Sputtered protective layers for organic electronics

Abstract

The present invention provides an organic gate insulator (OGI) layer with a low dielectric constant (k), which is coated with a cross-linked organic layer (OSPL) with a relatively high dielectric constant (k). The present invention also provides an electronic device comprising such an organic thin film transistor. The present invention also provides a solution for preparing the OSPL, and a method for preparing the OSPL.

Description

Technical Field

[0001] The present invention relates to electronic devices including organic thin film transistors (OTFTs) comprising a solution-coatable, cross-linkable organic sputter protection layer (OSPL) in direct contact with a low dielectric constant organic gate insulator (OGI), wherein the OSPL is added to prevent sputtering damage to the OGI during transistor processing and to provide a transistor that retains its pre-plasma electrical performance specifications. Background Art

[0002] Thermal evaporation of metals is a common laboratory technique for depositing contact electrodes in test arrays of electronic devices. Typically, the source materials are resistively heated to the extent that they sublime and condense onto the substrate forming the film. Due to the lack of any gas inclusions (as in sputtering) and the high vacuum required for the process, heat transfer or physical damage to the substrate is minimal, and the resulting film is generally of high purity. In the case of very high purity metal films, such as in the manufacture of electrochemical or biosensors, and in the case where surface purity may affect performance, evaporation is preferred. These characteristics have prompted the use of evaporation as a research and development technique to deposit electrodes on polymer organic substrates without compromising their physical and chemical structure. However, due to poor uniformity over large areas and low production volumes, evaporation is difficult to scale up and is therefore not widely used in industrial manufacturing processes.

[0003] In the industrial manufacture of electronic devices including transistor arrays, manufacturers use plasma processes to deposit metal electrodes. This is due to the high throughput of the sputtering process and the fact that sputtering tools already exist on most electronic production lines. The effects of plasma-induced damage on low-k dielectric surfaces are known and reported by Bao et al., Mechanical study of plasma induced damage to low k dielectric surfaces; Journal of Vac. Sci. & Tech., B: Microelectronics and Nanometer structures, Processing Measurement, and Phenomena, 26, 219, 2008, doi: 101116 / 1.2834562. This is particularly problematic when amorphous polymer organic materials are used as layers directly exposed to plasma. This is due to the bombardment of ions, electrons, and ultraviolet photons generated during the plasma sputtering process, which can cause structural damage to the organic material. In addition, plasma-induced damage to amorphous perfluoropolymer layers was reported in the Journal of Photopolymer Sci & Technology; Vol. 27, No. 3, 2014, pp. 393-398 [1] , which points out that CF bonds are particularly susceptible to plasma damage. The energy of the generated deep ultraviolet photons is 11.6-11.8 eV, which is sufficient to cause Cytop TM The CC, CO, and CF bonds in the OSC / OGI are broken. These broken bonds may cross-link or recombine to form defects / dipoles and wells at or near the OSC / OGI interface.

[0004] In organic transistors, low-k dielectric materials such as amorphous perfluoropolymers are preferred organic gate insulator materials, especially when small molecule organic semiconductors (OSCs) are used in combination with polymer binders. Veres et al., Adv. Func. Mat; 2003, 13, No. 3, pp. 199-204 reported that the use of low dielectric constant OGI materials in OTFTs minimizes the interface capture between organic semiconductors and organic gate insulators (OGIs). This is due to the minimization of the amplitude modulation of random dipole moments, resulting in organic thin film transistors having near-ideal electrical properties.

[0005] Particularly preferred OGI materials for top-gate (TG) OTFTs include perfluorinated polymers such as Cytop TM 、Hyflon TM and TEFLON AF TMIn this case, the perfluoropolymer is the layer in the organic thin film transistor that is directly exposed to plasma sputtering (layer 5, Figure 3 ). When including Cytop TM When a top-gate OTFT with a material such as Cytop as a gate insulator is exposed to a plasma sputtering process, ultraviolet photons will TM The chemical properties of the layer cause irreversible damage. In OTFTs, this damage manifests itself as many undesirable electrical properties, including high threshold voltage (Vth), high turn-on voltage (Vto), high subthreshold swing (SS), high off current, low I 开 / 关 The importance of these electrical parameters is well known to those skilled in the art.

[0006] Fig.10 The deleterious effects of energetic particles generated by plasma sputtering on the performance of organic field-effect transistors doped with perfluoropolymer OGI were shown in FIG. Fig.10 It shows that when a top-gate TFT (TFTS-SKBL756) is fabricated without an OSPL on top of the OGI, the Vth value increases from 8.0 V to 16.4 V, the Vto increases from 11.8 V to 23.5 V, and the subthreshold swing increases from 1.3 V / decade to 2.4 V / decade, compared to the control TFT (SKBL808) made with an evaporated gate. Fig.11 It was demonstrated that TFTs with an in-situ OSPL layer before exposure to the sputtering process and deposition of the gate metal retained their pre-plasma electrical properties. The resulting higher operating voltage in turn resulted in devices with higher power consumption. TM In an argon plasma, it is damaged. Using the in-situ OSPL, the post-plasma values ​​of Vth, Vto, SS, Ion, Ioff, and Ion / off ratio show minimal changes (≤ 20% change).

[0007] WO2008 / 131836 describes a method of making an organic field effect transistor (OFET) incorporating a layer that minimizes damage to exposed portions of the surface of the dielectric layer. Prior to exposure to a plasma or sputtering process, a protective layer is deposited onto the OGI and optionally removed from the device. The patent discloses that the preferred protective layer is a perfluoropolymer such as Cytop TM (See page 14, lines 23-25 ​​and page 15, lines 1-5.) However, in direct contradiction to the teaching of WO2008 / 131836, we have found that Cytop TMIrreversibly damaged upon exposure to even low levels of low energy Ar plasma. In addition to UV generated particles, other high energy particles may be formed in a typical sputtering process, such as reflected Ar (17-25 eV and sputtered atoms (~10 eV). The energy of these particles is sufficient to break CC (~3.7 eV), CO (~3.5 eV), and CF bonds (~5 eV) within the organic layer.

[0008] Cytop TM and perfluorinated polymers as a class of materials are not protected against sputtering damage and therefore should not be used as protective layers in OTFTs.

[0009] One of the problems solved by the present invention is how to uniformly apply the OSPL ink solution to low surface energy OGI materials (e.g., CYTOP with a surface free energy of only 14-18 mN / m). TM ) without using a surface pre-treatment process such as plasma or chemical etching of the OGI to increase its surface energy. In the case of OTFTs, plasma or chemical treatments will irreversibly damage the OGI and render the OTFT ineffective. WO2008 / 131836 does not provide any teaching on how to achieve uniform solution coating on a perfluoropolymer, and our invention solves this industrially relevant technical problem. In addition, in a TG OTFT such as the present invention, if the same material is coated as an OSPL solution on an amorphous perfluoropolymer OGI, it will simply re-dissolve the OGI. The teachings in WO2008 / 131836 are not applicable to TG devices. Another major difference of the present invention compared to WO2008 / 131836 is the need for an OSPL with a higher dielectric constant than OGI in order to have a higher capacitance in the TFT channel as described above. WO2008 / 131836 prefers low dielectric constant OGI and low dielectric constant OSPL. Summary of the invention

[0010] In a first aspect, the present invention provides an organic gate insulator (OGI) layer having a dielectric constant (k) <3.0@1000 Hz, the organic gate insulator layer being over-coated with a cross-linked organic layer (OSPL).

