WO2015170096A1 - Modification par dépôt sous vide de surfaces polymères - Google Patents

Modification par dépôt sous vide de surfaces polymères Download PDF

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Publication number
WO2015170096A1
WO2015170096A1 PCT/GB2015/051329 GB2015051329W WO2015170096A1 WO 2015170096 A1 WO2015170096 A1 WO 2015170096A1 GB 2015051329 W GB2015051329 W GB 2015051329W WO 2015170096 A1 WO2015170096 A1 WO 2015170096A1
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group
process according
substrate
compound
unsubstituted
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PCT/GB2015/051329
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English (en)
Inventor
Hazel Elaine ASSENDER
Ziqian DING
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Isis Innovation Limited
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Priority to GB1620640.1A priority Critical patent/GB2542713B/en
Publication of WO2015170096A1 publication Critical patent/WO2015170096A1/fr

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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • 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
    • H10K10/474—Insulated gate field-effect transistors [IGFETs] characterised by the gate dielectrics the gate dielectric comprising a multilayered structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers

Definitions

  • the present invention relates to buffered polymeric layers, for instance buffered dielectric layers, and to the modification of polymer surfaces.
  • the invention relates to a process for producing a buffered polymeric layer suitable for a semiconductor device, and in particular for a transistor.
  • Buffered polymeric layers obtainable by the process are also provided, as are devices, for instance semiconductor devices such as transistors, comprising such layers.
  • surface modifications of polymer surfaces have many applications. Surface modification of polymers may be used to alter the surface energy, smoothness, polarity or hydrophobicity of such polymers. This has a wide range of applications including electronics, film conversion and packaging. In particular, it is often desirable to modify the surface of polymer layers in semiconductor devices, for instance dielectric polymer layers. Such modifications can improve device performance. For instance, polymeric dielectric layers are desirable for flexible transistors (for instance organic thin film transistors (OTFTs)) due to their favourable processability and inherent flexibility. It is often preferable that dielectric layers used in semiconductor devices have a non-polar surface to contact a semiconductor. Amorphous linear polymers such as polystyrene may be used as non-polar dielectric layers.
  • electron beam (e-beam) curing or plasma curing may be used to polymerize deposited acrylate layers.
  • curing sources of this type allows sub-second curing.
  • the speed of this process allows these methods to be used in roll-to-roll processes which can yield tens of metres of polymer film per minute.
  • cross-linkable materials in the formation of polymeric dielectric layers can inevitably result in the presence of weakly polar chemical groups (such as ester groups) at the surface of the dielectric layer.
  • Surface polar groups in dielectric layers can affect the performance of semiconductor devices comprising such layers. For instance, surface polar groups are believed to affect the growth of subsequently deposited layers of organic semiconductors and are typically undesirable for achieving high charge carrier mobilities in transistors.
  • a main dielectric layer with a non-polar surface for instance formed by an amorphous linear polymer like polystyrene
  • the desirability of the processability and reliability of a cross-linked dielectric layer which may, however, comprise polar groups at the surface.
  • a process for producing a buffered polymeric layer for instance a buffered dielectric layer, which does not require solution processing, and which may be applied to high yield production techniques such as roll-to-roll processing. Such a process may then be applied to modify the surface of polymers in fields such as electronics, film conversion and packaging. Furthermore, it is an object of the invention to provide a process which reliably and efficiently produces buffered polymeric layers suitable for semiconductor devices.
  • the invention provides a process which allows for the efficient, effective and reliable production of a buffered polymeric layer.
  • the buffered polymeric layer produced by the process of the invention typically has dielectric properties, i.e. it may be a dielectric layer, and it may therefore be referred to as a buffered dielectric layer.
  • the process of the invention may be used to produce any buffered polymeric layer.
  • the process of the invention may produce flexible buffered polymeric layers including those which are suitable for semiconducting devices such as transistors.
  • Buffered polymeric layers produced by the process of the invention have been shown to provide significant improvements in transistor performance. At least a 5-fold increase in charge carrier (hole) mobility has been
  • a further advantage of the process of the invention is that it is suitable for roll-to-roll processing, a technique which can yield tens of metres of polymer film per minute; the process is therefore readily scalable for high-yield production.
  • the process of the invention also allows the production of buffered dielectric layers having a low surface roughness and often a "mirror-flat" finish may be obtained.
  • a polymerizable buffer compound for instance a polymerizable buffer compound having a polymerizable group attached to a non-polar chain
  • a substrate under reduced pressure e.g. by vacuum evaporation
  • the buffer compound may be disposed in this way onto a polymeric layer that has already been formed, i.e. the "substrate" may be a polymeric layer.
  • the main polymeric layer under the buffer layer can be formed in situ, by disposing a precursor compound for forming the polymeric layer at the same time as disposing the polymerizable buffer compound.
  • the polymeric layer is typically a dielectric layer.
  • the invention provides a process for producing a buffered polymeric layer, which process comprises:
  • composition comprising a buffer compound, which buffer compound comprises:
  • the invention also provides a buffered polymeric layer which is obtainable by the above- defined process of the invention. Often, the buffered polymeric layer is a buffered dielectric layer. Also, the non-polymerizable group T is typically a non-polar group.
  • the invention also provides a buffered dielectric layer, which buffered dielectric layer is obtainable by a process comprising:
  • composition comprising a buffer compound, which buffer compound comprises:
  • the buffered polymeric layer is often a buffered polymeric layer suitable for a semiconductor device.
  • the buffered polymeric layer is often a buffered dielectric layer, for instance a buffered dielectric layer suitable for a semiconductor device.
  • the invention also provides a process for producing a device, which process comprises producing a buffered polymeric layer by a process comprising:
  • composition comprising a buffer compound, which buffer compound comprises:
  • the invention also provides a device obtainable by a process for producing a device according to the invention.
  • the device may be a semiconductor device such as a transistor, for instance a thin-film transistor (TFT), an organic thin-film transistor (OTFT), or field effect transistor (FET), or an organic field effect transistor (OFET).
  • TFT thin-film transistor
  • OTFT organic thin-film transistor
  • FET field effect transistor
  • OFET organic field effect transistor
  • the invention also provides a device, which device comprises a buffered polymeric layer, which buffered polymeric layer is obtainable by a process comprising
  • composition comprising a buffer compound, which buffer compound comprises:
  • the device is often a semiconductor device, for instance a transistor.
  • the buffered polymeric layer generally has dielectric properties (i.e. it is generally a dielectric layer) and is usually therefore referred to as a "buffered dielectric layer”.
  • Figure 1 shows a schematic diagram of an apparatus for carrying out the process of the invention, wherein the curing source is a plasma curing source.
  • Figure 2 shows a schematic diagram of an apparatus for carrying out the process of the invention, wherein the curing source is an electron beam (e-beam) curing source.
  • Figure 3 shows (a) surface contact angle measurements of water on an unbuffered hexanediol diacrylate (HHDA) dielectric layer and (b) surface contact angle measurements of water on a hexanediol diacrylate (HHDA) dielectric layer buffered with lauryl acrylate by a process according to the invention. Also shown is a schematic diagram of the layers present in (a) and (b).
  • Figure 4 shows a general schematic device architecture for a transistor according to the invention.
  • Figure 5 shows a schematic device architecture for a transistor according to the invention.
  • Figure 6 shows an IV characterisation (transfer curve) plot for a transistor comprising an unbuffered FIDDA dielectric layer.
  • Figure 7 shows an IV characterisation (transfer curve) plot for a transistor comprising an HDDA dielectric layer buffered with a vacuum evaporated lauryl aery late/HDD A mixture.
  • Figure 8 shows an IV characterisation (transfer curve) plot for a transistor comprising an HDDA dielectric layer buffered with a spin coated layer of polystyrene (PS).
  • PS polystyrene
  • Figure 9 shows a plot comparing hole mobility for transistors comprising (i) an unbuffered HDDA dielectric layer, (ii) an HDDA dielectric layer buffered with vacuum evaporated LA, and (iii) an HDDA dielectric layer buffered with spin coated PS.
  • polymeric refers to a material or layer comprising one or more polymer molecules.
  • a polymeric material is typically a material obtainable by polymerizing one or more monomers (such as those defined herein).
  • a polymeric material or layer may comprise linear or branched polymer molecules which may or may not be cross-linked.
  • dielectric refers to a material or layer having a low electrical conductivity which may be polarized by an external electric field.
  • Dielectric materials typically have an electrical conductivity of less than or equal to 1 Sm “1 or less than or equal to 10 "2 Sm "1 .
  • a dielectric material may have an electrical conductivity of less than or equal to 10 "4 Sm “1 or, often, less than or equal to 10 "6 Sm “1 .
  • the term "dielectric” is well known in the art.
  • reduced pressure refers to an absolute pressure which is less than atmospheric pressure. Typically, a “reduced pressure” will be an absolute pressure which is less than or equal to 50% of atmospheric pressure. Atmospheric pressure may be taken to be sea level standard atmospheric pressure which has a value of 101325 Pa (1013.25 mbar).
  • absolute pressure takes its normal meaning in the art and means the pressure relative to a vacuum.
  • device refers to an article which typically comprises one or more components. A device may be a functioning device, or may be a component for producing a functioning device.
  • semiconductor device refers to any device which has a functional component which comprises a semiconductor.
  • a semiconductor device is an electronic device.
  • semiconductor devices include transistors, diodes, batteries, triodes, optoelectronic devices, light emitting diodes, and photovoltaic devices.
  • polymerizable group takes its normal meaning in the art and refers to a chemical group which is capable of polymerizing together with other
  • Polymerizable groups to form one or more polymers.
  • Polymerizable groups often form polymers by chain reactions.
