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  • C08F214/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
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  • C08F214/22—Vinylidene fluoride
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  • C08F214/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
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  • C09D127/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers
  • C09D127/02—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
  • C09D127/12—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
  • C09D127/16—Homopolymers or copolymers of vinylidene fluoride
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  • G03F7/004—Photosensitive materials
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  • G03F7/0384—Macromolecular compounds which are rendered insoluble or differentially wettable with ethylenic or acetylenic bands in the main chain of the photopolymer
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  • G03F7/20—Exposure; Apparatus therefor
  • G03F7/2002—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image
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  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K10/00—Organic devices specially adapted for rectifying, amplifying, oscillating or switching; Organic capacitors or resistors having potential barriers
  • H10K10/40—Organic transistors
  • H10K10/46—Field-effect transistors, e.g. organic thin-film transistors [OTFT]
  • H10K10/462—Insulated gate field-effect transistors [IGFETs]
  • H10K10/468—Insulated gate field-effect transistors [IGFETs] characterised by the gate dielectrics
  • H10K10/471—Insulated gate field-effect transistors [IGFETs] characterised by the gate dielectrics the gate dielectric comprising only organic materials
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  • H10K85/10—Organic polymers or oligomers
  • H10K85/141—Organic polymers or oligomers comprising aliphatic or olefinic chains, e.g. poly N-vinylcarbazol, PVC or PTFE
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  • H10K10/00—Organic devices specially adapted for rectifying, amplifying, oscillating or switching; Organic capacitors or resistors having potential barriers
  • H10K10/40—Organic transistors
  • H10K10/46—Field-effect transistors, e.g. organic thin-film transistors [OTFT]
  • H10K10/462—Insulated gate field-effect transistors [IGFETs]
  • H10K10/464—Lateral top-gate IGFETs comprising only a single gate
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  • H10K10/46—Field-effect transistors, e.g. organic thin-film transistors [OTFT]
  • H10K10/462—Insulated gate field-effect transistors [IGFETs]
  • H10K10/466—Lateral bottom-gate IGFETs comprising only a single gate

Definitions

• the dielectric constants of state-of-the-art PVDF-based polymers e.g., poly(vinylidene fluoride- trifluoroethylene), P(VDF-TrFE); poly(vinylidene fluoride-trifluoroethylene- chlorof uoroethylene), P(VDF-TrFE-CFE); and poly(vinylidene fluoride-tetraf uoroethylene- hexafluoropropylene), P(VDF-TFE-HFP)
• P(VDF-TFE-HFP) have been reported to be 20 or higher, and in some cases, 40 or higher, depending on the comonomers, backbone regiochemistry, and the ratio of the different repeating units.
• Their applicability in low- voltage devices has been confirmed by incorporating such PVDF-based polymers as gate dielectrics in OFETs.
• the fluoropolymer typically needs to incorporate a bromine- or iodine-containing monomer.
• crosslinking reactions involving peroxides are known to form unwanted ionic species as side products, which if remained in the crosslinked network, will cause leakage current-related problems (breakdown, current- voltage hysteresis, bias stress) and thus are detrimental to the performance of electronic devices.
• Past approaches of making PVDF-based polymers photocrosslinkable have focused mainly on incorporating a photocrosslinkable repeating unit into the polymer and/or the addition of bis-azides (e.g., 2,6-bis(4-azidebenzylidene)-4-methylcyclohexanone and other analogous compounds) as a photosensitive crosslinker in the polymer spin-coat solution.
• bis-azides e.g., 2,6-bis(4-azidebenzylidene)-4-methylcyclohexanone and other analogous compounds
• the present teachings relate to methods for preparing a patterned thin film component from a photopattemable composition that includes a vinylidene fluoride-based polymer, a photosensitive non-nucleophilic base, and a
• the present teachings also relate to various electronic, optical, and optoelectronic devices (including organic thin film transistors such as organic field-effect transistors and organic light-emitting transistors) including a gate dielectric component composed of a patterned thin film prepared from the photopattemable composition.
• organic thin film transistors such as organic field-effect transistors and organic light-emitting transistors
• Fig. 1 shows exemplary organic field-effect transistors (OFETs) having,
• a bottom-gate top-contact (a), a bottom-gate bottom-contact structure (b), a top- gate bottom-contact structure (c), and a top-gate top-contact structure (d).
• Fig. 2 shows the structure of an exemplary organic light-emitting transistor (OLET).
• OLET organic light-emitting transistor
• Fig. 3 shows the curing speed curves for various P(VDF-TrFE-CFE)-based formulations according to the present teachings.
• Fig. 4 shows representative optical images of films prepared from control P(VDF- TrFE-CFE)-based formulations without crosslinker after UV exposure and development.
• Fig. 5 shows the photopatternability of compositions according to the present teachings: (a) an optical image of a photopatterned film prepared from a P(VDF-TrFE-CFE)- based formulation with via hole openings (250 ⁇ x 250 ⁇ ); (b) the line profile across one of the via holes as measured by a profilometer. Good resolution is evident in the well- defined edges.
• Fig. 6 shows the curing speed curves for various P(VDF-HFP)-based formulations according to the present teachings.
• Fig. 7 shows the curing speed curves for various P(VDF-HFP)-based formulations according to the present teachings.
• Fig. 8 shows representative leakage current density (J) vs. electrical field (E) characterization for pristine P(VDF-TrFE-CFE) films and photocrosslinked P(VDF-TrFE- CFE) films according to the present teachings.
• Fig. 9 shows a bottom-gate top-contact thin film transistor structure.
• Fig. 10 shows representative transfer curves plots of bottom-gate top-contact OFETs incorporating as the gate dielectric a photocrosslinked P(VDF-TrFE-CFE) film according to the present teachings, a pristine P(VDF-TrFE-CFE) dielectric film, or a PMMA film.
• Fig. 11 shows a top-gate bottom-contact thin film transistor structure.
• Fig. 12 shows representative transfer curves plots of top-gate bottom-contact OFETs incorporating as the gate dielectric a photocrosslinked P(VDF-TrFE-CFE) film according to the present teachings, a pristine P(VDF-TrFE-CFE) dielectric film, or a PMMA film.
• Fig. 12 shows representative transfer curves plots of top-gate bottom-contact OFETs incorporating as the gate dielectric a photocrosslinked P(VDF-TrFE-CFE) film according to the present teachings, a pristine P(VDF-TrFE-CFE) dielectric film, or a PMMA film.
• Fig. 14 compares the device performance and stability of bottom-gate top-contact OFETs incorporating as the gate dielectric a single-layer photocrosslinked P(VDF-TrFE- CFE) film ( ⁇ 600 nm), as compared to a bilayer that includes a photocrosslinked P(VDF- TrFE-CFE) film ( ⁇ 600 nm) in contact with a non- ferroelectric polymer thin film ( ⁇ 50 nm): (a) the schematic device structure of the bottom-gate top-contact OFETs with the bilayer gate dielectric, (b) representative transfer curves for both the single-layer dielectric device and the bilayer dielectric device, (c) transfer curve shift under gate bias stress test for the single-layer dielectric device, and (d) transfer curve shift under gate bias stress test for the bilayer dielectric device.
• Fig. 15 compares the device performance and stability of top-gate bottom-contact OFETs incorporating as the gate dielectric a single-layer photocrosslinked P(VDF-TrFE- CFE) film ( ⁇ 600 nm), as compared to a bilayer that includes a photocrosslinked P(VDF- TrFE-CFE) film ( ⁇ 600 nm) in contact with a non- ferroelectric polymer thin film ( ⁇ 50 nm): (a) the schematic device structure of the top-gate bottom-contact OFETs with the bilayer gate dielectric, (b) transfer curve shift under gate bias stress test for the single-layer dielectric device, and (c) transfer curve shift under gate bias stress test for the bilayer dielectric device.
• compositions are described as having, including, or comprising specific components, or where processes are described as having, including, or comprising specific process steps, it is contemplated that compositions of the present teachings also consist essentially of, or consist of, the recited components, and that the processes of the present teachings also consist essentially of, or consist of, the recited process steps.
• halo or halogen refers to fluoro, chloro, bromo, and iodo.
• alkyl refers to a straight-chain, branched, or cyclic saturated hydrocarbon group.
• alkyl groups include methyl (Me), ethyl (Et), propyl (e.g., n-propyl and z ' so-propyl), butyl (e.g., n-butyl, z ' so-butyl, sec-butyl, tert-butyl), pentyl groups (e.g., n-pentyl, z ' so-pentyl, neopentyl), hexyl groups, cyclopropyl groups, cyclohexyl groups, and the like.
• an alkyl group can have 1 to 40 carbon atoms (i.e., Ci_ 40 alkyl group), for example, 1-20 carbon atoms (i.e., Ci_ 2 o alkyl group).
• Ci_ 40 alkyl group for example, 1-20 carbon atoms (i
• an alkyl group can have 1 to 6 carbon atoms, and can be referred to as a "lower alkyl group.”