[0011] Preferably, the dielectric constant (k) of the cross-linked organic layer is >3.3@1000 Hz, more preferably, the k of the cross-linked organic layer at 1000 Hz is >4.0.

[0012] In a second aspect of the present invention, there is provided an organic thin film transistor comprising a substrate, one or more source / drain electrodes, at least one gate electrode, an organic semiconductor layer, and an organic gate insulator layer comprising a dielectric material having a dielectric constant (k) < 3.0 @ 1000 Hz, the organic gate insulator layer being overcoated with a crosslinked organic layer. Preferably, the crosslinked organic layer has a dielectric constant (k) > 3.3 @ 1000 Hz, and more preferably, the k of the crosslinked organic layer at 1000 Hz is > 4.0.

[0013] In a third aspect of the present invention, there is provided an electronic device comprising an organic thin film transistor according to the second aspect of the present invention.

[0014] In a fourth aspect of the present invention, there is provided a solution comprising (a) at least one polyfunctional acrylate, (b) optionally a non-acrylate organic solvent, (c) a fluoropolymer surfactant and an acrylate and / or methacrylate functionalized organosilicon surfactant, and (d) at least one type of photoinitiator. This solution is commonly referred to as an ink in the art.

[0015] In a fifth aspect of the present invention, there is provided a method for depositing a crosslinkable organic layer solution on a low surface energy organic gate insulator, wherein the solution comprises at least one fluorosurfactant and at least one acrylate and / or methacrylate functionalized organosilicon surfactant. In this method, a crosslinked organic layer (OSPL) is formed from the solution according to the fourth aspect of the present invention. The method preferably provides a continuous, defect-free organic layer, and then crosslinks the organic crosslinkable layer. This aspect of the present invention enables effective overcoating of low surface energy OGI, especially fluoropolymers. The developed method avoids the need for aggressive chemical or plasma etching of the fluoropolymer surface prior to ink deposition; neither etching is desirable when manufacturing organic thin film transistors.

[0016] The fluorosurfactants used in the present invention are synthetic organic fluorine compounds having multiple fluorine atoms. They can be polyfluorinated or perfluorocarbon-based (fully fluorinated). As surfactants, they are more effective than comparable hydrocarbon surfactants in reducing the surface tension of water. Preferably, they have a fluorinated "tail" and a hydrophilic "head".

[0017] The crosslinkable organic layer has excellent curing characteristics in air or nitrogen, and preferably is capable of forming a substantially flat cured layer on the surface of the substrate having excellent hardness, high plasma resistance, excellent thermal durability, and high tensile strength.

[0018] In all aspects of the invention, the cross-linked organic layer is referred to as an organic sputtered protective layer (OSPL). Preferably, it is coated directly onto a low-k (dielectric constant) organic gate insulator (OGI) layer to minimize damage to the OGI by the sputtering / plasma process.

[0019] As used herein, OGI means organic gate insulator

[0020] As used herein, TG means top gate

[0021] As used herein, BG means bottom gate

[0022] As used herein, OTFT means organic thin film transistor

[0023] As used herein, OSC means organic semiconductor

[0024] Specifically, OSPL preferably has a high crosslink density of ≥3H pencil hardness and is preferably exposed to 2.4 J / cm at a wavelength of 365 nm. 2 >70% conversion (by FTIR) is achieved when the molten-salt silica is used (this provides high resistance to plasma-induced damage, high resistance to chemical damage, high thermal durability and high tensile strength).

[0025] OSPL also reduces the delamination of the low-k OGI layer from the underlying interface that could occur.

[0026] It is also possible to overcoat one OSPL with a second OSPL. Essentially, the first OSPL can serve as a primer for a second OSLP, which can have the same or different properties as the first OSPL. In this way, an OGI can build up multiple OSPL layers on its surface.

[0027] The cross-linkable OSPL may be cured chemically, thermally or photochemically. The pencil hardness of the cross-linked OSPL is preferably between 2H and 6H, preferably between 3H and 6H, measured using ASTM-D3363.

[0028] The present invention also enables overcoating of any low surface energy polymer layer. According to all aspects of the present invention, the surface free energy (SFE) of the OGI layer is ≤ 25 mN / m, preferably less than 20 mN / m, more preferably less than 15 mN / m. The method avoids the need to use aggressive chemical or plasma etching pre-treatments of the low surface energy organic gate insulator prior to OSPL deposition, both of which are undesirable when manufacturing thin film transistors due to ion doping of the OTFT.

[0029] According to a preferred embodiment of the fourth aspect of the present invention, the surface tension of the OSPL ink is 18 to 35 mN / m, more preferably 21 to 28 mN / m. The relatively low surface tension of the OSPL ink enables wetting of the OGI. This is preferably achieved by using a combination of a fluorosurfactant and a silicone surfactant. Preferably, the fluorosurfactant is a perfluorosurfactant. Preferably, the silicone surfactant is an silicone surfactant having an acrylate or methacrylate functional group. Examples of such silicone surfactants are described in EP1828813. Alternatively, such silicone surfactants are preferably polydimethylsiloxane or polytrimethylsiloxane polymers modified with one or more acrylate and / or methacrylate functional groups. Such silicone polymers preferably also contain a hydrophilic portion, such as a phosphate or sulfate portion. For example, preferred polymers include Dowsil TM fa 4103 silicone acrylates which are acrylates / polytrimethylsiloxymethacrylate copolymer (and) laureth-1 phosphate copolymer. Other preferred silicone surfactants include Silmer ACR D208, Silmer ACR Di-50, Silmer ACR Di-1508, Silmer ACR Di-2510, Silmer ACR Di-4515-O and Silmer ACR Di-10 available from Siltech.

[0030] It is hypothesized that the reason this combination works is because the fluorosurfactant migrates to the OGI interface, while the silicone surfactant crosslinks into the bulk of the OSPL layer.

[0031] Fluorinated surfactants for use in the present invention include perfluoro oligomers and perfluoro polymers. Examples of fluorinated surfactants suitable for use include F(CF2) n - linear fluorinated functional groups, wherein n = 3 to 50. Such surfactants are sold under the trade names CAPSTONE, MEGAFACE or FC-4332, and are sold by 3M under the Novec trade name. In particular, MEGAFACE F-563 from DIC is preferred.

