JP4570341B2 - THIN FILM TRANSISTOR, DISPLAY ELEMENT USING SAME, AND LIQUID CRYSTAL DISPLAY ELEMENT - Google Patents

Description

  The present invention relates to a transistor and a liquid crystal display element, and more particularly to a transistor including an organic polymer layer, a display element using the same, and a liquid crystal display element including an organic polymer layer.

  In recent years, liquid crystal displays (LCDs), organic EL, plasma display panels, and the like have attracted attention as display elements that replace CRTs, but these display elements have a problem that they are more expensive than CRTs. Therefore, further price reduction is required for further spread.

  As a first method for reducing the price, among thin film transistors (organic TFTs) using an organic thin film semiconductor, for example, a field effect transistor (organic FET) is applied to an active element (for example, Patent Documents 1 to 3). ). The organic TFT has an advantage that it can be manufactured by a relatively simple method.

  Current plasma chemical vapor deposition (CVD) apparatus for forming an insulating layer or semiconductor layer of amorphous silicon or polysilicon TFT, and a sputtering apparatus used for electrode formation are expensive. Further, the CVD method requires a high temperature condition of 230 to 350 degrees, and maintenance such as cleaning needs to be frequently performed, and the throughput is low. On the other hand, a coating apparatus, an inkjet apparatus, and the like for producing an organic TFT are cheaper than CVD apparatuses and sputtering apparatuses, have a low film formation temperature, and are easy to maintain. Therefore, if an organic FET is applied to a display element such as a liquid crystal display element or an organic EL, the cost can be reduced.

  Among liquid crystal display elements, among liquid crystal display elements, a method for simplifying the design of the display unit of the liquid crystal display element can be given as a second cost reduction technique.

In general, a liquid crystal display element is formed by forming electrodes on a substrate on which a TFT is formed and a substrate on which a color filter is formed by a method such as sputtering, applying an alignment film thereon, baking, rubbing, Since it is manufactured by bonding, injecting liquid crystal material, and sealing, the number of manufacturing steps is very large and the manufacturing cost is high. In addition, when a rubbing treatment or the like is performed, the yield is reduced due to the influence of static electricity or a rubbing cloth. Therefore, a process in which rubbing is not performed by forming ribs on the substrate in advance is used, or optical alignment techniques are studied (for example, Patent Documents 4 and 5).
JP-A-5-107523 JP 2003-192499 A Japanese Patent Laid-Open No. 10-125924 JP 2001-281669 A JP-A-10-123521

  However, in the first cost reduction method, a general organic TFT has a gate electrode, a gate insulating film, a source electrode, a drain electrode, and an organic semiconductor film formed on a transparent substrate such as glass. Since the number of manufacturing steps is large, the manufacturing cost of the organic TFT and the display element including the organic TFT cannot be sufficiently reduced even if a coating process can be used for the semiconductor layer.

  In addition, in the second cost reduction method for the liquid crystal display element, it is necessary to introduce a rib forming process and a photo-alignment process instead of rubbing, and the manufacturing cost of the liquid crystal display element is sufficiently reduced. Can not do it.

  The present invention has been made in view of the above-described points, and an object thereof is to provide a transistor, a display element using the transistor, and a liquid crystal display element that can be manufactured at low cost.

  The transistor of the present invention includes a first electrode, a second electrode, an organic layer provided between the first electrode and the second electrode, a third electrode for applying an electric field to the organic layer, And the organic layer includes a composite functional organic polymer having a conductive portion and an insulating portion, whereby the above-described problem is solved.

  The composite functional organic polymer may be a linear polymer.

  The composite functional organic polymer may be a dendritic polymer.

  It is preferable that the organic layer has a self-organized structure by noncovalent interaction through the insulating portion of the composite functional organic polymer.

  The organic layer may include a dopant.

  The transistor of the present invention may be a field effect transistor that utilizes the field effect of the organic layer with respect to the electric field applied by the third electrode.

  The transistor of the present invention may have a nanometer scale size.

  The display element of the present invention includes the above-described transistor and a pixel connected to the transistor, thereby solving the above-described problem.

  The display element of the present invention is a display element having a substrate and a transistor formed on the substrate, wherein the transistor is an organic layer including a composite functional organic polymer having a conductive portion and an insulating portion. A gate electrode, a source electrode, and a drain electrode, and no insulating layer is provided between the organic layer and the gate electrode, the source electrode, and the drain electrode. The above problem is solved.

  The organic layer may be in direct contact with each of the gate electrode, the source electrode, and the drain electrode.

  The liquid crystal display element of the present invention includes a first substrate and a second substrate facing each other, a liquid crystal layer disposed between the first substrate and the second substrate, and the liquid crystal layer and the first substrate. And an organic layer provided on at least one of the liquid crystal layer and the second substrate, the organic layer having a conductive portion and an insulating portion. The above-mentioned problems are solved by including a polymer.