• lower alkyl groups include methyl, ethyl, propyl (e.g., n-propyl and z ' so-propyl), and butyl groups (e.g., n-butyl, z ' so-butyl, sec-butyl, tert-butyl).
• alkyl groups can be substituted as described herein.
• An alkyl group is generally not substituted with another alkyl group, an alkenyl group, or an alkynyl group.
• haloalkyl refers to an alkyl group having one or more halogen substituents.
• a haloalkyl group can have 1 to 40 carbon atoms (i.e., Ci_4o haloalkyl group), for example, 1 to 20 carbon atoms (i.e., Ci_ 2 o haloalkyl group).
• Examples of haloalkyl groups include CF 3 , C 2 F 5 , CHF 2 , CH 2 F, CC1 3 , CHC1 2 , CH 2 C1, C 2 C1 5 , and the like.
• Perhaloalkyl groups i.e., alkyl groups where all of the hydrogen atoms are replaced with halogen atoms (e.g., CF 3 and C 2 F 5 ), are included within the definition of "haloalkyl.”
• a Ci_4o haloalkyl group can have the formula -C 3 H 2s+ i_ t X 0 t , where X°, at each occurrence, is F, CI, Br or I, s is an integer in the range of 1 to 40, and t is an integer in the range of 1 to 81 , provided that t is less than or equal to 2s+l .
• Haloalkyl groups that are not perhaloalkyl groups can be substituted as described herein.
• alkoxy refers to -O-alkyl group.
• alkoxy groups include, but are not limited to, methoxy, ethoxy, propoxy (e.g., n-propoxy and isopropoxy), t- butoxy, pentoxy, hexoxy groups, and the like.
• the alkyl group in the -O-alkyl group can be substituted as described herein.
• aryl refers to an aromatic monocyclic hydrocarbon ring system or a polycyclic ring system in which two or more aromatic hydrocarbon rings are fused (i.e., having a bond in common with) together or at least one aromatic monocyclic hydrocarbon ring is fused to one or more cycloalkyl and/or cycloheteroalkyl rings.
• An aryl group can have 6 to 22 carbon atoms in its ring system (e.g., C 6-14 aryl group), which can include multiple fused rings.
• a polycyclic aryl group can have from 8 to 22 carbon atoms. Any suitable ring position of the aryl group can be covalently linked to the defined chemical structure.
• aryl groups having only aromatic carbocyclic ring(s) include phenyl, 1-naphthyl (bicyclic), 2-naphthyl (bicyclic), anthracenyl (tricyclic), phenanthrenyl (tricyclic), pentacenyl (pentacyclic) and like groups.
• polycyclic ring systems in which at least one aromatic carbocyclic ring is fused to one or more cycloalkyl and/or cycloheteroalkyl rings include, among others, benzo derivatives of cyclopentane (i.e., an indanyl group, which is a 5,6-bicyclic cycloalkyl/aromatic ring system), cyclohexane (i.e., a tetrahydronaphthyl group, which is a 6,6-bicyclic cycloalkyl/aromatic ring system), imidazoline (i.e., a benzimidazolinyl group, which is a 5,6-bicyclic
• aryl groups include benzodioxanyl, benzodioxolyl, chromanyl, indolinyl groups, and the like.
• aryl groups can be substituted as described herein.
• an aryl group can have one or more halogen substituents, and can be referred to as a "haloaryl" group.
• Perhaloaryl groups i.e., aryl groups where all of the hydrogen atoms are replaced with halogen atoms (e.g., -C 6 F 5 ), are included within the definition of "haloaryl.”
• an aryl group is substituted with another aryl group and can be referred to as a biaryl group.
• Each of the aryl groups in the biaryl group can be substituted as disclosed herein.
• arylalkyl refers to an -alkyl-aryl group, where the arylalkyl group is covalently linked to the defined chemical structure via the alkyl group.
• An arylalkyl group is within the definition of a -Y-C 6-14 aryl group, where Y is as defined herein.
• An example of an arylalkyl group is a benzyl group (-CH 2 -C 6 H 5 ).
• An arylalkyl group can be optionally substituted, i.e., the aryl group and/or the alkyl group, can be substituted as disclosed herein.
• heteroaryl refers to an aromatic monocyclic ring system containing at least one ring heteroatom selected from oxygen (O), nitrogen (N), sulfur (S), silicon (Si), and selenium (Se) or a polycyclic ring system where at least one of the rings present in the ring system is aromatic and contains at least one ring heteroatom.
• Polycyclic heteroaryl groups include two or more heteroaryl rings fused together and monocyclic heteroaryl rings fused to one or more aromatic carbocyclic rings, non-aromatic carbocyclic rings, and/or non-aromatic cycloheteroalkyl rings.
• a heteroaryl group as a whole, can have, for example, 5 to 22 ring atoms and contain 1-5 ring heteroatoms (i.e., 5-20 membered heteroaryl group).
• the heteroaryl group can be attached to the defined chemical structure at any heteroatom or carbon atom that results in a stable structure. Generally, heteroaryl rings do not contain O-O, S-S, or S-0 bonds. However, one or more N or S atoms in a heteroaryl group can be oxidized (e.g., pyridine N-oxide, thiophene S-oxide, thiophene S,S-dioxide). Examples of heteroaryl groups include, for example, the 5- or 6-membered monocyclic and 5-6 bicyclic ring systems shown below:
• T is O, S, NH, N-alkyl, N-aryl, N-(arylalkyl) (e.g., N-benzyl), SiH 2 , SiH(alkyl), Si(alkyl) 2 , SiH(arylalkyl), Si(arylalkyl) 2 , or Si(alkyl)(arylalkyl).
• N-alkyl N-aryl, N-(arylalkyl) (e.g., N-benzyl)
• SiH 2 SiH(alkyl), Si(alkyl) 2 , SiH(arylalkyl), Si(arylalkyl) 2 , or Si(alkyl)(arylalkyl).
• heteroaryl rings examples include pyrrolyl, furyl, thienyl, pyridyl, pyrimidyl, pyridazinyl, pyrazinyl, triazolyl, tetrazolyl, pyrazolyl, imidazolyl, isothiazolyl, thiazolyl, thiadiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, indolyl, isoindolyl, benzofuryl, benzothienyl, quinolyl, 2-methylquinolyl, isoquinolyl, quinoxalyl, quinazolyl, benzotriazolyl, benzimidazolyl, benzothiazolyl, benzisothiazolyl, benzisoxazolyl, benzoxadiazolyl, benzoxazolyl, cinnolinyl, lH-indazolyl, 2H-indazo
• heteroaryl groups include 4,5,6,7- tetrahydroindolyl, tetrahydroquinolinyl, benzothienopyridinyl, benzofuropyridinyl groups, and the like. In some embodiments, heteroaryl groups can be substituted as described herein.
• Ci_ 6 alkyl is specifically intended to individually disclose Ci, C 2 , C 3 , C 4 , C 5 , C 6 , Ci-C 6 , C 1 -C 5 , C1-C4, Ci-C 3 , Ci-C 2 , C 2 -C 6 , C 2 -C 5 , C 2 -C 4 , C 2 -C 3 , C 3 -C 6 , C 3 -C 5 , C 3 -C 4 , C 4 -C 6 , C4-C5, and C 5 -C6 alkyl.
• an integer in the range of 0 to 40 is specifically intended to individually disclose 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, and 40, and an integer in the range of 1 to 20 is specifically intended to individually disclose 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20.
• phrases "optionally substituted with 1-5 substituents” is specifically intended to individually disclose a chemical group that can include 0, 1, 2, 3, 4, 5, 0-5, 0-4, 0-3, 0-2, 0-1, 1-5, 1-4, 1-3, 1-2, 2-5, 2-4, 2-3, 3-5, 3-4, and 4-5 substituents.
• mobility refers to a measure of the velocity with which charge carriers, for example, holes (or units of positive charge) in the case of a p-type semiconductor material and electrons in the case of an n-type semiconductor material, move through the material under the influence of an electric field.
• This parameter which depends on the device architecture, can be measured using a field-effect device or space-charge limited current measurements.
• the present teachings relate to a photopatternable composition
• a photopatternable composition comprising a vinylidene fluoride-based polymer (a PVDF-based polymer), a photosensitive non-nucleophilic base, and a crosslinking agent.
• the foregoing components generally do not react chemically with one another without irradiation. However, upon photoexposure, the photosensitive non-nucleophilic base causes deprotonation and eventually double bond generation in the polymer backbone (via dehydrohalogenation). The crosslinking agent then proceeds to crosslink the polymer by reacting with the newly generated double bonds.
• the vinylidene fluoride-based polymer can include vinylidene fluoride as a first repeating unit and at least a second repeating unit selected from the group consisting of vinyl fluoride, trifluoroethylene, tetrafluoroethylene,
• the vinylidene fluoride-based polymer further includes a third repeating unit selected from the group consisting of vinyl fluoride, trifluoroethylene, tetrafluoroethylene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene, vinylidene chloride, and hexafluoropropylene, where the third repeating unit is different from the second repeating unit.
