JP5902039B2 - Liquid crystal element, liquid crystal display device - Google Patents

Description

The present invention relates to a liquid crystal composition, a liquid crystal element, a liquid crystal display device, and a manufacturing method thereof.

In recent years, liquid crystals have been applied to various devices, and particularly liquid crystal display devices (liquid crystal displays) having thin and light features are used in displays in a wide range of fields.

In order to enable a larger and higher-definition display screen, an increase in response speed of liquid crystal is required and development is underway (see, for example, Patent Document 1).

As a liquid crystal display mode capable of high-speed response, there is a display mode using a liquid crystal exhibiting a blue phase. In the mode using a liquid crystal that exhibits a blue phase, a high-speed response is achieved, an alignment film is unnecessary, and a wide viewing angle is possible. 2).

JP 2008-303381 A International Publication No. 2005-090520

An object is to provide a novel liquid crystal composition with suppressed hysteresis that can be used in various liquid crystal devices.

An object is to provide a liquid crystal element and a liquid crystal display device with high display quality by using the novel liquid crystal composition.

One aspect of the present invention includes a polymerizable monomer represented by the following general formula (G1) in a proportion of 6% by weight or less based on the total weight, and a nematic liquid crystal, a chiral agent, and a polymerization initiator. The present invention provides a liquid crystal composition which is formed by polymerizing a polymerizable monomer and exhibits a blue phase having a ΔV ₅₀ which is an index representing hysteresis of less than 1 V.

In general formula (G1), n and m are integers of 10 to 20, and n = m.

Another aspect of the present invention is a liquid crystal composition having the above structure, in which n and m are even numbers in the general formula (G1).

One embodiment of the present invention provides a liquid crystal element, a liquid crystal display device, or an electronic device using the above liquid crystal composition.

One aspect of the present invention includes a polymer having a plurality of units represented by the following general formula (G2), a nematic liquid crystal, and a chiral agent, and ΔV _50, which is an index representing hysteresis, is less than 1 V and exhibits a blue phase. The liquid crystal composition. The liquid crystal composition may contain a polymerization initiator.

In general formula (G2), n and m are integers of 10 to 20, and n = m.

Another embodiment of the present invention is a liquid crystal composition having the above structure, in which n and m are even numbers in the general formula (G2).

One embodiment of the present invention provides a liquid crystal element, a liquid crystal display device, or an electronic device using the above liquid crystal composition.

The hysteresis in this specification is represented by the difference between the measurement of the rising voltage and the measurement of the falling voltage in the voltage-transmittance characteristics (VT characteristics) of the liquid crystal composition subjected to the polymer stabilization treatment. Note that ΔV ₅₀ , which is an index representing hysteresis, is a voltage difference at which the normalized transmittance is 50% at the time of rising voltage measurement and at the time of falling voltage measurement. The voltage at which the normalized transmittance is 100% is the saturation voltage V ₁₀₀ . The cause of the hysteresis is due to the structural distortion of the liquid crystal composition.

One aspect of the present invention includes a polymer having a plurality of units represented by the general formula (G2), a nematic liquid crystal, and a chiral agent, and ΔV ₅₀ that is an index representing hysteresis is less than 1 V and develops a blue phase. A liquid crystal composition with suppressed hysteresis can be provided.

In addition, a liquid crystal element having a high display quality and a liquid crystal display device using the liquid crystal composition can be provided.

The conceptual diagram explaining a liquid-crystal composition. 8A and 8B illustrate one embodiment of a liquid crystal display device. 3A and 3B each illustrate one embodiment of an electrode structure of a liquid crystal display device. FIG. 6 illustrates a liquid crystal display module. 10A and 10B each illustrate an electronic device. FIG. 9 shows hysteresis characteristics of a liquid crystal element and a comparative liquid crystal element. View for explaining a method of measuring the [Delta] V ₅₀ is an index representing the hysteresis characteristics. ¹ H NMR chart of RM-O10. The figure which shows the absorption spectrum of RM-O10.

Embodiments will be described in detail with reference to the drawings. However, it is not limited to the following description, and it will be easily understood by those skilled in the art that modes and details can be variously changed without departing from the spirit and scope of the invention. Therefore, the present invention is not construed as being limited to the description of the embodiments below. Note that in the structures described below, the same portions or portions having similar functions are denoted by the same reference numerals in different drawings, and description thereof is not repeated.

In addition, the ordinal numbers attached as the first, second, or third are used for convenience, and do not indicate the process order or the stacking order. In addition, a specific name is not shown as a matter for specifying the invention in this specification.

(Embodiment 1)
A liquid crystal composition according to one embodiment of the present invention, and a liquid crystal element or a liquid crystal display device using the liquid crystal composition will be described with reference to FIGS. 1A and 1B are cross-sectional views of a liquid crystal element or a liquid crystal display device.

A liquid crystal composition according to one aspect of the present invention includes a polymerizable monomer represented by the general formula (G1) in a ratio of 6% by weight or less based on the total weight, and uses a nematic liquid crystal, a chiral agent, and a polymerization initiator. , A liquid crystal composition formed by polymerizing a polymerizable monomer with a polymerization initiator and exhibiting a blue phase having a ΔV ₅₀ that is an index representing hysteresis of less than 1V.

In general formula (G1), n and m are integers of 10 to 20, and n = m.

The liquid crystal composition according to one embodiment of the present invention is the liquid crystal composition having the above structure, in which n and m are even numbers in the general formula (G1).

Specific examples of the polymerizable monomer represented by the general formula (G1) include polymerizable monomers represented by structural formulas (110) to (120). However, the present invention is not limited to these.

The liquid crystal composition according to one aspect of the present invention includes a polymer having a plurality of units represented by the general formula (G2), a nematic liquid crystal, and a chiral agent, and ΔV ₅₀ that is an index representing hysteresis is less than 1 V, A liquid crystal composition exhibiting a blue phase.

In general formula (G2), n and m are integers of 10 to 20, and n = m.

The liquid crystal composition according to one embodiment of the present invention is the liquid crystal display device having the above structure, in which n and m are even numbers in the general formula (G2).

Specific examples of the polymer having a plurality of units represented by the general formula (G2) include polymers having a plurality of units represented by the structural formulas (210) to (220). However, the present invention is not limited to these.

As a method for synthesizing the polymerizable monomer represented by General Formula (G1) contained in the liquid crystalline composition according to one aspect of the present invention, various reactions can be applied.

The nematic liquid crystal is not particularly limited and is a biphenyl compound, a terphenyl compound, a phenylcyclohexyl compound, a biphenylcyclohexyl compound, a phenylbicyclohexyl compound, a phenylbenzoate compound, a cyclohexylphenylbenzoate compound, a phenylbenzoate. Acid phenyl compounds, bicyclohexylcarboxylic acid phenyl compounds, azomethine compounds, azo compounds, and azooxy compounds, stilbene compounds, bicyclohexyl compounds, phenylpyrimidine compounds, biphenylpyrimidine compounds, pyrimidine compounds, and And biphenylethyne compounds.

The chiral agent is used to induce twist of the liquid crystal composition, to align the liquid crystal composition in a spiral structure and to develop a blue phase. The chiral agent is a compound having an asymmetric center, and a compound having a good compatibility with the liquid crystal composition and a strong twisting power is used. Further, the chiral agent is an optically active substance, and the higher the optical purity, the more preferable it is 99% or more.

Since the blue phase is optically isotropic, it does not depend on the viewing angle, and it is not necessary to form an alignment film, so that the quality of the display image can be improved and the cost can be reduced.

In the liquid crystal composition containing the polymerizable monomer represented by the general formula (G1), the nematic liquid crystal, the chiral agent, and the polymerization initiator, the treatment of polymerizing the polymerizable monomer with the polymerization initiator allows the blue phase Since the temperature range for expression can be expanded, the treatment can be referred to as polymer stabilization treatment.

The liquid crystal composition according to one embodiment of the present invention includes a polymer including a plurality of units represented by General Formula (G2). The liquid crystal composition has suppressed hysteresis. By using the liquid crystal composition, high display quality of a liquid crystal element, a liquid crystal display device, an electronic device, or the like can be achieved. Note that the liquid crystal composition according to one embodiment of the present invention can also be suitably used for an optical device that does not have a display function such as an optical shutter.

A plurality of polymerizable monomers may be used, and other polymerizable monomers may be used in addition to the polymerizable monomer represented by the general formula (G1).

Examples of the polymerizable monomer include a thermopolymerizable (thermosetting) monomer that undergoes polymerization by heat, a photopolymerizable (photocurable) monomer that undergoes polymerization by light, or a polymerization that undergoes polymerization by heat and light. A monomer can be used. In addition, a polymerization initiator is added to the liquid crystal composition.

The polymerizable monomer may be a monofunctional monomer such as acrylate or methacrylate, may be a polyfunctional monomer such as diacrylate, triacrylate, dimethacrylate, or trimethacrylate, or may be a mixture of these. Further, it may be liquid crystalline or non-liquid crystalline, and both may be mixed.

