KR20200067601A - Organic Light Emitting Diode Display Device Including Blue Phase Liquid Crystal And Method Of Fabricating The Same - Google Patents

Abstract

The present invention provides an organic light emitting diode display device comprising: a substrate; a color filter layer disposed under a first surface of the substrate; a blue phase liquid crystal layer disposed under the color filter layer and having selective reflection characteristics; a light emitting diode disposed under the blue phase liquid crystal layer; a quarter-wave plate disposed on a second surface of the substrate; and a polarizing plate disposed on the quarter-wave plate.

Description

Organic Light Emitting Diode Display Device Including Blue Phase Liquid Crystal And Method Of Fabricating The Same}

The present invention relates to an organic light emitting diode display device, and more particularly, to an organic light emitting diode display device including a blue phase liquid crystal having improved viewing angle dependence and improved light efficiency, and a method for manufacturing the same.

Recently, flat panel displays having excellent characteristics such as thinning, lightening, and low power consumption have been widely developed and applied to various fields.

Among flat panel display devices, an organic light emitting diode display device injects electric charges into a light emitting layer formed between a cathode as an electron injection electrode and an anode as a hole injection electrode, and then excitons are formed by a combination of electrons and holes. It is a device that emits light while disappearing.

In such an organic light emitting diode display device, a cholesteric liquid crystal layer may be disposed to increase light efficiency.

That is, the light efficiency of the organic light emitting diode display device can be improved by recycling light of a specific wavelength band among the light emitted from the light emitting diode using a cholesteric liquid crystal layer having selective reflection characteristics.

However, since the cholesteric liquid crystal has refractive index anisotropy in which the refractive indexes in the long and short axes are different, the reflectance is different depending on the viewing angle. There is a problem that the color shift occurs due to the asymmetry and deterioration of visibility.

The present invention has been proposed to solve this problem, and by recycling the light using a blue phase liquid crystal layer having refractive index isotropy, to provide an organic light emitting diode display device having improved viewing angle dependence and improved light efficiency, and a method for manufacturing the same It is aimed at.

Another object of the present invention is to provide an organic light emitting diode display device and a method of manufacturing the same, by forming a blue liquid crystal layer at a relatively high polymer concentration, thereby simplifying the manufacturing process and improving durability.

In order to achieve the above object, the present invention, a substrate; A color filter layer disposed under the first surface of the substrate; A blue liquid crystal layer disposed under the color filter layer and having selective reflection characteristics; A light emitting diode disposed under the blue liquid crystal layer; A quadrant plate disposed on the second surface of the substrate; An organic light emitting diode display device including a polarizing plate disposed on the quadrant wave plate is provided.

Further, the blue phase liquid crystal layer may include a nematic liquid crystal, a chiral dopant, and a polymer.

In addition, the polymer may have a concentration of 6% or more.

In addition, the blue liquid crystal layer may include a nematic liquid crystal, a chiral dopant, and a gelling agent.

In addition, the light emitting diode, the first electrode disposed under the blue liquid crystal layer; A first stack disposed under the first electrode and emitting blue light; A first charge generating layer disposed under the first stack; A second stack disposed under the first charge generating layer and emitting yellow-green light; A second charge generating layer disposed under the second stack; A third stack disposed under the second charge generating layer and emitting blue light; It may include a second electrode disposed under the third stack.

And, a plurality of thin film transistors disposed between the substrate and the color filter layer; An encapsulation layer disposed under the light emitting diode may be further included.

On the other hand, the present invention, forming a color filter layer on the bottom of the first surface of the substrate; Forming a blue phase liquid crystal layer having selective reflection characteristics under the color filter layer; Forming a light emitting diode under the blue liquid crystal layer; Forming a quarter wave plate on the second surface of the substrate; It provides a method for manufacturing an organic light emitting diode display comprising the step of forming a polarizing plate on top of the quarter wave plate.

The forming of the blue liquid crystal layer may include applying a mixed solution of nematic liquid crystal, chiral dopant and reactive liquid crystal monomer to form a mixed solution layer under the color filter layer; It may include the step of polymerizing the reactive liquid crystal monomer by irradiating ultraviolet rays to the mixed solution layer.