  • non-polar group refers to a chemical group which has a low polarity. Typically, non-polar groups have a low dipole moment, for instance less than or equal to 1 Debye.
  • non-polar groups include hydrocarbyl groups and fluorocarbyl groups, such as unsubstituted alkyl groups, unsubsituted perfluoroalkyl groups, unsubstituted alkenyl groups, unsubstituted perfluoroalkenyl groups, unsubstituted alkynyl groups, unsubstituted perfluoroalkynyl groups, unsubstituted aryl groups and unsubstituted perfluoroaryl groups.
  • Curing refers to any process whereby one or more compounds comprising one or more polymerizable groups are allowed or caused to polymerize to form one or more polymers.
  • Curing may comprise exposing the compounds comprising one or more polymerizable groups to a curing source or curing agent.
  • curing may comprise exposing the polymerizable compounds to heat, radiation or plasma, or curing may comprise exposing the polymerizable compounds to a compound which initiates polymerization such as a radical initiator.
  • curing may comprise allowing the polymerizable compounds to polymerize over time without exposure to an additional external factor.
  • vacuum flash evaporation takes its normal meaning in the art. Thus, it refers to any process whereby a jet of a vapour of material is condensed onto a substrate under reduced pressure.
  • roll-to-roll process takes its normal meaning in the art and refers to a process whereby one or more processes are performed on the surface of a flexible substrate (which may be referred to as the "web") which is in motion. Often the substrate is unrolled from a first roll, passes through one or more processes and is then rolled onto a second roll. Roll-to-roll processes are typically semi-continuous and may be performed on tens of kilometres of substrate (i.e. until a new roll of substrate needs to be loaded).
  • divalent organic moiety refers to any divalent organic moiety which may be obtained by removing two hydrogen atoms from an organic compound.
  • organic compound takes its normal meaning in the art.
  • an organic compound will comprise a carbon atom.
  • an organic compound may comprise a carbon atom covalently bonded to another carbon atom, or to a hydrogen atom, or to a halogen atom, or to a chalcogen atom (for instance an oxygen atom, a sulfur atom, a selenium atom, or a tellurium atom).
  • Divalent organic moieties may have from 1 to 30 carbon atoms, for instance from 1 to 20 carbon atoms. Examples of divalent organic moieties include alkylene, cycloalkylene, alkenylene, alkynylene, and arylene groups. Divalent organic moieties referred to herein may be substituted or unsubstituted.
  • alkyl refers to a linear or branched chain saturated hydrocarbon radical.
  • An alkyl group may be a Ci-40 alkyl group, a Ci-30 alkyl group, a C4-25 alkyl group, a C4-20 alkyl group or a C 6 -2o alkyl group.
  • Ci-40 alkyl group examples include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tertradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, and further groups in this homologous series with from 21 to 40 carbon atoms.
  • alkyl is used without a prefix specifying the number of carbons anywhere herein, it has from 1 to 40 carbon atoms (and this also applies to any other organic group referred to herein).
  • the alkyl groups referred to herein may be unsubstituted or substituted. Often, however, the groups are unsubstituted.
  • cycloalkyl refers to a saturated or partially unsaturated cyclic hydrocarbon radical.
  • a cycloalkyl group may be a C3-10 cycloalkyl group, a C3-8 cycloalkyl group or a C3-6 cycloalkyl group.
  • Examples of a C3-8 cycloalkyl group include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclohexenyl, cyclohex-l,3-dienyl, cycloheptyl and cyclooctyl.
  • Examples of a C3-6 cycloalkyl group include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl.
  • the cycloalkyl groups referred to herein may be unsubstituted or substituted. Often, however, the groups are unsubstituted.
  • alkenyl refers to a linear or branched chain hydrocarbon radical comprising one or more double bonds.
  • An alkenyl group may be a C2-40 alkenyl group, a C 2- 30 alkenyl group, a C4-25 alkenyl group, a C4-20 alkenyl group or a C 6 -2o alkenyl group.
  • C2-40 alkenyl groups include those related to C2-40 alkyl groups by the insertion of one or more double bonds.
  • Alkenyl groups typically comprise one or two double bonds.
  • the alkenyl groups referred to herein may be unsubstituted or substituted. Often, however, the groups are unsubstituted.
  • alkynyl refers to a linear or branched chain hydrocarbon radical comprising one or more triple bonds.
  • An alkynyl group may be a C2-40 alkynyl group, a C2-30 alkynyl group, a C4-25 alkynyl group, a C4-20 alkynyl group or a C 6 -2o alkynyl group.
  • C2-40 alkynyl groups include those related to C2-40 alkyl groups by the insertion of one or more triple bonds.
  • Alkynyl groups typically comprise one or two triple bonds.
  • the alkynyl groups referred to herein may be unsubstituted or substituted. Often, however, the groups are unsubstituted.
  • aryl refers to a monocyclic, bicyclic or poly cyclic aromatic ring which contains from 6 to 14 carbon atoms, typically from 6 to 10 carbon atoms, in the ring portion. Examples include phenyl, naphthyl, indenyl, indanyl, anthracenyl and pyrenyl groups.
  • Aryl groups may be unsubstituted or substituted. Typically, an aryl group is unsubstituted.
  • heteroaryl refers to monocyclic or bicyclic heteroaromatic rings which typically contains from six to ten atoms in the ring portion including one or more heteroatoms.
  • a heteroaryl group is generally a 5- or 6-membered ring, containing at least one heteroatom selected from O, S, N, P, Se and Si. It may contain, for example, one, two or three heteroatoms.
  • heteroaryl groups include pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, furanyl, thienyl, pyrazolidinyl, pyrrolyl, oxazolyl, oxadiazolyl, isoxazolyl, thiadiazolyl, thiazolyl, isothiazolyl, imidazolyl, pyrazolyl, quinolyl and isoquinolyl.
  • Heteroaryl groups may be unsubstituted or substituted. Typically, a heteroaryl group is unsubstituted.
  • fluorocarbyl refers to a group which consists essentially of carbon and fluorine atoms. Such groups may also comprise additional atoms, for instance oxygen atoms or hydrogen atoms. However, typically, a fluorocarbyl group will comprise fewer than 4 atoms which are not fluorine atoms or carbon atoms. For instance, examples of a fluorocarbyl group include -CH 2 (CF 2 ) 5 F and -CF2-0-(CF 2 )3F. Often, a fluorocarbyl group will be a group consisting of carbon atoms and fluorine atoms.
  • a fluorocarbyl group may be a perfluoroalkyl group, a perfluoroalkenyl group, a perfluoroalkynyl or a perfluoroaryl group.
  • these groups include C 1-20 perfluoroalkyl and
  • perfluoroalkyl refers to groups obtained by replacing all hydrogen atoms with fluorine atoms in an alkyl, alkenyl, alkynyl, or aryl group, respectively.
  • perfluoroalkyl groups include Ci-20 perfluoroalkyl groups such as trifluoromethyl, pentafluoroethyl, heptafluoropropyl, perfluorobutyl, perfluoropentyl, perfluorohexyl, perfluoroheptyl, perfluorooctyl,
  • a perfluoroalkyl group may be a Ci-40 perfluoroalkyl group, a Ci-30 perfluoroalkyl group, a C4-25 perfluoroalkyl group, a C4-20 perfluoroalkyl group or a C 6 -2o perfluoroalkyl group.
  • a perfluoroalkenyl group may be a C 2- 40 perfluoroalkenyl group, a C2-30 perfluoroalkenyl group, a C4-25 perfluoroalkenyl group, a C4-20 perfluoroalkenyl group or a C 6 -2o perfluoroalkenyl group.
  • a perfluoroalkynyl group may be a C2-40 perfluoroalkynyl group, a C2-30 perfluoroalkynyl group, a C4-25
  • perfluoroalkynyl group a C4-20 perfluoroalkynyl group or a C 6 -2o perfluoroalkynyl group.
  • a perfluoroaryl group may be a perfluorophenyl group, a perfluoronaphthyl group, a perfluoroindenyl group or a perfluoroindanyl group. Each of these groups may be substituted or unsubstituted. Often, these groups are unsubstituted.
  • alkylene cycloalkylene
  • alkenylene alkynylene
  • arylene alkenylene
  • heteroarylene refers to bivalent groups obtained by removing a hydrogen atom from an alkyl, cycloalkyl, alkenyl, alkynyl, aryl or heteroaryl group, respectively.
  • An alkylene group may be a Ci-40 alkylene group, a Ci-30 alkylene group, a C4-25 alkylene group, a C4-20 alkylene group or a C 6 -2o alkylene group.
  • Examples of Ci-6 alkylene groups are methylene, ethylene, propylene, butylene, pentylene and hexylene.
  • a cycloalkylene group may be a C3-10 cycloalkylene group, a C3-8 cycloalkylene group or a C3-6 cycloalkylene group.
  • Examples of C3-6 cycloalkylene groups include cyclopentylene and cyclohexylene.
  • An alkenylene group may be a C2-40 alkenylene group, C2-30 alkenylene group or a C2-20 alkenylene group.
  • An alkynylene group may be a C2-40 alkynylene group, C2-30 alkynylene group or a C2-20 alkynylene group.
  • Examples of arylene groups include phenylene and naphthalene.
  • heteroarylene groups include diradicals derived from thiophene or furan.
  • alkylene, cycloalkylene, alkenylene, alkynylene, arylene and heteroarylene these groups may be bonded to other groups at any two positions on the group.
  • propylene includes -CH2CH2CH2- and -CH2CH(CH3)-
  • phenylene includes ortho-, meta- and para- phenylene.