[0032] The present invention aims to protect OGI from plasma-induced damage by providing a highly cross-linked OSPL coated directly on OGI. This, in turn, enables the OTFT array to maintain its pre-sputtering / plasma electronic properties, such as low threshold voltage values ​​(preferably AVth < 2V@Vg volts after plasma (measured in the linear region), low turn-on voltage (preferably Vto < 3V after plasma), low off current (preferably < 10 -10 A), low subthreshold swing value change (preferably ΔSS < 0.5V after plasma) and high I 开 / 关 Ratio (preferably ≥10 6 ). Benefits include OTFTs with lower threshold voltage values, lower turn-on voltages, improved subthreshold swings, higher on-currents, lower off-currents, and high on / off ratios, all of which can improve drive capability. Lower off-currents reduce leakage current (and, with it, off-state power consumption). Low Vth is required to reduce the gate voltage required to keep the OTFT in the off-state. Low Vth combined with low subthreshold swings reduces power consumption and increases the switching speed of the device.

[0033] The OSPL of the present invention preferably has a higher dielectric constant than OGI. For example, the dielectric constant (k) of the OGI material is <3.0@1000Hz, preferably <2.5@1000Hz. The OSPL preferably has a higher dielectric constant than the OGI layer, typically >1 unit higher than OGI. The dielectric constant (k) of the OSPL is >3.3@1000Hz, preferably >3.5@1000Hz, preferably >4.0@1000Hz. This higher dielectric constant is provided by the polar, multifunctional acrylate component of the OSPL ink (discussed in detail below). This feature can be advantageously used to increase the total capacitance of the OGI / OSPL layer in the active channel region of the transistor. Higher gate capacitance is required to reduce the device operating voltage. However, this is best achieved by increasing the dielectric constant rather than reducing the thickness of the OGI to prevent dielectric breakdown. The bilayer formed by the low-k OGI and the higher-k OSPL has a higher effective dielectric constant than OGI, thereby increasing capacitance and maintaining dielectric integrity, while retaining the benefits of having a low-k insulator in direct contact with the OSC as described above. The sputtered protective layer remains in place in the OSC / OGI channel region of the OTFT throughout the lifetime of the device and is not removed.

[0034] The OSPL preferably has a lower dielectric constant than the OSC layer.

[0035] In a particularly preferred embodiment, the OTFT of the present invention may comprise more than one OSPL in the OTFT stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 :Curing conversion curve of OSPL-1

[0037] Figure 2 :Curing conversion curve of OSPL-2

[0038] Figure 3: TGBC (top gate, bottom contact TFT) with high dielectric constant OSPL, explanation of symbols: 1a substrate; 1b base layer; 2 electrodes (source and drain); 3 electrode surface treatment / SAM; 4 organic semiconductor layer (OSC); 5 insulator (OGI); 6 protective layer (OSPL); 7 gate electrode.

[0039] Figure 4 : TGTC (top gate, top contact TFT) with high dielectric constant OSPL, symbol explanation: 1a substrate; 1b base layer; 2 electrodes (source and drain); 3 electrode surface treatment / SAM; 4 organic semiconductor layer (OSC); 5 insulator (OGI); 6 protective layer (OSPL); 7 gate electrode.

[0040] Figure 5 : TGBC (top gate bottom contact TFT) with OSPL (6), base layer (1b), passivation layer (8) and metal interconnection (9), symbol explanation: 1a substrate; 1b base layer; 2 electrodes (source and drain); 3 electrode surface treatment / SAM; 4 organic semiconductor layer (OSC); 5 insulator (OGI); 6 protective layer (OSPL); 7 gate electrode; 8 passivation layer; 9 metal interconnection.

[0041] Figure 6 : TGBC (top gate bottom contact TFT) having two OSPL layers 6a and 6b, a base layer (1b), a passivation layer (8) and a metal interconnection (9), explanation of symbols: 1a substrate; 1b base layer; 2 electrodes (source and drain); 3 electrode surface treatment / SAM; 4 organic semiconductor layer (OSC); 5 insulator (OGI); 6a protective layer 1 (OSPL-1); 6b protective layer 2 (OSPL-2); 7 gate electrode; 8 passivation layer; 9 metal interconnection.

[0042] Figure 7 :SmartKem vertical TFT with high dielectric constant OSPL, symbol explanation: 1a substrate; 1b base layer; 2a electrode (source or drain); 2b electrode (source or drain); 3 electrode surface treatment / SAM; 4 organic semiconductor layer (OSC); 5 insulator (OGI); 6a protective layer 1 (OSPL-1); 6b protective layer 2 (OSPL-2); 7 gate electrode.

[0043] Figure 8 : Linear transfer and mobility plots of the OTFT array SKBL748 with 120nm OGI / 200nm OSPL and 50nm evaporated Au gate.

[0044] Fig. 9 : Linear transfer and mobility plots of OTFT device SKBL755 with 120nm OGI / 200nm OSPL and 50nm sputtered Au gate.

[0045] Fig.10 : Linear transfer and mobility plots of OTFT devices without OSPL layer. SKBL808 has 50nm evaporated Au gate and SKBL756 has sputtered 50nm Au gate.

[0046] Fig.11 : Linear transfer and mobility plots of devices with 120nm OGI / 200nm OSPL1. SKBL748 has evaporated Au gate and SKBL755 has sputtered Au gate. DETAILED DESCRIPTION

[0047] Preferably, the organic gate insulator (OGI) layer comprises a low dielectric constant polymer, such as a perfluoropolymer, having a dielectric constant (k) <3.0 @ 1000 Hz. As used herein, low k means a dielectric constant less than 3.0, preferably less than 2.8, preferably less than 2.5 when measured at 1000 Hz. Preferably, the dielectric constant of the low dielectric constant (k) polymer is in the range of 1.0 to 3.0. In the present invention, high dielectric constant means >3.3, more preferably >3.5, more preferably >4.0 @ 1000 Hz.

[0048] Preferably, the dielectric constant (k) of the OSPL is >3.3@1000 Hz, preferably k>3.5 at 1000 Hz, more preferably >4.0. If more than one OSPL is present, they may have different dielectric constants from each other. This may be affected by their relative chemical composition.

[0049] Some examples of low dielectric constant polymers preferably include perfluoropolymers, benzocyclobutene polymers (BCB), polyparaxylene, polyvinylidene fluoride (PVDF) polymers, cyclic olefin copolymers (e.g., norbornene, TOPAS TM ) polymers, adamantyl polymers, perfluorocyclobutylene polymers (PFCB), polymethylsiloxane (PDMS) and mixtures thereof.

[0050] The cross-linkable OSPL is coated on top of the OGI using any solution coating technique, preferably including spin coating, spray coating, slot-die coating, inkjet printing. The OSPL is cross-linked to provide a continuous layer.

[0051] Preferably, the perfluoropolymer OGI is selected from Cytop TM 、Hyflon TM and TEFLON AF TM These perfluorinated polymers have the structures shown below.

[0052]

[0053] wherein * represents the point of attachment of the repeat unit to the rest of the polymer and n is an integer (n is an integer commonly used for perfluoropolymers of this type).

[0054] In one embodiment, Cytop represents a homopolymer of the monomer on the left side of the structure above. Thus, for the Cytop example given above, preferably m=1 and n=0.

[0055] Preferred amorphous perfluorinated polymers are available from Du Pont ( AF), Asahi Glass (as ) and Solvay (as AD).