In addition, the ultraviolet light may be irradiated while the nematic liquid crystal is maintained at a temperature having a blue phase.

The forming of the blue liquid crystal layer may include applying a mixed solution of nematic liquid crystal, chiral dopant, and gelling agent to form a mixed solution layer under the color filter layer; And heat-treating the mixed solution layer to cure the gelling agent.

The present invention has an effect of improving viewing angle dependence and improving light efficiency by recycling light using a blue phase liquid crystal layer having refractive index isotropy.

In addition, the present invention has the effect of simplifying the manufacturing process and improving durability by forming the blue phase liquid crystal layer at a relatively high polymer concentration.

1 is a view showing an organic light emitting diode display device according to a first embodiment of the present invention.
2 is a view showing a blue phase liquid crystal of the blue phase liquid crystal layer of the organic light emitting diode display device according to the first embodiment of the present invention.
3 is a view showing an ellipsoid of a refractive index of a blue phase liquid crystal in a blue phase liquid crystal layer of an organic light emitting diode display device according to a first embodiment of the present invention.
4 is a view showing reflectance according to the wavelength of the blue phase liquid crystal of the blue phase liquid crystal layer of the organic light emitting diode display device according to the first embodiment of the present invention.
FIG. 5 is a view showing optical paths of external light and internal light of the organic light emitting diode display device according to the first exemplary embodiment of the present invention.
FIG. 6A is a view showing reflectance according to a viewing angle of light having a wavelength of 465 nm in a blue phase liquid crystal layer of an organic light emitting diode display device according to a first embodiment of the present invention.
FIG. 6B is a view showing an average reflectance according to a viewing angle for light having a wavelength of 435 nm, 480 nm, and 495 nm in the blue phase liquid crystal layer of the organic light emitting diode display device according to the first embodiment of the present invention.
7 is a view showing a blue phase liquid crystal stabilized by a polymer of the blue phase liquid crystal layer of the organic light emitting diode display device according to the first embodiment of the present invention.
8A and 8B are diagrams illustrating a blue phase liquid crystal layer including a low concentration polymer and a high concentration polymer of the organic light emitting diode display device according to the first embodiment, respectively.
9 is a diagram illustrating an electric field correlation distance according to a polymer concentration of a blue phase liquid crystal of a blue phase liquid crystal layer of an organic light emitting diode display device according to a first embodiment of the present invention.
10 is a flowchart illustrating a method of forming a blue phase liquid crystal layer in an organic light emitting diode display device according to a first embodiment of the present invention.
11 is a flowchart illustrating a method of forming a blue phase liquid crystal layer in an organic light emitting diode display device according to a second embodiment of the present invention.

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

1 is a view showing an organic light emitting diode display device according to a first embodiment of the present invention.

As shown in FIG. 1, the organic light emitting diode display device 110 according to the first embodiment of the present invention includes a substrate 120, a color filter layer 122 sequentially disposed on a lower surface of the substrate 120, and blue Phase liquid crystal layer 124, first electrode 126, first stack ST1, first charge generation layer CGL1, second stack ST2, second charge generation layer CGL2, third stack ( ST3), a second electrode 158, a quarter wave plate (QWP) 160 sequentially disposed on the upper surface of the substrate 120, and a polarizing plate 162.

The first and second electrodes 126 and 158 may be an anode and a cathode, respectively, and the first electrode 126 is disposed for each of red, green, and blue subpixels, and the second electrode 158 Can be placed on the front.

The color filter layer 122 includes red, green, and blue color filters (R-CF, G-CF, and B-CF) arranged for each red, green, and blue subpixel.

The blue phase liquid crystal layer 124 includes a blue phase liquid crystal, and the configuration and function of the blue phase liquid crystal layer 124 will be described in detail in FIGS. 2 to 9.

The first stack ST1 for emitting blue light includes a hole injection layer (HIL) 222, a first hole transport layer (HTL1) 130, a first blue-emitting material layer (B-EML1) 132, and a first And an electron transport layer (ETL1) 134.

