KR102146533B1 - Polarizing plate and organic light emitting device - Google Patents

Abstract

The present application relates to a polarizing plate and an organic light emitting device. The present application can provide a polarizing plate for an organic light emitting device and an organic light emitting device having an effect of improving the lifespan through low power driving by improving the luminance of blue light, and having excellent antireflection properties at a viewing angle.

Description

Polarizing plate and organic light emitting device

The present application relates to a polarizing plate and an organic light emitting device.

The organic light emitting device has advantages such as self-luminescence, large vision, short reaction time, compact size, light weight, reduced thickness, high luminance, low power consumption, simple manufacturing, and light emission capability in all color areas. Organic light emitting devices are widely used in display devices for displaying images in addition to display devices such as LCDs and PDPs.

Organic light emitting devices generally emit red, green, and blue light, but the blue lifespan is the weakest, which causes an increase in driving power. In addition, when replacing a glass substrate with a polymer substrate to implement a rollable organic light emitting device, there is a problem in that the viewing angle characteristic of the organic light emitting device is deteriorated due to optical anisotropy of the polymer.

Korean Patent Publication No. 10-2008-0073256

The present application provides a polarizing plate for an organic light-emitting device and an organic light-emitting device having an effect of improving the lifespan through low-power driving by improving the luminance of blue light, and having excellent antireflection properties at a viewing angle.

This application relates to a polarizing plate. An exemplary polarizing plate may be a polarizing plate for an organic light emitting device. As shown in FIG. 1, the polarizing plate may include an absorption type polarizer 10, a retardation layer 20, and an optical compensation layer 30. The retardation layer may have a function of converting circularly polarized light into linearly polarized light or from linearly polarized light into circularly polarized light. The optical compensation layer may include a cholesteric liquid crystal layer. The cholesteric liquid crystal layer may have a reflection band in the range of 420 nm to 530 nm.

The absorption type polarizer is a linear polarizer, and may have an absorption axis in one direction. In the present specification, the linearly polarized light refers to a case where the selectively transmitted light is linearly polarized light vibrating in any one direction, and the selectively absorbed light is linearly polarized light that vibrates in a direction orthogonal to the vibrational direction of the linearly polarized light.

As the polarizer, for example, a polarizer in which iodine is dyed on a polymeric stretched film such as a PVA stretched film or a liquid crystal polymerized in an aligned state as a host, and an anisotropic dye arranged according to the orientation of the liquid crystal as a guest- A host type polarizer may be used, but is not limited thereto.

As the polarizer, a PVA stretched film may be used. The transmittance or polarization degree of the polarizer may be appropriately adjusted in consideration of the purpose of the present application. For example, the transmittance of the polarizer may be 42% to 53%, and the polarization degree may be 65% to 99.9997%.

In the present specification, the terms polarizer and polarizing plate may be used with different meanings. For example, the polarizer may refer to a layer, film or sheet exhibiting a polarizing function, and the polarizing plate may refer to an optical element including another functional layer, film or sheet in addition to the polarizer. In the above, the additional functional layer, film or sheet may include a polarizer protective film, an optical compensation layer, an antireflection layer, an adhesive layer or an adhesive layer.

A protective film may be provided on one or both sides of the polarizer. The protective film may be attached to the polarizer by, for example, a known pressure-sensitive adhesive or adhesive.

As the protective film, for example, a cellulose film such as a triacetyl cellulose (TAC) film; Polyester films such as PET (poly(ethylene terephthalate)) film; Polycarbonate film; Polyethersulfone film; An acrylic film and/or a polyethylene film, a polypropylene film, a polyolefin film including a cyclo-based or norbornene structure, or a polyolefin-based film such as an ethylene-propylene copolymer film may be used, but is not limited thereto. As the protective film, an anisotropic film or an isotropic film such as NRT (No Retardation TAC) may be used.

In the present specification, the retardation layer is an optical 　 anisotropic layer, and may mean a device capable of converting incident polarization by controlling birefringence. In the present specification, the x-axis, y-axis, and z-axis of the retardation layer are described, and unless otherwise specified, the x-axis means a direction parallel to the plane slow axis of the retardation layer, and the y-axis is a direction parallel to the plane fast axis of the retardation layer. Means, and the z-axis means the thickness direction of the retardation layer. In the present specification, the slow axis direction is a direction representing the highest refractive index on a plane, the fast axis direction is a direction orthogonal to the slow axis on a plane, and the thickness direction may mean a direction perpendicular to the slow axis and the fast axis. . When the retardation layer includes a rod-shaped liquid crystal molecule, the slow axis may mean a long axis direction of the rod shape, and when a disk-shaped liquid crystal molecule is included, the slow axis may mean the disk-shaped normal direction. Unless otherwise specified while describing the refractive index of the retardation layer, it means the refractive index for light having a wavelength of about 550 nm.