[0056] AF and AD is a copolymer of 2,2-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxole (I) and 2,2-bis(trifluoromethyl)-4-fluoro-5-trifluoromethoxy-1,3-dioxole (II) with tetrafluoroethylene.

[0057] 809M is the most preferred OGI material for use in the present invention.

[0058] These materials are commercially available and their preparation is well known in the art.

[0059] The organic gate insulator (OGI) layer can be completely protected from sputtering damage by the present invention, and the resulting OTFT maintains its electrical characteristics before sputtering.

[0060] The crosslinked protective organic layer of the present invention is preferably a free radical photocured crosslinked layer.

[0061] Preferably, the thickness of the OSPL layer is 10-1000nm, more preferably 10-250nm, and most preferably 100-500nm. The thickness of the OSPL layer required depends on the energy and duration of the plasma process used to deposit the gate metal. The higher the plasma energy, or the longer the exposure time, the thicker the OSPL layer is required to provide protection from sputtering damage. For example, sputtering deposition of gold gate metal (about 100nm thick) requires an OSPL thickness of only 100-250nm. The sputtering yield of noble metals such as Au or Ag is 2-3 times higher than that of Al or Mo. Therefore, in order to provide the same level of protection, a thicker OSPL layer (~400-500nm) is required when depositing metals such as Al or Mo.

[0062] The OSPL is preferably obtained by polymerizing an ink composition containing at least one polyfunctional acrylate. The polyfunctional acrylate should preferably be capable of crosslinking with other components of the ink.

[0063] The OSPL is preferably obtained by coating the ink composition solution onto the OGI.

[0064] The crosslinking density of the OSPL is preferably 3 to 6H pencil hardness.

[0065] Preferably, the polyfunctional acrylate contains a nitrogen-containing nucleus having at least two acrylate side group moieties.

[0066] The OSPL is preferably obtained by polymerizing an ink composition comprising (a1) a first polyfunctional acrylate compound containing a nitrogen-containing nucleus having at least two acrylate side group moieties, and (a2) a second polyfunctional acrylate compound having an oxyalkane or polyoxyalkane nucleus.

[0067] Both components (a1) and (a2) are preferably not silicone-based and are preferably not surfactants.

[0068] Preferably, the polyfunctional acrylate compound (a1) contains at least two (acryloyloxy)ethyl side group moieties, preferably three (acryloyloxy)ethyl side group moieties. The polyfunctional acrylate compound may have up to six acrylate moieties.

[0069] Preferably, the polyfunctional acrylate compound (a1) of the OSPL contains a nitrogen-containing nucleus having at least two acrylate side group moieties, and more preferably is an isocyanurate nucleus having at least two acrylate groups, preferably at least two (acryloyloxy)ethyl moieties, preferably three (acryloyloxy)ethyl moieties.

[0070] Specific preferred examples of the polyfunctional acrylate compound (a1) of the OSPL are isocyanurate compounds selected from tris(2-hydroxyethyl)isocyanurate triacrylate, Photomer 5662 amine-modified polyether acrylate, Photomer 5930 amine-modified polyether acrylate, Sartomer CN550, and Sartomer CN503.

[0071] Preferably, the polyfunctional acrylate compound (a1) of the OSPL is tris[2-(acryloyloxy)ethyl]isocyanurate, which has the following structure:

[0072]

[0073] The polyfunctional acrylate compound (a1) of the OSPL provides the crosslinking density required for the cured layer. This component preferably has a high Tg, which imparts hardness to the layer.

[0074] The multifunctional acrylate monomer compound (a2) is used to provide fast curing and impart hardness and chemical resistance to the OSPL layer coating.

[0075] Preferably, the highly reactive monomer (a2) is a multifunctional acrylate compound having an oxy- or polyoxy-alkane core and at least two acrylate groups. 2-24 Alkanes or polyoxy-C 2-24 Alkane core, such as polyoxy-C 4-12 Some examples of (a2) acrylates include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate (DiTMPTA), dipentaerythritol hexaacrylate, pentaerythritol tetraacrylate, polyester hexaacrylate, dipentaerythritol hexaacrylate (DPHA), and multifunctional acrylate oligomers, such as Photomer 5434 polyester tetraacrylate, Photomer 5443 polyester hexaacrylate, Photomer 5050 multifunctional acrylate, Photomer 6628 aliphatic urethane hexaacrylate, Photomer 6692 aliphatic urethane hexaacrylate, and cresol novolac epoxy acrylate.

[0076] Preferably, monomer (a2) comprises a polyoxy-C having at least two pendant acrylate moieties, preferably three pendant acrylate moieties. 4-12 Preferably, monomer (a2) comprises a polyoxy-C having three acrylate side groups. 4-12 Alkane core. Monomer (a2) may have up to six acrylate moieties.

[0077] Preferably, the multifunctional acrylate monomer (a2) comprises (is) trimethylolpropane triacrylate.

[0078] Preferably, the multifunctional acrylate monomer (a2) is highly reactive so as to enable rapid curing of the OSPL in both surface curing and bulk curing.

[0079] The combination of monomers (a1) and (a2) enables a high degree of crosslinking.

[0080] Furthermore, it is preferred that the OSPL ink also comprises a relatively high viscosity component so that once it is applied to the OGI, the higher viscosity prevents the wet film from reticulating from the OGI surface.

[0081] Preferably, after evaporation of the solvent from the OSPL ink, the viscosity of the pre-cured OSPL layer should be >2000 cPs to prevent reticulation from the OGI surface. Therefore, preferably, the ink composition comprises a multifunctional acrylate oligomer having a viscosity >3000 MPa.S. The multifunctional acrylate oligomer optionally comprises a bisphenol acrylate oligomer.

[0082] The OSPL is preferably obtainable by polymerizing the composition according to the fourth aspect of the invention. In a preferred embodiment, the ink comprises monomers (a1) and (a2) as defined above. The non-acrylate solvent (b) may be used to adjust the viscosity of the composition during the preparation process or in the coating operation, or to improve wettability relative to the substrate to be coated.

[0083] Examples of the solvent (b) include aromatic hydrocarbons such as benzene, toluene, xylene, cumene, ethylbenzene, aliphatic hydrocarbons such as hexane, heptane, octane, petroleum ether, light petroleum, cyclohexane and methylcyclohexane; halogenated hydrocarbons such as chlorobenzene and bromobenzene; alcohols such as methanol, ethanol, isopropanol, butanol, pentanol, hexanol, cyclopentanol, cyclohexanol, ethylene glycol, propylene glycol, propylene carbonate, glycerol, ethylene glycol monomethyl ether and diethylene glycol; ketones such as acetone, methyl ethyl Ketone, methyl isobutyl ketone and cyclohexanone; ethers such as ethyl ether, dipropyl ether, butyl ethyl ether, dibutyl ether, ethylene glycol, propylene carbonate, dimethyl ether and diethylene glycol dimethyl ether; nitriles such as acetonitrile, propionitrile and capronitrile; and esters such as methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isobutyl acetate, butyl acetate, amyl acetate, methyl benzoate, ethyl benzoate, and lactones such as gamma-butyrolactone. Preferably, the organic solvent comprises ethyl lactate or consists of ethyl lactate.