The first charge generation layer CGL1 includes a first N type charge generation layer (N-CGL1) 136 and a first P type charge generation layer (P-CGL1) 138.

The second stack for emitting yellow-green light (ST2) includes a second hole transport layer (HTL2) 140, a yellow-green light-emitting material layer (YG-EML1) 142, and a second electron transport layer (ETL2) 144. .

The second charge generation layer CGL2 includes a second N-type charge generation layer (N-CGL2) 146 and a second P-type charge generation layer (P-CGL2) 148.

The third stack (ST3) for emitting blue light includes a third hole transport layer (HTL3) 150, a second blue light-emitting material layer (B-EML2) 152, a third electron transport layer (ETL3) 154, and electrons. And an injection layer (EIL) 156.

The first electrode 126, the first to third stacks ST1, ST2, and ST3, and the second electrode 158 constitute a light emitting diode.

Although not illustrated, a plurality of thin film transistors are disposed in each sub-pixel between the substrate 120 and the color filter layer 122, and the first electrode 220 can be connected to a driving thin film transistor among the plurality of thin film transistors.

In addition, an encapsulation layer may be disposed under the second electrode 158.

Here, the hole injection layer 128 serves to inject holes, and the first to third hole transport layers 130, 140, and 150 serve to transport holes, and the first to third electron transport layers 134, 144 and 154 serve to transport electrons, and the first and second N-type charge generation layers 136 and 146 serve to generate electrons, and the first and second P-type charge generation layers 138 and 148 Plays a role in creating holes.

The organic light emitting diode display 110 emits light using one stack containing one light emitting material, instead of three stacks including a plurality of light emitting materials having a photoluminescence peak at different wavelengths. Light is emitted using (ST1, ST2, ST3), and light emitted from three stacks (ST1, ST2, ST3) is combined to emit white light.

The three stacks ST1, ST2, and ST3 may include a stack including a fluorescence emitting material and a stack including a phosphorescence emitting material, for example, the first of the first stack ST1. The blue-emitting material layer 132 includes a fluorescent light-emitting material, and the yellow-green-emitting material layer 142 of the second stack ST2 contains a phosphorescent material, and the second blue of the third stack ST3 The light emitting material layer 152 may include a fluorescent light emitting material.

The quarter wave plate 160 has a retardation of λ/4 and serves to convert linearly polarized light into circularly polarized light or to convert circularly polarized light into linearly polarized light, and the polarizing plate 162 passes only linearly polarized light in a specific direction, and the remaining polarized light Ingredients absorb.

In the first embodiment, it has been exemplified that the organic light emitting diode display device 110 includes the first to third stacks ST1, ST2, and ST3, but in another embodiment, the organic light emitting diode display device emits blue light. One stack and a second stack emitting yellow-green light may be included.

In addition, in the first embodiment, the second stack ST2 of the organic light emitting diode display device 110 is exemplified as including the yellow-green light-emitting material layer 142. However, in another embodiment, the organic light emitting diode display device is manufactured. The two stacks may also include a yellow-green and light-emitting layer.

2 is a view showing a blue phase liquid crystal of a blue phase liquid crystal layer of the organic light emitting diode display device according to the first embodiment of the present invention, and FIG. 3 is a view of the organic light emitting diode display device according to the first embodiment of the present invention. FIG. 4 is a view showing an ellipsoid of the blue phase liquid crystal of the blue phase liquid crystal layer, and FIG. 4 shows reflectance according to the wavelength of the blue phase liquid crystal of the blue phase liquid crystal layer of the organic light emitting diode display device according to the first embodiment of the present invention. As a drawing, it will be described with reference to FIG. 1 together.

As illustrated in FIG. 2, the blue phase liquid crystal layer 124 of the organic light emitting diode display device 110 according to the first embodiment of the present invention is made of blue phase liquid crystal (BPLC). The phase liquid crystal (BPLC) has a three-dimensional cube of a plurality of double twist cylinders 170 arranged in a vertical direction and a horizontal direction in a unit lattice structure, and each double twist cylinder 170 has a direction ( director) (172) has a cross section of a double helix structure arranged in two directions orthogonal.