The polymerization initiator may be a radical polymerization initiator that generates radicals by light irradiation, an acid generator that generates acid, or a base generator that generates a base. Since the polymerizable monomer represented by the general formula (G1) is a photopolymerizable monomer, a photopolymerization initiator is used.

A photopolymerization initiator is added to a liquid crystal composition containing a polymerizable monomer represented by the general formula (G1), which is a photopolymerizable monomer, and the polymerizable monomer represented by the general formula (G1) and photopolymerization Polymer stabilization treatment can be performed by irradiating light having a wavelength at which the initiator reacts.

The polymer stabilization treatment may be performed on a liquid crystal composition exhibiting an isotropic phase, or may be performed on a liquid crystal composition exhibiting a blue phase by controlling temperature. The temperature at which the phase transitions from the blue phase to the isotropic phase when the temperature rises or the temperature at which the phase transition from the isotropic phase to the blue phase when the temperature falls is called the phase transition temperature between the blue phase and the isotropic phase. As an example of polymer stabilization treatment, after heating the liquid crystal composition to which the photopolymerizable monomer has been added to the isotropic phase, the temperature is gradually lowered to the blue phase to maintain the temperature at which the blue phase appears. In this state, light irradiation can be performed.

Examples of a liquid crystal element and a liquid crystal display device according to one embodiment of the present invention are illustrated in FIGS.

A liquid crystal element according to one embodiment of the present invention includes a polymer having a plurality of units represented by the general formula (G2) between at least a pair of electrode layers (a pixel electrode layer 230 and a common electrode layer 232 having different potentials), a nematic liquid crystal, It has a liquid crystal composition 208 that contains a chiral agent and a polymerization initiator, has an ΔV ₅₀ that is an indicator of hysteresis, of less than 1 V, and develops a blue phase.

The liquid crystal composition 208 contains a polymerizable monomer represented by the general formula (G1) in a proportion of 6% by weight or less based on the total weight, and uses a nematic liquid crystal, a chiral agent, and a polymerization initiator. A liquid crystal composition that is formed by polymerizing a polymerizable monomer and exhibits a blue phase having an ΔV ₅₀ that is an index representing hysteresis of less than 1 V is used.

1A and 1B illustrate a liquid crystal display device in which a first substrate 200 and a second substrate 201 are arranged to face each other with a liquid crystal composition 208 interposed therebetween. 1A and 1B is an example in which the arrangement of the pixel electrode layer 230 and the common electrode layer 232 with respect to the liquid crystal composition 208 is different.

In the liquid crystal element and the liquid crystal display device in FIG. 1A, the pixel electrode layer 230 and the common electrode layer 232 are provided adjacent to each other between the first substrate 200 and the liquid crystal composition 208. In the structure of FIG. 1A, a method is used in which an electric field that is substantially parallel to the substrate (that is, a horizontal direction) is generated and liquid crystal molecules are moved in a plane parallel to the substrate to control gradation. Can do.

Such a structure in FIG. 1A can be preferably applied to the case where the liquid crystal composition 208 that expresses the blue phase, which is the liquid crystal composition according to an embodiment of the present invention, is used.

A liquid crystal is controlled by forming an electric field between the pixel electrode layer 230 and the common electrode layer 232. Since a horizontal electric field is formed in the liquid crystal, the liquid crystal molecules can be controlled using the electric field. Since the liquid crystal composition that exhibits a blue phase can respond at high speed, the performance of the liquid crystal element and the liquid crystal display device can be improved.

For example, since a high-speed response is possible, an RGB light emitting diode (LED) or the like is arranged in the backlight device, and a continuous additive color mixing method (field sequential method) in which color display is performed by time division, or for left eye by time division. The present invention can be suitably applied to a three-dimensional display method using a shutter glasses method in which images and right-eye images are alternately viewed.

In the liquid crystal element and the liquid crystal display device in FIG. 1B, the pixel electrode layer 230 is provided on the first substrate 200 side and the common electrode layer 232 is provided on the second substrate 201 side with the liquid crystal composition 208 interposed therebetween. . With the structure in FIG. 1B, a method can be used in which a gray scale is controlled by generating an electric field substantially perpendicular to a substrate and moving liquid crystal molecules in a plane perpendicular to the substrate. Further, an alignment film 202 a and an alignment film 202 b may be provided between the liquid crystal composition 208 and the pixel electrode layer 230 and the common electrode layer 232. The liquid crystal composition according to one embodiment of the present invention can be used for liquid crystal elements with various structures and liquid crystal display devices with various display modes.

The distance between the pixel electrode layer 230 adjacent to the liquid crystal composition 208 and the common electrode layer 232 is determined by applying a predetermined voltage to the pixel electrode layer 230 and the common electrode layer 232, respectively. It is a distance to which the liquid crystal of the liquid crystal composition 208 interposed between the layers 232 responds. The voltage to be applied is appropriately controlled according to the distance.

The maximum value of the thickness (film thickness) of the liquid crystal composition 208 is preferably 1 μm or more and 20 μm or less.

As a method for forming the liquid crystal composition 208, a dispensing method (a dropping method) or an injection method in which liquid crystal is injected using a capillary phenomenon after the first substrate 200 and the second substrate 201 are bonded to each other is used. Can do.

Although not shown in FIGS. 1A and 1B, an optical film such as a polarizing plate, a retardation plate, and an antireflection film is provided as appropriate. For example, circularly polarized light using a polarizing plate and a retardation plate may be used. Further, a backlight or the like can be used as the light source.

In this specification, a substrate on which a semiconductor element (for example, a transistor) or a pixel electrode layer is formed is referred to as an element substrate (first substrate), and a substrate facing the element substrate with a liquid crystal composition interposed therebetween is a counter substrate. (Second substrate).

As a liquid crystal display device according to one embodiment of the present invention, a transmissive liquid crystal display device that performs display by transmitting light from a light source, a reflective liquid crystal display device that performs display by reflecting incident light, or a transmissive liquid crystal display device A transflective liquid crystal display device having both a reflection type and a reflection type can be provided.

In the case of a transmissive liquid crystal display device, a pixel electrode layer, a common electrode layer, a first substrate, a second substrate, other insulating films, a conductive film, and the like that exist in a pixel region through which light is transmitted are in a visible light wavelength region It is made translucent with respect to the light. In the liquid crystal display device having the structure of FIG. 1A, the pixel electrode layer and the common electrode layer are preferably light-transmitting. However, in the case of having an opening pattern, a non-light-transmitting material such as a metal film is used depending on the shape. Also good.

On the other hand, in the case of a reflective liquid crystal display device, a reflective member (such as a reflective film or substrate) that reflects light transmitted through the liquid crystal composition is provided on the side opposite to the viewing side with respect to the liquid crystal composition. That's fine. Therefore, the light-transmitting substrate, the insulating film, and the conductive film which are provided from the viewing side to the reflective member have a light-transmitting property with respect to light in the visible wavelength region. In this specification, translucency refers to a property of transmitting at least light in the visible wavelength region. In the liquid crystal display device having the structure of FIG. 1B, the pixel electrode layer or the common electrode layer on the side opposite to the viewing side can be made reflective and used as a reflective member.

The pixel electrode layer 230 and the common electrode layer 232 include indium tin oxide, a conductive material in which zinc oxide is mixed with indium oxide, a conductive material in which silicon oxide is mixed in indium oxide, indium oxide containing organic indium, organic tin, and tungsten oxide. Indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, graphene, tungsten, molybdenum, zirconium, hafnium, vanadium, niobium, tantalum, chromium, cobalt, nickel , Titanium, platinum, aluminum, copper, silver and other metals, alloys thereof, or metal nitrides thereof, or one or more of them can be used.

As the first substrate 200 and the second substrate 201, a glass substrate such as barium borosilicate glass or alumino borosilicate glass, a quartz substrate, a plastic substrate, or the like can be used. In the case of a reflective liquid crystal display device, a metal substrate such as an aluminum substrate or a stainless steel substrate may be used as the substrate opposite to the viewing side.

As described above, a liquid crystal composition, a liquid crystal display element, and a liquid crystal display device having high display quality can be provided as the liquid crystal composition, the liquid crystal display element, and the liquid crystal display device according to an embodiment of the present invention.

This embodiment can be implemented in appropriate combination with the structures described in the other embodiments.

(Embodiment 2)
As a liquid crystal display device according to one embodiment of the present invention, a passive matrix liquid crystal display device and an active matrix liquid crystal display device can be provided. In this embodiment, an example of an active matrix liquid crystal display device according to one embodiment of the present invention will be described with reference to FIGS.

FIG. 2A is a plan view of the liquid crystal display device and shows one pixel. FIG. 2B is a cross-sectional view taken along line X1-X2 in FIG.

In FIG. 2A, a plurality of source wiring layers (including the wiring layer 405a) are arranged in parallel to each other (extending in the vertical direction in the drawing) and separated from each other. The plurality of gate wiring layers (including the gate electrode layer 401) extend in a direction substantially orthogonal to the source wiring layer (the left-right direction in the drawing) and are arranged so as to be separated from each other. The common wiring layer 408 is disposed at a position adjacent to each of the plurality of gate wiring layers, and extends in a direction substantially parallel to the gate wiring layer, that is, a direction substantially orthogonal to the source wiring layer (the left-right direction in the drawing). ing. A substantially rectangular space is surrounded by the source wiring layer, the common wiring layer 408, and the gate wiring layer, and the pixel electrode layer and the common electrode layer of the liquid crystal display device are disposed in this space. The transistor 420 for driving the pixel electrode layer is arranged at the upper left corner in the drawing. A plurality of pixel electrode layers and transistors are arranged in a matrix.