  • substituted refers to an organic group which bears one or more substituents selected from Ci-10 alkyl, aryl, heteroaryl, cyano, amino, nitro, Ci-10 alkylamino, di(Ci-io)alkylamino, arylamino,
  • substituted alkyl groups include haloalkyl, perhaloalkyl, hydroxyalkyl, aminoalkyl, alkoxyalkyl and alkaryl groups.
  • a substituted group When a group is substituted, it may bear 1, 2 or 3 substituents. For instance, a substituted group may have 1 or 2 substitutents. Often, however, the term "substituted" as used herein may refer to groups which are substituted with non polar substituents.
  • a substituted organic group may bear one or more substituents selected from C1-5 alkyl groups, C2-5 alkynyl groups, C2-5 alkenyl groups, aryl groups, C1-5 perfluoroalkyl groups, C2-5 perfluoroalkynyl groups, C2-5 perfluoroalkenyl groups, and perfluoroaryl groups. Often, non-polar substituents are selected from C1-5 alkyl groups, C2-5 alkynyl groups, C2-5 alkenyl groups, and aryl groups.
  • acrylamide group refers to a group of formula term "alkylacrylamide group” (or
  • e oxy group refers to a group of formula , wherein each R is independently a group selected from H and C 1-10 alkyl. For instance, R may be H.
  • acid anhydride group refers to a group of formula -C(0)-0- C(0)-R, wherein R is a group selected from H, C 1-10 alkyl and aryl.
  • An acid anhydride group may also be a cyclic acid anhydride group, for instance a group derived from succinic anhydride or maleic anhydride.
  • silane group refers to a group of formula - Si(R) 3 wherein each R is a group independently selected from H, Ci-io alkyl and aryl.
  • linear group refers to an unbranched group.
  • linear group applies to aliphatic hydrocarbyl groups such as alkyl groups, alkenyl groups, and alkynyl groups.
  • a linear group will comprise a single linear chain of atoms, typically carbon atoms. Often this linear chain is substituted only with hydrogen atoms. Examples of linear groups include a straight chain hexyl group.
  • hydrocarbyl group refers to a group comprising only carbon atoms and hydrogen atoms. Thus, hydrocarbyl groups are those derived by the removal of a hydrogen atom from a hydrocarbon compound.
  • hydrocarbyl groups include unsubstituted alkyl groups, unsubstituted cycloalkyl groups, unsubstituted alkenyl groups, unsubstituted alkynyl groups, unsubstituted aryl groups, and unsubstituted arylalkyl groups.
  • interrupted refers to a group comprising a carbon chain, which carbon chain comprises one or more of the groups with which it is interrupted. For instance, an alkyl group may be interrupted with an oxygen atom.
  • a butyl group interrupted with an oxygen atom includes -CH2-0-C 3 H 7 , -C2H4- O-C2H5 and -C 3 H 6 -0-CH 3 .
  • the term "monolayer”, as used herein, refers to layer of a molecule or compound which is only one molecule or compound thick. A monolayer may be a self-assembled monolayer whereby at least some of the molecules or compounds in the monolayer have the same orientation. These terms are well known in the art.
  • electrode material refers to any material suitable for use in an electrode.
  • An electrode material will typically have a high electrical conductivity.
  • semiconductor and “semiconductor material”, as used herein, refer to a material with electrical conductivity intermediate in magnitude between that of a conductor and a dielectric.
  • a semiconductor may be an n-type semiconductor, a p-type semiconductor or an intrinsic semiconductor.
  • disposing refers to any process whereby a material is placed on or near, or made available on or near, the object on which it is disposed. If a material is disposed on a surface, it may be disposed directly on the surface such that the material is in contact with said surface, or there may be intervening layers between the surface and the disposed material. Typically the material is disposed directly onto the surface.
  • the invention provides a process for producing a buffered polymeric layer, which process comprises:
  • composition comprising a buffer compound, which buffer compound comprises:
  • the process is a process for producing a buffered polymeric layer suitable for a semiconductor device.
  • the invention provides a process for producing a buffered polymeric layer suitable for a semiconductor device, which process comprises:
  • composition comprising a buffer compound, which buffer compound comprises:
  • the buffered polymeric layer is typically a buffered dielectric layer, for instance a buffered dielectric layer suitable for a semiconductor device.
  • the non-polymerizable group is usually a non-polar group.
  • the composition comprising a buffer compound is disposed under reduced pressure.
  • the immediate environment in which the composition is disposed has a reduced pressure.
  • the substrate and the source from which the composition is disposed are usually both under reduced pressure.
  • a reduced pressure is desirable as particles under reduced pressure may have a longer mean free path (i.e. may travel a long distance before collision with another particle) than particles under atmospheric or increased pressure.
  • Particles and molecules with a long mean free path may travel in a straight line from a source and thus the direction and distribution of disposition of such particles and molecules may be controlled.
  • reduced pressure allows the even distribution of disposed molecules onto the sub strate .
  • Disposing on a substrate under reduced pressure may comprise disposing on a substrate at an absolute pressure which is less than or equal to 50% of standard atmospheric pressure. It is often preferable to dispose under a very low pressure. Thus, disposing on a substrate under reduced pressure often comprises disposing on a substrate at an absolute pressure which is less than or equal to 0.1% of standard atmospheric pressure. For instance, disposing on a substrate under reduced pressure may comprise disposing on a substrate at an absolute pressure which is less than or equal to 0.001% of standard atmospheric pressure.
  • Disposing on a substrate under reduced pressure typically comprises disposing on a substrate at an absolute pressure of less than or equal to 100 mbar.
  • disposing on a substrate under reduced pressure comprises disposing on a substrate at an absolute pressure of less than or equal to 0.1 mbar.
  • disposing on a substrate under reduced pressure may comprise disposing on a substrate at an absolute pressure of less than or equal to 10 "2 mbar.
  • disposing on a substrate under reduced pressure comprises disposing on a substrate at an absolute pressure of less than or equal to 10 "3 mbar, for instance from 10 "3 mbar to 10 "5 mbar.
  • the composition comprising the buffer compound is typically a liquid composition.
  • Deposition of the composition under reduced pressure means that solvents are not typically required for deposition of the composition comprising the buffer compound.
  • the composition comprising the buffer compound comprises less than 2% by volume of a solvent.
  • typically the composition comprising the buffer compounds does not comprise a solvent.
  • solvents include toluene, alcohols and haloalkanes.
  • the composition comprising the buffer compound may comprise less than 1% by volume of toluene, alcohols and haloalkanes.
  • Step (i) usually comprises exposing the substrate to a vapour of the composition comprising the buffer compound.
  • step (i) may comprise exposing the substrate to a vapour comprising the buffer compound.
  • the vapour of the composition comprising the buffer compound may be produced by any method.
  • the vapour of the composition comprising the buffer compound may be produced by heating the composition, by exposing the composition comprising the buffer compound to said reduced pressure, or by heating the composition and, either simultaneously or subsequently, exposing the composition to said reduced pressure.
  • step (i) comprises disposing on the substrate the composition comprising the buffer compound by vacuum evaporation.
  • vacuum refers to a greatly reduced pressure (such as the values given above, for instance less than 10 "2 mbar). As the skilled person will understand, it is not necessary that there be a complete vacuum. Vacuum evaporation may comprise heating the composition comprising the buffer compound to form a vapour of the composition and allowing vapour of the composition to condense onto the substrate.
  • step (i) comprises disposing the composition comprising the buffer compound by vacuum flash evaporation.
  • Vacuum flash evaporation allows the production of very smooth layers of the buffer compound.
  • Using vacuum flash evaporation allows the production of layers of the composition having a mirror-flat finish which may be
  • a vapour of the composition is produced by heating the composition in a tank or container, and then the vapour is ejected out of, or allowed to exit, the tank into the reduced pressure environment in which the substrate is situated.
  • Apparatus for vacuum evaporation typically comprises a tank or container for heating the composition to be disposed, a means to inject the composition into the tank or container, and an aperture through which the vapour of the composition may be ejected.
  • apparatus for performing vacuum flash evaporation may comprise an atomiser to inject a liquid composition.
  • the liquid composition is often first injected into a heated tank or container.
  • the composition may be degassed before use.
  • the liquid composition will then typically be vaporised, for instance to form a vapour.
  • the vapour is often a molecular gas.
  • the vapour may then exit the tank or container through an aperture into the reduced pressure chamber in which the substrate is situated.
  • the aperture through which the vapour exits the heated tank or container may be of any shape.
  • the aperture may be a slit.
  • the aperture may also comprise a baffle, for instance a heated pressure baffle.
  • step (i) comprises heating the composition comprising a buffer compound in a container to form a vapour comprising the composition and ejecting the vapour comprising said composition from said container onto the substrate, wherein the atmosphere between the container and the substrate is at said reduced pressure.
  • the composition may be injected into the container (in which it is heated) at a rate of from 0.01 ml/min to 10 ml/min. For instance, the composition may be injected at a rate of from 0.3 ml/min to 2 ml/min.
  • the composition may be disposed on the substrate for any length of time, for instance from 10 seconds to 1000 seconds.
  • the composition is typically disposed until a layer of the desired thickness is produced.
  • the desired thickness may for instance be any of the thicknesses or thickness ranges discussed below.
  • the composition may be disposed for from 30 seconds to 90 seconds.
  • the substrate may be in motion and the disposition of the composition may be continuous.
  • the temperature of the container or tank in which the composition is heated is optimized to prevent both the condensation of the composition within the tank and also reaction or polymerization of the composition before deposition onto the substrate.
  • the composition is heated at a temperature of from 100°C to 400°C.
  • the composition may be heated at a temperature of from 100°C to 300°C.
  • the composition is heated at a temperature of from 200°C to 300°C.
  • the composition may be heated at a temperature of from 250°C to 270°C (i.e. about 260°C).