In the blue phase liquid crystal (BPLC), refractive index anisotropy is induced by applying a voltage. As shown in FIG. 3, in a state in which an electric field is not generated due to no voltage applied (E Off), the x-axis, y-axis, and z-axis Refractive index anisotropy (nx≠ny≠) having the same refractive index of the same refractive index (nx=ny=nz) and different refractive indices of the x-axis, y-axis, and z-axis due to the Kerr effect in a state in which an electric field is applied by applying a voltage (E On) nz) is induced.

The blue phase liquid crystal (BPLC) has a relatively short pitch and a relatively high selective reflection characteristic. As shown in FIG. 4, the left circular polarization and the right circular polarization of the wavelength band corresponding to blue of about 450 nm are blue phase liquid crystals. It is reflected by (BPLC), and left circularly polarized light and right circularly polarized light of the remaining wavelength band pass through the blue phase liquid crystal (BPLC) as it is.

Accordingly, in the case of a single layer of the left circularly polarized blue phase liquid crystal layer and a single layer of the right circularly polarized blue phase liquid crystal layer, a relatively high reflectance of about 38% can be obtained for light in a wavelength band corresponding to blue, respectively. In the case of the double layer of the phase liquid crystal layer and the right-circular polarization blue phase liquid crystal layer, a relatively high reflectance of about 68% can be obtained for light in a wavelength band corresponding to blue.

Accordingly, a relatively high recycling efficiency can be obtained by applying a single layer of the left circularly polarized blue phase liquid crystal layer or a single layer of the right circularly polarized blue phase liquid crystal layer to the blue phase liquid crystal layer 124.

In the first embodiment of the present invention, the optical efficiency of the organic light emitting diode display 110 may be improved by using the isotropic and selective reflection characteristics of the blue phase liquid crystal (BPLC), which will be described with reference to the drawings.

FIG. 5 is a view showing optical paths of external light and internal light of the organic light emitting diode display device according to the first exemplary embodiment of the present invention, and the layers affecting the polarization state will be described with reference to FIG. 1.

As shown in FIG. 5, the external light EL of the entire wavelength band incident on the organic light emitting diode display device 110 according to the first embodiment of the present invention from the outside is the first externally polarized state of non-polarized light. (PSE1), the external light EL passes through the polarizing plate 162, and the second externally polarized state of linear polarization in a predetermined direction (for example, a direction parallel to the ground) of the entire wavelength band ( PSE2), passing through the quarter-wave plate 160, and having a third external polarization state (PSE3) of circularly polarized light (eg, left circularly polarized light) in a certain direction of the entire wavelength band, and having a blue phase liquid crystal The third external polarization state (PSE3) of circularly polarized light (eg, left circularly polarized light) in a certain direction of the entire wavelength band is maintained through the layer 124, and is reflected by the second electrode 158 before being transmitted ( It has a fourth externally polarized state (PSE4) of circularly polarized light (eg, right-circularly polarized light) of different directions in the wavelength band, and circularly polarized light of a different wavelength band (eg, a blue phase liquid crystal layer 124) , Right circularly polarized light is reflected, and the remaining components pass through the blue liquid crystal layer 124, and the fourth externally polarized state (PSE4) of circularly polarized light (for example, rightly circularly polarized light) of different wavelengths other than a predetermined wavelength band is reflected. ) Is maintained, passes through the quarter wave plate 160 to have a fifth external polarization state (PSE5) of linearly polarized light in different directions of different wavelength bands (for example, a direction perpendicular to the ground), and the polarizing plate 162 All are absorbed.

That is, the external light (EL) incident on the organic light emitting diode display 110 is absorbed by the organic light emitting diode display 110 and finally displayed in black. Quality degradation of the image of the light emitting diode display 110 is prevented.