[0084] The OSPL is preferably obtainable by polymerizing the composition according to the fourth aspect of the invention.

[0085] The photocuring mechanism should not result in the presence of ionic contaminants in the OTFT device. This means that photoresist materials containing photogenerated acids are not preferred.

[0086] The specific acrylate component of the OSPL is selected to be orthogonal to the underlying OGI layer, imparting fast cure speeds, providing excellent depth of cure and surface cure, and most importantly, providing high crosslink density. Crosslink density is believed to be related to resistance to sputtering damage.

[0087] The organic semiconductor layer used in the present invention preferably comprises at least one semiconductor ink. Preferably, the ink comprises a small molecule polyacene and / or polytriarylamine binder formulation. Preferred semiconductive inks include those disclosed in WO2010 / 0020329, WO2012 / 003918, WO2012 / 164282, WO2013 / 000531, WO2013 / 124682, WO2013 / 124683, WO2013 / 124684, WO2013 / 124685, WO2013 / 124686, WO2013 / 124687, WO2013 / 124688 13 / 124688, WO2013 / 159863, WO2014 / 083328, WO2015 / 028768, WO2015 / 058827, WO2014 / 005667, WO2012 / 160383, WO2012 / 160382, WO2016 / 015804, WO2017 / 0141317, WO2018 / 078080.

[0088] Other OSC materials useful in the present invention include discrete compounds, oligomers and derivatives of the following compounds: conjugated hydrocarbon polymers such as polyacenes, polyphenylenes, poly(phenylene vinylenes), polyfluorenes, including oligomers of those conjugated hydrocarbon polymers; condensed aromatic hydrocarbons such as tetracene, , pentacene, pyrene, perylene, hexabenzophenone, diketopyrrolopyrrole, substituted benzothiophene benzothiophene (C8-BTBT), dinaphthothiophene thiophene (DNTT) or substituted derivatives thereof; oligomeric para-substituted phenylenes, such as p-quaterphenyl (p-4P), p-pentaphenyl (p-5P), p-hexylene (p-6P) or soluble substituted derivatives thereof; conjugated heterocyclic polymers, such as poly (3-substituted thiophene), poly (3,4-disubstituted thiophene), polybenzothiophene, polyisothiophene, poly ([λ ] / -substituted pyrrole), poly(3-substituted pyrrole), poly(3,4-disubstituted pyrrole), polyfuran, polypyridine, poly-1,3,4-oxadiazole, polyisothionaphthene, poly([λ] / -substituted aniline), poly(2-substituted aniline), poly(3-substituted aniline), poly(2,3-disubstituted aniline), polyazulene, polypyrene; pyrazoline compounds; polyselenophene; polybenzofuran; polyindole; polypyridazine; benzidine compounds; stilbene compounds; triazine; substituted metal porphine or metal-free porphine, phthalocyanine, fluorophthalocyanine, naphthalocyanine, naphthalene diimide or fluoronaphthalocyanine; C60 and C70 fullerenes; A / .[λ] / '-dialkyl, substituted dialkyl, diaryl or substituted diaryl-1,4,5,8-naphthalenetetracarboxylic acid diimides and fluorine derivatives; [λ] / , [λ] / '-dialkyl, substituted dialkyl, diaryl or substituted diaryl 3,4,9,10-perylenetetracarboxylic acid diimides; bathophenanthroline; diphenoquinone (diphenoquinone); 1,3,4-oxadiazole; 11,11,12,12-tetracyanonaphthalene-2,6-quinolinodimethane; [α],[α]′-bis(dithieno[3,2-b2′,3′-d]thiophene); dithieno[2,3-d;2',3'-d']benzo[1,2-b;4,5-b']dithiophene (DTBDT); polydithienobenzodithiophene-co-diketopyrrolopyrrolothiophene (PDPDBD); isoindigo-thiophene-(II DDT-C3), thieno[3,2-b]thiophene-5-fluorobenzo[c][1,2,5]thiadiazole copolymer, di(thiophene-2-yl)thieno[3,2-b]thiophene (DTTT); 2,8-dialkyl, substituted dialkyl, diaryl or substituted diaryl anthracene dithiophene (anthradithiophene); 2,2'-dibenzo[1,2-b:4,5-b'-dithiophene, benzothiophene and benzothiophene (BTBT) polymers, benzodithiazole polymers and mixtures thereof.

[0089] Preferred compounds are those listed above and their soluble derivatives.

[0090] The OSPL is preferably prepared from the composition of the fourth aspect of the invention, comprising: (a1) one or more multifunctional acrylate compounds; (a2) a highly reactive monomer; (b) an organic solvent; (c) a fluoropolymer surfactant and an acrylate and / or methacrylate functionalized silicone surfactant, and (d) at least one photoinitiator.

[0091] The amount of multifunctional acrylate (a1) and optionally (a2) in the final layer is preferably 10-99% by weight, more preferably 20-99% by weight of the final OSPL.

[0092] The organic solvent (b) is preferably substantially removed from the final OSPL, and thus, it is preferably maintained at less than 0.5 wt. % of the final OSPL.

[0093] Typically, the amount of initiator (d) used in the polymerizable composition is from about 0.01 to about 25 weight percent, preferably from about 5 to about 20 weight percent, and most preferably from about 8 to about 15 weight percent of the polymerizable composition.

[0094] Preferably, the thin film transistor of the second aspect of the present invention is a top gate device. The device of the second aspect of the present invention preferably has improved electrical characteristics (low Vth, low Vto, low SS, low Ioff and high Ion / off ratio). It also optionally includes one or more of a planarization layer and a self-assembled monolayer. Such a device is Figure 1 shown.

[0095] The OSPL is preferably obtainable by polymerizing a composition comprising:

[0096] (a) a multifunctional acrylate compound;

[0097] (b) non-acrylate organic solvents;

[0098] (c) a surfactant composition comprising a fluoropolymer surfactant and an acrylate and / or methacrylate functionalized silicone surfactant;

[0099] (d) at least one photoinitiator; and

[0100] (e) Optionally acrylate-functionalized oligomers.

[0101] The OSPL is preferably obtainable by polymerizing a composition comprising:

[0102] (a1) a multifunctional acrylate compound having a nitrogen-containing cyclic core and at least two pendant acrylate moieties;

[0103] (a2) monomers having a polyacrylate monomer having an oxy or polyoxy alkane core and at least two pendant acrylate moieties;

[0104] (b) non-acrylate organic solvents;

[0105] (c) a surfactant composition comprising a fluoropolymer surfactant and an acrylate and / or methacrylate functionalized silicone surfactant;

[0106] (d) at least one photoinitiator; and

[0107] (e) Optionally acrylate-functionalized oligomers.