  The organic layer may include a dopant.

  The composite functional organic polymer may be a linear polymer.

  The composite functional organic polymer may be a dendritic polymer.

  It is preferable that the organic layer has a self-organized structure by noncovalent interaction through the insulating portion of the composite functional organic polymer.

  The organic layer may be in direct contact with the liquid crystal layer.

  The organic layer may align liquid crystal molecules contained in the liquid crystal layer in a predetermined direction associated with a self-organized structure.

  A liquid crystal display element according to the present invention includes a first substrate and a second substrate facing each other, a liquid crystal layer disposed between the first substrate and the second substrate, and a transistor connected to a pixel. The device further includes a first organic layer between at least one of the liquid crystal layer and the first substrate and between the liquid crystal layer and the second substrate. One electrode, a second electrode, a second organic layer provided between the first electrode and the second electrode, and a third electrode for applying an electric field to the second organic layer, The first and second organic layers include a composite functional organic polymer having a conductive portion and an insulating portion, thereby solving the above problem.

  The first organic layer may include a dopant.

  The composite functional organic polymer may be a linear polymer.

  The composite functional organic polymer may be a dendritic polymer.

  It is preferable that the first and second organic layers have a self-organized structure by non-covalent interaction through the insulating portion of the composite functional organic polymer.

  The present invention provides a transistor, a display element using the transistor, and a liquid crystal display element that can be manufactured at low cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a transistor 10 according to an embodiment of the present invention includes a gate electrode 2 (third electrode) formed on an insulating substrate 1, an organic layer 3 formed so as to cover the gate electrode 2, It has a source electrode 4 (first electrode) and a drain electrode 5 (second electrode) formed on the organic layer 3. The organic layer 3 includes a composite functional organic polymer having a conductive portion and an insulating portion.

  In FIG. 1 and the following description, a bottom-gate field effect transistor (FET) 10 is illustrated, but the present invention is not limited to a bottom-gate FET, and is widely applied to various types of FETs and other transistors. Applied.

  In the transistor 10, the organic layer 3 can have the functions of a gate insulating film and a semiconductor layer that a conventional transistor has. Therefore, the transistor can be formed using the organic layer 3 instead of the gate insulating film and the semiconductor layer of the conventional transistor.

  That is, it is not necessary to provide an insulating layer between the organic layer 3 and the gate electrode 2, between the organic layer 3 and the source electrode 4, and between the organic layer 3 and the drain electrode 5. The organic layer 3 is fabricated so as to be in direct contact with each of the gate electrode 2, the source electrode 4 and the drain electrode 5.

  Since the organic layer 3 is formed under a lower temperature condition than the process of manufacturing the semiconductor layer using, for example, an ink jet method or the like, the manufacturing process is easy. Inkjet devices are cheaper and easier to maintain than CVD devices and sputtering devices. Therefore, the transistor 10 is manufactured with fewer manufacturing steps than a conventional transistor, and the manufacturing cost is low.

  In addition, the transistor 10 does not require a gate insulating film that has been conventionally required, and can have a nanometer-scale size. Therefore, the transistor 10 has extremely superior characteristics as compared with a conventional transistor. For example, the organic layer 3 of the transistor 10 preferably has a thickness of 0.5 nm to 10 nm and a length (corresponding to a channel length) of 1 nm to 20 nm.

  Note that the gate electrode 2, the source electrode 4, and the drain electrode 5 of the transistor 10 may be formed using a metal material, ITO, or a conductive polymer material as in the conventional transistor, but the organic layer 3 described above. It is also possible to form using a composite functional organic polymer material contained in When forming the said electrode using composite functional type organic polymer material, it is preferable to add a dopant as needed.

  As shown in FIG. 2, the liquid crystal display element 100 according to the embodiment of the present invention includes two substrates 11 facing each other, a liquid crystal layer 13 disposed between the substrates 11, and the two substrates 11. And an organic layer 12 provided between the liquid crystal layer 13 and the liquid crystal layer 13. Similar to the organic layer 3 described above, the organic layer 12 includes a composite functional organic polymer having a conductive portion and an insulating portion. Note that the liquid crystal display element 100 illustrated in FIG. 2 exemplifies homogeneous liquid crystal alignment (parallel alignment), but the alignment of the liquid crystal is not limited thereto.

  In the liquid crystal display element 100, the organic layer 12 can have the functions of a pixel electrode (or a counter electrode) and a liquid crystal alignment film included in a conventional liquid crystal display element.

  When the organic layer 12 has the functions of the pixel electrode (or counter electrode) of the conventional liquid crystal display element and the liquid crystal alignment film, the pixel electrode (or counter electrode) of the conventional liquid crystal display element and the liquid crystal alignment film Alternatively, a liquid crystal display element can be configured using the organic layer 12. That is, the organic layer 12 is disposed so as to be in direct contact with the liquid crystal layer 13.