On the other hand, the internal light IL of the entire wavelength band emitted from the first to third stacks ST1, ST2, and ST3 has the first internal polarization state PSI1 of non-polarization, among the internal light IL The circularly polarized light (eg, left circularly polarized light) component of the entire wavelength band passes through the blue phase liquid crystal layer 124 and circularly polarized light (eg, left circularly polarized light) of a predetermined wavelength band through the blue phase liquid crystal layer 124. Having a second internal polarization state (PSI2) of the third internal polarization state of linear polarization in a certain direction (for example, a direction parallel to the ground) of the entire wavelength band through the quadrant plate 160 PSI3), and passes through the polarizing plate 162 and is emitted as the first light L1.

In addition, the circularly polarized light (eg, right-circular polarized light) component of a certain wavelength band of the internal light IL is reflected by the blue liquid crystal layer 124 and circularly polarized light of a different wavelength band (eg, right-circular beam). Polarization), and has a fifth internal polarization state (PSI5) reflected in the second electrode 158 and a certain wavelength band in a certain direction (eg, left circular polarization). The fifth internal polarization state (PSI5) in a certain direction (eg, left circularly polarized light) of a certain wavelength band is maintained by passing through the blue phase liquid crystal layer 124, and passing through the quarter wave plate 160 to a certain direction of a certain wavelength band. It has a sixth internal polarization state (PSI6) of linearly polarized light (for example, in a direction parallel to the ground) and passes through the polarizing plate 162 and is emitted as the second light L2.

That is, the internal light IL emitted from the first to third stacks ST1, ST2, and ST3 is recycled by the blue liquid crystal layer 124 to be the first and second lights L1 and L2. It is emitted, and the light efficiency of the organic light emitting diode display 110 is improved.

Since the blue phase liquid crystal layer 124 has isotropy, the viewing angle dependence is improved, which will be described with reference to the drawings.

FIG. 6A is a view showing reflectivity of a blue-phase liquid crystal layer according to a viewing angle for light having a wavelength of 465 nm in the organic light emitting diode display device according to the first embodiment of the present invention, and FIG. 6B is a first embodiment of the present invention A diagram showing an average reflectance according to viewing angles for light having a wavelength of 435 nm, 480 nm, and 495 nm in the blue-phase liquid crystal layer of the organic light emitting diode display according to FIG. 1, which will be described with reference to FIG. 1 together.

6A and 6B, the center corresponds to a viewing angle (0 degrees) in the front direction of the organic light emitting diode display 110, and a radius changing from the center to an arc is relative to the front direction of the organic light emitting diode display 110 It corresponds to the viewing angle in the diagonal direction, and the position of the arc corresponds to the viewing angle in the diagonal direction based on the right direction of the organic light emitting diode display 110 (0 degrees).

6A and 6B, the blue phase liquid crystal layer 124 of the organic light emitting diode display device 110 according to the first embodiment of the present invention has the same isotropy as that of the x-axis, y-axis, and z-axis. Therefore, the reflectance is the same regardless of the viewing angle direction, the reflectances in the front and diagonal directions are similar, and the reflectances in the diagonal directions of up, down, left, and right are symmetrical, reflectance for light of 465 nm wavelength and 435 nm wavelength, 480 nm wavelength, and 495 nm wavelength The average reflectance for the light has a concentric shape.

That is, the diagonal viewing angle of the organic light emitting diode display 110 is symmetrical up, down, left, and right, and accordingly, the viewing angle dependence of the organic light emitting diode display 110 is improved to prevent color shift and to decrease visibility. Is prevented.

On the other hand, the blue phase liquid crystal (BPLC) is stabilized by a polymer to maintain the blue phase, which will be described with reference to the drawings.

FIG. 7 is a view showing a blue phase liquid crystal stabilized by a polymer of a blue phase liquid crystal layer of the organic light emitting diode display device according to the first embodiment of the present invention, and FIGS. 8A and 8B are respectively according to the first embodiment. A blue phase liquid crystal layer including a low concentration polymer and a high concentration polymer of an organic light emitting diode display device, and FIG. 9 is a blue phase liquid crystal of the blue phase liquid crystal layer of the organic light emitting diode display device according to the first embodiment of the present invention. It is a view showing the electric field correlation distance according to the polymer concentration of, it will be described with reference to FIG.