• the vinylidene fluoride-based polymer can include vinylidene fluoride as a first repeating unit, a second repeating unit selected from the group consisting of vinyl fluoride, trifluoroethylene, and hexafluoropropylene, and an optionally third repeating unit different from the second repeating unit that is selected from the group consisting of vinyl fluoride, trifluoroethylene, and hexafluoropropylene, chlorofluoroethylene, chlorotrifluoroethylene, and vinylidene chloride.
• the foregoing vinylidene fluoride-based polymers typically have a high dielectric constant (k).
• various embodiments of the vinylidene fluoride-based polymer can have a dielectric constant greater than about 10, preferably greater than about 15, and more preferably, greater than about 20.
• the vinylidene fluoride-based polymer can be a copolymer of vinylidene fluoride and trifluoroethylene (P(VDF-TrFE)), a copolymer of vinylidene fluoride and chlorotrifluoroethylene (P(VDF-CTFE)), or a copolymer of vinylidene fluoride and hexafluoropropylene (P(VDF-HFP)).
• the vinylidene fluoride- based polymer can be a terpolymer including vinylidene fluoride as a first repeating unit, trifluoroethylene as a second repeating unit, and a third repeating unit selected from the group consisting of vinyl fluoride, tetrafluoroethylene, hexafluoropropylene, chlorofluoroethylene, chlorotrifluoroethylene, and vinylidene chloride.
• the vinylidene fluoride-based polymer can be a terpolymer selected from the group consisting of poly(vinylidene fluoride- trifluoroethylene-chlorotrifluoroethylene), poly( vinylidene fluoride-trifluoroethylene- chlorofluoroethylene), poly(vinylidene fluoride-trifluoroethylene-hexafluoropropylene), poly( vinylidene fluoride-trifluoroethylene-tetrafluoroethylene), poly(vinylidene fluoride- trifluoroethylene-vinyl fluoride), and poly( vinylidene fluoride-trifluoroethylene -vinylidene chloride).
• the terpolymer can be an alternating terpolymer, where the repeating units are regularly alternating; a periodic terpolymer where the repeating units are arranged in a repeating sequence; a statistical or random terpolymer; or a block terpolymer containing three or more homopolymer subunits linked by covalent bonds.
• the terpolymer can be linear or branched.
• the vinylidene fluoride-based polymer can be represented by formula (I):
• X 2 , X 3 , and X 4 are selected from the group consisting of H, F and CI, provided that no more than one of X 2 , X 3 , and X 4 is CI and not all of X 2 , X 3 , and X 4 are F; x is between about 30 mol% and about 85 mol%, y is between about 10 mol% and about 65 mol%, and x+y ⁇ 100 mol%.
• polymers of formula (I) have only two units, hence the sum of x and y is 100 mol%.
• Xi can be, for example, H or CI.
• the sum of x and y can be no more than 99 mol%, preferably no more than 97 mol%, and more preferably no more than 90 mol%.
• the sum of x and y can be about 90 mol%.
• x can be greater than about 50 mol%.
• x can be between about 55 mol% and about 75 mol%.
• y can be between 15 mol% and about 35 mol%.
• X 2 for example, can be CI, and both X 3 and X 4 can be H or F.
• the vinylidene fluoride-based polymers described herein are chemically inert.
• photosensitive radical initiators have been used to photocrosslink certain vinylidene fluoride-based polymers, to the inventors' knowledge, the actual photocrosslinkers used are limited to bis-azides (specifically, 2,6-bis(4-azidebenzylidene)-4-methylcyclohexanone and other analogous compounds), and their efficiencies are quite low.
• the bis-azides can produce highly active dinitrenes upon irradiation, which can then cross-link the chains of the polymer (either by inserting into carbon-hydrogen bonds, or by abstracting hydrogen atoms from -CH 2 - groups and leaving free radicals, which terminate by coupling reactions), it was found that the bis-azides generally do not disperse well within the polymer matrix. As a result, sufficient photocrosslinking can be achieved only either with a high crosslinkenpolymer ratio (for example, at least a ratio of 1 : 10 or 10 wt % crosslinker) and/or by modifying the polymer to include a photocrosslinkable group (e.g., an azide-containing group).
• a photocrosslinkable group e.g., an azide-containing group
• the inventors have unexpectedly discovered that vinylidene fluoride-based polymers can be efficiently photocrosslinked by using a crosslinking system that includes a photosensitive non-nucleophilic base and a crosslinking agent that includes two or more crosslinking groups.
• the photosensitive non-nucleophilic base is a compound which, prior to photoexposure, is substantially chemically unreactive with the vinylidene fluoride-based polymer; however, upon photoexposure, it is capable of reacting with the vinylidene fluoride- based polymer to generate unsaturation (double bonds).
• the mechanism is believed to involve deprotonation and subsequently direct or indirect dehydrohalogenation (i.e., eliminating HX (e.g., HF or HC1) from the polymer backbone).
• the crosslinking agent can be any crosslinking agent known in the art that can react or promote the reactivity of the resulting double bonds in the vinylidene fluoride-based polymer (after reaction with the non-nucleophilic base but not the pristine polymer) to enable a crosslinked network.
• the photosensitive non-nucleophilic base is a strong organic base, specifically, one that has an increased pKa upon photoexposure compared to its unexcited state.
• the photosensitive non-nucleophilic base inherently or upon
• photosensitization can absorb light in a wavelength range from about 270 nm to about 420 nm, and upon such photoexposure, its pKa can increase to at least about 15, preferably greater than 20.
• the pKa of the photosensitive non-nucleophilic base increases significantly upon photoexposure, and the photosensitive non-nucleophilic base extracts a proton from the vinylidene fluoride- based polymer, which is followed by elimination of a halide anion (e.g., F " or CI " ) to generate unsaturation.
• a halide anion e.g., F " or CI "
• the photosensitive non-nucleophlic base can react with vinylidene fluoride repeating units in the polymer and causes them to undergo dehydrof uorination as follows:
• the photosensitive non-nucleophilic base can be represented by one of the formulae selected from the group consisting of:
• Z is selected from the group consisting of NR, an optionally substituted pyridyl group, or a covalent bond;
• R a , R b , R c , and R d independently are H, a Ci_ 6 alkyl group, an optionally substituted phenyl group, or an optionally substituted benzyl group, or R a and R b together and/or R c and R d together can be joined with the nitrogen atom to form a guanidinyl group, an amidinyl group, or a triaminophosphazenyl group;
• R e and R f independently are a halo group, a cyano group, a nitro group, a Ci_ 6 alkyl group, a Ci_6 haloalkyl group, or a Ci_ 6 alkoxy group;
• R g , R h , R', and R j independently are H, a halo group, a cyano group, a nitro group, a Ci_ 6 alkyl group, a Ci_6 haloalkyl group, or a Ci_ 6 alkoxy group, an optionally substituted phenyl group, or an optionally substituted benzyl group, or R g and R h together or R h and R 1 together or R 1 and R J together can be joined with the two carbon atoms therebetween to form an optionally substituted C 6-14 aryl group or an optionally substituted 5-14 membered heteroaryl group;
• R k , R 1 , R m , and R n independently are H, a halo group, a cyano group, a nitro group, a Ci_ 6 alkyl group, a Ci_ 6 haloalkyl group, or a Ci_ 6 alkoxy group, an optionally substituted phenyl group, or an optionally substituted benzyl group, or R k and R 1 together or R 1 and R m together or R m and R n together can be joined with the two carbon atoms therebetween to form an optionally substituted C 6-14 aryl group or an optionally substituted 5-14 membered heteroaryl group; or if neither R g and R h together nor R m and R n together join to form an optionally substituted C 6- 14 aryl group or an optionally substituted 5-14 membered heteroaryl group, then R g and R n together can be joined with Q and the four carbon atoms therebetween to form an optionally substituted C 6-14 aryl
• pyridine-based compounds such as those including a pyridine coupled with an amine group or a nitro en-containing heteroaryl group.
• Illustrative examples include:
• R 1 , R g , R h , R', and R j are as defined herein.
• the photosensitive non-nucleophilic base can be represented by one of the formulae selected from the group consisting of:
• each R 1 and R 2 independently is H or a Ci_ 6 alkyl group; each R 3 indepi
• Ci_6 alkyl group or an optionally substituted benzyl group is 0, 1, or 2.
• the photosensitive non-nucleophilic base can be selected from the group consisting of:
• the photosensitive non-nucleophilic base can be a
• photosensitive base generator examples include oxime esters, benzyl carbamates (e.g. amines protected by a benzyloxycarbonyl substituent), benzoin carbamates, O-carbamoylhydroxyamines, O-carbamoyloximes, aryl (e.g., benzyl) sulfonamides, N-arylformamides, imines, and nifedipine and its derivatives.
• Other photosensitive base generators suitable for use in the present invention will be known to those skilled in the art such as those disclosed in "Base Catalysis in Imaging Materials," by J. Frechet et al. J. Org. Chem.