  • the thickness of the resulting layer of the disposed composition is typically from 5 nm to 500 nm.
  • the composition disposed may comprise compounds suitable for forming the bulk of the main polymeric layer (which may be dielectric and is often therefore referred to as the "main dielectric layer") in addition to the buffer compound as discussed further below, and in such an instance the thickness of resulting layer of the disposed composition is typically from 200 nm to 500 nm.
  • the composition disposed mostly comprises (e.g. greater than 50% by volume of the composition) the buffer compounds.
  • the layer of the disposed composition is typically thinner.
  • the thickness of the disposed layer of the composition may be from 10 nm to 100 nm, or from 20 nm to 70 nm.
  • step (ii) comprises curing the composition disposed on the substrate.
  • the composition disposed on the substrate may be cured by any means.
  • curing the composition disposed on the substrate may comprise exposing the composition to heat, light, radiation, plasma, electrons or a compound suitable for causing or initiating polymerization.
  • Curing the composition disposed on the substrate may also comprise allowing the composition to cure, for instance by leaving the composition for a time or exposing the composition to air.
  • step (ii) comprises exposing the substrate to a curing source.
  • the curing source may be a curing source which produces heat, electromagnetic radiation (for instance UV radiation), electrons or plasma.
  • the curing source is selected from an electron beam curing source or a plasma curing source.
  • An electron beam curing source may have a beam current of from 10 mA to 1000 mA.
  • an electron beam curing source may have a beam current of from 50 mA to 500 mA.
  • An electron beam curing source may have a voltage of from 0.5 to 20 kV.
  • the plasma curing source may be an argon plasma curing source.
  • the plasma curing source may generate plasma using a DC magnetron source.
  • the extent of curing of the composition may be measured using spectroscopy (e.g. IR spectroscopy) to analyse the loss of signals due to the presence of uncured composition.
  • the resulting cured layer may be very smooth.
  • the cured layer of the composition comprising the buffer compound may have a root mean square (RMS) surface roughness of less than or equal to 1 nm.
  • RMS surface roughness is less than or equal to 0.5 nm or less than or equal to 0.4 nm, and more preferably less than or equal to 0.3 nm.
  • the substrate on which the composition is disposed may be any suitable substrate.
  • the substrate is typically laminar.
  • the substrate may be a roll of material.
  • the substrate is a flexible substrate.
  • a substrate is flexible if it may be bent and/or deformed without damage to the substrate, i.e. the substrate is typically not brittle or rigid.
  • the substrate may be a long sheet of flexible material.
  • the substrate may be a sheet of flexible material with a width of from 5 to 100 cm and a length of from 10 cm to 100 m.
  • the substrate may have a thickness of from 100 nm to 1 mm.
  • the substrate may have a thickness of from 1 ⁇ to 500 ⁇ .
  • the substrate comprises a layer of a material comprising at least one of paper, fabric, and one or more plastics.
  • the substrate comprises one or more plastics.
  • the substrate comprises a plastic.
  • the plastic is typically a polymeric insulating material.
  • the substrate may comprise a polymer selected from polyalkenes, polydienes, polyesters, polyethers, polyamides, polyurethanes, epoxy resins, polycarbonates and polyarenes.
  • the substrate may comprise a polymer selected from polyethylene (PE), polypropylene (PP), polystyrene (PS), polycarbonate, polyethylene terephthalate (PET) and polyethylene naphthalate (PEN).
  • the substrate may consist essentially of one or more of these polymers.
  • the substrate comprises a polymer selected from PEN, PET and polycarbonate (for instance poly(bisphenol A carbonate).
  • the substrate may further comprise one or more electrodes disposed thereon.
  • the substrate may be pre-patterned with electrodes.
  • the electrodes may comprise any conductive material.
  • the electrodes comprise one or more metals.
  • the electrodes comprise one or more of gold and aluminium.
  • the substrate may comprise a layer of a plastic, for instance PEN or polycarbonate, and one or more electrodes.
  • the electrodes are often gate electrodes suitable for use in a transistor.
  • the substrate may further comprise a layer of a dielectric material.
  • the substrate is in motion and the direction of disposition of the buffer compound is at from 45° to 135° relative to the surface of the substrate.
  • Motion of the surface of substrate is typically in a direction which is parallel to the dimension of the substrate having the greatest extent.
  • the substrate is a laminar sheet having a length of 10 m and a width of 30 cm
  • motion of the surface of the substrate is typically in the direction in which the substrate has a length of 10 m.
  • the substrate may be a long sheet of material unwinding from a first roll, passing under the disposition source and curing source (and optionally other sources), and winding onto a second roll, and thus the substrate is in transverse motion.
  • the length of the substrate may be any suitable length.
  • the substrate may have a length of from 1 m to 10 km, for instance from 10 m to 500 m.
  • the substrate remains at a fixed distance from the disposition source.
  • the direction of disposition of the buffer compound is measured relative the surface of the substrate along the line which is the direction in which the substrate is in motion.
  • the direction of disposition is 90° relative to the surface of the substrate.
  • the direction of disposition is from 75° to 105° relative to the surface of the substrate.
  • the substrate is at a moderate temperature, for instance ambient temperature.
  • the substrate is at a temperature low enough that the composition condenses onto the substrate.
  • the substrate is often at a temperature of less than or equal to 50°C.
  • the substrate may be at an ambient temperature. For instance, the temperature of the substrate may be from 10°C to 40°C, or from 12°C to 30°C.
  • the substrate may be affixed to, or in contact with, a coating drum or surface which supports the substrate.
  • a coating drum may be any substantially cylindrical means which may support the substrate (and which may optionally rotate in order to move the substrate in motion).
  • the coating drum or surface which supports the substrate is maintained at a temperature in order to control the temperature of the substrate.
  • the process of the invention may be used in a roll-to-roll process.
  • the process may be a roll-to-roll process.
  • the term "roll-to-roll process" is well known in the art.
  • a roll-to-roll process is a process whereby a long (rolled) sheet of material is unwound from a first roll, passes through one or more processes, and is wound onto a second roll.
  • Roll-to-roll processing allows rapid processing and production of flexible electronics on a large scale.
  • the web speed (i.e. the speed with which the substrate moves from one roll to the other) may be from 1 cm/minute to 50 m/minute. For instance, the web speed may be from 1 m/minute to 10 m/minute.
  • the buffer compound used in the process of the invention comprises: (a) a polymerizable group, P 1 , and (b) a non-polymerizable group, T.
  • the non-polymerizable group is typically a non-polar group.
  • the buffer compound used in the process of the invention comprises: (a) a polymerizable group, P 1 , and (b) a non-polar group, T.
  • the buffer compound may be any compound of this type which is suitable for producing a buffered polymeric layer, for instance a buffered dielectric.
  • the buffer compound is usually an organic compound.
  • the buffer compound has a molecular weight of less than or equal to 500 gmol "1 .
  • the buffer compound may be an organic compound having a molecular weight of less than or equal to 300 gmol "1 .
  • the polymerizable group in the buffer compound may react or crosslink with the substrate or with itself to form a buffer layer which comprises the non-polymerizable group T.
  • the buffer compound if disposed alone or as the major component of the composition forms a buffer layer on top of a main polymeric layer (which is typically, but not-exclusively, dielectric in nature and thus may be referred to as a "main dielectric layer") to form a buffered polymeric layer (which may, in some embodiments, be a buffered dielectric layer).
  • the buffer compound may form a layer at the surface of the disposed composition with the non-polymerizable groups, T, at the surface of the disposed composition before curing. Then, when cured, the groups P 1 may polymerize and crosslink with the bulk of the main polymeric layer and form a buffer layer disposed on the bulk of the polymeric layer.
  • the buffer compound is a compound represented by formula (I): p ! -L-T (I);
  • P 1 is the polymerizable group
  • L is a divalent organic moiety or a covalent bond
  • T is the non-polymerizable group.
  • L may be a covalent bond or any divalent organic moiety and typically has a molecular weight of less than or equal to 100 gmol "1 .
  • L may be a covalent bond or a group selected from unsubstituted or substituted Ci-6-alkylene, unsubstituted or substituted C3-6-cycloalkylene, unsubstituted or substituted C2-6-alkenylene, unsubstituted or substituted C2-6-alkynylene, unsubstituted or substituted arylene, or unsubstituted or substituted heteroarylene.
  • L is a covalent bond.
  • the buffer compound is often a compound represented by formula (II):
  • P 1 is a polymerizable group
  • T is a non-polymerizable group.
  • the buffer compound is typically a compound represented by formula (II):
  • P 1 is a polymerizable group
  • T is a non-polar group.
  • P 1 is usually a group comprising a carbon-carbon double bond, a carbon-carbon triple bond, or an epoxy group (also referred to as an epoxide group). Each of these groups may polymerize with compounds comprising other polymerizable groups which may be the same or different. Often, P 1 is a group comprising a carbon-carbon double bond. Examples of groups comprising a carbon-carbon double include an alkenyl group, an unsubstituted or substituted acrylate group, an unsubstituted or substituted alkylacrylate group, an
  • P 1 is a group comprising a carbon-carbon double bond and one or more heteroatoms.
  • P 1 is a often a group selected from an alkenyl group, an unsubstituted or substituted acrylate group, an unsubstituted or substituted alkylacrylate group, an unsubstituted or substituted acrylamide group, an unsubstituted or substituted alkyl acrylamide group, a vinyl ether group, an alkynyl group, an epoxy group, an acid anhydride group, a cinnamate group or a silane group.