As shown in FIG. 7, the blue phase liquid crystal (BPLC) of the blue phase liquid crystal layer 124 of the organic light emitting diode display device 110 according to the first embodiment of the present invention includes a plurality of double twisted cylinders 170. Although it has a unit lattice structure of a three-dimensional cube, in this unit lattice structure, the liquid crystal molecules 178 are not continuously arranged in a three-dimensional space, thus forming a foreground (disclination) 174.

After mixing a reactive mesogen (RM) 176 with the blue phase liquid crystal (BPLC), curing the polymerized polymer by following the foreground line 174 by curing (polymerizing) the reactive liquid crystal monomer 176 by irradiating ultraviolet rays. The network 182 can be formed, and as a result, the blue phase liquid crystal (BPLC) can be stably maintained in a wide temperature range.

At this time, as shown in FIG. 8A, when the polymer 180 adjacent to the foreground line 174 of the polymer network 182 has a relatively low concentration, the liquid crystal molecules 178 are relatively surrounded by the polymer network 182. While the wide first space S1 is used as an available operating region, as shown in FIG. 8B, when the polymer 180 adjacent to the foreground line 174 of the polymer network 182 has a relatively high concentration, liquid crystal molecules Reference numeral 178 uses a relatively narrow second space S2 (S1>S2) surrounded by the polymer network 182 as an available operating area.

Accordingly, as shown in FIG. 9, as the concentration of the polymer 180 increases, the electric field correlation distance representing the minimum distance required for driving the liquid crystal molecules 178 decreases.

When the electric field correlation distance decreases, an electric field must be generated by applying a larger voltage to drive the liquid crystal molecules 178. Therefore, as the concentration of the polymer 180 increases, the driving voltage required to drive the liquid crystal molecules 178 increases. Increases.

For example, when the polymer 180 has a concentration of about 6% or more, the electric field correlation distance is about 100 nm, and the driving voltage for driving the liquid crystal molecules 178 is about 30 V or more, so that the organic light emitting diode display 110 It is difficult to apply blue phase liquid crystal (BPLC) as an active element.

However, in the organic light emitting diode display device 110 according to the first embodiment of the present invention, the blue phase liquid crystal (BPLC) is not used as an active element operated by applying a voltage, and a passive element using isotropy without applying a voltage ( passive element), there is no problem of such a relatively high driving voltage.

Accordingly, the blue phase liquid crystal layer 124 is formed of a blue phase liquid crystal (BPLC) having a concentration of about 6% or more so that the polymer 180 has a stable durability and strength regardless of the driving voltage. can do.

A method of forming the blue liquid crystal layer 124 will be described with reference to the drawings.

10 is a flowchart illustrating a method of forming a blue phase liquid crystal layer of an organic light emitting diode display device according to a first embodiment of the present invention, and will be described with reference to FIG. 1.

As shown in FIG. 10, a liquid crystal, a dopant, and a liquid crystal monomer are mixed to form a mixed solution (st110).

For example, the liquid crystal may be a nematic liquid crystal, the dopant may be a chiral dopant, and the liquid crystal monomer may be a reactive mesogen (RM).

The nematic liquid crystal implements a blue phase by the chirality of the dopant, for example, a transition temperature of about 70 degrees (Tni: the temperature that transitions from the nematic phase to the isotropic phase). When stabilizing a nematic liquid crystal having a polymer, a blue phase may be realized until it becomes glass at a transition temperature (Tni) or lower.

The chiral dopant is a material that can be mixed with the liquid crystal, so that the nematic liquid crystal is twisted, and the reflective wavelength for the selective reflection characteristic of the blue phase of the nematic liquid crystal can be determined by the chiral dopant.

The reactive liquid crystal monomer is polymerized within a defect such as the foreground line 174 of the blue phase liquid crystal (BPLC) to form a polymer network (182 of FIG. 7 ), and the blue phase liquid crystal layer 124 as a passive element is stable. To have durability and strength, it can be mixed at a concentration of about 6% or more.