• Preferred photobase generators include bis[(2,6-dinitrobenzyl) oxycarbonyl]hexane-l,6-diamine, N-(2- nitrobenzyloxycarbonyl)-cyclohexylamine, N-[[(2-nitrophenyl)- 1 - methylmethoxy]carbonyl]decylamine, N-[[l-(3,5-dimethoxyphenyl)-l-methyl-ethoxy]- carbonyljcyclohexylamine or the corresponding bis-carbamate of 1 ,6-diaminohexane, 1 , 1- bis(4-dimethylaminophenyl)-l -phenyl-methanol and analogous substituted triphenyl methanol.
• the photosensitive base generator can absorb light in the 270-420 nm region to generate the base. Specific examples include:
• the crosslinking agent can be selected from various compounds known by those skilled in the art to be reactive with double bonds.
• the crosslinking agent can be a small molecule or a polymer having one or more thiol groups that can react with the double bonds present in the dehydrohalogenated polymer via thiol-ene click chemistry.
• the crosslinking agent can be a small molecule or a polymer having one or more amine groups that can react with the double bonds present in the dehydrohalogenated polymer via hydroamination.
• the crosslinking agent can be a small molecule or a polymer having one or more maleimide groups that can react with the double bonds present in the dehydrohalogenated polymer via, for example, conjugate addition.
• the crosslinker can be a small molecule or a polymer that can promote a [2+2] or a [2+4] cycloaddition; for example, such small molecule or polymer can have one or more vinyl groups.
• the crosslinking agent should not have any significant absorption in the 270-420 nm region so that it does not compete with the photosensitive non-nucleophilic base.
• the crosslinking agent preferably is not thermally activated and is not peroxide-based. Specific examples of such mercapto-, amino-, vinyl or maleimido-functionalized crosslinkers include:
• the photosensitive non-nucleophilic base and the crosslinking agent generally are present in the present photopatternable composition, individually, at no more than about 10 wt% of the vinylidene fluoride-based polymer.
• the vinylidene fluoride-based polymer for example, the
• photosensitive non-nucleophilic base can be present in the present photopatternable composition at no more than about 5 wt%, preferably no more than about 3 wt%, of the vinylidene fluoride-based polymer.
• the crosslinking agent can be present in the present photopatternable composition at no more than about 10 wt% of the vinylidene fluoride-based polymer. It is preferred that the crosslinking agent is present at a higher mol % than the photosensitive non-nucleophilic base to make sure all double bonds created from dehydrohalogenation of the polymer are reacted to prevent the polymer from becoming electrically conducting.
• the present photopatternable composition can provide quickly-cured, robust thin films (for example, as demonstrated by minimal thickness loss after developing with various organic solvents) after no more than 10 minutes (typically, no more than about 5 minutes, and usually, no more than about 2 minutes) of photoexposure, and the dielectric constant of the resulting thin film dielectrics generally is 10 or higher, in some embodiments, 12 or higher, and in certain embodiments, 15 or higher. In particular embodiments, the dielectric constant of the resulting thin film dielectrics can be 20 or higher.
• the vinylidene fluoride-based polymer, the photosensitive non-nucleophilic base, and the crosslinking agent can be mobilized in a liquid medium to provide a composition (a photopatternable composition) for forming a photopatternable material.
• the composition can be a solution, a dispersion, a suspension, an emulsion, or a gel, although in most
• the composition is a solution or a dispersion suitable for solution-phase processes.
• the term "mobilized in a liquid medium” broadly means that the designated liquid medium causes a designated solid to take on properties of a liquid.
• the solid can be dissolved in the liquid medium to form a single-phase solution, or the solid can be dispersed in the liquid medium to form a two-phase dispersion.
• the solid and the liquid medium can be combined together to form an emulsion, a suspension, or a gel.
• solution means that a substantial proportion of a designated solute has formed a single phase with a designated solvent, but a substantial second phase that can include dispersed particulate matter also can be present.
• the liquid medium can be an organic solvent or a solvent mixture in which each of the vinylidene fluoride-based polymer, the photosensitive non-nucleophilic base, and the crosslinking agent has satisfactory solubility.
• a compound can be considered soluble in a solvent when at least 1 mg of the compound can be dissolved in 1 ml of the solvent.
• ester solvents such as ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, cyclohexyl acetate, heptyl acetate, ethyl propionate, propyl propionate, butyl propionate, iso
• ketone solvents such as acetone, acetylacetone, methyl ethyl ketone, methyl isobutyl ketone, 2-butanone, 2-pentanone, 3-pentanone, 2-heptanone, 3-heptanone, cyclopentanone, and cyclohexanone; halogenated solvents such as chloroform, carbon tetrachloride, and halogenated alkanes; and mixtures of any of the foregoing solvents.
• the present photopatternable composition can be used to deposit thin film materials via various solution-phase processes known in the art, where the thin film materials can be subsequently photocrosslinked and become insoluble in the mother liquid medium used for film deposition.
• the solution-phase process can be selected from spin-coating, slot coating, printing (e.g., inkjet printing, screen printing, pad printing, offset printing, gravure printing, flexographic printing, lithographic printing, mass- printing and the like), spray coating, electrospray coating, drop casting, dip coating, and blade coating.
• spin-coating involves applying an excess amount of the coating solution onto the substrate, then rotating the substrate at high speed to spread the fluid by centrifugal force.
• the thickness of the resulting film prepared by this technique can be dependent on the spin- coating rate, the concentration of the solution, as well as the solvent used.
• Printing can be performed, for example, with a rotogravure printing press, a f exoprinting press, pad printing, screen printing or an inkjet printer.
• the thickness of the resulting film as processed by these printing methods can be dependent on the concentration of the solution, the choice of solvent, and the number of printing repetitions.
• Ambient conditions such as temperature, pressure, and humidity also can affect the resulting thickness of the film.
• printing quality can be affected by different parameters including, but not limited to, rheological properties of the formulations/compositions such as tension energy and viscosity.
• the solubility requirement generally can be less stringent and a solubility range as low as about 1-4 mg/ml can suffice.
• a solubility range may be necessary, often in the range of about 20-100 mg/ml.
• Other contact printing techniques such as screen- printing and flexo printing can require even higher solubility ranges, for example, about 100- 1000 mg/ml.
• the strength of the polymer in the present photopatternable composition can be between about 1 mg/ml and about 200 mg/ml, preferably between about 20 mg/ml and about 100 mg/ml.
• the present photopatternable composition also can include one or more additives, processing aids and/or fillers (e.g., metal oxide nanoparticles).
• the present photopatternable composition can exclude any inorganic (e.g., metal) fillers.
• the total solid loading of all the non-polymer components i.e., the photosensitive non-nucleophilic base, the crosslinking agent, and any optional additives
• Materials prepared from the present photopatternable composition can be photopatterned directly (without using a photoresist). Accordingly, a patterned thin film dielectric component can be formed by depositing a photopatternable composition according to the present teachings to provide an uncrosslinked film, subjecting the uncrosslinked film to radiation in an imagewise pattern (for example, through a photomask) such that exposed areas of the film become crosslinked; and removing the unexposed areas (which remain uncrosslinked and soluble).
• the process can include depositing the photopatternable composition on a substrate to form a film of desired thickness, exposing the film radiation (for example, flood exposure or irradiation at specific wavelengths in the UV region e.g., the H, I, or G line wavelengths) through a photomask (one having the desired imagewise pattern) to provide crosslinked areas and uncrosslinked areas, and subjecting the film to a developing agent to remove the film radiation (for example, flood exposure or irradiation at specific wavelengths in the UV region e.g., the H, I, or G line wavelengths) through a photomask (one having the desired imagewise pattern) to provide crosslinked areas and uncrosslinked areas, and subjecting the film to a developing agent to remove the film radiation (for example, flood exposure or irradiation at specific wavelengths in the UV region e.g., the H, I, or G line wavelengths) through a photomask (one having the desired imagewise pattern) to provide crosslinked areas and uncrosslinked areas, and subjecting the film
• Thin film materials prepared from the present photopatternable composition can have good mechanical properties and chemical resistance. For example, after
• the thin film materials can become substantially insoluble in various organic solvents in which the pristine polymer is soluble. More specifically, the photocrosslinked film can be immersed in the mother solvent, for example, for a period of time sufficient to develop the desired pattern, and the loss in the thickness of the film
• thickness loss can be less than about 50%, preferably less than about 20%, and more preferably less than about 10%.
• a "thin film material” or a “thin film” is a layer of material deposited with controlled thickness typically between about 1 nm and about 5000 nm (or 5 microns).
• a “thin film transistor” is a transistor having a stacked architecture comprising different thin film layers.
• a thin film transistor typically includes a thin film substrate having a thickness between about 10 nm and about 1000 nm, electrical contacts (source, drain, gate electrodes) having a thickness between about 10 nm and about 100 nm, a thin film semiconductor layer between about 50 nm and about 500 nm, and a thin film dielectric layer having a thickness between about 200 nm and about 1000 nm.