In the liquid crystal display device in FIG. 2, the first electrode layer 447 electrically connected to the transistor 420 functions as a pixel electrode layer, and the second electrode layer 446 electrically connected to the common wiring layer 408 is a common electrode layer. Function as. Note that a capacitor is formed by the first electrode layer and the common wiring layer. Although the common electrode layer can be operated in a floating state (electrically isolated state), it should be set to a level at which no flicker occurs near a fixed potential, preferably a common potential (intermediate potential of image signals sent as data). May be.

A method can be used in which an electric field substantially parallel (that is, in a horizontal direction) is generated on the substrate and liquid crystal molecules are moved in a plane parallel to the substrate to control gradation. As such a system, an electrode configuration used in the IPS mode as shown in FIGS. 2 and 3 can be applied.

The horizontal electric field mode shown in the IPS mode or the like includes a first electrode layer (for example, a pixel electrode layer whose voltage is controlled for each pixel) and a second electrode layer (for example, all pixels) having an opening pattern below the liquid crystal composition. A common electrode layer to which a common voltage is supplied. Accordingly, a first electrode layer 447 and a second electrode layer 446, one of which is a pixel electrode layer and the other is a common electrode layer, are formed over the first substrate 441, and at least the first electrode layer and the second electrode layer 446 are formed. One of the two electrode layers is formed on the insulating film. The first electrode layer 447 and the second electrode layer 446 have various opening patterns instead of a planar shape, and include bent portions and branched comb-teeth shapes. Since the first electrode layer 447 and the second electrode layer 446 generate an electric field between the electrodes, an arrangement with the same shape and completely overlapping is avoided.

Alternatively, an electrode structure used in an FFS mode may be used as the first electrode layer 447 and the second electrode layer 446. The transverse electric field mode shown in the FFS mode is a first electrode layer having an opening pattern below the liquid crystal composition (for example, a pixel electrode layer in which voltage is controlled for each pixel) and a flat plate below the opening pattern. A second electrode layer (for example, a common electrode layer to which a common voltage is supplied to all pixels) is disposed. In this case, a first electrode layer 447 and a second electrode layer 446 are formed over the first substrate 441, one of which is a pixel electrode layer and the other is a common electrode layer. The layers are arranged so as to be stacked with an insulating film (or an interlayer insulating layer) interposed therebetween. One of the pixel electrode layer and the common electrode layer is formed below the insulating film (or interlayer insulating layer) and has a flat plate shape, and the other is formed above the insulating film (or interlayer insulating layer), and It has various opening patterns and has a shape including a bent portion and a branched comb-teeth shape. Since the first electrode layer 447 and the second electrode layer 446 generate an electric field between the electrodes, an arrangement with the same shape and completely overlapping is avoided.

The liquid crystal composition 444 includes a polymer having a plurality of units represented by the general formula (G2) described in Embodiment 1, a nematic liquid crystal, and a chiral agent, and ΔV ₅₀ that is an index representing hysteresis is less than 1V. Yes, a liquid crystal composition exhibiting a blue phase is used. Note that the liquid crystal composition 444 may include a polymerization initiator. In this embodiment, the liquid crystal composition 444 includes a polymerizable monomer represented by the general formula (G1) in a proportion of 6% by weight or less based on the total weight, and uses a nematic liquid crystal, a chiral agent, and a polymerization initiator. It can be formed using a liquid crystal composition which is formed by polymerizing a polymerizable monomer with a polymerization initiator and expresses a blue phase having a ΔV ₅₀ which is an index representing hysteresis of less than 1V. By a polymer stabilization process that is a polymerization process, the liquid crystal element and the liquid crystal display device are provided in a state in which a blue phase is developed (a state in which a blue phase is exhibited or a state in which a blue phase is exhibited).

By forming an electric field between the first electrode layer 447 that is a pixel electrode layer and the second electrode layer 446 that is a common electrode layer, the liquid crystal of the liquid crystal composition 444 is controlled. Since a horizontal electric field is formed in the liquid crystal, the liquid crystal molecules can be controlled using the electric field. Since the liquid crystal molecules aligned to exhibit a blue phase can be controlled in a direction parallel to the substrate, the viewing angle is widened.

Another example of the first electrode layer 447 and the second electrode layer 446 is illustrated in FIG. As shown in the top views of FIGS. 3A to 3D, the first electrode layers 447a to 447d and the second electrode layers 446a to 446d are formed to be staggered, and FIG. In FIG. 3B, the first electrode layer 447a and the second electrode layer 446a have wavy shapes, and in FIG. 3B, the first electrode layer 447b and the second electrode layer 446b have concentric openings. In FIG. 3C, the first electrode layer 447c and the second electrode layer 446c are comb-shaped and partly overlapped. In FIG. 3D, the first electrode layer 447d is formed. The second electrode layer 446d is comb-shaped and has a shape in which the electrodes are engaged with each other. 3A to 3C, when the first electrode layers 447a, 447b, and 447c overlap with the second electrode layers 446a, 446b, and 446c, the first electrode layer 447 and An insulating film is formed between the second electrode layer 446 and a first electrode layer 447 and a second electrode layer 446 are formed over different films.

Note that the first electrode layer 447 and the second electrode layer 446 have a shape having an opening pattern, and thus are illustrated as a plurality of divided electrode layers in the cross-sectional view of FIG. The same applies to other drawings in this specification.

The transistor 420 is an inverted staggered thin film transistor which is formed over a first substrate 441 which is a substrate having an insulating surface and serves as a gate electrode layer 401, a gate insulating layer 402, a semiconductor layer 403, and a source electrode layer or a drain electrode layer. It includes wiring layers 405a and 405b that function.

There is no particular limitation on the structure of the transistor that can be applied to the liquid crystal display device disclosed in this specification. For example, a staggered type or a planar type with a top gate structure or a bottom gate structure can be used. The transistor may have a single gate structure in which one channel formation region is formed, a double gate structure in which two channel formation regions are formed, or a triple gate structure in which three channel formation regions are formed. Alternatively, a dual gate type having two gate electrode layers arranged above and below the channel region with a gate insulating layer interposed therebetween may be used.

An insulating film 407 and an insulating film 409 which cover the transistor 420 and are in contact with the semiconductor layer 403 are provided, and an interlayer film 413 is stacked over the insulating film 409.

The formation method of the interlayer film 413 is not particularly limited, and depending on the material, spin coating, dipping, spray coating, droplet discharge method (inkjet method, etc.), printing method (screen printing, offset printing, etc.), roll coating A curtain coat, a knife coat or the like can be used.

The first substrate 441 and the second substrate 442 which is a counter substrate are fixed to each other with a sealant with the liquid crystal composition 444 interposed therebetween. As a method for forming the liquid crystal composition 444, a dispenser method (a dropping method) or an injection method in which liquid crystal is injected using a capillary phenomenon after the first substrate 441 and the second substrate 442 are bonded to each other is used. Can do.

As the sealing material, it is typically preferable to use a visible light curable resin, an ultraviolet curable resin, or a thermosetting resin. Typically, an acrylic resin, an epoxy resin, an amine resin, or the like can be used. Further, it may contain a light (typically ultraviolet) polymerization initiator, a thermosetting agent, a filler, and a coupling agent.

In the present embodiment, since a polymerizable monomer having photopolymerizability is used as the polymerizable monomer represented by the general formula (G1), the photopolymerization initiator is used as the polymerization initiator, and the polymer is stabilized by light irradiation. Processing can be performed.

The liquid crystal composition is filled in the gap between the first substrate 441 and the second substrate 442 and then irradiated with light to perform polymer stabilization treatment, whereby the liquid crystal composition 444 is formed. The light is light having a wavelength at which the polymerizable monomer represented by the general formula (G1) contained in the liquid crystal composition used as the liquid crystal composition 444 and the photopolymerization initiator react. By this polymer stabilization treatment by light irradiation, the temperature range in which the liquid crystal composition 444 develops a blue phase can be widely improved.

The sealing material may be cured by a light irradiation process of polymer stabilization treatment, for example, when a photocurable resin such as ultraviolet rays is used for the sealing material and a liquid crystal composition is formed by a dropping method.

In this embodiment, a polarizing plate 443a is provided outside the first substrate 441 (on the side opposite to the liquid crystal composition 444), and a polarizing plate 443b is provided outside the second substrate 442 (on the side opposite to the liquid crystal composition 444). . In addition to the polarizing plate, an optical film such as a retardation plate or an antireflection film may be provided. For example, circularly polarized light using a polarizing plate and a retardation plate may be used. Through the above steps, a liquid crystal display device can be completed.