Thereafter, the mixed solution is applied to the color filter layer 122 formed on the first surface of the substrate 120 to form a mixed solution layer (st120).

At this time, a plurality of thin film transistors may be formed between the substrate 120 and the color filter layer 122.

Thereafter, the blue liquid crystal layer 124 is formed on the color filter layer 122 by polymerizing the reactive liquid crystal monomer by irradiating ultraviolet rays to the mixed solution layer of the substrate 120 (st130).

At this time, the mixed solution layer is cured by irradiating ultraviolet rays while the nematic liquid crystal is maintained at a temperature having a blue phase.

In the first embodiment, it was exemplified that the mixed solution was applied directly onto the color filter layer 122 on the substrate 120 and cured by irradiating with ultraviolet rays. In another embodiment, the mixed solution was applied to a separate base film and the ultraviolet rays were applied. After forming the blue-phase liquid crystal film by irradiating, the blue-phase liquid crystal layer 124 may be formed by attaching the blue-phase liquid crystal film to the color filter layer 122 on the substrate 120.

Thereafter, the first electrode 126, the first to third stacks ST1, ST2, ST3, and the second electrode 158 are formed on the blue phase liquid crystal layer 124, and the second surface of the substrate 120 is formed. The organic light emitting diode display device 110 can be completed by forming the quarter wave plate 160 and the polarizing plate 162 on the upper portion.

As described above, in the organic light emitting diode display device 110 according to the first embodiment of the present invention, the blue phase liquid crystal layer 124 is formed by forming the blue phase liquid crystal layer 124 using a polymer having a concentration of about 6% or more. ) Durability and rigidity are improved.

In addition, the manufacturing process is simplified by applying a mixed solution in which a liquid crystal, a dopant, and a liquid crystal monomer are mixed and curing by irradiating with ultraviolet rays.

Meanwhile, in another embodiment, a blue liquid crystal layer may be stabilized using a gel agent, which will be described with reference to the drawings.

11 is a flowchart illustrating a method of forming a blue phase liquid crystal layer of an organic light emitting diode display device according to a second embodiment of the present invention, and will be described with reference to FIG. 1.

11, a liquid crystal, a dopant, and a gelling agent are mixed to form a mixed solution (st210).

For example, the liquid crystal is a nematic liquid crystal, the dopant is a chiral dopant, and the gelling agent has a low molecular weight gelling agent having a content of less than about 10 wt% for the liquid crystal or a content for the liquid crystal of about 30 wt% It may be from about 50wt% to a high molecular weight gelling agent.

For example, the gelling agent is 1,3:2,4-bis-O-benzylidene-D-glucitol (dibenzylidene sorbitol), 1,3:2,4-bis-O-(4-methylbenzylidene)-D-sorbitol It may include.

The nematic liquid crystal implements a blue phase by the chirality of the dopant, for example, a transition temperature of about 45 degrees (Tni: the temperature that transitions from the nematic phase to the isotropic phase). When stabilizing a nematic liquid crystal having a gelling agent, a blue phase may be realized until it becomes glass at a transition temperature (Tni) or lower.

The chiral dopant is a material that can be mixed with the liquid crystal, so that the nematic liquid crystal is twisted, and the reflective wavelength for selective reflection characteristics of the blue phase of the nematic liquid crystal can be determined by the chiral dopant.

The gelling agent is cured in a defect such as the foreground line 174 of the blue phase liquid crystal (BPLC) to form a polymer network (182 in FIG. 7).

Thereafter, the mixed solution is applied to the color filter layer 122 formed on the first surface of the substrate 120 to form a mixed solution layer (st220).

At this time, a plurality of thin film transistors may be formed between the substrate 120 and the color filter layer 122.

Thereafter, a blue liquid crystal layer 124 is formed on the color filter layer 122 by curing the gelling agent by heat-treating (drying) the mixed solution layer of the substrate 120 (st230).