In the present specification, a retardation layer that satisfies Equation 1 below may be referred to as a +C plate. In the present specification, a retardation layer that satisfies Equation 2 below may be referred to as a -C plate.

[Equation 1]

nx = ny <nz

[Equation 2]

nx = ny> nz

In Equations 1 and 2, nx, ny, and nz are refractive indices in the x-axis, y-axis and z-axis directions, respectively. In the description of the refractive index in the present specification, it may mean a refractive index for light having a wavelength of 550 nm unless otherwise specified.

In the present specification, the plane retardation Rin of the retardation layer is calculated by Equation 3 below. In the present specification, the retardation Rth in the thickness direction of the retardation layer is calculated by Equation 4 below.

[Equation 3]

Rin = d × (nx-ny)

[Equation 4]

Rth = d × (nz-ny)

In Equations 3 and 4, Rin is a plane retardation, Rth is a retardation in the thickness direction, d is a thickness of the retardation layer, and nx, ny, and nz are refractive indices in the x-axis, y-axis and z-axis directions, respectively.

The phase difference and the thickness direction retardation of the cholesteric liquid crystal layer can also be calculated by Equations 3 and 4, respectively. At this time, in Equations 3 and 4, d is the thickness of the cholesteric liquid crystal layer, nx is the refractive index in the planar slow axis direction of the cholesteric liquid crystal layer, and ny is the refractive index in the planar fast axis direction of the cholesteric liquid crystal layer, nz is the refractive index of the cholesteric liquid crystal layer in the thickness direction.

In the present specification, reverse wavelength dispersion may mean a characteristic that satisfies Equation 5 below, and the normal wavelength dispersion may mean a characteristic that satisfies Equation 6 below, and flat The flat wavelength dispersion may mean a property that satisfies Equation 7 below.

[Equation 5]

R(450)/R(550) <R(650)/R(550)

[Equation 6]

R(450)/R(550)> R(650)/R(550

[Equation 7]

R(450)/R(550) = R(650)/R(550)

In Equation 5, Equation 6, and Equation 7, R(λ) means a planar retardation value at a wavelength of λnm.

In one example, when the retardation layer has a reverse wavelength dispersion characteristic, the R(450)/R(550) value is 0.81 to 0.99, 0.82 to 0.98, 0.83 to 0.97, 0.84 to 0.96, 0.85 to 0.95, 0.86 to 0.94 , 0.87 to 0.93, 0.88 to 0.92, or 0.89 to 0.91, and R(650)/R(550) values of 1.01 to 1.19, 1.02 to 1.18, 1.03 to 1.17, 1.04 to 1.16, 1.05 to 1.15, 1.06 to 1.14 , 1.07 to 1.13, 1.08 to 1.12, or 1.09 to 1.11.

In one example, when the retardation layer has a normal wavelength dispersion characteristic, the R(450)/R(550) values are 1.01 to 1.19, 1.02 to 1.18, 1.03 to 1.17, 1.04 to 1.16, 1.05 to 1.15, 1.06 to 1.14 , 1.07 to 1.13 or 1.08 to 1.12, and R(650)/R(550) may be 0.81 to 0.99, 0.82 to 0.98, 0.83 to 0.97, 0.84 to 0.96, 0.85 to 0.95, or 0.86 to 0.94.

In one example, the absolute value of the difference between the R(450)/R(550) value and the R(650)/R(550) value having a flat wavelength dispersion characteristic of the retardation layer is within 5, within 4, and within 3, Within 2 may be within 1 or substantially 0. In one example, the retardation layer having a flat wavelength dispersion characteristic has an R(450)/R(550) value of 0.95 to 1.05 or 0.99 to 1.01, and an R(650)/R(550) value of 0.95 to 1.05 Alternatively, it may be 0.99 to 1.01.

The retardation layer may have a function of converting circularly polarized light into linearly polarized light or from linearly polarized light into circularly polarized light. The phase difference layer may have a quarter wavelength phase delay characteristic. The retardation layer may have a plane retardation value of 110 nm to 180 nm for light having a wavelength of 550 nm. The retardation layer may have a slow axis forming 40 degrees to 50 degrees with an absorption axis of the polarizer.

The retardation layer may have a reverse wavelength dispersion characteristic, a normal wavelength dispersion characteristic, or a flat wavelength dispersion characteristic. In one example, when the phase difference layer has a reverse wavelength dispersion characteristic, it may be advantageous to exhibit excellent omnidirectional reflection prevention performance and color characteristics at a viewing angle.