  When the organic layer 12 has the function of a liquid crystal alignment film, the rubbing process can be omitted, so that the manufacturing process can be further simplified and the yield of the liquid crystal display element can be prevented from being lowered due to generation of static electricity. . If the organic layer 12 does not have a sufficient liquid crystal alignment function, the organic layer 12 itself is subjected to a rubbing treatment as necessary, or a liquid crystal alignment film such as a polyimide film is provided on the organic layer 12, A rubbing treatment may be performed. Of course, even if the organic layer 12 has a liquid crystal alignment function, a rubbing process similar to the above may be performed as necessary to obtain a desired liquid crystal alignment function.

  A configuration in which the pixel layer, the counter electrode, and the liquid crystal alignment film can be omitted by providing the organic layer 12 between the liquid crystal layer 13 and each of the two substrates 11 is most preferable. The element 100 is not limited to this. For example, the organic layer 12 is provided only between the liquid crystal layer 13 and one of the two substrates 11, and a pixel electrode or a counter electrode and a liquid crystal alignment film are provided between the liquid crystal layer 13 and the other substrate. It may be provided.

  Hereinafter, the transistor 10 (FIG. 1) will be described in detail. First, the organic layer 3 will be described. The organic layer 3 includes, for example, a linear polymer or a dendritic polymer. Organic polymers such as linear polymers and dendritic polymers are composite functional organic polymers that have both insulating properties and semiconducting properties. The organic layer 3 preferably has a self-organized structure by non-covalent interaction via an insulating site of the composite functional organic polymer.

  As shown in FIG. 3A, the linear polymer preferably contains a carrier-conductive linear π-conjugated molecule in the polymer main chain and an insulating residue in the side chain. . As the π-conjugated main chain, poly (p-phenylene), poly-p (phenylene vinylene), polythiophene, polyfluorene, polynaphthene, poly (arylene vinylene), poly (thienylene vinylene), polypyrrole, polyacetylene, etc. are preferable. Although used, it is not restricted to these. Insulating side chains include alkyl groups (hexyl group, octyl group, decyl group, dodecyl group, etc.), mesogen, ethylene glycol, cyclic unsaturated compounds, hydrogen bonding residues, carbohydrate compounds, lipids (cholesterol, bile acids Etc.) is preferable, but not limited thereto. By adjusting the molecular size of the insulating side chain, it is possible to appropriately adjust ON / OFF of the gate electrode. As the insulating residue, a molecule having a self-organizing function such as a hydrogen bonding residue or a mesogen is preferably used.

  As shown in FIG. 4A, the dendritic polymer preferably includes a carrier-conducting π-conjugated molecule in the core, and the dendron includes an insulating residue. 4A illustrates the case where the dendritic polymer has a disc shape (disk shape), the shape of the dendritic polymer is not limited to this. The dendritic polymer may be spherical, for example.

  As the π-conjugated core, benzene, naphthalene, anthracene, phenanthrene, pyrene, perylene, aluminum quinoline complex and the like and porphyrins, oligofluorene, oligothiophene, oligophenylene vinylene, spiro-NPB, spiro-TAD, spiro-DPVBi Thus, molecules having high planarity are preferable, but not limited thereto. As the insulating dendron, benzyl ether, polystyrene sulfonic acid and the like are preferable, but not limited thereto. By adjusting the molecular size (number of generations) of the insulating dendron, it is possible to appropriately adjust on / off of the gate electrode. As the insulating residue, a molecule having a self-organizing function such as a hydrogen bonding residue or a mesogen is preferably used.

  In the above organic polymer, adjusting the molecular size of the insulating molecule can provide the same effect as adjusting the thickness of the insulating film of the conventional transistor. When the insulating residue has a self-organizing function, mobility can be increased by increasing molecular orientation.

  Self-assembly is achieved by aggregation between molecules due to any interaction other than chemical covalent bonds (non-covalent interactions that work between molecules). Non-covalent interactions include hydrogen bonds, van der Waals forces, permanent dipole interactions, permanent dipole-induced dipole interactions, temporary dipole-induced dipole interactions, charge transfer forces (electron donation) Body-electron acceptor interaction), coordination bonds, electrostatic interactions, and affinity (hydrophobic interactions).

  The disc-shaped dendritic polymer shown in FIG. 4 (a) is self-organized such that the disc surfaces are arranged in parallel to each other and the core portions overlap each other as shown in FIG. 4 (b). Forming a chemical structure. The linear polymer shown in FIG. 3 (a) is self-assembled in which main chains and side chains are alternately stacked as shown in FIG. 3 (b), for example, when the association property between side chain molecules is high. Form an organized structure.

  A known film forming method can be widely applied to the method of forming the organic layer 3 containing the composite functional organic polymer material such as the linear polymer and the dendritic polymer. Since the above-described composite functional organic polymer material is excellent in solubility in a solvent, the solution can be prepared using various solvents. This solution is applied or printed on a substrate by a method such as spin coating, dip coating, casting, printing, or ink jet, and after drying, heat treatment is performed as necessary to obtain a composite functional organic polymer. A film of material can be formed. Alternatively, a composite functional organic polymer material layer may be formed on a support and transferred from the support to the substrate.