In the case where a plurality of liquid crystal display devices are manufactured using a large substrate (so-called multi-cavity), the dividing step can be performed before the polymer stabilization treatment or before the polarizing plate is provided. Considering the influence on the liquid crystal composition by the dividing step (alignment disorder due to force applied during the dividing step), it is preferable that the first substrate and the second substrate are bonded together and before the polymer stabilization treatment. .

Although not shown, a backlight, a sidelight, or the like may be used as the light source. The light source is irradiated so as to transmit from the first substrate 441 side which is an element substrate to the second substrate 442 which is the viewing side.

The first electrode layer 447 and the second electrode layer 446 include indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, A light-transmitting conductive material such as indium tin oxide, indium zinc oxide, indium tin oxide to which silicon oxide is added, or graphene can be used.

The first electrode layer 447 and the second electrode layer 446 are formed using metals such as tungsten, molybdenum, zirconium, hafnium, vanadium, niobium, tantalum, chromium, cobalt, nickel, titanium, platinum, aluminum, copper, and silver, Alternatively, an alloy thereof, or a metal nitride thereof can be used by using one or more kinds.

Alternatively, the first electrode layer 447 and the second electrode layer 446 can be formed using a conductive composition including a conductive high molecule (also referred to as a conductive polymer).

An insulating film serving as a base film may be provided between the first substrate 441 and the gate electrode layer 401. The base film has a function of preventing diffusion of an impurity element from the first substrate 441 and is formed using one or a plurality of films selected from a silicon nitride film, a silicon oxide film, a silicon nitride oxide film, and a silicon oxynitride film. A single layer or a stacked structure can be used. The material of the gate electrode layer 401 is a single layer or a stacked layer using a metal material such as molybdenum, titanium, chromium, tantalum, tungsten, aluminum, copper, neodymium, or scandium, or an alloy material containing these as a main component. can do. As the gate electrode layer 401, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus, or a silicide film such as nickel silicide may be used. When a light-shielding conductive film is used for the gate electrode layer 401, light from the backlight (light which enters from the first substrate 441) can be prevented from entering the semiconductor layer 403.

For example, the two-layer structure of the gate electrode layer 401 includes a two-layer structure in which a molybdenum layer is stacked over an aluminum layer, a two-layer structure in which a molybdenum layer is stacked over a copper layer, or a copper layer. A two-layer structure in which a titanium nitride layer or a tantalum nitride layer is stacked, or a two-layer structure in which a titanium nitride layer and a molybdenum layer are stacked is preferable. The three-layer structure is preferably a stacked structure in which a tungsten layer or a tungsten nitride layer, an aluminum / silicon alloy layer or an aluminum / titanium alloy layer, and a titanium nitride layer or a titanium layer are stacked.

The gate insulating layer 402 is formed using a silicon oxide film, a gallium oxide film, an aluminum oxide film, a silicon nitride film, a silicon oxynitride film, an aluminum oxynitride film, a silicon nitride oxide film, or the like by a plasma CVD method, a sputtering method, or the like. Can be formed. Alternatively, as the material of the gate insulating layer 402, hafnium oxide, yttrium oxide, lanthanum oxide, hafnium silicate (HfSi _x O _y (x> 0, y> 0)), hafnium aluminate (HfAl _x O _y (x> 0, y) > 0)), high-k materials such as nitrogen-added hafnium silicate and nitrogen-added hafnium aluminate may be used. The gate leakage current can be reduced by using these high-k materials.

Alternatively, a silicon oxide layer can be formed as the gate insulating layer 402 by a CVD method using an organosilane gas. Examples of the organic silane gas include tetraethoxysilane (TEOS: chemical formula Si (OC ₂ H ₅ ) ₄ ), tetramethylsilane (TMS: chemical formula Si (CH ₃ ) ₄ ), tetramethylcyclotetrasiloxane (TMCTS), octamethylcyclotetra Use of silicon-containing compounds such as siloxane (OMCTS), hexamethyldisilazane (HMDS), triethoxysilane (SiH (OC ₂ H ₅ ) ₃ ), trisdimethylaminosilane (SiH (N (CH ₃ ) ₂ ) ₃ ) Can do. Note that the gate insulating layer 402 may have a single-layer structure or a stacked structure.

The material used for the semiconductor layer 403 is not particularly limited and may be set as appropriate depending on characteristics required for the transistor 420. Examples of materials that can be used for the semiconductor layer 403 are described.

As a material for forming the semiconductor layer 403, an amorphous material (also referred to as an amorphous material) formed by a chemical vapor deposition method using a semiconductor material gas typified by silane or germane or a physical vapor deposition method such as a sputtering method is used. .) A semiconductor, a polycrystalline semiconductor obtained by crystallizing the amorphous semiconductor using light energy or thermal energy, a microcrystalline semiconductor, or the like can be used. The semiconductor layer can be formed by a sputtering method, an LPCVD method, a plasma CVD method, or the like.

A typical example of an amorphous semiconductor is hydrogenated amorphous silicon, and a typical example of a crystalline semiconductor is polysilicon. Polysilicon (polycrystalline silicon) is mainly made of so-called high-temperature polysilicon using polysilicon formed through a process temperature of 800 ° C. or higher as a main material, or polysilicon formed at a process temperature of 600 ° C. or lower. And so-called low-temperature polysilicon, and polysilicon obtained by crystallizing amorphous silicon using an element that promotes crystallization. Needless to say, as described above, a microcrystalline semiconductor or a semiconductor including a crystalline phase in part of a semiconductor layer can be used.

An oxide semiconductor may be used, and the oxide semiconductor preferably contains at least indium (In), particularly In and zinc (Zn). In addition, it is preferable to include gallium (Ga) in addition to the stabilizer for reducing variation in electrical characteristics of the transistor including the oxide. Moreover, it is preferable to have tin (Sn) as a stabilizer. Moreover, it is preferable to have hafnium (Hf) as a stabilizer. Moreover, it is preferable to have aluminum (Al) as a stabilizer. Moreover, it is preferable to have a zirconium (Zr) as a stabilizer.

Other stabilizers include lanthanoids such as lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), and terbium (Tb). , Dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), or lutetium (Lu).

For example, as an oxide semiconductor, indium oxide, tin oxide, zinc oxide, binary metal oxides In—Zn oxide, In—Mg oxide, In—Ga oxide, ternary metal In-Ga-Zn-based oxide (also referred to as IGZO), In-Al-Zn-based oxide, In-Sn-Zn-based oxide, In-Hf-Zn-based oxide, In-La -Zn oxide, In-Ce-Zn oxide, In-Pr-Zn oxide, In-Nd-Zn oxide, In-Sm-Zn oxide, In-Eu-Zn oxide In-Gd-Zn-based oxide, In-Tb-Zn-based oxide, In-Dy-Zn-based oxide, In-Ho-Zn-based oxide, In-Er-Zn-based oxide, In-Tm- Zn-based oxide, In-Yb-Zn-based oxide, In-Lu-Zn-based oxide, four In-Sn-Ga-Zn-based oxides, In-Hf-Ga-Zn-based oxides, In-Al-Ga-Zn-based oxides, and In-Sn-Al-Zn-based oxides that are oxides of the base metal In-Sn-Hf-Zn-based oxides and In-Hf-Al-Zn-based oxides can be used.

Note that here, for example, an In—Ga—Zn-based oxide means an oxide containing In, Ga, and Zn as its main components, and there is no limitation on the ratio of In, Ga, and Zn. Moreover, metal elements other than In, Ga, and Zn may be contained.

Alternatively, a material represented by InMO ₃ (ZnO) _m (m> 0 is satisfied, and m is not an integer) may be used as the oxide semiconductor. Note that M represents one metal element or a plurality of metal elements selected from Ga, Fe, Mn, and Co. Alternatively, a material represented by In ₂ SnO ₅ (ZnO) _n (n> 0 is satisfied, and n is an integer) may be used as the oxide semiconductor.

For example, In: Ga: Zn = 1: 1: 1 (= 1/3: 1/3: 1/3), In: Ga: Zn = 2: 2: 1 (= 2/5: 2/5: 1) / 5), or an In—Ga—Zn-based oxide having an atomic ratio of In: Ga: Zn = 3: 1: 2 (= 1/2: 1/6: 1/3) and oxidation in the vicinity of the composition. Can be used. Alternatively, In: Sn: Zn = 1: 1: 1 (= 1/3: 1/3: 1/3), In: Sn: Zn = 2: 1: 3 (= 1/3: 1/6: 1) / 2) or In: Sn: Zn = 2: 1: 5 (= 1/4: 1/8: 5/8) atomic ratio In—Sn—Zn-based oxide or oxide in the vicinity of the composition Should be used.

However, the oxide semiconductor is not limited thereto, and an oxide semiconductor having an appropriate composition may be used depending on required semiconductor characteristics (mobility, threshold value, variation, and the like). In order to obtain the required semiconductor characteristics, it is preferable that the carrier concentration, impurity concentration, defect density, atomic ratio of metal element to oxygen, interatomic bond distance, density, and the like are appropriate.