• the present thin film materials generally have excellent dielectric properties.
• the present thin film materials typically have a dielectric constant of 10 or greater.
• the present thin film materials can have a dielectric constant of about 15 or greater.
• the present thin film materials can have a dielectric constant of about 20.
• the present thin film materials can exhibit very low leakage current densities. Leakage current density typically is defined as a vector whose magnitude is the leakage current per cross-sectional area.
• leakage current refers to uncontrolled (“parasitic") current flowing across region(s) of a semiconductor structure or device in which no current should be flowing, for example, current flowing across the gate dielectric in a metal-oxide-semiconductor (MOS) structure.
• MOS metal-oxide-semiconductor
• the leakage current density of a dielectric material can be determined by fabricating a standard metal-insulator-semiconductor (MIS) and/or metal- insulator-metal (MIM) capacitor structures with the dielectric material, then measuring the leakage current, and dividing the measured current by the area of the metal electrodes.
• photopatterned thin film dielectrics according to the present teachings can have a leakage current density of less than or equal to about 2 x 10 "3 A/cm 2 at 1 MV/cm, less than or equal to about 5 x 10 "4 A/cm 2 at 1 MV/cm, or less than or equal to about 2 x 10 "4 A/cm 2 at 1 MV/cm.
• photopatterned thin films according to the present teachings can be used as a patterned gate dielectric component in various electronic, optical, and
• Such gate dielectric components can exhibit a wide range of desirable properties and characteristics including, but not limited to, low leakage current densities, high breakdown voltages, large capacitance values, thermal, air and moisture stability, resistance to harsh reagents, and/or compatibility with diverse interlayer, semiconductor and/or metal contact materials (including interfacial compatibility and compatibility with methods used to process such interlayer, semiconductor and/or metallic materials).
• the electronic, optical, or optoelectronic devices incorporating the present gate dielectric component in turn, can have improved device performance including, but not limited to, low hysteresis, better stability, and lower operating voltages.
• pristine vinylidene fluoride-based polymers are ferroelectric (i.e., these polymers have a spontaneous electric polarization that can be reversed by the application of an external electric field), such ferroelectric properties can be detrimental to transistor performance causing threshold voltage shift and I-V hysteresis issues.
• crosslinking the vinylidene fluoride-based polymers the ferroelectric properties are significantly suppressed; however, there may be residual ferroelectric domains that can still negatively affect device performance.
• the inventors have found that by including a thin film of non-ferroelectric polymeric material between the patterned gate dielectric component and either the semiconductor layer or the gate electrode, enhanced device stability can be achieved.
• the non-ferroelectric layer can help prevent the vinylidene fluoride-based polymer from forming ferroelectric domains when an electric field is applied. This is supported by experimental data obtained from MIM capacitor structures, where capacitors incorporating the bilayer dielectric showed steady capacitance that was independent of turn-on voltages as well as reduced gate leakage. While the patterned thin film dielectric component composed of the crosslinked vinylidene fluoride-based polymer typically has a thickness between about 200 nm and about 1000 nm, the second organic thin film layer composed of the non- ferroelectric polymer can be much thinner, for example, between about 10 nm and about 100 nm.
• non-ferroelectric polymers that are useful as dielectrics include CYTOP, polystyrene, polyethylene, poly- alpha-methylstyrene, polyisobutene, polypropylene, polyvinylcyclohexane,
• Photocrosslinkable polymers especially, UV- crosslinkable polymers
• those functionalized with coumarin, cinnamate, and/or diene moieties also can be used.
• Non-limiting examples of electronic, optical, and optoelectronic devices that can include a gate dielectric component composed of the present thin film materials include capacitors, organic field-effect transistors, metal oxide field-effect transistors, and organic light-emitting transistors. Referring to Fig.
• a field-effect transistor generally includes source and drain electrodes (2, 2', 2", 2"' and 4, 4', 4", 4"'), a semiconductor layer (6, 6', 6", 6 * "), a gate dielectric layer (8, 8 * , 8", 8 * "), a gate electrode (10, 10 * , 10", 10 * "), a substrate (12, 12', 12", 12"'), and optionally one or more interlayers (e.g., a surface-modifying layer, a passivation layer, or an encapsulation layer).
• the gate electrode, and the source and drain electrodes can be arranged in different configurations relative to the gate dielectric layer and the semiconductor layer to provide, for example, a bottom-gate top- contact (Fig.
• a potential is applied on the gate electrode, charge carriers are accumulated in the semiconductor layer at an interface with the gate dielectric. As a result, a conductive channel is formed between the source electrode and the drain electrode and a current will flow if a potential is applied to the drain electrode.
• a field-effect transistor has a gate dielectric layer prepared from a photopatternable composition described herein, and can be characterized by an operating voltage that is less than about
• the semiconductor layer of a field-effect transistor can be composed of one or more organic (small molecule or polymeric) semiconducting compounds or semiconducting metal oxides.
• the semiconducting metal oxide can be selected from indium oxide (ln 2 0 3 ), indium zinc oxide (IZO), zinc tin oxide (ZTO), indium gallium oxide (IGO), indium-gallium-zinc oxide (IGZO), indium-gallium-oxide (IGO), indium-ittrium-oxide (IYO), indium tin zinc oxide (ITZO), tin oxide (Sn0 2 ), and zinc oxide (ZnO).
• semiconductor can be formed by sputtering from a target.
• solution-phase processes as described, for example, in U.S. Patent No. 8,017,458, also can be used for preparing a metal oxide thin film semiconductor.
• An annealing step (between about 250- 400°C, preferably below about 300°C) can be performed to improve the semiconducting properties of the metal oxide layer.
• the organic semiconductor layer can be composed of one or more small molecule and/or polymeric compounds that exhibit n-type (electron-transporting), p-type (hole-transporting), or ambipolar (both n-type and p-type) semiconducting activity.
• a "p-type semiconductor material” or a "p-type semiconductor” refers to a semiconductor material having holes as the majority current carriers.
• a p-type semiconductor material when a p-type semiconductor material is deposited on a substrate, it can provide a hole mobility in excess of about 10 ⁇ 5 cm 2 /V s.
• a p-type semiconductor can also exhibit a current on/off ratio of greater than about 10.
• An "n-type semiconductor material” or an "n-type semiconductor” refers to a semiconductor material having electrons as the majority current carriers. In some
• an n-type semiconductor material when it is deposited on a substrate, it can provide an electron mobility in excess of about 10 ⁇ 5 cm 2 /V s. In the case of field-effect devices, an n-type semiconductor can also exhibit a current on/off ratio of greater than about 10.
• the term "mobility" refers to a measure of the velocity with which charge carriers, for example, holes (or units of positive charge) in the case of a p-type semiconductor material and electrons in the case of an n-type semiconductor material, move through the material under the influence of an electric field. This parameter, which depends on the device architecture, can be measured using a field-effect device or space-charge limited current measurements.
• Exemplary p-type semiconductors include soluble pentacenes (e.g., those described in U.S. Patent No. 7,125,989); oligothiophenes and polythiophenes (e.g., dihexyl
• C n -DNTTs Organic Semiconductors for High-Performance Thin-Film Transistors
• p-type semiconductors include linear acenes, bent acenes, arylvinylenes, phenylenes, and fused (hetero)arenes substituted with alkyl and/or alkoxy groups.
• Exemplary n-type semiconductors include fluorocarbon substituted-oligothiophenes (e.g., ⁇ , ⁇ -diperfluorohexylsexithiophenes and other fluorocarbon-substituted thiophene oligomers are described in U.S. Patent No. 6,585,914); fused ring tetracarboxylic diimides and their derivatives (e.g., cyanated perylene diimides (PDIs) or naphthalene diimides (NDIs) such as those described in U.S. Patent No.
• fluorocarbon substituted-oligothiophenes e.g., ⁇ , ⁇ -diperfluorohexylsexithiophenes and other fluorocarbon-substituted thiophene oligomers are described in U.S. Patent No. 6,585,914
• n-type semiconductors include linear acenes, bent acenes, arylvinylenes, phenylenes, and fused (hetero)arenes substituted with alkylcarbonyl, arylcarbonyl, and/or cyano groups.
• a plurality of organic and/or metal oxide field-effect transistors can be arranged in an array which can be used as switching devices or peripheral drivers in active matrix liquid crystal displays (AMLCDs) and as pixel drivers for active matrix organic light-emitting diodes (AMOLEDs).
• AMLCDs active matrix liquid crystal displays
• AMOLEDs active matrix organic light-emitting diodes
• OLET Organic light-emitting transistor
• electroluminescent light-emitting material has been shown to achieve much higher external quantum efficiency (EQE) in an OLET than in an equivalent OLED.
• an organic light-emitting transistor includes a number of layers and can be configured in various ways.
• a trilayer heterostructure bottom-gate top-contact OLET can include, from bottom to top, a transparent substrate (1), a gate electrode (2), a gate dielectric (3), an active layer consisting of the superposition of three organic layers (4, 5, 6), and source and drain electrodes (7, 8) on top of the active layer.