  Next, a method for manufacturing the transistor 10 shown in FIG. 1 using this composite functional organic polymer material will be exemplified.

  First, the gate electrode 2 is formed on the insulating substrate 1. The material of the gate electrode 2 includes Cr, Al, Ta, Mo, Nb, Cu, Ag, Au, Pt, Pd, In, Ni, Nd and alloys thereof, polysilicon, amorphous silicon, tin oxide, Inorganic materials such as indium oxide and indium tin oxide (ITO), and organic materials such as doped conductive polymers (for example, a mixture of polyethylene dioxythiophene (PEDOT) and sodium polystyrene sulfonate). Materials. Two or more films may be stacked. After depositing a conductive film using a known film formation method according to a material such as an evaporation method, a sputtering method, a coating method, a printing method, or an ink jet method, the conductive film is gated by a photolithography process and an etching process. The electrode 2 is processed into a predetermined shape.

  Next, an organic layer 3 containing a composite functional organic polymer material is formed so as to cover the gate electrode 2. As described above, the organic layer 3 can be formed by preparing a solution of an organic polymer material and using this solution by various coating methods and printing methods. The organic layer 3 can be formed by heat-processing as needed after drying.

  A source electrode 4 and a drain electrode 5 are formed on the organic layer 3. As the material of the source electrode 4 and the drain electrode 5, the same material as that of the gate electrode 2 can be used and formed by the same method. Of course, the material of the gate electrode 2 and the material of the source electrode 4 and the drain electrode 5 may be different or the same. Two or more films may be stacked.

  Through the above steps, the transistor 10 is manufactured.

  Note that the structure of the transistor 10 is not limited to the above example, and is a vertical structure in which a top gate type, a coplanar type, or a source electrode / gate electrode / drain electrode is stacked and a semiconductor layer is formed between the source and drain. Further, a structure in which the drain electrode / gate electrode / source electrode are arranged in the same layer may be used.

  The transistor 10 has high carrier mobility when the organic layer 3 has molecular orientation. Further, in the process of forming the organic layer 3, the carrier mobility can be further improved by performing an alignment process on the underlying layer and aligning the organic layer 3.

  The organic layer 3 can be formed simply by applying or printing a solution containing an organic polymer, and since a high temperature is not required for forming the organic layer 3, it can be easily formed on a plastic substrate. Can be formed.

  Further, by adding a dopant to the above-mentioned composite functional organic polymer material, the conductivity can be increased to a level that can be sufficiently used as an electrode. Therefore, all of the gate electrode 2, the source electrode 4, and the drain electrode 5 can be formed using the composite functional organic polymer material.

  Note that the gate electrode 2, the source electrode 4, and the drain electrode 5 can also be formed using a known conductive organic material. Examples of the conductive organic material include, for example, phthalocyanine derivatives, azo compound derivatives, perylene derivatives, quinacridone derivatives, polycyclic quinones on main chains such as polystyrene, polysiloxane, polyether, polyester, polyamide, and polyimide. And derivatives having introduced side chains such as nitrogen-containing cyclic compound derivatives such as benzene derivatives, cyanine derivatives, fullerene derivatives, indole and carbazole, hydrazone derivatives, triphenylamine derivatives and polycyclic aromatic compound derivatives. Furthermore, aromatic conjugated polymers such as poly (p-phenylene) which are π-conjugated polymers, aliphatic conjugated polymers such as polyacetylene, heterocyclic conjugated polymers such as polypyrrole and polythiophene, poly ( Carbon-type conjugated polymers such as p-phenylene vinylene), poly (arylene vinylene), and complex conjugated polymers having a structure in which structural units of the conjugated polymers such as poly (thienylene vinylene) are alternately bonded. Examples include molecules, polysilanes, disilanylene polymers, and disilanylene-carbon conjugated polymer structures.

  The transistor 10 is suitably used for a display element such as a liquid crystal display element or an organic EL display element.

  The display element has, for example, a pixel electrode connected to the drain electrode 5 of the transistor 10. In the case of a transmissive liquid crystal display element, the pixel electrode is formed using a transparent conductive film such as tin oxide, indium oxide, or ITO. In the case of a reflective liquid crystal display element, it is formed using a metal film such as Al or Ag. In the case of an organic EL display element, it is formed using a metal film such as Mg, Ca, Al, or Au. When the same material as the drain electrode and the source electrode is used for the pixel electrode, there is an advantage that the pixel electrode can be formed in the same process as the drain electrode and the source electrode. When a different material is used, the pixel electrode is formed before or after the drain electrode and the source electrode are formed.

  Next, the liquid crystal display element 100 will be described in detail.