Note that for example, the composition of an oxide in which the atomic ratio of In, Ga, and Zn is In: Ga: Zn = a: b: c (a + b + c = 1) has an atomic ratio of In: Ga: Zn = A: B: C (A + B + C = 1) is in the vicinity of the oxide composition, a, b, c are (a−A) ² + (b−B) ² + (c−C) ² ≦ r ² Satisfying. For example, r may be 0.05. The same applies to other oxides.

An oxide semiconductor film is in a single crystal state, a polycrystalline (also referred to as polycrystal) state, an amorphous state, or the like.

Preferably, the oxide semiconductor film is a CAAC-OS (C Axis Crystallized Oxide Semiconductor) film.

The CAAC-OS film is not completely single crystal nor completely amorphous. The CAAC-OS film is an oxide semiconductor film with a crystal-amorphous mixed phase structure where crystal parts are included in an amorphous phase. Note that the crystal part is often large enough to fit in a cube whose one side is less than 100 nm. Further, in the observation image obtained by a transmission electron microscope (TEM), the boundary between the amorphous part and the crystal part included in the CAAC-OS film is not clear. Further, a grain boundary (also referred to as a grain boundary) cannot be confirmed in the CAAC-OS film by TEM. Therefore, in the CAAC-OS film, reduction in electron mobility due to grain boundaries is suppressed.

In the crystal part included in the CAAC-OS film, the c-axis is aligned in a direction parallel to the normal vector of the formation surface of the CAAC-OS film or the normal vector of the surface, and triangular when viewed from the direction perpendicular to the ab plane. It has a shape or hexagonal atomic arrangement, and metal atoms are arranged in layers or metal atoms and oxygen atoms are arranged in layers as viewed from the direction perpendicular to the c-axis. Note that the directions of the a-axis and the b-axis may be different between different crystal parts. In this specification, a simple term “perpendicular” includes a range from 85 ° to 95 °. In addition, a simple term “parallel” includes a range from −5 ° to 5 °.

Note that the distribution of crystal parts in the CAAC-OS film is not necessarily uniform. For example, in the formation process of the CAAC-OS film, when crystal growth is performed from the surface side of the oxide semiconductor film, the ratio of crystal parts in the vicinity of the surface of the oxide semiconductor film is higher in the vicinity of the surface. In addition, when an impurity is added to the CAAC-OS film, the crystal part in a region to which the impurity is added becomes amorphous in some cases.

Since the c-axis of the crystal part included in the CAAC-OS film is aligned in a direction parallel to the normal vector of the formation surface of the CAAC-OS film or the normal vector of the surface, the shape of the CAAC-OS film (formation surface) Depending on the cross-sectional shape of the surface or the cross-sectional shape of the surface). Note that the c-axis direction of the crystal part is in a direction parallel to the normal direction of the surface where the CAAC-OS film is formed or the normal direction of the surface. The crystal part is formed by film formation or by performing crystallization treatment such as heat treatment after film formation.

A transistor including a CAAC-OS film can reduce variation in electrical characteristics due to irradiation with visible light or ultraviolet light. Therefore, the transistor has high reliability.

Note that part of oxygen included in the oxide semiconductor film may be replaced with nitrogen.

Further, in an oxide semiconductor having a crystal part such as a CAAC-OS, defects in a bulk can be further reduced, and mobility higher than that of an oxide semiconductor in an amorphous state can be obtained by increasing surface flatness. . In order to improve the flatness of the surface, it is preferable to form an oxide semiconductor on the flat surface. Specifically, the average surface roughness (Ra) is 1 nm or less, preferably 0.3 nm or less, more preferably Is preferably formed on a surface of 0.1 nm or less.

In the manufacturing process of the semiconductor layer and the wiring layer, an etching process is used to process the thin film into a desired shape. For the etching process, dry etching or wet etching can be used.

Etching conditions (such as an etchant, etching time, and temperature) are adjusted as appropriate depending on the material so that the material can be etched into a desired shape.

As a material of the wiring layers 405a and 405b functioning as the source electrode layer or the drain electrode layer, an element selected from aluminum, chromium, tantalum, titanium, molybdenum, tungsten, or an alloy containing the above-described element as a component, or the above-described element is used. Examples include alloy films combining elements. In the case where heat treatment is performed, it is preferable that the conductive film has heat resistance enough to withstand the heat treatment. For example, aluminum alone is inferior in heat resistance and has problems such as being easily corroded, so it is formed in combination with a heat resistant conductive material. As a heat-resistant conductive material combined with aluminum, an element selected from titanium, tantalum, tungsten, molybdenum, chromium, neodymium, scandium, or an alloy containing the above elements as a component, or an alloy film combining the above elements, Alternatively, a nitride containing the above-described element as a component is formed.

The gate insulating layer 402, the semiconductor layer 403, and the wiring layers 405a and 405b functioning as a source electrode layer or a drain electrode layer may be continuously formed without being exposed to the air. By continuously forming a film without exposure to the atmosphere, each stacked interface can be formed without being contaminated by atmospheric components or contaminating impurity elements floating in the atmosphere, so that variation in transistor characteristics can be reduced. it can.

Note that the semiconductor layer 403 is a semiconductor layer which is etched only partly and has a groove (concave portion).

As the insulating film 407 and the insulating film 409 which cover the transistor 420, an inorganic insulating film or an organic insulating film formed by a dry method or a wet method can be used. For example, a silicon nitride film, a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, a tantalum oxide film, or the like obtained by a CVD method, a sputtering method, or the like can be used. Alternatively, an organic material such as polyimide, acrylic, benzocyclobutene resin, polyamide, or epoxy can be used. In addition to the above organic materials, a low dielectric constant material (low-k material), a siloxane resin, PSG (phosphosilicate glass), BPSG (boron phosphosilicate glass), or the like can be used. Alternatively, a gallium oxide film may be used as the insulating film 407.

Note that the siloxane-based resin corresponds to a resin including a Si—O—Si bond formed using a siloxane-based material as a starting material. Siloxane resins may use organic groups (for example, alkyl groups and aryl groups) and fluoro groups as substituents. The organic group may have a fluoro group. A siloxane-based resin can be used as the insulating film 407 by forming a film by a coating method and baking it.

Note that the insulating film 407 and the insulating film 409 may be formed by stacking a plurality of insulating films formed using these materials. For example, an organic resin film may be stacked on the inorganic insulating film.

As described above, a liquid crystal composition and a liquid crystal display device having high display quality can be provided as the liquid crystal composition and the liquid crystal display device according to an embodiment of the present invention.

This embodiment can be implemented in appropriate combination with the structures described in the other embodiments.

(Embodiment 3)
A transistor is manufactured, and a liquid crystal display device having a display function can be manufactured using the transistor in a pixel portion and further in a driver circuit. In addition, part or the whole of the driver circuit can be formed over the same substrate as the pixel portion by using a transistor, so that a system-on-panel can be formed.

A liquid crystal display device includes a liquid crystal element (also referred to as a liquid crystal display element) as a display element.

Further, the liquid crystal display device includes a panel in which the display element is sealed, and a module in which an IC or the like including a controller is mounted on the panel. Furthermore, in the process of manufacturing the liquid crystal display device, an element substrate corresponding to one embodiment before the display element is completed, the element substrate includes means for supplying current to the display element in each of the plurality of pixels. . Specifically, the element substrate may be in a state where only the pixel electrode of the display element is formed, or after the conductive film to be the pixel electrode is formed, the pixel electrode is formed by etching. The previous state may be used, and all forms are applicable.

Note that a liquid crystal display device in this specification means an image display device, a display device, or a light source (including a lighting device). In addition, a connector, for example, a module with a FPC (Flexible Printed Circuit) or TAB (Tape Automated Bonding) tape or TCP (Tape Carrier Package), a module with a printed wiring board at the end of a TAB tape or TCP, or a display All modules in which an IC (integrated circuit) is directly mounted on the element by a COG (Chip On Glass) method are also included in the liquid crystal display device.

The appearance and a cross section of a liquid crystal display panel, which is an embodiment of a liquid crystal display device, will be described with reference to FIGS. 4A1 and 4A2 illustrate a panel in which the transistors 4010 and 4011 and the liquid crystal element 4013 formed over the first substrate 4001 are sealed with a sealant 4005 between the second substrate 4006 and FIGS. 4B is a top view, and FIG. 4B corresponds to a cross-sectional view taken along line MN in FIGS. 4A1 and 4A2.

A sealant 4005 is provided so as to surround the pixel portion 4002 provided over the first substrate 4001 and the scan line driver circuit 4004. A second substrate 4006 is provided over the pixel portion 4002 and the scan line driver circuit 4004. Therefore, the pixel portion 4002 and the scan line driver circuit 4004 are sealed together with the liquid crystal composition 4008 by the first substrate 4001, the sealant 4005, and the second substrate 4006.

4A1 is formed using a single crystal semiconductor film or a polycrystalline semiconductor film over a separately prepared substrate in a region different from the region surrounded by the sealant 4005 over the first substrate 4001. A signal line driver circuit 4003 is mounted. 4A2 illustrates an example in which part of the signal line driver circuit is formed using a transistor provided over the first substrate 4001. The signal line driver circuit 4003b is formed over the first substrate 4001. In addition, a signal line driver circuit 4003a formed of a single crystal semiconductor film or a polycrystalline semiconductor film is mounted on a separately prepared substrate.