  • P 1 is a often a group selected from a C2-6-alkenyl group, an unsubstituted or substituted acrylate group, an unsubstituted or substituted alkylacrylate group, an
  • alkyl aery 1 amide group a vinyl ether group, an C2-6 alkynyl group, an epoxy group, an acid anhydride group, a cinnamate group or a silane group.
  • R independently a group selected from H, C 1-10 alkyl and aryl.
  • R may be H.
  • An epoxy group may be a group of formula
  • each R is independently a group selected from H and C 1-10 alkyl.
  • R may be H or methyl.
  • T is a non-polymerizable group. Typically, T is a non-polar group. Thus, T typically does not have a significant dipole.
  • Non-polar groups include hydrocarbyl groups and fluorocarbyl groups.
  • T is often a non-polar C2- 3 o-group.
  • a C2- 3 o-group is an organic group having from 2 to 30 atoms.
  • T may be a group selected from a C2- 3 o hydrocarbyl group, a C2- 3 o fluorcarbyl group, a C2- 3 o hydrocarbyl group interrupted with one or more groups selected from -O- and - N(H)- or a C2- 3 o fluorocarbyl group interrupted with one or more groups selected from -O- and - N(H)-.
  • T is preferably a C2- 3 o-hydrocarbyl group.
  • T is often a linear group.
  • T may be a linear C2- 3 o-group.
  • T is often a group selected from a substituted or unsubstituted C2- 3 o-alkyl group, a substituted or unsubstituted C2- 3 o-alkenyl group, a substituted or unsubstituted C2- 3 o-alkynyl group, a substituted or unsubstituted C2- 3 o-fluoroalkyl group, a substituted or unsubstituted C2- 3 o- fluoroalkenyl group, and a substituted or unsubstituted C2-3o-fluoroalkynyl group.
  • T is often a group selected from an unsubstituted C2-3o-alkyl group, an unsubstituted C2-3o-alkenyl group, an unsubstituted C2-3o-alkynyl group, an unsubstituted C2-3o-fluoroalkyl group, an unsubstituted C2-3o-fluoroalkenyl group, and an unsubstituted C2-3o-fluoroalkynyl group.
  • T is a group selected from a C2-3o-alkyl group, a C2-3o-alkenyl group, and a C2-3o-alkynyl group.
  • T is often a group selected from a C4-2o-alkyl group, a C4-3o-alkenyl group, and a C4-3o-alkynyl group.
  • T is an alkyl group, for instance a C4-is-alkyl group, a C 5 -i6-alkyl group or a C 5 -i4-alkyl group. T may be substituted or unsubstituted.
  • T is substituted is may be substituted with one or more non-polar groups, for instance one or more Ci-6 hydrocarbyl groups.
  • T may be substituted with one or more groups selected from C1-4 alkyl groups and phenyl groups. Typically, however, T is unsubstituted.
  • T is a linear C4-3o-alkyl group.
  • T may be a linear C 6 -3o-alkyl group or a linear C 6 -2o-alkyl group.
  • T may be a hexyl group, or a lauryl (C12) group.
  • the buffer com ound is a compound of formula (IIA):
  • R 1 is a C4-3o-alkyl group or a C 6 -3o alkyl group
  • each R 2 group is independently selected from H, Ci-6 alkyl, and aryl.
  • the buffer compound is a C4-30 alkyl acrylate or a C4-30 alkyl alkyl aery late, for instance a C4-30 alkyl methacrylate.
  • R 1 may a linear C4-3o-alkyl group or a linear C 6 -3o alkyl group.
  • the buffer com ound is a compound of formula (III): wherein R 1 is a linear C4-3o-alkyl group or a linear C 6 -3o alkyl group.
  • the buffer compound may for instance be hexyl acrylate or lauryl acrylate.
  • Pre-deposited polymeric layer As described above, the substrate may, for instance, comprise a flexible material such as a plastic and optionally one or more electrodes.
  • the process according to the invention can be used to form the whole of a buffered polymeric layer (and thus there is no pre-deposited polymeric layer on the substrate).
  • the process of the invention may be used to modify the surface of a pre-existing, or pre-deposited, main polymeric layer.
  • the main polymeric layer is typically a main dielectric layer.
  • the buffered polymeric layer is often a buffered dielectric layer.
  • the substrate comprises a layer of a polymeric material.
  • the polymeric material may be a dielectric material.
  • the polymeric material may be a polymeric dielectric material.
  • a layer of a polymeric material may have already been disposed on the substrate.
  • the substrate preferably comprises a polymeric dielectric material.
  • the polymeric dielectric material is preferably in the form of a layer.
  • the substrate typically comprises a cross-linked polymeric material, for instance a polymeric dielectric material.
  • the substrate may comprise a polymeric material obtainable by polymerizing a compound comprising two or more polymerizable groups.
  • the polymeric material, or polymeric dielectric material, obtainable by polymerizing a compound comprising two or more polymerizable groups may be produced by any process, or may be pre-deposited.
  • the substrate comprises a layer of a polymeric material obtainable by a process comprising:
  • the process also comprises a step of producing the main polymeric layer which is to be buffered.
  • the main polymeric layer is typically a main dielectric layer.
  • the process often further comprises producing said layer of a polymeric material by a process comprising:
  • the disposed layer of the compound comprising two or more polymerizable groups it can be preferable to cure only part of the disposed layer of the compound comprising two or more polymerizable groups. This is because this can leave uncured polymerizable groups available in the dielectric layer which may then react with the polymerizable groups of the disposed buffer compound at a later stage. As mentioned previously, the extent of curing may be measured using spectroscopy such as IR
  • spectroscopy In one embodiment, less than or equal to 90% of the polymerizable groups present in the layer of the compound comprising two or more polymerizable groups are cured.
  • the process for producing said layer of a polymeric material may be as described anywhere above for the process according to the invention, except that the composition comprising the buffer compound is replaced with a composition comprising a compound comprising two or more polymerizable groups.
  • the process of the invention for producing a buffered polymeric layer may further comprise, prior to disposing the composition comprising a buffer compound: disposing on a substrate under reduced pressure a composition comprising a compound comprising two or more polymerizable groups; and curing the composition disposed on the substrate.
  • Disposing on a substrate under reduced pressure may comprise disposing on a substrate at an absolute pressure of less than or equal to 100 mbar, or less than 0.1 mbar or any reduced pressure described above.
  • the main polymeric layer may be formed by exposing the substrate to a vapour comprising the compound comprising two or more polymerizable groups, again as described for the process of the invention using the buffer compound.
  • disposing on a substrate a layer of a compound comprising two or more polymerizable groups comprises disposing a composition comprising the compound comprising two or more polymerizable groups by vacuum flash evaporation.
  • Vacuum flash evaporation may be as described anywhere above.
  • the composition may be heated at a temperature of from 100°C to 300°C; curing the composition may comprise exposing the substrate to a curing source, which curing source is optionally selected from an electron beam curing source or a plasma curing source; the substrate may be a flexible substrate; and the substrate may be in transverse motion.
  • the method for forming the main polymeric layer is a roll-to-roll process.
  • the compound comprising two or more polymerizable groups is a compound suitable for forming a reliable main polymeric layer.
  • the compound comprising two or more polymerizable groups is suitable for forming a pinhole free polymeric layer.
  • the polymeric layer is typically a dielectric layer, for instance a polymeric dielectric layer.
  • the presence of two or more polymerizable groups allows extensive cross-linking which produces a robust layer.
  • the compound comprising two or more polymerizable groups is a compound of formula (IV):
  • each P 2 is independently a polymerizable group
  • D is a divalent organic moiety.
  • each P 2 is the same polymerizable group.
  • the P 1 group in the buffer compound is the same as each P 2 group in the compound comprising two or more polymerizable groups. This is preferable as it can promote effective bonding and cross-linking between the disposed buffer compound and the main dielectric layer to form a buffered dielectric layer.
  • the buffer compound is an acrylate compound
  • the compound comprising two or more polymerizable groups is preferably a diacrylate compound
  • the buffer compound is an epoxide compound
  • the compound comprising two or more polymerizable groups is preferably a compound comprising two or more epoxide groups.
  • P 2 may be as described anywhere above for P 1 .
  • each P 2 is independently a group comprising a carbon-carbon double bond, a carbon-carbon triple bond, or an epoxy group.
  • P 2 may be a group selected from an alkenyl group, a substituted or unsubstituted acrylate group, a substituted or unsubstituted alkylacrylate group, a substituted or unsubstituted acrylamide group, a substituted or unsubstituted alkyl aery 1 amide group, a vinyl ether group, an alkynyl group, an epoxy group, an acid anhydride group, a cinnamate group or a silane group.
  • Each of these groups may be as described above for P 1 in the buffer compound.
  • P 2 is preferably an unsubstituted or substituted acrylate group or an unsubstituted or substituted alkylacrylate group.
  • P 2 may be substituted or unsubstituted acrylate, substituted or unsubstituted methacrylate, substituted or unsubstituted ethylacrylate or substituted or unsubstituted propyl acrylate.
  • P 2 is a substituted or unsubstituted acrylate group or a substituted or unsubstituted alkylacrylate group.
  • D is typically a divalent organic moiety selected from an unsubstituted or substituted C 1-20 - alkylene group, an unsubstituted or substituted C 2-2 o-alkenylene group, and an unsubstituted or substituted C 2-2 o-alkynylene group, each of which may be optionally interrupted with one or more groups selected from -0-, -S- and -N(H)-.
  • D is a divalent organic moiety selected from an unsubstituted C 3 - i5-alkylene group optionally interrupted with from 1 to 10 - O- groups.
  • D may be a divalent organic moiety selected from an unsubstituted Cs-io-alkylene group optionally interrupted with from 1 to 5 -O- groups.