[0108] The OSPL is preferably obtainable by polymerizing a composition comprising:

[0109] (a1) 100 parts by weight of a multifunctional acrylate compound having a nitrogen-containing cyclic core and at least two pendant acrylate moieties;

[0110] (a2) 5 to 1000 parts by weight of a polyacrylate monomer having a polyoxyalkylene core and at least two side acrylate moieties;

[0111] (b) 1 to 10,000 parts by weight of an organic solvent per 100 parts by weight of components (a1) and (a2) combined;

[0112] (c) per 100 parts by weight of components (a1) and (a2) combined, 0.01 to 20 parts by weight of a surfactant composition comprising a fluoropolymer surfactant and an acrylate and / or methacrylate functionalized silicone surfactant; and

[0113] (d) 0.01 to 20 parts by weight of at least one photoinitiator per 100 parts by weight of components (a1) and (a2) combined.

[0114] Preferably, the initiator compound (d) is selected from an amine-based initiator, a thioxanone-based initiator, and a combination thereof. Preferably, the initiator compound (d) comprises a benzoate compound, a substituted thioxanone compound, or a combination thereof, preferably a combination of ethyl 4-(diamino)benzoate and diethylthioxanone, or a combination of ethyl 4-(diamino)benzoate and isopropylthioxanone.

[0115] Examples of effective OSPL formulations are included in Tables 1, 2, and 3:

[0116]

[0117]

[0118]

[0119] For cost and ease of manufacturing, it is desirable to coat the OSPL solution onto the gate insulator, with some suitable coating techniques including but not limited to spin coating, slot die coating or ink jet printing. However, the very low surface free energy of perfluoropolymers (11-20< dynes / cm) means that it is preferred to modify the surface tension of the OSPL ink formulation prior to coating.

[0120] Preferably, the surface tension of the formulated OSPL ink is from 18 to 35 mN / m, more preferably from 20 to 30 mN / m, more preferably from 19 to 28 mN / m.

[0121] In one embodiment, the OSPL composition is modified to reduce its surface tension by adding a surfactant composition comprising a fluoropolymer surfactant and a silicone surfactant. Preferably, the ink composition comprises less than 2 wt% of the surfactant, more preferably less than 1 wt%. The surfactant is preferably compatible with the acrylate-based OSPL composition.

[0122] Preferred surfactants include fluorosurfactants and acrylate and / or methacrylate functionalized silicone surfactants. Nonionic fluorosurfactants, especially nonionic perfluorosurfactants, are particularly preferred.

[0123] Preferred surfactants are those having a 0.1% solution surface tension (mN / m) in toluene of less than 24 mN / m, preferably less than 23 mN / m, preferably ≤ 21 mN / m.

[0124] Preferably, a surfactant-containing OSPL composition solution is deposited onto the gate insulator layer and any optional solvent is removed by thermal evaporation. The resulting layer is then cross-linked.

[0125] Once the OSPL layer is in place (~10-500nm thick layer), a metal gate can be deposited on it using a plasma sputtering process. Testing of the resulting OTFT devices showed zero to minimal degradation in transistor performance after plasma exposure with the OSPL in place, so the OSPL protects the OTFT from plasma-induced damage.

[0126] experiment

[0127] 1. Preparation of OSPL / OGI / OSC / glass substrates to evaluate coating uniformity, curing, and surface free energy

[0128] OSPL screening experiments were performed using glass substrates coated with OSC / OGI, with OSPL overcoated on OSC / OGI and cured. Microscope slides (50 mm x 50 mm) were cleaned, plasma etched and treated with β-phenylethyl-trichlorosilane. They were then coated with a 25 μm layer of SKL09 organic semiconductor (SKL09 ink contained 1.7% solids 30:70 (wt:wt) TMTES:methoxy-PTAA in tetralin) followed by a 500 μm layer of Cytop 809M. The composite stack with CYTOP / OSC / glass was then overcoated with a sputtering protective layer ink formulation, which was UV cured and evaluated for coverage and film uniformity. Highly cross-linked, uniform OSPL films were obtained.

[0129] The detailed experimental method is described below:

[0130] 1a. Preparation of glass substrate

[0131] Slides were prepared as follows:

[0132] The slides were cut into 5 cm × 5 cm pieces and washed with acetone for 10 seconds and then with IPA for 10 seconds; 2 The film was air dried and baked at 120°C for 5 minutes. The film was cooled on an aluminum plate at room temperature for 2 minutes.

[0133] Plasma etching was performed in a Plasmalab PE 100 at a substrate pressure of 200 mbar, a power of 250 mW and an etching gas (oxygen and argon) flow rate of 50 sccm. 2 Dry to remove dust. Treat the glass with a solution of β-phenylethyltrichlorosilane (B-PTS) in anhydrous toluene (25 mM (59.9 mg) B-PTS in 10 ml toluene). Immerse the substrate in the solution for 2 minutes and separate by centrifugation (spin at 500 rpm for 60 seconds, stop for 10 seconds and immerse with toluene, spin at 500 rpm to 1000 rpm while rinsing with more toluene). Heat the substrate at 100°C for 1 minute and then cool to room temperature for 1 minute.

[0134] 1b. Coating OSC solution on glass substrate:

[0135] 1 ml of semiconductor ink was dispensed onto the substrate through a 0.45 μm filter to immerse the entire surface. Cover with a tightly fitting bowl facing upwards and spin-coat using a Laurell spin coater (500 rpm / 5 s / 500 rpms -1 , then 1500rpm / 60s / 500rpms -1 ). Bake at 100℃ for 1 minute and then cool on an aluminum plate for 1 minute.

[0136] 1c. Coating OGI (organic gate insulator):

[0137] Dispense ~1 ml of a 4.5% solid solution of Cytop CTL 809M in FC43 solvent onto the substrate. Spin coating (500 rpm / 5 s / 500 rpms -1 , then 1500rpm / 20s / 6000rpms -1 ), heated at 50°C for 90 seconds and at 100°C for 1 minute; cooled on an aluminum plate for 1 minute.

[0138] 1d. Coating and cross-linking of OSPL layer:

[0139] The organic sputtering protective layer formulation (SPL 184 / 2 + optionally fluorinated surfactant) was dispensed onto the substrate through a 0.45 μm filter. Spin coating (500 rpm / 5 s / 500 rpms -1 , then 1500rpm / 60s / 500rpms -1 .

[0140] Exposure to 300 to 3000 mJ / cm 2 UV light, i-line, and then baked at 100°C for 1 minute.

[0141] 1e. Measuring film thickness

[0142] The film thickness was measured using a DektakXT from Bruker Nano Surfaces Division.

[0143] 1f. Measuring the surface free energy of the membrane

[0144] The surface free energy was determined using a Dataphysics OCA 15EC goniometer using the Owens, Wendt, Rabel and Kaelble models using the sitting drop technique with at least three solvents.

[0145] Lg.Measure the surface tension of ink

[0146] Surface tension was determined using the pendant drop technique and a Dataphysics OCA 15EC goniometer.