Note that a connection method of a driver circuit which is separately formed is not particularly limited, and a COG method, a wire bonding method, a TAB method, or the like can be used. 4A1 illustrates an example in which the signal line driver circuit 4003 is mounted by a COG method, and FIG. 4A2 illustrates an example in which the signal line driver circuit 4003 is mounted by a TAB method.

The pixel portion 4002 and the scan line driver circuit 4004 provided over the first substrate 4001 include a plurality of transistors. In FIG. 4B, the transistor 4010 included in the pixel portion 4002 and the scan line The transistor 4011 included in the driver circuit 4004 is illustrated. An insulating layer 4020 and an interlayer film 4021 are provided over the transistors 4010 and 4011.

The transistors described in any of Embodiments 2 and 3 can be used as the transistors 4010 and 4011.

Alternatively, a conductive layer may be provided over the interlayer film 4021 or the insulating layer 4020 so as to overlap with a channel formation region of the semiconductor layer of the transistor 4011 for the driver circuit. The potential of the conductive layer may be the same as or different from that of the gate electrode layer of the transistor 4011, and the conductive layer can function as a second gate electrode layer. Further, the potential of the conductive layer may be GND, 0 V, or the conductive layer may be in a floating state.

In addition, a pixel electrode layer 4030 and a common electrode layer 4031 are formed over the interlayer film 4021, and the pixel electrode layer 4030 is electrically connected to the transistor 4010. The liquid crystal element 4013 includes a pixel electrode layer 4030, a common electrode layer 4031, and a liquid crystal composition 4008. Note that polarizing plates 4032a and 4032b are provided outside the first substrate 4001 and the second substrate 4006, respectively.

A liquid crystal composition 4008 contains the polymerizable monomer represented by the general formula (G1) described in Embodiment 1 in a proportion of 6% by weight or less based on the total weight, and includes a nematic liquid crystal, a chiral agent, and a polymerization initiator. And a liquid crystal composition that is formed by polymerizing a polymerizable monomer with a polymerization initiator and exhibits a blue phase having an ΔV ₅₀ that is an index representing hysteresis of less than 1 V. For the pixel electrode layer 4030 and the common electrode layer 4031, the structure of the pixel electrode layer and the common electrode layer as described in Embodiment 1 or 2 can be applied.

In this embodiment, the liquid crystal composition 4008 includes a polymer having a plurality of units represented by the general formula (G2) described in Embodiment 1, a nematic liquid crystal, and a chiral agent, and ΔV that is an index representing hysteresis A liquid crystal composition in which ₅₀ is less than 1 V and develops a blue phase is used. The liquid crystal composition 4008 may include a polymerization initiator. A liquid crystal composition 4008 is formed by polymerizing a polymerizable monomer with a polymerization initiator using a liquid crystal composition containing a polymerizable monomer represented by the general formula (G1), a nematic liquid crystal, a chiral agent, and a polymerization initiator. can do. The liquid crystal element and the liquid crystal display device are provided in a state where a blue phase is developed (also referred to as a blue phase or a state showing a blue phase) by polymer stabilization treatment which is a polymerization treatment. Therefore, in this embodiment mode, the pixel electrode layer 4030 and the common electrode layer 4031 have an opening pattern as illustrated in FIG. 1A of Embodiment Mode 1 and FIG. 3 of Embodiment Mode 2.

By forming an electric field between the pixel electrode layer 4030 and the common electrode layer 4031, the liquid crystal of the liquid crystal composition 4008 is controlled. Since a horizontal electric field is formed in the liquid crystal, the liquid crystal molecules can be controlled using the electric field.

Note that the first substrate 4001 and the second substrate 4006 can be formed using light-transmitting glass, plastic, or the like. As the plastic, a PVF (polyvinyl fluoride) film, a polyester film, or an acrylic resin film can be used. Alternatively, a sheet having a structure in which an aluminum foil is sandwiched between PVF films or polyester films, or an FRP (Fiberglass-Reinforced Plastics) plate can be used.

Reference numeral 4035 denotes a columnar spacer obtained by selectively etching the insulating film, and is provided for controlling the film thickness (cell gap) of the liquid crystal composition 4008. A spherical spacer may be used. In a liquid crystal display device using the liquid crystal composition 4008, the cell gap which is the thickness of the liquid crystal composition is preferably 1 μm or more and 20 μm or less. In the present specification, the thickness of the cell gap is the maximum value of the thickness (film thickness) of the liquid crystal composition.

Although FIG. 4 shows an example of a transmissive liquid crystal display device, the present invention can be applied to either a transflective liquid crystal display device or a reflective liquid crystal display device.

4 shows an example in which a polarizing plate is provided on the outer side (viewing side) of the substrate, the polarizing plate may be provided on the inner side of the substrate. What is necessary is just to set suitably according to the material and preparation process conditions of a polarizing plate. Further, a light shielding layer functioning as a black matrix may be provided.

A color filter layer or a light shielding layer may be formed as part of the interlayer film 4021. FIG. 4 illustrates an example in which a light-blocking layer 4034 is provided on the second substrate 4006 side so as to cover the upper portions of the transistors 4010 and 4011. By providing the light-blocking layer 4034, the effects of improving contrast and stabilizing the transistor can be further increased.

A structure covered with an insulating layer 4020 functioning as a protective film of the transistor may be employed, but is not particularly limited.

Note that the protective film is for preventing entry of contaminant impurities such as organic substances, metal substances, and water vapor floating in the atmosphere, and a dense film is preferable. The protective film is formed by a sputtering method using a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a silicon nitride oxide film, an aluminum oxide film, an aluminum nitride film, an aluminum oxynitride film, or an aluminum nitride oxide film, Alternatively, a stacked layer may be formed.

In the case where a light-transmitting insulating layer is further formed as the planarizing insulating film, a heat-resistant organic material such as polyimide, acrylic, benzocyclobutene resin, polyamide, or epoxy can be used. In addition to the above organic materials, a low dielectric constant material (low-k material), a siloxane resin, PSG (phosphosilicate glass), BPSG (boron phosphosilicate glass), or the like can be used. Note that the insulating layer may be formed by stacking a plurality of insulating films formed using these materials.

The method of forming the insulating layer to be stacked is not particularly limited, and depending on the material, sputtering method, spin coating, dipping method, spray coating method, droplet discharge method (inkjet method, etc.), printing method (screen printing, offset) Printing, etc.), roll coat, curtain coat, knife coat and the like.

The pixel electrode layer 4030 and the common electrode layer 4031 include indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium tin oxide, A light-transmitting conductive material such as indium zinc oxide, indium tin oxide to which silicon oxide is added, or graphene can be used.

The pixel electrode layer 4030 and the common electrode layer 4031 are formed using tungsten, molybdenum, zirconium, hafnium, vanadium, niobium, tantalum, chromium, cobalt, nickel, titanium, platinum, aluminum, copper, silver, or an alloy thereof, or The metal nitride can be formed using one or more kinds.

The pixel electrode layer 4030 and the common electrode layer 4031 can be formed using a conductive composition including a conductive high molecule (also referred to as a conductive polymer).

In addition, a variety of signals and potentials are supplied to the signal line driver circuit 4003 which is formed separately, the scan line driver circuit 4004, or the pixel portion 4002 from an FPC 4018.

Further, since the transistor is easily broken by static electricity or the like, it is preferable to provide a protective circuit for protecting the driver circuit over the same substrate for the gate line or the source line. The protection circuit is preferably configured using a non-linear element.

In FIG. 4, the connection terminal electrode 4015 is formed using the same conductive film as the pixel electrode layer 4030, and the terminal electrode 4016 is formed using the same conductive film as the source and drain electrode layers of the transistors 4010 and 4011.

The connection terminal electrode 4015 is electrically connected to a terminal included in the FPC 4018 through an anisotropic conductive film 4019.

FIG. 4 illustrates an example in which the signal line driver circuit 4003 is formed separately and mounted on the first substrate 4001; however, the present invention is not limited to this structure. The scan line driver circuit may be separately formed and then mounted, or only part of the signal line driver circuit or part of the scan line driver circuit may be separately formed and then mounted.

As described above, a liquid crystal composition, a liquid crystal element, and a liquid crystal display device having high display quality can be provided as the liquid crystal composition, the liquid crystal element, and the liquid crystal display device according to an embodiment of the present invention.

This embodiment can be implemented in appropriate combination with the structures described in the other embodiments.

(Embodiment 4)
The liquid crystal display device disclosed in this specification can be applied to a variety of electronic devices (including game machines). Examples of the electronic device include a television device (also referred to as a television or a television receiver), a monitor for a computer, a digital camera, a digital video camera, a digital photo frame, a mobile phone (also referred to as a mobile phone or a mobile phone device). ), Large game machines such as portable game machines, portable information terminals, sound reproducing devices, and pachinko machines.

FIG. 5A illustrates a laptop personal computer, which includes a main body 3001, a housing 3002, a display portion 3003, a keyboard 3004, and the like. By applying the liquid crystal display device described in any of Embodiments 1 to 3 to the display portion 3003, a laptop personal computer with high display quality can be obtained.