  • the compound comprising two or more polymerizable groups is preferably a compound of formula (V) or (VI):
  • each R 2 is independently selected from H and unsubstituted Ci-5-alkyl; n is an integer from 1 to 20; and
  • n is an integer from 1 to 10.
  • each R 2 is independently selected from H, methyl and ethyl; n is an integer from 2 to 10; and m is an integer from 2 to 5.
  • R 2 is often a group selected from H and methyl, n may be an integer from 4 to 10.
  • m may be an integer from 1 to 5.
  • the compound comprising two or more polymerizable groups may be a compound of formula (VIA):
  • each R 2 is independently selected from H and unsubstituted Ci-5-alkyl (for instance methyl); and m is an integer from 1 to 10.
  • HDDA hexanediol diacrylate
  • TPGDA tripropylene glycol diacrylate
  • the layer of a polymeric material typically has a thickness of from 50 nm to 1500 nm. Often, the layer of a polymeric material has a thickness of from 200 nm to 500 nm. For instance, the polymeric layer may have a thickness of from 300 nm to 400 nm.
  • the buffer compound may be disposed alone.
  • the composition comprising the buffer compound may comprise further compounds.
  • the composition may comprise said buffer compound and a compound comprising two or more polymerizable groups.
  • the composition may comprise greater than or equal to 60% by volume of the buffer compound or greater than or equal to 80% by volume of the buffer compound. For instance, the composition may comprise greater than or equal to 90% by volume of the buffer compound.
  • the composition may consist essentially of the buffer compound.
  • This composition comprising said buffer compound and a compound comprising two or more polymerizable groups may be disposed either onto a substrate comprising a layer of a main polymeric material as described above (which may be a layer of a main dielectric material), or directly onto a substrate which has not been pre-deposited upon with a layer of a main polymeric material.
  • the composition will comprise a large proportion (e.g.
  • the composition disposed on the substrate may comprise a greater portion (e.g. greater than or equal to 5 times by volume of the other components) of the buffer compound.
  • the substrate will comprise a layer of a polymeric dielectric material as described above.
  • the step (i) comprises disposing on a substrate under reduced pressure a composition comprising:
  • the compound comprising two or more polymerizable groups may be as defined anywhere above.
  • the compound comprising two or more polymerizable groups may be a compound of formula (IV), (V), (VI) or (VIA).
  • the compound comprising two or more polymerizable groups is a compound of formula (V), (VI) or (VIA).
  • the compound comprising two or more polymerizable groups may be HDDA or TPGDA.
  • the buffer compound and the compound comprising two or more polymerizable groups both comprise the same polymerizable groups, i.e. P 1 is the same as each P 2 .
  • the ratio (volume of the buffer compound disposed): (volume of the compound comprising two or more polymerizable groups disposed) is typically from 10: 1 to 1 : 10.
  • the ratio (volume of the buffer compound disposed): (volume of the compound comprising two or more polymerizable groups disposed) may be from 8: 1 to 1 :2.
  • the ratio (volume of the buffer compound disposed): (volume of the compound comprising two or more polymerizable groups disposed) is from 7: 1 to 3 : 1, or from 6: 1 to 4: 1.
  • the composition comprises a buffer compound which is an acrylate compound and a compound comprising two or more polymerizable groups which is a diacrylate compound, and the ratio by volume is from 6: 1 to 4: 1.
  • the T groups of the buffer compound orientate to the surface so as to form the buffer layer.
  • at least part of the buffer compound forms a monolayer at the surface of the disposed material.
  • at least part of the buffer compound forms a self assembled monolayer at the surface of the disposed material.
  • the process for producing a buffered polymeric layer comprises:
  • the substrate comprises a layer of a polymeric material, which layer of a polymeric material is obtainable by a process comprising
  • P 1 , T, P 2 and D may be as defined anywhere herein.
  • P 1 and each P 2 are the same.
  • P 1 and each P 2 may all be substituted or unsubstituted acrylate groups or substituted or unsubstituted alkylacrylate groups.
  • the process for producing a buffered polymeric layer comprises:
  • the substrate comprises a layer of a polymeric material, which layer of a polymeric material is obtainable by a process comprising
  • P 1 , T, P 2 and D may be as defined anywhere herein.
  • P 1 and each P 2 are the same.
  • P 1 and each P 2 may all be substituted or unsubstituted acrylate groups or substituted or unsubstituted alkylacrylate groups.
  • the process for producing a buffered polymeric layer comprises:
  • the substrate comprises a layer of a polymeric material
  • the process further comprises producing said layer of a polymeric material (prior to step (i)) by a process comprising
  • P 1 , T, P 2 and D may be as defined anywhere herein.
  • P 1 and each P 2 are the same.
  • P 1 and each P 2 may all be substituted or unsubstituted acrylate groups or substituted or unsubstituted alkylacrylate groups.
  • the process for producing a buffered polymeric layer comprises:
  • step (ii) curing the composition disposed on the substrate; wherein the substrate comprises a layer of a polymeric material, and wherein the process further comprises producing said layer of a polymeric material (prior to step (i)) by a process comprising
  • P 1 , T, P 2 and D may be as defined anywhere herein.
  • P 1 and each P 2 are the same.
  • P 1 and each P 2 may all be substituted or unsubstituted acrylate groups or substituted or unsubstituted alkylacrylate groups.
  • the process for producing a buffered polymeric layer often comprises:
  • composition comprising a buffer compound of Formula (IIA) as defined above and a compound comprising two or more polymerizable groups of Formula (V) or (VI) as defined above;
  • the substrate comprises a layer of a polymeric material, which layer of a dielectric material is obtainable by a process comprising
  • the process for producing a polymeric dielectric layer often comprises:
  • composition comprising a buffer compound of Formula (IIA) as defined above and a compound comprising two or more polymerizable groups of Formula (V) or (VI) as defined above;
  • the substrate comprises a layer of a polymeric material
  • the process further comprises producing said layer of a polymeric material (prior to step (i)) by a process comprising (1) disposing on a substrate a layer of a compound comprising two or more polymerizable groups of Formula (V) or (VI) as defined above; and
  • the invention also provides a buffered polymeric layer obtainable by a process comprising:
  • composition comprising a buffer compound, which buffer compound comprises:
  • the buffered polymeric layer is typically a buffered dielectric layer.
  • the buffered polymeric layer is typically suitable for a semiconductor device.
  • T is typically a non-polar group as defined herein.
  • the buffered polymeric layer and the process for producing a buffered polymeric layer may be as further defined hereinbefore.
  • the invention also provides a process for producing a device, which process comprises producing a buffered polymeric layer by:
  • composition comprising a buffer compound, which buffer compound comprises:
  • the buffered polymeric layer and the process for producing a buffered polymeric layer may be as further described anywhere hereinbefore.
  • the substrate may comprise a layer of a polymeric material.
  • the buffer compound may be any compound as described above, for instance an acrylate.
  • T is typically a non-polar group as defined herein.
  • the process is a process for producing a semiconductor device.
  • the substrate may comprise pre-deposited gate electrodes particularly if the buffered polymeric layer (typically a buffered dielectric layer) is intended for use in a transistor.
  • the substrate comprises an electrode material.
  • the substrate may comprise a uniform layer of an electrode material, or it may comprise a patterned layer of an electrode material.
  • the substrate comprises a pre- patterned layer of electrodes.
  • the electrode material may be any suitable conductive material.
  • the electrode material may be a material having an electrical conductivity of greater than or equal to 100 Sm "1 , or preferably greater than or equal to 1000 Sm "1 .
  • the electrode material has a
  • the electrode material is often selected from one or more metals, or from one or more inorganic compounds having a high conductivity, for instance transparent conducting oxides such as FTO, ITO or AZO.
  • the electrode material may comprise one or more metals selected from Groups 1 to 14 of the Periodic Table of the Elements.
  • the electrode material may comprise one or more metals selected from Groups 2 to 13 of the Periodic Table of the Elements.
  • the electrode material may comprise one or more metals selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Ta, W, Os, Ir, Pt, Au and Pb.
  • the electrode material comprises one or more metals selected from Al, Au, Pt, Ag, Rh, Fe, and Ni.
  • the electrode material comprises one or more of Al and Au.
  • the substrate may comprise pre-patterned electrodes which comprise one or more of Al and Au. Such electrodes may be gate electrodes.
  • the substrate may also comprise a layer of a flexible material such as a plastic, for instance PEN, PET or polycarbonate.
  • the substrate may also comprise a layer of a polymeric material.
  • the substrate may comprise the following in the following order: (i) a layer of a flexible substrate as defined anywhere herein, (ii) one or more electrodes and (iii) a layer of a polymeric material, for instance a polymeric dielectric material, as defined anywhere herein. If the substrate comprises a layer of a polymeric material, this layer of a polymeric material may be obtainable by a process for producing a layer of a polymeric material described herein.
  • the process when producing a device by a process according to the invention, also comprises a step of producing the main polymeric layer on the substrate.
  • the process often further comprises producing a layer of a polymeric material by a process comprising: (1) disposing on a substrate a layer of a compound comprising two or more polymerizable groups; and
  • the compound comprising two or more polymerizable groups may be a compound according to formula (IV), (V), (VI) or (VIA).
  • the process further comprises (iii) disposing on the buffered polymeric layer a layer of a semiconductor material.
  • the semiconductor material may be any semiconductor material suitable for a semiconductor device.
  • the semiconductor may be an intrinsic semiconductor, and n-type semiconductor or a p-type semiconductor.
  • the semiconductor may comprise an inorganic semiconductor or an organic semiconductor.
  • the semiconductor comprises an organic semiconductor.
  • the semiconductor material may consist essentially of an organic semiconductor.