[0147] 1h. Determination of C=C bond conversion percentage by FTIR

[0148] FTIR spectra were recorded for wet, uncured films before any UV exposure and for a series of films cured to varying degrees by increasing UV exposure (Perkin Elmer Spectrum 2 instrument with diamond ATR module). The baselines of the spectra were accurately determined at three points using the troughs around the absorption peaks of interest. They were typically around 1846, 1657 and 1573 cm -1 Wave number. Measured at 1725cm -1 The carbonyl peak at 1635 cm -1 The height of the olefin peak at 1635 cm -1 The absorbance at 1725 cm -1 The ratio of the absorbance at 400 nm and 100 nm was calculated and compared with the ratio obtained for the uncured sample. The degree of cure was calculated using the following formula:

[0149]

[0150] 2. Preparation of OTFT Arrays

[0151] Figure 1 A top-gate bottom-contact (TGBC) OTFT is described that includes the following components:

[0152] -Substrate (1)

[0153] - Source and drain (2)

[0154] - (optional) electrode surface treatment (3) or self-assembled monolayer (SAM)

[0155] - Organic semiconductor layer (OSC, 4)

[0156] - Organic gate insulator layer (OGI, 5)

[0157] - Organic sputtering protective layer (6)

[0158] - Gate electrode (7)

[0159] The process steps for making a TGBC OTFT include patterning source and drain electrodes (2) on top of a substrate, optionally applying an electrode surface treatment (3), applying an OSC layer (4) to cover the substrate (1) and the source and drain electrodes (2), applying an OGI layer (5) on top of the OSC layer (4), coating an OSPL (6) on top of the OGI layer (5), cross-linking the OSPL layer (6), and applying a gate electrode (7) on top of the OSPL. A layer of photoresist (8) is deposited on top of the gate electrode (7) and patterned to provide a mask for defining the gate electrode (7). Those portions of the OSPL, OGI and OSC layers (6), (5) and (4) respectively surrounding the gate electrode (7) are optionally removed, but the OSPL always remains intact in the channel region, such as Figure 4 shown.

[0160] 2a. Experimental method: coating on glass substrate

[0161] The TGBC OTFTs in the following examples were fabricated using the following process steps:

[0162] 1. Corning Eagle 2000 glass substrates were cleaned by ultrasonication in a solution of 5% Decon 90 in deionized water for 20 minutes, rinsed with deionized water, and dried in a convection oven at 70°C for 30 minutes.

[0163] 2. Plasma treatment (50 sccm O 2 , 70 W, 1.5 min, Oxford Instruments PLasmaLab 80+), a base layer comprising 500 nm SU-8 2000 series (MicroChem) was spin coated onto the substrate at 3000 rpm for 25 sec.

[0164] 3. First, heat the base layer on a hot plate at 95°C for 1 minute and expose it to i-line radiation (400 mJ / cm 2 ), after exposure, bake at 95°C for 1 minute, and then harden the film at 200°C for 15 minutes.

[0165] 4. Sputter 50nm Au source and drain (Ar gas, process pressure 10mTorr, 200W RF power) and pattern using standard photolithography and wet etching techniques. 5.

[0167] 6. O the substrate 2 / He plasma (15 sccm O 2, 50 sccm He, 60 W) for 3 minutes (AlphaPlasma, AL76) to increase the surface energy of the base layer and remove any residue on the patterned gold electrode. The SAM layer was formed by spin coating (speed and duration), 10 mM solution of pentafluorobenzenethiol (PFBT) in electronic grade 2-propanol, rinsed twice with 2-propanol and heated on a hot plate at 100 ° C for 1 minute.

[0168] 7. Spin coat the OSC layer (1250 rpm, 2 min) and then bake at 100 °C for 1 min.

[0169] 8. An OGI layer was formed by spin coating a solution of insulator Cytop (AGC) at 1500 rpm for 20 seconds.

[0170] 9. The OGI was then heated on a hot plate at 85°C for 1 minute.

[0171] 10. Expose the entire device to 2.4 J / cm by immersing the device and spin coating at 1500 rpm for 2 minutes. 2 OSPL was applied by ultraviolet light (i-line) followed by heating at 120°C for 2 minutes on a hot plate.

[0172] 11. Sputter a 50 nm Au gate electrode (Ar gas, process pressure 10 mTorr, 200 W RF power) and pattern it according to standard photolithography and wet etching processes.

[0173] The OTFT characteristics are obtained by biasing the gate electrode and drain of the transistor relative to the source. All example transistors comprise a p-type organic semiconductor such that when there is a negative gate voltage V G When the OTFT is biased in the linear region (i.e., V D <V G ), a negative voltage V applied to the drain D Lead current I D flows depending on the charge carrier density, mobility, μ, channel length L and width W, as described by the following formula:

[0174]

[0175] V th is the threshold voltage, I L is the leakage current. C i It is the capacitance per unit area of ​​the OGI or OGI / OSPL layer below the gate, which determines the charge carrier density in the channel.

[0176] Electrical measurements were obtained using a Keithley 4200SCS parameter analyzer coupled to a Wentworth S200 probe station. To measure the device in the linear region, the drain voltage was set to -2 V and the gate voltage was swept from +30 V to -30 V with a step size of 1 V.

[0177] The field effect mobility is calculated according to formula 2:

[0178]

[0179] in For I D -V G Gradient of the graph. Note that where the mobility depends on the gate voltage, the value quoted is V D <V G The maximum value of the accumulated records.

[0180] Threshold voltage V th and the turn-on voltage V to The normalized drain current NI D =I D × L / W and is defined as th , NI D =1nA(10 -9 A) and for V to 1pA(10 -12 A) when the gate voltage is

[0181] The transistor's off current I 关 is considered as the lowest current recorded during the gate voltage sweep. G = leakage current at -30V divided by I 关 To calculate I 开 / 关 .

[0182] Dielectric constant

[0183] The dielectric constant of OSPL was determined by fabricating metal-insulator-metal (MIM) capacitors. A 3×5 array of MIM capacitors was fabricated as follows:

[0184] 1. Cut a 25 mm × 25 mm substrate from a silicon wafer, then rinse with acetone and 2-propanol, bake on a hot plate at 150 °C for 10 min, and finally expose to O 2 Plasma (25sccm, 250W, Diener Nano) 5 minutes

[0185] 2. The OSPL formulation was spin coated at 1500 rpm for 2 minutes.

[0186] 3. Expose the device to 2.4 J / cm 2The substrate was then exposed to i-line radiation (EVG 620) and then baked at 120°C for 5 minutes.

[0187] 4. Then, 80nm Au was evaporated through a shadow mask to form each array of 3×5 MIM capacitors.

[0188] Thus, a MIM capacitor with two layers of dielectric is formed, the first layer consisting of 300 nm of thermal oxide and the second layer formed of OSPL. The thickness of the OSPL depends on the spin coating conditions and the solid content of the formulation. For a two-layer capacitor, the capacitance C is defined as the oxide capacitance C OX and OSPL capacitor C SPL The series sum of:

[0189]

[0190] in:

[0191] C OX =ε 0 ε OX A / d OX Formula 4

[0192] and C SPL =ε 0 ε SPL A / d SPL Formula 5

[0193] ε OX ,d OX ,d SPL and ε SPL are the relative dielectric constant and thickness of the oxide layer and OSPL layer, A, and the area of ​​the capacitor, ε 0 is the dielectric constant of free space.