FIG. 5B illustrates a personal digital assistant (PDA). A main body 3021 is provided with a display portion 3023, an external interface 3025, operation buttons 3024, and the like. There is a stylus 3022 as an accessory for operation. By applying the liquid crystal display device described in any of Embodiments 1 to 3 to the display portion 3023, a personal digital assistant (PDA) having high display quality can be obtained.

FIG. 5C illustrates an electronic book, which includes two housings, a housing 2701 and a housing 2703. The housing 2701 and the housing 2703 are integrated with a shaft portion 2711 and can be opened / closed using the shaft portion 2711 as an axis. With such a configuration, an operation like a paper book can be performed.

A display portion 2705 and a display portion 2707 are incorporated in the housing 2701 and the housing 2703, respectively. The display unit 2705 and the display unit 2707 may be configured to display a continuous screen or may be configured to display different screens. By adopting a configuration in which different screens are displayed, for example, text is displayed on the right display unit (display unit 2705 in FIG. 5C) and an image is displayed on the left display unit (display unit 2707 in FIG. 5C). Can be displayed. By applying the liquid crystal display device described in any of Embodiments 1 to 3 to the display portion 2705 and the display portion 2707, an electronic book with low power consumption can be provided. In the case where a transflective or reflective liquid crystal display device is used as the display portion 2705, it is expected to be used in a relatively bright situation. Therefore, a solar cell is provided, and power generation by the solar cell and charging with the battery can be performed. You may do it. In addition, when a lithium ion battery is used as a battery, there exists an advantage, such as achieving size reduction.

FIG. 5C illustrates an example in which the housing 2701 is provided with an operation portion and the like. For example, the housing 2701 is provided with a power supply 2721, operation keys 2723, a speaker 2725, and the like. Pages can be turned with the operation keys 2723. Note that a keyboard, a pointing device, or the like may be provided on the same surface as the display portion of the housing. In addition, an external connection terminal (such as an earphone terminal or a USB terminal), a recording medium insertion portion, or the like may be provided on the rear surface or side surface of the housing. Further, the electronic book may have a structure as an electronic dictionary.

Further, the electronic book may have a configuration capable of transmitting and receiving information wirelessly. It is also possible to adopt a configuration in which desired book data or the like is purchased and downloaded from an electronic book server wirelessly.

FIG. 5D illustrates a mobile phone, which includes two housings, a housing 2800 and a housing 2801. The housing 2801 is provided with a display panel 2802, a speaker 2803, a microphone 2804, a pointing device 2806, a camera lens 2807, an external connection terminal 2808, and the like. The housing 2800 is provided with a solar cell 2810 for charging the mobile phone, an external memory slot 2811, and the like. An antenna is incorporated in the housing 2801. By applying the liquid crystal display device described in any of Embodiments 1 to 3 to the display panel 2802, a mobile phone having high display quality can be obtained.

In addition, the display panel 2802 is provided with a touch panel. A plurality of operation keys 2805 that are displayed as images is illustrated by dashed lines in FIG. Note that a booster circuit for boosting the voltage output from the solar battery cell 2810 to a voltage required for each circuit is also mounted.

In the display panel 2802, the display direction can be appropriately changed depending on a usage pattern. In addition, since the camera lens 2807 is provided on the same surface as the display panel 2802, a videophone can be used. The speaker 2803 and the microphone 2804 can be used for videophone calls, recording and playing sound, and the like as well as voice calls. Further, the housing 2800 and the housing 2801 can be slid to be in an overlapped state from the deployed state as illustrated in FIG. 5D, and thus can be reduced in size suitable for carrying.

The external connection terminal 2808 can be connected to an AC adapter and various types of cables such as a USB cable, and charging and data communication with a personal computer are possible. Further, a recording medium can be inserted into the external memory slot 2811 so that a larger amount of data can be stored and moved.

In addition to the above functions, an infrared communication function, a television reception function, or the like may be provided.

FIG. 5E illustrates a digital video camera which includes a main body 3051, a display portion (A) 3057, an eyepiece portion 3053, operation switches 3054, a display portion (B) 3055, a battery 3056, and the like. By applying the liquid crystal display device described in any of Embodiments 1 to 3 to the display portion (A) 3057 and the display portion (B) 3055, a digital video camera having high display quality can be obtained.

FIG. 5F illustrates a television device, which includes a housing 9601 including a display portion 9603 and the like. Images can be displayed on the display portion 9603. Here, a structure in which the housing 9601 is supported by a stand 9605 is illustrated. By applying the liquid crystal display device described in any of Embodiments 1 to 3 to the display portion 9603, a television device having high display quality can be obtained.

The television device can be operated with an operation switch provided in the housing 9601 or a separate remote controller. Further, the remote controller may be provided with a display unit that displays information output from the remote controller.

Note that the television device is provided with a receiver, a modem, and the like. General TV broadcasts can be received by a receiver, and connected to a wired or wireless communication network via a modem, so that it can be unidirectional (sender to receiver) or bidirectional (sender and receiver). It is also possible to perform information communication between each other or between recipients).

This embodiment can be implemented in appropriate combination with the structures described in the other embodiments.

In this example, a liquid crystal element using the liquid crystal composition of one embodiment of the present invention and a comparative liquid crystal element not using the liquid crystal composition of one embodiment of the present invention were manufactured for evaluation. .

Table 1 shows the structure of the liquid crystal composition used in the liquid crystal element manufactured in this example and the comparative liquid crystal element. In Table 1, all the mixing ratios are expressed in weight percentage (wt%).

In the liquid crystal element and the comparative liquid crystal element, MDA-00-3506 (manufactured by Merck Co., Ltd.) is used as the liquid crystal 1 and 4-cyano-3,5-difluorophenyl 4- (trans-4-n-propylcyclohexyl) benzoate is used as the liquid crystal 2. (Abbreviation: CPEP-3FCNF), 4-n-propylbenzoic acid 4-cyano-3,5-difluorophenyl (abbreviation: PEP-3FCNF) as liquid crystal 3, and 4-n-ethylbenzoic acid 4-cyano- as liquid crystal 4. 3,5-difluorophenyl (abbreviation: PEP-3FCNF), (R) (R) -4,5-bis [hydroxy (diphenanthryl) methyl] -2,2-dimethyl-1,3-dioxolane (abbreviation) as a chiral agent : R-DOL-Pn), a non-liquid crystalline ultraviolet polymerizable monomer as a polymerizable monomer, dodecyl methacrylate (approximately) : DMeAc) (manufactured by Tokyo Kasei Kogyo Co., Ltd.), and was used DMPAP (abbreviation) (manufactured by Tokyo Kasei Kogyo Co., Ltd.) as a polymerization initiator.

Liquid crystal 2: CPEP-3FCNF (abbreviation), liquid crystal 3: PEP-3FCNF (abbreviation), liquid crystal 4: PEP-2FCNF (abbreviation), chiral agent: RR-DOL-Pn (abbreviation), used in this example. Structural formulas of dodecyl methacrylate (DMeAc) (abbreviation) and polymerization initiator: DMPAP (abbreviation) are shown below.

In addition, in the liquid crystal element and the comparative liquid crystal element shown in Table 1, as a polymerizable monomer, the liquid crystal element is RM-O10 (abbreviation) which is a polymerizable monomer represented by the following structural formula (110). The element is a polymerizable monomer shown below, 1,4-bis- [4- (4-acryloyloxy-n-hexyl-1-oxy) benzoyloxy] -2-methylbenzene (abbreviation: RM-O6) ( A liquid crystal composition containing Synton Chemicals Co., Ltd. was used. Note that each liquid crystal element was manufactured using a liquid crystal composition in which the mixing ratio of RM-O10 (abbreviation) was 4.5 wt%, 5.0 wt%, 5.5 wt%, and 6.0 wt%. The comparative liquid crystal element was manufactured using a liquid crystal composition in which the ratio of RM-O6 (abbreviation) to be mixed was 4.5 wt%. In addition, DMeAc (abbreviation) which is another polymerizable monomer was mixed in the same ratio as RM-O10 (abbreviation) or RM-O6 (abbreviation). For example, when the mixing ratio of RM-O10 (abbreviation) is 6.0 wt%, DMeAc (abbreviation) is also mixed at a ratio of 6.0 wt%.

In the liquid crystal element and the comparative liquid crystal element, a gap (4 μm) is provided between a glass substrate in which a pixel electrode layer and a common electrode layer are formed in a comb shape as shown in FIG. Each of the liquid crystal compositions mixed in the materials and ratios shown in Table 1 stirred in an isotropic phase by an injection method was injected between the substrates.

The pixel electrode layer and the common electrode layer were provided on a rib using an acrylic resin, and were formed by sputtering using indium tin oxide containing silicon oxide. The film thickness was 50 nm, the width between the pixel electrode layer and the common electrode layer was 3 μm, and the distance between the pixel electrode layer and the common electrode layer was 2 μm. The rib width was 2 μm, the gap between the ribs was 3 μm, and the height was about 2 μm.