  • the semiconductor may comprise a semiconductor selected from a perovskite, a metal oxide, a metal sulphide, a metal selenide, a metal telluride, silicon, a group IV semiconductor, a group III-V semiconductor, a group II- VI semiconductor, a group I- VII semiconductor, a group IV- VI semiconductor, a group V-VI semiconductor, a group II- V semiconductor, an organometallic compound and an organic semiconductor.
  • the semiconductor often comprises a polymeric or molecular organic semiconductor.
  • the semiconductor may be doped or undoped.
  • the semiconductor material may comprise an oxide of titanium, tin, zinc, niobium, tantalum, tungsten, indium, gallium, neodinium, palladium, or cadmium, or an oxide of a mixture of two or more of said metals.
  • the semiconductor may comprise Ti0 2 , Sn0 2 , ZnO, Nb 2 0 5 , Ta 2 0 5 , WO3, W 2 0 5 , ln 2 0 3 , Ga 2 0 3 , Nd 2 0 3 , PbO, or CdO.
  • the semiconductor may comprise a semiconductor selected from sulphides of cadmium, tin, copper, or zinc, including sulphides of a mixture of two or more of said metals.
  • the sulphide may be FeS 2 , CdS, ZnS or Cu 2 ZnSnS4.
  • the semiconductor material may, for instance, comprise a selenide of cadmium, zinc, indium, or gallium or a selenide of a mixture of two or more of said metals; or a telluride of cadmium, zinc, cadmium or tin, or a telluride of a mixture of two or more of said metals.
  • the selenide may be Cu(In,Ga)Se 2 .
  • the telluride is a telluride of cadmium, zinc, cadmium or tin.
  • the telluride may be CdTe.
  • the semiconductor may be a hole-transporting (i.e. a p-type) material.
  • the semiconductor may be a single p-type compound or elemental material, or a mixture of two or more p-type compounds or elemental materials, which may be undoped or doped with one or more dopant elements.
  • the p-type layer may comprise an inorganic or an organic p-type material.
  • Suitable p-type materials may be selected from polymeric and molecular hole transporters.
  • the semiconductor may comprise an organic semiconductor selected from unsubstituted or substituted rubrene, unsubstituted or substituted napthalene, unsubstituted or substituted anthracene, unsubstituted or substituted tetracene, unsubstituted or substituted perylene, unsubstituted or substituted diindenoperylene, unsubstituted or substituted pentacene, unsubstituted or substituted fluorene, unsubstituted or substituted fullerenes, unsubstituted or substituted tetracyanoquinodimethane, unsubstituted or substituted polythiophene, unsubstituted or substituted polyfluorene, unsubstituted or substituted polyalkynes, unsubstituted or substituted poly(2,5-thienylene vinylene), unsubstituted or substituted poly(p-phenylene vinylene), and a mixture of two
  • the semiconductor comprises an organic semiconductor selected from unsubstituted or substituted rubrene, unsubstituted or substituted napthalene, unsubstituted or substituted anthracene, unsubstituted or substituted tetracene, unsubstituted or substituted perylene, unsubstituted or substituted diindenoperylene, unsubstituted or substituted pentacene, and unsubstituted or substituted fluorene.
  • an organic semiconductor selected from unsubstituted or substituted rubrene, unsubstituted or substituted napthalene, unsubstituted or substituted anthracene, unsubstituted or substituted tetracene, unsubstituted or substituted perylene, unsubstituted or substituted diindenoperylene, unsubstituted or substituted pentacene, and unsubstituted or substituted fluorene.
  • the semiconductor comprises an organic semiconductor selected from unsubstituted or substituted napthalene, unsubstituted or substituted anthracene, unsubstituted or substituted tetracene, and unsubstituted or substituted pentacene.
  • the semiconductor may be selected from pentacene, m-MTDATA (4,4',4"- tris(methylphenylphenylamino)triphenylamine), MeOTPD (N,N,N',N'-tetrakis(4- methoxyphenyl)-benzidine), BP2T (5,5'-di(biphenyl-4-yl)-2,2'-bithiophene), Di- PB ( ⁇ , ⁇ 1 - Di-[(l-naphthyl)-N,N'-diphenyl]-l, 1 '-biphenyl)-4,4'-diamine), a- PB (N,N'-di(naphthalen-l- yl)-N,N'-diphenyl-benzidine), TNATA (4,4',4"-tris-(N-(naphthylen-2-yl)-N- phenylamine)triphenylamine), BPA
  • the semiconductor is an organic semiconductor selected from DNTT and substituted or unsubstituted pentacene.
  • the semiconductor material comprises an organic semiconductor compound, preferably wherein the semiconductor material comprises dinaphtho[2,3-£:2',3'- /]thieno[3,2-6]thiophene (DNTT).
  • the layer of a semiconductor material may have any thickness suitable for the semiconductor device.
  • the layer of a semiconductor material may be from 10 nm to 1000 nm.
  • the layer of a semiconductor material has a thickness of from 20 nm to 200 nm.
  • the process does not comprise a step of disposing a layer of a semiconductor material.
  • a device i.e. an article which comprises a substrate, an electrode, said buffered polymeric layer (typically a buffered dielectric layer) and optionally one or more source and drain electrodes.
  • a device may, for instance, be used for testing the buffered polymeric layer or as a component for use in the production of other devices.
  • the device produced by the process may comprise: a flexible substrate, one or more gate electrodes, said buffered polymeric layer (typically a buffered dielectric layer), one or more source electrodes and one or more drain electrodes.
  • the process further comprises disposing one or more electrodes onto the device (which may or may not comprise a layer of a semiconductor material).
  • the process may further comprise (iv) disposing one or more electrodes on the device. If a layer of a semiconductor material is present, the process may further comprise (iv) disposing on the layer of a semiconductor material one or more electrodes. If no layer of semiconductor material is present, the process may further comprise (iv) disposing on the buffered polymeric layer (typically a buffered dielectric layer) one or more electrodes.
  • the electrodes may be disposed by any suitable technique. For instance, the electrodes may be disposed by vacuum evaporation, optionally through a shadow mask.
  • the steps of disposing the layer of a semiconductor material and disposing the one or more electrodes may occur in either order.
  • the process for producing a device may comprise steps (i), (ii), (iii) and (iv) in that order, or steps (i), (ii), (iv) and (iii) in that order.
  • the process further comprises steps (1) and (2) of producing the main dielectric layer, the process may comprise steps (1), (2), (i), (ii), (iii) and (iv) in that order or steps (1), (2), (i), (ii), (iv) and (iii) in that order.
  • the process is a process for producing a device which does not comprise a layer of a semiconductor material, the process typically comprises the steps (1), (2), (i), (ii), and (iv) in that order.
  • the electrodes may be one or more source electrodes and one or more drain electrodes.
  • the one or more electrodes typically comprise one or more source electrodes and one or more drain electrodes.
  • the electrodes may comprise any suitable electrode material, such as those described above.
  • the one or more electrodes may comprise one or more of aluminium and gold.
  • the one or more electrodes comprise gold.
  • the semiconductor device may be any semiconductor device such as those described hereinbefore.
  • semiconductor devices include transistors, diodes, batteries, triodes, optoelectronic devices, light emitting diodes, and photovoltaic devices.
  • the semiconductor device is a transistor.
  • the transistor may be a bipolar junction transistor or a field effect transistor.
  • the semiconductor device is a field effect transistor (FET), for instance an organic field effect transistor (OFET).
  • FET field effect transistor
  • OFET organic field effect transistor
  • TFT thin-film transistor
  • the semiconductor device is preferably an organic thin film transistor.
  • the invention also provides a semiconductor device obtainable by a process for producing a semiconductor device as defined anywhere hereinbefore.
  • the invention also provides a device, which device comprises a buffered polymeric layer obtainable by a process comprising
  • composition comprising a buffer compound, which buffer compound comprises:
  • the process for producing the buffered polymeric layer may be as further defined anywhere hereinbefore.
  • the buffered polymeric layer may be a buffered polymeric layer suitable for a semiconductor device.
  • the device may have any device architecture. Often the semiconductor device comprises:
  • the device may comprise one or more additional layers.
  • the device may further comprise a layer of a semiconductor material.
  • the semiconductor device may comprise one or more additional layers of a semiconductor material. If the device further comprises a layer of a semiconductor material, the layer of a semiconductor material is typically situated between said buffered dielectric layer and said one or more source electrodes. Alternatively, the layer of the semiconductor material may be disposed on top of the one or more source electrodes and one or more drain electrodes.
  • the device comprises (i) a flexible substrate, (ii) one or more gate electrodes, (iii) said buffered polymeric layer, and (iv) one or more source electrodes and one or more drain electrodes.
  • any of the components of the semiconductor device may be as described anywhere hereinbefore.
  • the thickness of each of the components may be as follows: (i) from 100 nm to 1 mm; (ii) from 10 nm to 200 nm; (iii) from 100 nm to 500 nm; (iv) from 10 nm to 100 nm.
  • the layer of a semiconductor material may have a thickness of from 50 nm to 200 nm.
  • the substrate comprises one or more materials selected from paper, fabric, and one or more plastics; the one or more gate electrodes comprise one or more metals; the layer of a semiconductor material comprises an organic semiconductor compound; or the one or more source electrodes or one or more drain electrodes comprises one or more metals.
  • the substrate comprises one or more materials selected from paper, fabric, and one or more plastics; the one or more gate electrodes comprise one or more metals; the layer of a semiconductor material comprises an organic semiconductor compound; or the one or more source electrodes or one or more drain electrodes comprises one or more metals.