• the trilayer active layer generally includes a light-emitting host-guest matrix sandwiched between an n-type (electron-transporting) semiconductor and a p-type (hole-transporting) semiconductor.
• One or more optional layers (e.g., charge injection layers) and/or additional electrodes can be present, for example, as described in U.S. Patent
• An OLET can be operated by applying a first appropriate bias voltage to the gate electrode, and injecting electrons from the electron electrode and holes from the hole electrode, while maintaining a second bias voltage between the latter two electrodes.
• the first and second bias voltages can be continuous voltages. Alternatively, the first and second bias voltages also can be pulsed voltages.
• OLETs of different architectures can be fabricated using processes known to those skilled in the art as described in, for example, International Publication Nos.
• WO2013/018000 and WO2013/128344 For example, in a bottom-gate configuration, an optional planarization or surface-modifying layer can be formed onto a transparent substrate, e.g., by spin-coating. A metallic thin film can be thermally evaporated thereon, followed by etching or other patterning techniques to form the gate electrode.
• An OLET incorporates a patterned high-k thin film dielectric herein as the gate electric, wherein the patterned high-k thin film dielectric can be prepared by depositing (e.g., spin-coating) onto the gate electrode a film from a photopatternable composition comprising a vinylidene fluoride -based polymer, a photosensitive non-nucleophilic base, and a crosslinking agent as described herein; drying the film; photopatterning the film (exposing the film to radiation through a photomask thereby inducing photocrosslinking in the exposed areas, and subsequently using a developer to remove the soluble, unexposed areas), and optionally annealing the film.
• a photopatternable composition comprising a vinylidene fluoride -based polymer, a photosensitive non-nucleophilic base, and a crosslinking agent as described herein.
• a second thin film dielectric comprising a non- ferroelectric polymer can be deposited on the patterned high-k thin film dielectric before deposition and patterning of the high-k thin film dielectric.
• This second thin film dielectric can be photopatternable, in which case, the photopatterning step of the high-k thin film dielectric can be delayed and conducted together with the photopatterning of the non- ferroelectric polymer.
• the active channel layer can be prepared over the gate dielectric via sequential deposition of a first charge transport sublayer (e.g., hole transport sublayer), an emissive sublayer, and a second charge transport sublayer (e.g., electron transport sublayer).
• the various organic layers can be formed by chemical vapor deposition, physical vapor deposition, different types of printing techniques (e.g., flexo printing, litho printing, gravure printing, ink-jetting, pad printing, and so forth), drop casting, slot coating, dip coating, doctor blading, roll coating, or spin-coating.
• printing techniques e.g., flexo printing, litho printing, gravure printing, ink-jetting, pad printing, and so forth
• drop casting slot coating, dip coating, doctor blading, roll coating, or spin-coating.
• the hole transport sublayer can be used as the hole transport sublayer, the electron transport sublayer, and the emissive sublayer.
• the channel layer can comprise one or more of the small molecule or polymeric p-type and n-type semiconducting compounds described hereinabove in connection with organic field-effect transistors.
• the energy of the hole- transporting semiconductor material must match that of the electron transporting
• the energy difference between the highest occupied molecular orbital (HOMO) of the hole -transporting semiconductor material and the lowest unoccupied molecular orbital (LUMO) of the electron-transporting semiconductor material should be, at a minimum, between about 1.6V and about 1.8 eV.
• the energy difference between the HOMO of the hole -transporting semiconductor material and the LUMO of the electron-transporting semiconductor material has to be, at a minimum, between about 2.2 eV and about 2.5 eV.
• the energy difference between the HOMO of the hole- transporting semiconductor material and the LUMO of the electron-transporting semiconductor material has to be, at a minimum, between about 2.8 eV and about 3.2 eV.
• the emissive sublayer can be a blend that includes a host material and a guest emitter selected from a fluorescent emitter and a phosphorescent emitter.
• the emissive sublayer can be prepared from a single-component host-emitting material. Suitable organic electroluminescent light-emitting materials include those having been used in OLED applications.
• the emissive sublayer can be composed of a blend of host tris(8- hydroxyquinolinato)aluminium (Alq 3 ) and guest 4-(dicyanomethylene)-2-methyl-6-(p- dimethylaminostyryl)-4H-pyran (DCM).
• Some exemplary host materials include polymers such as poly(/?-phenylene vinylene), poly(alkyphenylphenylvinylene), poly(alkyphenylphenylvinylene-co- alkoxyphenylenevinylene), polyfluorene, poly(n-vinylcarbazole), and copolymers thereof.
• polymers such as poly(/?-phenylene vinylene), poly(alkyphenylphenylvinylene), poly(alkyphenylphenylvinylene-co- alkoxyphenylenevinylene), polyfluorene, poly(n-vinylcarbazole), and copolymers thereof.
• Various carbazole compounds, triphenylamine compounds, including hybrids with oxadiazole or benzimidazole also have been used as host materials.
• Some exemplary guest emitters include fluorescent dyes such as various perylene derivatives, anthracene derivatives, rubrene derivatives, carbazole dervatives, fluorene derivatives, and quinacridone derivatives, and phosphorescent emitters such as various transition metal complexes including Ir, Os, or Pt.
• Some exemplary host-emitting materials include phosphorescent host-emitting compounds based on carbazole derivatives, fluorene derivatives, or 9-naphthylanthracene derivatives, and fluorescent host-emitting compounds based on organometallic chelates such as tris(8-quinolinol) aluminum complexes.
• the hole/electron (or souce/drain) electrodes can be formed using similar or different techniques as the gate electrode.
• any of the electrical contacts can be deposited through a mask, or can be deposited then etched or lifted off (photolithography).
• Suitable deposition techniques include electrodeposition, vaporization, sputtering, electroplating, coating, laser ablation and offset printing, from metal or metal alloy including copper, aluminum, gold, silver, molybdenum, platinum, palladium, and/or nickel, or an electrically conductive polymer such as polyethylenethioxythiophene (PEDOT).
• PEDOT polyethylenethioxythiophene
• Charge carrier injection can be facilitated by the use of a material for the injection electrode (hole electrode or electron electrode) that has a low barrier against injection of a charge carrier type into the hole transport sublayer and the electron transport sublayer, respectively.
• the hole electrode can comprise at least one material selected from the group consisting of Au, indium tin oxide, Cr, Cu, Fe, Ag, poly(3,4-ethylenedioxthiophene) combined with poly(styrenesulfonate) (PEDOT:PSS), and a perovskite manganite (Rei_ x A x Mn03).
• the hole electrode and the electron electrode can be made of conductors with different work functions to favor both hole and electron injection.
• the hole and electron injection layers can be prepared by self-assembly of thiolates, phosphonates, or aliphatic or aromatic carboxylates; by thermal evaporation of various charge transfer complexes and other heteroaromatic or organometallic complexes; or by thermal evaporation or sputtering of various metal oxides, fluorides, or carbonates.
• the hole injection layer and the electron injection layer can be made of materials that provide a staircase of electronic levels between the energy level of the hole electrode and the electron electrode, and the energy level required for injection into the hole transport sublayer and the electron transport sublayer, respectively.
• OLETs can be fabricated on various substrates including plastic, flexible substrates that have a low temperature resistance.
• flexible substrates include polyesters such as polyethylene terephthalate, polyethylene naphthalate, polycarbonate; polyolefms such as polypropylene, polyvinyl chloride, and polystyrene; polyphenylene sulfides such as polyphenylene sulfide; polyamides; aromatic polyamides; polyether ketones; polyimides; acrylic resins; polymethylmethacrylate, and blends and/or copolymers thereof.
• the substrate can be a rigid transparent substrate such as glass, quartz and VYCOR®.
• Substrate-gate materials commonly used in thin-film transistors also can be used. Examples include doped silicon wafer, tin-doped indium oxide (ITO) on glass, tin-doped indium oxide on polyimide or mylar film, aluminum or other metals alone or coated on a polymer such as polyethylene terephthalate, a doped polythiophene, and the like.
• ITO tin-doped indium oxide
• polyimide or mylar film aluminum or other metals alone or coated on a polymer such as polyethylene terephthalate, a doped polythiophene, and the like.
• a plurality of OLETs can be arranged in a matrix to provide a display device.
• the display device can include optional driving and switching elements, compensating transistor elements, capacitors, and/or light-emitting diodes.
• photopatternable polymeric materials according to the present teachings were prepared and characterized by various analytical techniques including optical microscopy, metal-insulator-metal (MIM) device leakage and capacitance
• Example 1 P(VDF-TrFE-CFE)-based compositions, film fabrication and photocuring
• This example demonstrates the photocrosslinkability of various embodiments of the present photopatternable compositions based on P(VDF-TrFE-CFE).
• Formulations with different photosensitive non-nucleophilic base and crosslinking agents were tested and compared to a control formulation with neither a crosslinking agent nor a photosensitive non- nucleophilic base, and a control formulation with only a crosslinking agent but not a photosensitive non-nucleophilic base.