  First, the organic layer 12 will be described. Similar to the organic layer 3, the organic layer 12 includes, for example, a linear polymer or a dendritic polymer. The organic polymer such as the linear polymer and the dendritic polymer is a composite functional polymer that has both conductivity (function of an electrode) and liquid crystal alignment (function of a liquid crystal alignment film). The organic layer 12 preferably has a self-organized structure by non-covalent interaction via an insulating site of the composite functional organic polymer.

  As shown in FIG. 3A, the linear polymer has a structure containing a conductive linear π-conjugated molecule in the polymer main chain and an insulating residue having liquid crystal orientation in the side chain. preferable. As the π-conjugated main chain, poly (p-phenylene), poly-p (phenylene vinylene), polythiophene, polyfluorene, polynaphthene, poly (arylene vinylene), poly (thienylene vinylene), polypyrrole, polyacetylene, etc. are preferable. Although used, it is not restricted to these. Insulating side chains having liquid crystal alignment include alkyl groups (hexyl group, octyl group, decyl group, dodecyl group, etc.), mesogen, ethylene glycol, cyclic unsaturated compounds, hydrogen bonding residues, carbohydrate compounds, lipids (Cholesterol, bile acids, etc.) are preferred, but not limited to these. It is possible to adjust the pretilt angle by adjusting the molecular structure and molecular size of the insulating side chain. As the insulating residue, a molecule having a self-organizing function such as a hydrogen bonding residue or a mesogen is preferably used.

  As shown in FIG. 4, the dendritic polymer preferably has a structure containing a conductive π-conjugated molecule in the core and an insulating residue having liquid crystal orientation in the dendron. As the π-conjugated core, benzene, naphthalene, anthracene, phenanthrene, pyrene, perylene, aluminum quinoline complex and the like and porphyrins, oligofluorene, oligothiophene, oligophenylene vinylene, spiro-NPB, spiro-TAD, spiro-DPVBi Thus, molecules having high planarity are preferable, but not limited thereto. As the insulating dendron having liquid crystal orientation, benzyl ether, polystyrene sulfonic acid and the like are preferable, but not limited thereto. The pretilt angle can be appropriately adjusted by adjusting the molecular size (number of generations) of the insulating dendron. As the insulating residue, a molecule having a self-organizing function such as a hydrogen bonding residue or a mesogen is preferably used.

In order to use the composite functional polymer as an electrode material, it is preferable to add a small amount of dopant. As dopant agent, alkali metals (e.g., Li, Na, K, Cs, etc.), alkyl ammonium ion (e.g., tetraethyl ammonium salts, tetrabutylammonium salts), halogens _{(e.g., Br 2, I 2, Cl} 2), Lewis acids (eg, BF ₂ , PF ₅ , AsF ₅ , BF ₄ , PF ₆ , AsF _6, etc.), proton acids (eg, HNO ₃ , H ₂ SO ₄ , HF, HCl, etc.), transition metal halides (eg, FeCl ₃ , MoCl ₅ , WCl ₅ , SnCL ₄ , MoF ₅ , RuF ₅ ), porphyrins, amino acids, alkyl sulfonates, polystyrene sulfonates, polymer sulfonates and the like, and the like, but are not limited thereto.

  When the organic layer 12 has a self-assembled structure formed by non-covalent interaction through an insulating residue, the liquid crystal molecules contained in the liquid crystal layer are aligned in a predetermined direction associated with the self-assembled structure. Thus, no rubbing process is required.

  Self-assembly is achieved by aggregation between molecules due to any interaction other than chemical covalent bonds (non-covalent interactions that work between molecules). Non-covalent interactions include hydrogen bonds, van der Waals forces, permanent dipole interactions, permanent dipole-induced dipole interactions, temporary dipole-induced dipole interactions, charge transfer forces (electron donation) Body-electron acceptor interaction), coordination bonds, electrostatic interactions, and affinity (hydrophobic interactions).

  The linear polymer shown in FIG. 3 (a) has a self-organization in which main chains and side chains are alternately stacked as shown in FIG. 3 (b), for example, when the association between the side chains is high. Forming a chemical structure. In this linear polymer, the pretilt angle is determined by the interaction of the non-π-conjugated part of the side chain with the liquid crystal. Although the specific pretilt angle varies depending on the type of non-π conjugated molecules and liquid crystal molecules in the side chain, it is considered that the pretilt angle of the liquid crystal molecules can be stably controlled if any order exists between the side chains. . If the film does not have sufficient orientation, it may be rubbed.

  The disc-shaped dendritic polymer shown in FIG. 4 (a) is self-organized such that the disc surfaces are arranged in parallel to each other and the core portions overlap each other as shown in FIG. 4 (b). Forming a chemical structure. The dendritic polymer interacts with liquid crystal molecules to determine the pretilt angle. When the dendritic polymer is used, the above self-organized structure is formed, so that it is considered that sufficient orientation can be obtained without performing a rubbing treatment.