In the second embodiment, it was exemplified to apply the mixed solution directly onto the color filter layer 122 above the substrate 120 and heat-treat it, but in another embodiment, apply the mixed solution to a separate base film and heat-treat the blue. After forming the phase liquid crystal film, the blue phase liquid crystal layer 124 may be formed by attaching the blue phase liquid crystal film to the color filter layer 122 above the substrate 120.

Thereafter, the first electrode 126, the first to third stacks ST1, ST2, ST3, and the second electrode 158 are formed on the blue liquid crystal layer 124, and the second surface of the substrate 120 is formed. The organic light emitting diode display device 110 can be completed by forming the quarter wave plate 160 and the polarizing plate 162 on the upper portion.

As described above, in the organic light emitting diode display device 110 according to the second embodiment of the present invention, the manufacturing process is simplified by applying a heat treatment and curing the mixed solution containing a liquid crystal, a dopant, and a gelling agent.

In the first and second embodiments, the blue light-emitting liquid crystal layer, which is a passive element, is formed on the organic light emitting diode display device as an example, but in other embodiments, the blue light-emitting liquid crystal layer, which is a passive device, is formed on the liquid crystal display device to improve light efficiency. You can also

Although described above with reference to preferred embodiments of the present invention, those skilled in the art variously modify and change the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. You can understand that you can.

110: display device 120: substrate
122: color filter layer 124: blue phase liquid crystal layer
126: first electrode ST1, ST2, ST3: first to third stack
158: second electrode 160: quarter wave plate
162: polarizing plate

Claims (10)

A substrate;
A color filter layer disposed under the first surface of the substrate;
A blue liquid crystal layer disposed under the color filter layer and having selective reflection characteristics;
A light emitting diode disposed under the blue liquid crystal layer;
A quadrant plate disposed on the second surface of the substrate;
Polarizing plate disposed on the quadrant plate
An organic light emitting diode display device comprising a.
According to claim 1,
The blue liquid crystal layer is an organic light emitting diode display device including a nematic liquid crystal, a chiral dopant, and a polymer.
According to claim 2,
The polymer is an organic light emitting diode display having a concentration of 6% or more.
According to claim 1,
The blue liquid crystal layer, an organic light emitting diode display device comprising a nematic liquid crystal, a chiral dopant and a gelling agent.
According to claim 1,
The light emitting diode,
A first electrode disposed under the blue liquid crystal layer;
A first stack disposed under the first electrode and emitting blue light;
A first charge generating layer disposed under the first stack;
A second stack disposed under the first charge generating layer and emitting yellow-green light;
A second charge generating layer disposed under the second stack;
A third stack disposed under the second charge generating layer and emitting blue light;
A second electrode disposed under the third stack
An organic light emitting diode display device comprising a.
According to claim 1,
A plurality of thin film transistors disposed between the substrate and the color filter layer;
Encapsulation layer disposed under the light emitting diode
An organic light emitting diode display device further comprising a.
Forming a color filter layer under the first surface of the substrate;
Forming a blue phase liquid crystal layer having selective reflection characteristics under the color filter layer;
Forming a light emitting diode under the blue liquid crystal layer;
Forming a quarter wave plate on the second surface of the substrate;
Forming a polarizing plate on the quadrant wave plate
Method of manufacturing an organic light emitting diode display comprising a.
The method of claim 7,
The step of forming the blue phase liquid crystal layer,
Forming a mixed solution layer under the color filter layer by applying a mixed solution of nematic liquid crystal, chiral dopant and reactive liquid crystal monomer;
Polymerizing the reactive liquid crystal monomer by irradiating ultraviolet rays to the mixed solution layer
Method of manufacturing an organic light emitting diode display comprising a.
The method of claim 8,
The ultraviolet light is a method of manufacturing an organic light emitting diode display device irradiated while the nematic liquid crystal is maintained at a temperature having a blue phase.
The method of claim 7,
The step of forming the blue phase liquid crystal layer,
Forming a mixed solution layer under the color filter layer by applying a mixed solution of nematic liquid crystal, chiral dopant and gelling agent;
Curing the gelling agent by heat-treating the mixed solution layer
Method of manufacturing an organic light emitting diode display comprising a.

Images