[0194] The dielectric constant of OSPL can be calculated using equations 3, 4, and 5:

[0195]

[0196] The Agilent 4264 Precision LCR meter was used at 1kHz frequency and 200mV P-P The capacitance of each MIM device was measured at 100 nm. The OSPL and oxide thickness were measured using a JA Woollam M2000 variable angle ellipsometer at wavelengths of 300-1500 nm and incident angles of 55°-75°. The area of ​​each MIM device was measured using a calibrated Nikon microscope.

[0197]

[0198] Table 4: Dielectric constants of organic sputtered protective layers

[0199]

Claims

1. An organic gate insulator (OGI) layer having a dielectric constant (k) <3.0@1000Hz, the organic gate insulator layer being coated with a cross-linked organic layer (OSPL); wherein the cross-linked organic layer is a free radical photocured layer; wherein the dielectric constant (k) of the cross-linked organic layer thereon is >3.3@1000Hz; wherein the crosslinked organic layer thereon is obtained by polymerizing a solution comprising at least one multifunctional acrylate, a fluoropolymer surfactant and an acrylate and / or methacrylate functionalized silicone surfactant, and one or more initiators.

2. The OGI layer of claim 1, wherein the cross-linked organic layer has a dielectric constant (k) > 3.5 at 1000 Hz.

3. The OGI layer according to claim 1 or 2, wherein the material of the OGI layer is selected from perfluoropolymers, benzocyclobutene polymers (BCB), polyparaxylene, polyvinylidene fluoride (PVDF) polymers, cycloolefin copolymers, perfluorocycloolefin polymers, adamantane polymers, perfluorocyclobutylene polymers (PFCB), siloxane polymers and mixtures thereof. The OGI layer according to claim 3 , wherein the material of the OGI layer is a perfluoropolymer.

5. The OGI layer according to claim 1 or 2, wherein the cross-linked organic layer thereon is 50-4000 nm thick.

6. The OGI layer according to claim 1 or 2, wherein the surface free energy of OGI is 15-22 mN / m.

7. The OGI according to claim 1 or 2, wherein the surface free energy of the cross-linked organic layer thereon is 16-35 mN / m.

8. The OGI according to claim 1 or 2, wherein the dielectric constant of the cross-linked organic layer thereon is ≥4.

9. The OGI according to claim 1 or 2, wherein the cross-linked organic layer thereon is obtained by polymerizing a solution further comprising an acrylate functional oligomer and / or a non-acrylate organic solvent.

10. A thin film transistor comprising a substrate, one or more source / drain electrodes, at least one gate electrode, an organic semiconductor layer and an organic gate insulator (OGI) layer according to any one of claims 1 to 9.

11. The thin film transistor of claim 10, wherein the organic semiconductor layer comprises one or more materials selected from the group consisting of polyacenes, polyphenylenes, poly(phenylene vinylenes), polyfluorenes, including oligomers of conjugated hydrocarbon polymers; condensed aromatic hydrocarbons, tetracene, Pentacene, diketopyrrolopyrrole, substituted benzothiophene-benzothiophene (C8-BTBT), dinaphthothiophene-benzothiophene (DNTT), pyrene, perylene, hexaphenylene or substituted derivatives thereof; oligomeric para-substituted phenylene, p-quaterphenyl (p-4P), p-pentaphenyl (p-5P), p-hexylene (p-6P) or soluble substituted derivatives thereof; conjugated heterocyclic polymers, poly(3-substituted thiophene), poly(3,4-disubstituted thiophene), polybenzothiophene, poly(isothianaphthene), poly([λ] / -substituted pyrrole), poly(3 ... substituted pyrroles), polyfurans, polypyridines, poly-1,3,4-oxadiazoles, poly([λ] / '-substituted anilines), poly(2-substituted anilines), poly(3-substituted anilines), poly(2,3-disubstituted anilines), polyazulenes, polypyrenes; pyrazoline compounds; polyselenophenes; polybenzofurans; polyindoles; polypyridazines; benzidine compounds; stilbene compounds; triazines; substituted metal porphines or metal-free porphines, phthalocyanines, fluorophthalocyanines, naphthalocyanines, naphthalene diimides or fluoronaphthalocyanines; C60 and C70 fullerenes; A / .[λ] / '-dialkyl, substituted dialkyl, diaryl or substituted diaryl -1,4,5,8-naphthalenetetracarboxylic acid diimide and fluorine derivatives; [λ] / , [λ] / '-dialkyl, substituted dialkyl, diaryl or substituted diaryl 3,4,9,10-perylenetetracarboxylic acid diimide; bathophenanthroline; diphenoquinone; 1,3,4-oxadiazole; 11,11,12,12-tetracyanonaphthalene-2,6-quinolinolidine methane; [α][α],'-bis(dithieno[3,2-b2',3'-d]thiophene); dithieno[2,3-d; 2',3'-d']benzo[1,2-b; 4,5-b']dithiophene (DTBDT); polydithiophene Thienobenzodithiophene-co-diketopyrrolopyrrolothiophene (PDPDBD); isoindigo-thiophene-(IIDDT-C3), thieno[3,2-b]thiophene-5-fluorobenzo[c][1,2,5]thiadiazole copolymer, di(thiophen-2-yl)thieno[3,2-b]thiophene (DTTT); 2,8-dialkyl, substituted dialkyl, diaryl or substituted diaryl anthracene dithiophene; 2,2'-dibenzo[1,2-b:4,5-b'-dithiophene, benzothienobenzothiophene (BTBT) polymer, benzodithiazole polymer and mixtures thereof. 12 . The thin film transistor according to claim 10 , wherein the organic semiconductor layer comprises one or more of polyacene molecules, semiconducting polymer binders and / or insulating polymer binders. 13 . The thin film transistor according to claim 12 , wherein the organic semiconductor layer comprises bis[triisopropylsilylethynyl]pentacene or bis[triisopropylsilylethynyl]tetramethylpentacene. 14 . The thin film transistor according to claim 13 , wherein the organic semiconductor layer comprises bis[triisopropylsilylethynyl]pentacene or bis[triisopropylsilylethynyl]tetramethylpentacene in a binder.

15. An electronic device comprising the thin film transistor according to any one of claims 10 to 14.

16. A solution comprising at least one multifunctional acrylate, a non-acrylate organic solvent, a fluoropolymer surfactant, and an acrylate and / or methacrylate functionalized silicone; wherein the solution is crosslinkable; wherein the multifunctional acrylate of the solution comprises: (a1) a multifunctional acrylate compound comprising a nitrogen-containing cyclic core having at least two pendant acrylate moieties, and (a2) Polyacrylate monomers having an oxyalkane or polyoxyalkane core.

17. The solution according to claim 16, having a surface tension of 18 to 35 mN / m.

18. The solution of claim 16 or 17, wherein the surface tension of a 0.1% solution of the surfactant in toluene is less than 24 mN / m.

19. A method for solution deposition of a crosslinkable organic layer onto a low surface energy organic gate insulator, wherein the solution comprises at least one fluorosurfactant and at least one acrylate and / or methacrylate functionalized silicone.

20. The method of claim 19, wherein the surface tension of a 0.1% solution of the fluorosurfactant in toluene is less than 24 mN / m.

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