As the sealing material, ultraviolet rays and a thermosetting sealing material were used. As a curing treatment, an ultraviolet ray (irradiance: 100 mW / cm ² ) irradiation treatment for 90 seconds was performed, and then a heat treatment was performed at 120 ° C. for 1 hour.

In each of the liquid crystal element and the comparative liquid crystal element, a band pass that is constant temperature at an arbitrary temperature in a temperature range in which a blue phase is developed and transmits ultraviolet rays (light source metal halide lamp, wavelength 365 nm, irradiance 8 mW / cm ² ) in the vicinity of wavelength 365 nm. Polymer stabilization treatment was performed by irradiation for 6 minutes through a filter.

The hysteresis characteristics of each liquid crystal composition of the liquid crystal element and the comparative liquid crystal element were evaluated. As an evaluation of the hysteresis characteristics, ΔV ₅₀ , which is an index representing hysteresis, was measured. A method of measuring ΔV ₅₀ will be described with reference to FIG.

The hysteresis in this specification is represented by the difference between the measurement of the rising voltage and the measurement of the falling voltage in the voltage-transmittance characteristics (VT characteristics) of the liquid crystal composition subjected to the polymer stabilization treatment. Note that ΔV ₅₀ , which is an index representing hysteresis, is a voltage difference at which the normalized transmittance is 50% at the time of rising voltage measurement and at the time of falling voltage measurement. The voltage at which the normalized transmittance is 100% is the saturation voltage V ₁₀₀ .

In FIG. 7, the voltage and normalized transmittance graph in the rising voltage measurement is indicated by black dots, and the voltage and normalized transmittance graph in the falling voltage measurement is indicated by white dots. As shown in FIG. 7, the voltage at which the normalized transmittance is 100% is the saturation voltage V ₁₀₀ , and ΔV ₅₀ , which is an index representing hysteresis, is the normalized transmittance 50% at the time of rising voltage measurement and at the time of falling voltage measurement. Is the difference in voltage.

The saturation voltage V ₁₀₀ and ΔV ₅₀ representing hysteresis characteristics of the liquid crystal element and the comparative liquid crystal element were measured. FIG. 6 shows the relationship between the saturation voltage V ₁₀₀ and ΔV ₅₀ representing the hysteresis characteristics of the liquid crystal element and the comparative liquid crystal element. In FIG. 6, the vertical axis represents ΔV ₅₀ representing the hysteresis characteristic, and the horizontal axis represents the saturation voltage V ₁₀₀ . The black dot is a comparative liquid crystal element, and the white dot is a liquid crystal element. As the amount of the polymerizable monomer increases in the liquid crystal element, the hysteresis characteristic becomes lower and the saturation voltage V ₁₀₀ becomes higher. ing.

The transmittance was measured under the condition that the light source was a halogen lamp and the temperature was room temperature, and the liquid crystal element and the comparative liquid crystal element were sandwiched between crossed Nicols polarizers.

As shown in FIG. 6, in the liquid crystal element indicated by white dots, ΔV ₅₀ representing the hysteresis characteristics was less than 1 V regardless of the amount of the polymerizable monomer added. Therefore, it can be seen that the hysteresis is suppressed even when the addition amount of the polymerizable monomer is as small as 9 wt% to 12 wt%. On the other hand, in the comparative liquid crystal element in which the addition amount of the polymerizable monomer was 9 wt%, ΔV ₅₀ representing the hysteresis characteristic was as high as 1.6 V or more.

Therefore, in a liquid crystal element in which polymer stabilization is performed using RM-O10 (abbreviation) as a polymerizable monomer, it is confirmed that hysteresis can be suppressed and the addition amount can be reduced, so that low voltage driving is possible. did it.

As described above, hysteresis is suppressed in the liquid crystal composition of this example, and a liquid crystal element, a liquid crystal display device, and an electronic device using the liquid crystal composition can have high display quality. Further, the liquid crystal composition can be driven at a low voltage, and a liquid crystal display device and an electronic device using the liquid crystal element can also achieve lower power consumption.

In this example, 1,4-bis [4- (10-acryloyloxy-n-decyl-1-oxy) benzoyloxy] represented by the structural formula (110) in Embodiment 1 used in Example 1 was used. An example of synthesizing 2-methylbenzene (abbreviation: RM-O10) is shown.

Method for synthesizing 1,4-bis [4- (10-acryloyloxy-n-decyl-1-oxy) benzoyloxy] -2-methylbenzene (abbreviation: RM-O10)

A synthesis scheme of RM-O10 (abbreviation) represented by Structural Formula (110) is shown in (A-1) below.

In a 300 mL eggplant flask, 2.0 g (5.7 mmol) of 4- (10-acryloyloxy-n-decyl-1-oxy) benzoic acid and 0.29 g (2.3 mmol) of 2-methyl-1,4 Benzenediol, 0.11 g (0.86 mmol) 4-dimethylaminopyridine (DMAP) and 1.1 g (5.7 mmol) 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride ( EDC), 100 mL of acetone, and 50 mL of dichloromethane were added and the solution was stirred at room temperature for 20 hours under air. Then, it was confirmed that the reaction was completed by thin layer chromatography (TLC). The obtained solution was concentrated, chloroform, saturated aqueous sodium hydrogen carbonate solution and saturated brine were added, the organic layer was taken out, and the aqueous layer was extracted with chloroform three times. The organic layer and the extract were combined and dried over magnesium sulfate, and the mixture was separated by gravity filtration. The filtrate was concentrated, and the resulting solid was purified by silica gel column chromatography (developing solvent: chloroform). The obtained fraction was concentrated to obtain a white solid substance. The obtained white solid material was purified by high performance liquid chromatography (HPLC) to obtain 1.2 g of a white solid in a yield of 68%.

This compound is the target 1,4-bis [4- (10-acryloyloxy-n-decyl-1-oxy) benzoyloxy] -2-methylbenzene (abbreviation: RM) by nuclear magnetic resonance (NMR). -O10).

¹ H NMR data of the obtained substance is shown below. ¹ H NMR (CDCl ₃ , 300 MHz): δ (ppm) = 1.34-1.52 (m, 24H), 1.60-1.87 (m, 8H), 2.24 (s, 3H), 4.05 (t, J = 6.6 Hz, 4H), 4.16 (t, J = 6.6 Hz, 4H), 5.82 (dd, J1 = 10.2 Hz, J2 = 1.5 Hz, 2H) 6.13 (dd, J1 = 10.5 Hz, J2 = 17.4 Hz, 2H), 6.40 (dd, J1 = 1.8 Hz, J2 = 17.4 Hz, 2H), 6.98 (dd, J1) = 3.6 Hz, J2 = 9.0 Hz, 4H), 7.06-7.19 (m, 3H), 8.15 (t, J = 8.6 Hz, 4H). Further, the ¹ H NMR chart is shown in FIG. Note that FIG. 8B is a chart in which the range of 5.5 ppm to 8.5 ppm in FIG. Note that FIG. 8C is a chart in which the range of 1.0 ppm to 4.5 ppm in FIG.

Further, FIG. 9 shows an absorption spectrum of RM-O10 in dichloromethane. An ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, model V550) was used for measuring the absorption spectrum. The solution was placed in a quartz cell for measurement. The absorption spectrum showed the absorption spectrum which deducted the absorption spectrum measured only by putting dichloromethane in the quartz cell. In FIG. 9, the horizontal axis represents wavelength (nm) and the vertical axis represents absorption intensity (arbitrary unit). In the absorption spectrum, an absorption peak was observed at around 266 nm.

The synthesis method of CPEP-3FCNF (abbreviation), PEP-3FCNF (abbreviation), PEP-2FCNF (abbreviation), and R-DOL-Pn (abbreviation) used in Example 1 is described below.

4- (trans-4-n-propylcyclohexyl) benzoic acid 4-cyano-3,5-difluorophenyl (abbreviation: CPEP-3FCNF) synthesis method

A synthesis scheme of CPEP-5FCNF is shown in (F-1) below.

4-n-propylbenzoic acid 4-cyano-3,5-difluorophenyl (abbreviation: PEP-3FCNF) synthesis method

A synthesis scheme of PEP-3FCNF is shown in (G-1) below.

4-n-ethylbenzoic acid 4-cyano-3,5-difluorophenyl (abbreviation: PEP-2FCNF) synthesis method

A synthesis scheme of PEP-3FCNF is shown in (G-2) below.

Synthesis method of (R) (R) -4,5-bis [hydroxy (diphenanthryl) methyl] -2,2-dimethyl-1,3-dioxolane (abbreviation: R-DOL-Pn)

A synthesis scheme of R-DOL-Pn (abbreviation) is shown in (L-1) below.

Claims (3)

A polymer having a plurality of units represented by the following formula (G2);
Nematic liquid crystal,
A liquid crystal element having a liquid crystal composition containing a chiral agent.

(In formula (G2), n and m are integers of 10 to 20, n = m, and n and m are even numbers .) In claim 1,
ΔV which is an index representing hysteresis ₅₀ Is a liquid crystal element having a voltage of less than 1V. A liquid crystal display device comprising the liquid crystal element according to claim 1 .