• photosensitive non-nucleophilic base about 1-5% by weight
• the crosslinking agent about 3-10%) by weight
• the compositions were spin-coated onto clean ITO substrates at 1000-4000 rpm to give films of thickness in the range of about 400-700 nm.
• Polycrystalline ITO 60 nm (sheet resistance 100 ⁇ / ⁇ ) on glass substrates were cleaned by sonication sequentially in Liquinox® solution, deionized water, acetone and isopropyl alcohol before use.
• the resulting films were exposed to ultraviolet light generated from a 400 W medium pressure mercury arc lamp at a distance of about 20 cm from the lamp housing for up to 240 s.
• the films were then annealed on a 110°C hot plate for about 1-5 minutes to remove any volatile additives that were not reacted during the photocuring process.
• the exposed films were developed by soaking the films for about 30-60 s in a variety of solvents (butyl acetate, cyclopentanone, propylene glycol methyl ether acetate, and methyl ethyl ketone), followed by a hard bake at 110°C for about 10 minutes to remove any residual solvents.
• solvents butyl acetate, cyclopentanone, propylene glycol methyl ether acetate, and methyl ethyl ketone
• Table 1 summarizes the remaining thickness of the different films tested after development with common organic solvents. As shown, compositions including P(VDF- TrFE-CFE), the crosslinking agent, and the photosensitive non-nucleophilic base led to physically robust, highly photocured films, whereas neither of the control films survived after development, indicating a lack of photocrosslinking.
• Figs. 3a and 3b show the curing speed curves for various P(VDF-TrFE-CFE)-based formulations.
• all the formulations include PMS as the crosslinking agent but different photosensitive non-nucleophilic base.
• all the formulations include proton sponge as the photosensitive non-nucleophilic base but different crosslinking agents.
• Additional control films were prepared from formulations including P(VDF-TrFE- CFE) and different photosensitive non-nucleophilic base but no crosslinking agent.
• the films were exposed to UV light as described in Example 1 (-40-240 s).
• the exposed films then were developed by soaking the films for -30-60 s in a variety of solvents (butyl acetate, cyclopentanone, propylene glycol methyl ether acetate, and methyl ethyl ketone) followed by a hard bake at 110°C for 10 minutes to remove any residual solvents.
• solvents butyl acetate, cyclopentanone, propylene glycol methyl ether acetate, and methyl ethyl ketone
• Fig. 4 shows the optical images of the resulting films. Although the developing step did not remove the films completely, the film surface was severely damaged with surface RMS roughness measured at > 15 nm.
• Fig. 5a shows an optical microscopy image of 250 ⁇ x 250 ⁇ size via holes opened in the P(VDF-TrFE-CFE) film through the photo mask with well-defined edges. A line scan across a representative via hole is shown in Fig. 5b.
• Example 3 P(VDF-HFP)-based compositions, film fabrication and photocuring
• This example demonstrates the photocrosslinkability of various embodiments of the present photopatternable compositions based on P(VDF-HFP). Formulations with different photosensitive non-nucleophilic base and crosslinking agents were tested and compared to a control formulation with neither a crosslinking agent nor a photosensitive non-nucleophilic base.
• P(VDF-HFP)-based photopatternable compositions were prepared by dissolving -60-100 mg P(VDF-HFP) in 1 mL of cyclopentanone, followed by addition of the photosensitive non-nucleophilic base (about 1-5% by weight) and the crosslinking agent (about 3-10% by weight), and stirring for at least one hour before spin- coating.
• the compositions were spin-coated onto clean ITO substrates at 1000-4000 rpm to give films of thickness in the range of about 400-700 nm.
• Polycrystalline ITO 60 nm (sheet resistance 100 ⁇ / ⁇ ) on glass substrates were cleaned by sonication sequentially in Liquinox® solution, deionized water, acetone and isopropyl alcohol before use. After spin-coating the film, the resulting films were exposed to ultraviolet light generated from a 400 W medium pressure mercury arc lamp at a distance of about 20 cm from the lamp housing for up to 240 s. The films were then annealed on a 110°C hot plate for about 1-5 minutes to remove any volatile additives that were not reacted during the photocuring process.
• the exposed films were developed by soaking the films for about 30-60 s in a variety of solvents (butyl acetate, cyclopentanone, propylene glycol methyl ether acetate, and methyl ethyl ketone), followed by a hard bake at 110°C for about 10 minutes to remove any residual solvents.
• solvents butyl acetate, cyclopentanone, propylene glycol methyl ether acetate, and methyl ethyl ketone
• Table 2 above summarizes the remaining thickness of the different films tested after development with common organic solvents.
• Fig. 6 shows the curing speed curves for various P(VDF-HFP)-based formulations. As shown, compositions including P(VDF-HFP), the crosslinking agent, and the photosensitive non-nucleophilic base led to physically robust, highly photocured films, whereas the control film (with neither a crosslinking agent nor a photosensitive non-nucleophilic base) was completely removed after development, indicating a lack of photocrosslinking.
• This example demonstrates the photocrosslinkability of various embodiments of the present photopattemable compositions based on P(VDF-TrFE). Formulations with different photosensitive non-nucleophilic base and crosslinking agents were tested and compared to a control formulation with neither a crosslinking agent nor a photosensitive non-nucleophilic base.
• P(VDF-TrFE)-based photopattemable compositions were prepared by dissolving -60-100 mg P(VDF-HFP) in 1 mL of cyclopentanone, followed by addition of the photosensitive non-nucleophilic base (about 1-5% by weight) and the crosslinking agent (about 3-10% by weight), and stirring for at least one hour before spin- coating.
• the compositions were spin-coated onto clean ITO substrates at 1000-4000 rpm to give films of thickness in the range of about 400-700 nm.
• Polycrystalline ITO 60 nm (sheet resistance 100 ⁇ / ⁇ ) on glass substrates were cleaned by sonication sequentially in Liquinox® solution, deionized water, acetone and isopropyl alcohol before use. After spin-coating the film, the resulting films were exposed to ultraviolet light generated from a 400 W medium pressure mercury arc lamp at a distance of about 20 cm from the lamp housing for up to 240 s. The films were then annealed on a 110°C hot plate for about 1-5 minutes to remove any volatile additives that were not reacted during the photocuring process.
• the exposed films were developed by soaking the films for about 30-60 s in a variety of solvents (butyl acetate, cyclopentanone, propylene glycol methyl ether acetate, and methyl ethyl ketone), followed by a hard bake at 110°C for about 10 minutes to remove any residual solvents.
• solvents butyl acetate, cyclopentanone, propylene glycol methyl ether acetate, and methyl ethyl ketone
• Table 3 summarizes the remaining thickness of the different films tested after development with common organic solvents.
• Fig. 7 shows the curing speed curves for various P(VDF-TrFE)-based formulations. As shown, compositions including P(VDF-TrFE), the crosslinking agent, and the photosensitive non-nucleophilic base led to physically robust, highly photocured films, whereas the control film (with neither a crosslinking agent nor a photosensitive non-nucleophilic base) was completely removed after development, indicating a lack of photocrosslinking.
• Metal-insulator-metal (MIM) capacitor structures were fabricated using dielectric films according to the present teachings. The capacitance of the dielectric films was measured.
• MIM structure fabrication polycrystalline ITO on glass was used as the bottom electrode onto which the dielectric film was spin-coated to form the insulating layer. To photocrosslink the dielectric film, the spin-coated films were exposed in the Dymax Flood UV lamp (Model 2000-EC) for 2 minutes and were developed by PGMEA.
• the capacitance values were obtained from measurements taken with a digital capacitance meter (GLK instrument Model 3000) operated at 24 kHz and DC voltage 5V.
• Table 4 compares the capacitance values and the dielectric constants of pristine P(VDF- TrFE-CFE), P(VDF-TrFE), and P(VDF-HFP) films versus photocrosslinked films prepared from compositions according to the present teachings based on the same polymers.
• pristine refers to films prepared from polymer compositions that include neither a crosslinking agent nor a photosensitive non-nucleophilic base. Also, pristine films are not crosslinked. All of the films are about 600 nm thick. Table 4
• Figure 8 compares the leakage current density (J) of the uncured P(VDF-TrFE-CFE) (no additives) with the photocured P(VDF-TrFE-CFE) as the insulating layer.
• the leakage current density (J) was obtained by normalizing the current (I) by the area of the gold top contact.
• Fig. 9 illustrates the structure of a typical bottom-gate top-contact OFET.
• Photocrosslinked P(VDF-TrFE-CFE) films according to the present teachings (prepared as described in Example 1) were incorporated into bottom-gate top-contact OFETs as the gate dielectric. Specifically, a photocrosslinked P(VDF-TrFE-CFE) film was formed on an ITO substrate (which functions as the gate electrode) as the gate dielectric in bottom-gate top- contact test OFET devices. Comparison devices were made similarly with (a) a - 600 nm pristine P(VDF-TrFE-CFE) film, and (b) a - 600 nm thick poly(methyl methacrylate) (PMMA)-based dielectric film, which has a dielectric constant of -3.3. 50 nm.