  In order to form the organic layer 12 using the above-described composite functional organic polymer material, known film forming methods can be widely applied. Since this composite functional organic polymer material is excellent in solubility in a solvent, the solution can be prepared using various solvents. This solution is applied or printed on a substrate by a method such as spin coating, dip coating, casting, printing, or ink jet, and after drying, heat treatment is performed as necessary to obtain a composite functional organic polymer. A film of material can be formed. Alternatively, a composite functional organic polymer material layer may be formed on a support and transferred from the support to the substrate.

  Next, a method for manufacturing the liquid crystal display element 100 shown in FIG. 2 using this composite functional organic polymer material will be exemplified.

  First, the organic layer 12 is formed on each main surface of the two insulating substrates 11. For the formation of the organic layer 12, a known film formation method corresponding to the material such as a coating method, a printing method, or an ink jet method is used. Moreover, you may perform a rubbing process as needed.

  Next, two insulating substrates on which the organic layer 12 is formed are bonded together. The bonding is performed using a known method. For example, a sealing agent is applied to one substrate, and beads of a predetermined size are applied to the other substrate and bonded together. After the bonding is completed, a predetermined liquid crystal material is injected. In the case of an active matrix liquid crystal display element, a switching element is mounted on one side of the substrate.

  Through the above process, the liquid crystal display element 100 is manufactured. The liquid crystal mode of the display device according to the present embodiment is not limited to homogeneous alignment, and can be applied to all liquid crystal modes such as twist alignment, spray-bend alignment, homeotropic alignment, and ferroelectric / antiferroelectric liquid crystal.

  The organic layer 12 has high liquid crystal orientation when it has molecular orientation by self-organization. Further, in the process of forming the organic layer, when the alignment treatment is performed on the base layer and the organic layer is aligned, the liquid crystal alignment becomes more stable and a high contrast ratio can be obtained.

  The organic layer 12 can be formed by simply applying or printing a solution containing an organic polymer, and does not require a high temperature for the production of the organic layer, so it can be easily formed on a plastic substrate. it can.

  In the liquid crystal display element of this embodiment, the organic layer 12 may not have the function of a liquid crystal alignment film as long as it has at least the function of an electrode. Conventionally, an electrode is formed by forming an ITO electrode by sputtering, which is a vacuum process, or by forming an Al electrode by vapor deposition. On the other hand, the organic layer 12 has at least an electrode function. If it does, the effect that it can produce by a simple method like the printing method will be acquired.

  Next, examples of the transistor and the liquid crystal display element in this embodiment will be described.

Example 1
In Example 1, a field effect transistor 10 using a composite functional polymer material (linear polymer) represented by the following (Chemical Formula 1) for the organic layer 3 was produced. The composite functional polymer material has a poly (p-phenylene vinylene) structure having a carrier transport ability in a polymer main chain, and an insulating ethylene glycol structure in a side chain. Ta is used for the gate electrode 2, and Au is used for the source electrode 4 and the drain electrode 5.

  The transistor 10 of Example 1 was manufactured by the following procedure.

  (1) Ta is deposited on the substrate 1 by vapor deposition using a mask to form the gate electrode 2.

  (2) The organic layer 3 is formed on the gate electrode 2 by applying a solution containing the composite functional polymer material represented by (Chemical Formula 1) to a predetermined position by an ink jet method and drying it. The organic layer 3 may be a monomolecular layer or more, and is preferably in the range of 100 nm to 1000 nm.

  (3) Au is deposited by an evaporation method using a mask to form the source electrode 4 and the drain electrode 5. At this time, the distance between the source electrode 4 and the drain electrode 5 was set so that the channel length was 8 μm.

When the transistor 10 obtained by the above manufacturing method is used, an on / off current ratio of about 10 ⁵ can be obtained as current-voltage characteristics, and 0.5 cm ² / Vs can be obtained as carrier mobility. I was able to. Both the on / off current ratio and carrier mobility results are comparable to current a-Si performance.

(Example 2)
FIG. 5 is a schematic cross-sectional view of the liquid crystal display element 1000 of the second embodiment. The liquid crystal display element 1000 includes a combination of the transistor 10 (FIG. 1) and the liquid crystal display element 100 (FIG. 2).

  That is, the liquid crystal display element 1000 includes the organic layer 112 instead of the conventional pixel electrode, and the transistor provided in each pixel in the display region includes the organic layer 103 instead of the gate insulating film and the semiconductor layer.

  The organic layer 112 and the organic layer 103 include the composite functional polymer material represented by the above (Chemical Formula 1). The organic layer 112 includes, for example, polystyrene sulfonate (PSS) as a dopant. Note that an alkali metal, an alkaline earth metal, a Lewis acid, a Lewis base, a polymer electrolyte, or the like may be used as the dopant.

  The liquid crystal display element 1000 is a typical TN mode TFT liquid crystal display element.