  • the substrate comprises one or more plastics selected from polyesters, polyalkenes, polyamides and polycarbonates; the one or more gate electrodes comprise one or more metals selected from gold, silver, copper and aluminium; the layer of a semiconductor material comprises dinaphtho[2,3-£:2',3'-/]thieno[3,2-£]thiophene (DNTT); or the one or more source electrodes or one or more drain electrodes comprises a metal selected from gold, silver, copper and aluminium.
  • plastics selected from polyesters, polyalkenes, polyamides and polycarbonates
  • the one or more gate electrodes comprise one or more metals selected from gold, silver, copper and aluminium
  • the layer of a semiconductor material comprises dinaphtho[2,3-£:2',3'-/]thieno[3,2-£]thiophene (DNTT)
  • DNTT dinaphtho[2,3-£:2',3'-/]thieno[3,2-£]thiophen
  • the device is a semiconductor device.
  • the semiconductor device is a transistor.
  • the semiconductor device is a field effect transistor.
  • the semiconductor device may be an organic thin-film transistor. The invention will be described by the following Examples.
  • Example 1 preparation of buffered dielectric layer by vacuum flash evaporation.
  • Buffered polymeric layers were prepared by the following process. Production of main dielectric layer by vacuum flash evaporation A TPGDA or HDDA dielectric layer was deposited by vacuum flash evaporation onto a PEN substrate which was pre-patterned with gold or aluminium electrodes. The substrate was attached to the coating drum. The TPGDA or HDDA monomer was injected into a hot tank heated to 260°C where it was vaporised. The vapour then entered the main coating chamber where it condensed onto the cool substrate attached to the rotating drum. The coated substrate then passed through an argon plasma generated by a DC magnetron source which cured the diacrylate monomer to form a solid dielectric polymer layer ( Figure 1).
  • the thicknesses of the main dielectric films were measured by a VeecoDektak 6M Stylus Profiler taking an average from at least three readings.
  • the thicknesses of the dielectric layers fabricated in this experiment were from 350 nm to 450 nm.
  • the parameters for the vacuum flash evaporation of the main dielectric layer were as follows: drum (web) width: 35cm; drum rotating speed: 25m/min (not R2R, multiple pass); monomer injection speed: 0.5 ml/min (or optionally greater); liquid monomer injection amount 0.7 ml to 0.8 ml; deposition time: 1 minute; resulting film thickness: 350-450 nm; tank temperature: 260°C; drum temperature: 17°C; chamber pressure: about 10 "4 mbar (for instance 10 "3 mbar to 10 "5 mbar); and curing source: argon plasma from a DC magnetic sputtering cathode.
  • a surface modification layer of lauryl acrylate (LA) mixed with HDDA was flash evaporated following the main dielectric film deposition process.
  • the lauryl acrylate/HDDA layer was cured by electron beam under a beam current of 100 raA ( Figure 2).
  • Other formulas were also used, including lauryl acrylate, hexyl acrylate, and hexyl acrylate together with HDDA. All of these buffer layers were more stable on acrylic (TPGDA or HDDA) substrate than on glass substrate.
  • the film can be wiped away by cotton tip if it is on glass but cannot be wiped away when deposited on an acrylic surface. This may demonstrate an extent of bonding between the buffer compound and the pre-deposited dielectric layer.
  • the parameters for the vacuum flash evaporation of the buffer layer were as follows: drum rotating speed: 3 m/min; liquid monomer injection: lml; monomer injection speed: 0.7 ml/min (or optionally greater); tank temp: 260°C; drum temp: 17°C; pressure: about 10 "4 mbar (for instance 10 "3 mbar to 10 "5 mbar); and curing source: electron gun with 100 raA current.
  • buffer layers were coated directly onto a microscopy slide surface before measurement with a MicroXAM 5000B 3d ADE Phase shift interference contrast optical profiler.
  • Example 2 measurement of surface energy of unbuffered and buffered dielectric layers.
  • the surface energies of the untreated (unbuffered) and the treated (buffered by vacuum flash evaporation process) surfaces were tested the second day after production by depositing droplets of deionised water on their surfaces.
  • the water contact angle was increased for surface treated by the vacuum evaporated buffer layer.
  • the surface contact angle for the buffered layer was 90°, whereas the unbuffered layer demonstrated a contact angle of 60° ( Figure 3).
  • the same test was performed a week later, with the same result observed, indicating that the surface energy change lasts a long time.
  • the surface roughness of the buffer layer was measured by atomic force microscopy (AFM), giving a roughness of 0.3 nm, which is better (flatter) than known surface coating layers.
  • AFM atomic force microscopy
  • Example 3 preparation of buffer layer by spin coating (comparative).
  • a 20 nm to 40 nm polystyrene buffer layer was also made as a comparative example by spin coating a 0.6 vol% toluene solution of polystyrene on the main dielectric surface with a spin speed of 3000 rpm for 30s.
  • the polystyrene buffer layer is a known buffer layer which may provide good performance for transistors.
  • the spin coated buffer layer was annealed at 70°C for 10 minutes to remove solvent. (The buffer layers produced by vacuum flash evaporation do not require annealing as no solvent is required in the deposition process.) Example 4 - completion of transistor construction.
  • a layer of dinaphtho[2,3-£:2',3'-/]thieno[3,2-£]thiophene (DNTT) semiconductor of thickness approximately 70 nm was deposited on top of the dielectric layers (buffered and unbuffered) by thermal evaporation in a Eurocoater thermal evaporator, at a deposition rate of 0.02 nms "1 .
  • the substrate was held at room temperature during deposition.
  • a 50 nm thick top gold contact source and drain layer was then deposited and patterned in an Edwards 306 thermal evaporation with a shadow mask.
  • the resulting device architecture is shown in Figure 4 and 5.
  • Example 5 evaluation of transistor characteristics and performance.
  • the transistors which had been produced were characterised using a pair of Keithley 2400 Source Measure Units. All measurements were carried in the dark at room temperature, following the code of standard IEEE Standard Test Methods for the Characterization of Organic Transistors and Materials.
  • the IV characterisation (transfer curves) plot for the transistor comprising an unbuffered HDDA dielectric layer is shown in Figure 6.
  • the IV characterisation (transfer curves) plot for the transistor comprising an HDDA dielectric layer buffered with a vacuum evaporated lauryl aery late/HDD A mixture is shown in Figure 7.
  • the IV characterisation (transfer curves) plot for the transistor comprising an HDDA dielectric layer buffered with a spin coated layer of polystyrene (PS) is shown in Figure 8.
  • the parameters for each of the three types of transistors produced namely (i) the comparative transistor comprising an unbuffered dielectric layer, (ii) the transistor according to the invention comprising a dielectric layer buffered with vacuum flash evaporated LA and HDDA, and (iii) the comparative transistor comprising a dielectric layer buffered with a spin coated PS layer, are shown in Table 1.
  • / S at ranged from 0.74cm 2 V “1 s “1 up to 1.14cm 2 V “1 s “1 , with an average of 0.97cm 2 V “1 s “1 for all working OTFT devices on the substrate.
  • Jon Joff ranged from 10 1 to 10 6 , with 36 of the transistors having an I Q JI Q s of 10 6 .
  • V ranged from -5V to -25V, the average being -11 V.
  • a number of the OTFTs displayed an unacceptably high IG in excess of 10% of IT,. This leads to higher 7 0 ff and a reduced Jon Joff.

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  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
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  • Microelectronics & Electronic Packaging (AREA)
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  • Thin Film Transistor (AREA)
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Abstract

La présente invention concerne la production de couches polymères tamponnées, par exemple, des couches diélectriques tamponnées. Plus précisément, l'invention concerne un procédé de fabrication d'une couche polymère tamponnée, ledit procédé comprenant les étapes consistant à : (i) disposer sur un substrat sous pression réduite une composition comprenant un composé tampon, ledit composé tampon composé comprenant : (a) un groupe polymérisable, P1, et (b) un groupe non polymérisable, T ; et (ii) sécher la composition disposée sur le substrat. L'invention concerne en outre un procédé de fabrication de dispositifs comprenant une couche polymère tamponnée. L'invention concerne de plus des couches polymères tamponnées et des dispositifs comprenant les couches polymères tamponnées. Les dispositifs selon l'invention peuvent être des dispositifs à semi-conducteur, par exemple des transistors.
PCT/GB2015/051329 2014-05-06 2015-05-06 Modification par dépôt sous vide de surfaces polymères WO2015170096A1 (fr)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017200705A1 (fr) * 2016-05-20 2017-11-23 ARES Materials, Inc. Substrat polymère pour la microfabrication d'électronique flexible et procédés d'utilisation
US10736212B2 (en) 2016-05-20 2020-08-04 Ares Materials Inc. Substrates for stretchable electronics and method of manufacture

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6433359B1 (en) * 2001-09-06 2002-08-13 3M Innovative Properties Company Surface modifying layers for organic thin film transistors
WO2010078414A2 (fr) * 2008-12-31 2010-07-08 3M Innovative Properties Company Procédé de fabrication d'un composant d'un dispositif, et composants et dispositifs résultants

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6433359B1 (en) * 2001-09-06 2002-08-13 3M Innovative Properties Company Surface modifying layers for organic thin film transistors
WO2010078414A2 (fr) * 2008-12-31 2010-07-08 3M Innovative Properties Company Procédé de fabrication d'un composant d'un dispositif, et composants et dispositifs résultants

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017200705A1 (fr) * 2016-05-20 2017-11-23 ARES Materials, Inc. Substrat polymère pour la microfabrication d'électronique flexible et procédés d'utilisation
US10615191B2 (en) 2016-05-20 2020-04-07 Ares Materials Inc. Polymer substrate for flexible electronics microfabrication and methods of use
US10736212B2 (en) 2016-05-20 2020-08-04 Ares Materials Inc. Substrates for stretchable electronics and method of manufacture

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