• the active semiconductor layer comprises C8-BTBT (2,7-dioctyl[l]benzothieno[3,2-b][l]
• benzothiophene which was deposited by thermal evaporation in a vacuum chamber.
• the OFETs were completed by vapor deposition of 50 nm thick gold source and drain contacts through a shadow mask.
• the channel lengths and widths are 100 ⁇ and 1000 ⁇ , respectively.
• Fig. 10 compares the transfer characteristic curves of the test devices
• Example 7 Top-Gate Bottom-Contact OFETs with Photocrosslinked P(VDF- TrFE-CFE) Dielectric as the Gate Dielectric
• Fig. 11 illustrates the structure of a typical top-gate bottom-contact OFET.
• Photocrosslinked P(VDF-TrFE-CFE) films according to the present teachings (prepared as described in Example 1) were incorporated into top-gate bottom-contact OFETs as the gate dielectric. Specifically, polyethylene naphthalate (PEN) films with a spin-coated surface modifier layer were used as substrates. Source/drain electrodes were defined by thermal evaporation of 50 nm thick silver foil through shadow masks. The channel lengths and widths are 60 ⁇ and 1000 ⁇ , respectively. Prior to deposition of the semiconductor layer, the source/drain electrodes were modified using a thiol treatment process.
• PEN polyethylene naphthalate
• Source/drain electrodes were defined by thermal evaporation of 50 nm thick silver foil through shadow masks. The channel lengths and widths are 60 ⁇ and 1000 ⁇ , respectively. Prior to deposition of the semiconductor layer, the source/drain electrodes were modified using a thiol treatment process.
• the active semiconductor layer (-50-100 nm) comprises a molecular cyano-functionalized perylene diimide semiconductor, which was formed by spin-coating then annealing on a 120°C hot plate for 5 min to remove the solvent residues.
• a photocrosslinked P(VDF-TrFE-CFE) film (Example 1) was formed on the semiconductor layer as the gate dielectric.
• the devices were completed by thermally evaporating 50 nm thick gold foil as the gate electrode.
• Comparative devices were made similarly with (a) a - 600 nm pristine P(VDF-TrFE-CFE) film, and (b) a - 600 nm thick poly(methyl methacrylate) (PMMA)-based dielectric film, which has a dielectric constant of -3.3. 50 nm.
• Fig. 12 compares the transfer characteristic curves of the test devices
• Metal-insulator-metal (MIM) capacitor structures were fabricated with a bilayer dielectric which includes a non- ferroelectric interlayer dielectric (PMMA, k ⁇ 3.3) in contact with a photocrosslinked P(VDF-TrFE-CFE) dielectric.
• PMMA was deposited by spin-coating at 2000 r.p.m. for 60 s from an anisole (or PGMEA) solution (20 ⁇ 30 mg/ml), followed by annealing at about 110°C for 10 min to dry the solvent. The capacitance of the dielectric films was measured.
• Fig. 13a polycrystalline ITO on glass was used as the bottom electrode onto which the dielectric film was spin-coated to form the insulating layer.
• the spin-coated films were exposed using a Dymax Flood UV lamp (Model 2000-EC) for 2 minutes and were developed by PGMEA.
• Comparative capacitor structures were fabricated with either a single-layer photocrosslinked P(VDF-TrFE-CFE) dielectric or a single-layer pristine (uncrosslinked) P(VDF-TrFE-CFE) dielectric.
• Top square-shaped gold electrodes of which the feature size ranges from 100 ⁇ x 100 ⁇ to 2000 ⁇ x 2000 ⁇ , were thermally evaporated in vacuum through shadow masks on top of the dielectric layers to complete the MIM capacitance structures.
• the capacitance-voltage characterization was obtained from measurements taken with a digital precision LCR meter (Agilent model E4980A) operated at AC voltage 0.5V and 1 kHz.
• Figure 13b shows representative capacitance of uncrosslinked, photocrosslinked P(VDF-TrFE-CFE) with and without the PMMA as a function of applied DC voltage.
• the combination of the 50 nm - 100 nm PMMA with the high-k dielectric reduced capacitance from 53 nF/cm 2 to 25 nF/cm 2 , as suggested by series capacitance model.
• One distinguished feature is that the capacitance-voltage curve becomes much less voltage dependent for the bilayer dielectric.
• the leakage current was reduced by more than an order of magnitude for electric field larger than 0.1 MV/cm, indicating that combining a photocrosslinked P(VDF-TrFE- CFE), and in general a film with residual ferroelectric domains, with a non-ferroelectric layer substantially enhances dielectric strength.
• Bottom-gate top-contact OFETs were fabricated with (a) a bilayer gate dielectric (photocrosslinked P(VDF-TrFE-CFE) + PMMA) (Fig. 14a) or (b) a single-layer gate dielectric (photocrosslinked P(VDF-TrFE-CFE)).
• the photocrosslinked P(VDF-TrFE-CFE) film has a thickness of about 600 nm, while the PMMA film has a thickness of about 50 nm.
• the gate dielectric was formed on an ITO-coated glass substrate, with ITO as the gate electrode.
• the active semiconductor layer comprises C8-BTBT (2,7- dioctyl[l]benzothieno[3,2-b][l] benzothiophene), which was deposited by thermal evaporation in a vacuum chamber.
• the OFETs were completed by vapor deposition of 50 nm thick gold source and drain contacts through a shadow mask.
• the channel lengths and widths are 100 ⁇ and 1000 ⁇ , respectively.
• Figure 14b shows representative transfer curves plot of the two groups of OFETs. Mobilities of 1.5 ⁇ 3.0 cm 2 /Vs and 1.0 ⁇ 2.0 cm 2 /Vs, respectively, were obtained for the bilayer dielectric and the single-layer dielectric devices. On-off current ratios of 10 6 ⁇ 10 8 were obtained for both groups of devices.
• Figure 14c (without the PMMA interlayer) and Figure 14d (with the PMMA interlayer) show the transfer curve shift of the OFETs under gate bias stress test.
• the bias stress test was performed as follows: (1) an initial transfer curve was performed; (2) right after the measurement, a DC voltage of -30 V was applied to the gate electrodes for 200 s during while keeping both source and drain electrodes at 0 V; (3) an transfer curve was performed at the end of 200 s stress; (4) steps (2) and (3) were subsequently repeated for a total of 7 times.
• the plot compares the transfer curve before (solid dark), in between (solid light) and after (dotted) the gate stress.
• the gate bias results in 5 to 10 V late turn-on of the OFET in the absence of the interlayer, the shift was significantly depressed with the use of the bilayer dielectric.
• Top-gate bottom-contact OFETs were fabricated with (a) a bilayer gate dielectric (photocrosslmked P(VDF-TrFE-CFE) + PMMA) (Fig. 15a) or (b) a single-layer gate dielectric (photocrosslmked P(VDF-TrFE-CFE)).
• Polyethylene naphthalate (PEN) films with a spin-coated surface modifier layer were used as substrates.
• Source/drain electrodes were defined by thermal evaporation of 50 nm thick silver through shadow masks. The channel length and channel width were 60 ⁇ and 1000 ⁇ , respectively. Prior to deposition of the semiconductor layers, the source / drain electrodes were modified using a thiol treatment process.
• a PDICN 2 -based semiconductor layer (50 nm - 100 nm) was deposited by spin- coating, followed by annealing on a 120 °C hotplate for 5 min to remove the solvent residues.
• the interlayer dielectric ( ⁇ 50-100 nm thick) was deposited by spin-coating a photocurable, non- ferroelectric polymer ( ⁇ 20-30 mg/ml in PGMEA, k ⁇ 3.2), followed by UV curing of 200 mJ/cm 2 and an annealing step performed at 110 C for 10 min to remove the solvent.
• a photocrosslmked P(VDF-TrFE-CFE) film (prepared as described in Example 1) was deposited on top of the interlayer dielectric to provide a bilayer gate dielectric.
• the devices were finished by thermal evaporating 50 nm thick gold as the gate electrodes.
• Table 5 summarizes the mobilities and on-off current ratios for the various OFETs tested in Example 9 and Example 10.
• Figure 15b (without the non-ferroelectric interlayer) and Figure 15c (with the non- ferroelectric interlayer) show the transfer curve shift of the OFETs under gate bias stress test.
• the bias stress test was performed as follows: (1) an initial transfer curve was performed; (2) right after the measurement, a DC voltage of -30 V was applied to the gate electrodes for 200 s during while keeping both source and drain electrodes at 0 V; (3) an transfer curve was performed at the end of 200 s stress; (4) steps (2) and (3) were subsequently repeated for a total of 7 times.
• the plot compares the transfer curve before (solid dark), in between (solid light) and after (dotted) the gate stress.
• the gate bias results in 3 to 5 V late turn-on of the OFET in the absence of the interlayer, the shift was significantly depressed with the use of the bilayer dielectric.

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