  The liquid crystal display element 1000 has a known configuration except for the above two points, and is manufactured by a known method. Hereinafter, the liquid crystal display element 1000 will be described in more detail with reference to FIG.

  In the liquid crystal display element 1000, a gate electrode 102, an organic layer 103, a drain electrode 104, and a source electrode 105 are formed on a glass substrate 101. The organic layer 103 has both semiconductor properties and insulator properties.

  An organic layer 112 is connected to the drain electrode 104. An organic layer 112 is also provided on the glass substrate 101 of the counter substrate. The organic layer 112 used in this example has a function of an electrode, but does not have a sufficient function of a liquid crystal alignment film.

  The liquid crystal molecules of the liquid crystal layer 113 between the pair of substrates 101 are TN aligned between the opposing organic layers 112. A nematic liquid crystal having positive dielectric anisotropy was used as the liquid crystal material. In addition, a polyimide alignment film having a pretilt angle of 2 ° was formed on the surface of the organic layer 112.

  The liquid crystal display element 1000 could be driven at 5V. The contrast ratio was 300. Since the transistor 10 has mobility and on / off characteristics comparable to those of the a-Si TFT, the liquid crystal display element 1000 can be used as a display element for a large moving image such as a liquid crystal TV, a game machine, a car navigation system, and the like. it can.

Further, since the transistor 10 can be made smaller than the a-Si TFT, the aperture ratio, which has been about 65%, can be improved to 85%. As a result, it was possible to improve the luminance when using a cold negative tube backlight from the conventional 300 Cd / m ² to 500 Cd / m ² .

  As described above, by combining the transistor 10 and the liquid crystal display element 100, a liquid crystal display element having characteristics equal to or higher than those of the conventional one can be manufactured in a short process.

(Example 3)
In Example 3, a field effect transistor 10 using the composite functional polymer material represented by the following (Chemical Formula 2) for the organic layer 3 was produced. The composite functional polymer material has a fluorene structure having a carrier transport capability in the core, and an insulating benzyl ether structure in the dendron. Ta is used for the gate electrode 2, and Au is used for the source electrode 4 and the drain electrode 5.

  The transistor 10 of Example 3 is manufactured in the same procedure as the transistor 10 of Example 1.

When the transistor 10 obtained in Example 3 is used, an on / off current ratio of about 10 ⁵ can be obtained as the current-voltage characteristics, and 0.5 cm ² / Vs can be obtained as the carrier mobility. I was able to. Both the on / off current ratio and carrier mobility results are comparable to current a-Si performance.

Example 4
The liquid crystal display element 1000 of Example 4 has the same configuration as the liquid crystal display element 1000 of Example 2 as shown in FIG. The liquid crystal display element 1000 of Example 4 is configured by a combination of the transistor 10 (FIG. 1) and the liquid crystal display element 100 (FIG. 2).

  That is, the liquid crystal display element 1000 includes the organic layer 112 instead of the conventional liquid crystal alignment film and pixel electrode, and the transistor provided in each pixel in the display region includes the organic layer 103 instead of the gate insulating film and the semiconductor layer. Have

  The organic layer 112 and the organic layer 103 include the composite functional polymer material (dendritic polymer) represented by the above (Chemical Formula 2). The organic layer 112 includes, for example, polystyrene sulfonate (PSS) as a dopant. Note that an alkali metal, an alkaline earth metal, a Lewis acid, a Lewis base, a polymer electrolyte, or the like may be used as the dopant. The liquid crystal display element 1000 is a typical TN mode TFT liquid crystal display element.

  The liquid crystal display element 1000 has a known configuration except for the above two points, and is manufactured by a known method. In addition, unlike the liquid crystal display element 1000 of the second embodiment, in the liquid crystal display element 1000 of the fourth embodiment, since the organic layer 112 has sufficient liquid crystal orientation, it is sufficient even if the organic layer 112 is not rubbed. Orientation was obtained.

  The liquid crystal display element 1000 could be driven at 5V. The contrast ratio was 400. Since the transistor 10 has mobility and on / off characteristics comparable to those of the a-Si TFT, the liquid crystal display element 1000 can be used as a display element for a large moving image such as a liquid crystal TV, a game machine, a car navigation system, and the like. it can.

Further, since the transistor 10 can be made smaller than the a-Si TFT, the aperture ratio, which has been about 65%, can be improved to 85%. As a result, it was possible to improve the luminance when using a cold negative tube backlight from the conventional 300 Cd / m ² to 500 Cd / m ² .

  As described above, by combining the transistor 10 and the liquid crystal display element 100, a liquid crystal display element having characteristics equal to or higher than those of the conventional one can be manufactured in a short process.

  Even when the organic layer 112 is formed using the composite functional polymer material (linear polymer) represented by the above (Chemical Formula 1), if the organic layer 112 is rubbed, the organic layer 112 Therefore, the alignment film can be omitted similarly to the liquid crystal display element of Example 4.

