of 10 mJ / cm 2 to 600 mJ / cm 2 for a time in the range of 1 second to 60 seconds.

17. The method according to claim 10, wherein The development comprises exposing the unpatterned regions of the thin film to a certain solvent for a time in the range of 10 seconds to 10 minutes, the solvent comprising: chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,2,4-trichlorobenzene, dioxane, p-xylene, m-xylene, toluene, cyclopentanone, cyclohexanone, methyl lactate, 2-butanone, 2-pentanone, 3-pentanone, 2-heptanone, 3-heptanone, anisole, 1,3,5-trimethylbenzene, decalin, butylbenzene, cyclooctane, 1,2,3,4-tetrahydronaphthalene, chloroform, or a combination thereof.

18. The method according to claim 12, further comprising: Forming a gate electrode above the substrate; Forming a gate dielectric layer above the substrate and the gate electrode; Forming a patterned source and drain layer above the gate dielectric layer; And Forming an insulator layer above the patterned source and drain layer.

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