It is sectional drawing for demonstrating the transistor of embodiment of this invention. It is sectional drawing for demonstrating the liquid crystal display element of embodiment of this invention. (A) is a schematic diagram for demonstrating the linear polymer contained in an organic layer, (b) is a schematic diagram for demonstrating a self-organization structure. (A) is a schematic diagram for demonstrating the dendritic polymer contained in an organic layer, (b) is a schematic diagram for demonstrating a self-organization structure. 6 is a cross-sectional view for explaining liquid crystal display elements of Example 2 and Example 4. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Gate electrode 3 Organic layer 4 Source electrode 5 Drain electrode 10 Transistor 11 Substrate 12 Organic layer 13 Liquid crystal layer 100 Liquid crystal display element 101 Substrate 102 Gate electrode 103 Organic layer 104 Drain electrode 105 Source electrode 112 Organic layer 113 Liquid crystal layer

Claims (12)

A first electrode, a second electrode, an organic layer provided between the first electrode and the second electrode, and a third electrode for applying an electric field to the organic layer,
There is no insulating layer between the organic layer and the third electrode,
The organic layer has a linear polymer,
The linear polymer has at least one of a poly (p-phenylene vinylene) structure having a conductive linear π-conjugated molecule in the main chain, a polythiophene structure, and a polyfluorene structure, and has a side chain . has an insulating property residues et Chi glycol structure,
The thin film transistor, wherein the linear polymer has a self-organized structure by non-covalent interaction via the side chain. A first electrode, a second electrode, an organic layer provided between the first electrode and the second electrode, and a third electrode for applying an electric field to the organic layer,
There is no insulating layer between the organic layer and the third electrode,
The organic layer has a dendritic polymer,
The dendritic polymer, fluorene structure having a π-conjugated molecules of the conductive core, oligothiophene structure has an oligo-phenylenevinylene structure, anthracene structure, at least one of porphyrins structure, base Nji ether to dendron An insulating residue having a structure or a benzyl ether structure in which an amine is added to a terminal group;
The thin film transistor in which the dendritic polymer has a self-organized structure by noncovalent interaction via the dendron.   The thin film transistor according to claim 1, wherein the organic layer includes a dopant.   4. The thin film transistor according to claim 1, wherein the thin film transistor is a field effect transistor utilizing a field effect of the organic layer with respect to an electric field applied by the third electrode.   5. The thin film transistor according to claim 1, wherein the first electrode, the second electrode, and the third electrode are in direct contact with the organic layer.   A display element comprising the thin film transistor according to claim 1 and a pixel connected to the thin film transistor. A first substrate and a second substrate facing each other;
A liquid crystal layer disposed between the first substrate and the second substrate;
A liquid crystal display element having a thin film transistor connected to a pixel,
And a first organic layer between at least one of the liquid crystal layer and the first substrate and between the liquid crystal layer and the second substrate,
The thin film transistor includes a first electrode, a second electrode, a second organic layer provided between the first electrode and the second electrode, and a third for applying an electric field to the second organic layer. With electrodes,
There is no insulating layer between the second organic layer and the third electrode,
The first and second organic layers have a linear polymer,
The linear polymer has at least one of a poly (p-phenylene vinylene) structure having a conductive linear π-conjugated molecule in the main chain, a polythiophene structure, and a polyfluorene structure, and has a side chain . has an insulating property residues et Chi glycol structure,
The liquid crystal display device, wherein the linear polymer has a self-organized structure by non-covalent interaction via the side chain.   The liquid crystal display element according to claim 7, wherein the liquid crystal layer is in direct contact with the first organic layer. A first substrate and a second substrate facing each other;
A liquid crystal layer disposed between the first substrate and the second substrate;
A liquid crystal display element having a thin film transistor connected to a pixel,
And a first organic layer between at least one of the liquid crystal layer and the first substrate and between the liquid crystal layer and the second substrate,
The thin film transistor includes a first electrode, a second electrode, a second organic layer provided between the first electrode and the second electrode, and a third for applying an electric field to the second organic layer. With electrodes,
There is no insulating layer between the second organic layer and the third electrode,
The first and second organic layers have dendritic polymers;
The dendritic polymer, fluorene structure having a π-conjugated molecules of the conductive core, a oligothiophene structure, oligo-phenylenevinylene structure, at least one of an anthracene structure and porphyrins structure, base Nji ether to dendron An insulating residue having a structure or a benzyl ether structure in which an amine is added to a terminal group;
The liquid crystal display device, wherein the dendritic polymer has a self-organized structure by noncovalent interaction via the dendron.   The liquid crystal display element according to claim 9, wherein the liquid crystal layer is in direct contact with the first organic layer.   The liquid crystal display element according to claim 10, wherein the first organic layer is not subjected to an alignment treatment.   The liquid crystal display element according to claim 7, wherein the first organic layer includes a dopant.

Images