The phase difference layer is a single layer structure of the 1/4 wave plate 201, as shown in FIG. 2, or, as shown in FIG. 3, of the 1/2 wave plate 202 and the 1/4 wave plate 203. It may be a stacked structure.

When the phase difference layer has a single-layer structure of a 1/4 wave plate, an angle formed between the slow axis of the 1/4 wave plate and the absorption axis of the absorption polarizer may be 40 degrees to 50 degrees. The angle may be specifically 43 degrees to 47 degrees or about 45 degrees.

In the present specification, the angle formed by the A-axis and the B-axis is 0 degrees in any one of the A-axis and the B-axis, and may mean a clockwise or counterclockwise angle formed by the other axis with respect to the 0-degree axis. have. In the description of the angle in the present specification, it may be used to include both the clockwise and counterclockwise angles that are not specifically mentioned. As shown in Equations 8 and 9 below, when it is necessary to distinguish between a clockwise angle and a counterclockwise angle, a clockwise angle may be referred to as a positive number and a counterclockwise angle may be referred to as a negative number.

The quarter-wave plate may have a plane retardation value of 110 nm to 180 nm for light having a wavelength of 550 nm. The planar retardation value may be specifically 110 nm or more, 120 nm or more, 130 nm or more, or 135 nm or more, and may be 180 nm or less, 160 nm or less, 150 nm or less, or 145 nm or less. In one example, when the 1/4 wavelength plate has a reverse wavelength dispersion characteristic, it may be advantageous to exhibit excellent omnidirectional reflection prevention performance and color characteristics at a viewing angle.

When the retardation layer has a stacked structure of a 1/2 wave plate and a 1/4 wave plate, an angle formed by the slow axis of the 1/2 wave plate and the absorption axis of the absorption polarizer may be 10 degrees to 80 degrees. The angle may mean an angle formed by the slow axis of the half wave plate in a clockwise or counterclockwise direction compared to the absorption axis of the absorption polarizer at 0 degrees.

The slow axis of the 1/4 wave plate satisfies Equation 8 below when the angle of the slow axis of the 1/2 wave plate is greater than 0 degrees, and Equation 9 below when the angle of the slow axis of the 1/2 wave plate is less than 0 degrees. I can be satisfied.

[Equation 8]

H×2 + 35 ≤ Q ≤ H×2 + 55

[Equation 9]

H×2-55 ≤ Q ≤ H×2-35

In Equations 8 and 9, H is the angle of the slow axis of the 1/2 wave plate, Q is the angle of the slow axis of the 1/4 wave plate, and the angles of the slow axis of the 1/4 wave plate and the 1/2 wave plate are respectively This is the angle when the absorption axis of the absorption type polarizer is set to 0 degrees, and when the angle is clockwise relative to the absorption axis, the angle is greater than 0 degrees, and when the angle is counterclockwise to the absorption axis, the angle is less than 0 degrees. Have.

For example, when the slow axis of the 1/2 wave plate has an angle of 10 degrees to 80 degrees clockwise with respect to the absorption axis of the absorption polarizer, the slow axis of the 1/4 wave plate may satisfy Equation 8, and 1 When the slow axis of the /2 wave plate has an angle of -10 degrees to -80 degrees in a counterclockwise direction with respect to the absorption axis of the absorption polarizer, the slow axis of the 1/4 wave plate may satisfy Equation 9.

In one example, an angle formed between the 1/2 wave plate and the absorption axis of the absorption polarizer may be, for example, 10 degrees to 60 degrees, 10 degrees to 40 degrees, or 10 degrees to 20 degrees. In one example, an angle formed by the slow axis of the 1/4 wave plate and the slow axis of the 1/2 wave plate may be about 10 degrees to 70 degrees or 55 degrees to 65 degrees.

The half-wave plate may have a plane retardation value of 200 nm to 300 nm for light having a wavelength of 550 nm. The planar retardation value may be specifically 200 nm or more, 220 nm or more, or 240 nm or more, and may be 300 nm or less, 280 nm or less, or 260 nm or less. The quarter-wave plate may have a plane retardation value of 100 nm to 150 nm for light having a wavelength of 550 nm. The phase retardation value of the 1/4 wave plate may be specifically 100 nm or more, 110 nm or more, or 120 nm or more, and may be 150 nm or less, 140 nm or less, or 130 nm or less.

The 1/2 wave plate and the 1/4 wave plate may each independently have a normal wavelength dispersion characteristic, a reverse wavelength dispersion characteristic, or a flat wavelength dispersion characteristic. In one example, the 1/2 wave plate and the 1/4 wave plate may each have normal wavelength dispersion characteristics. In one example, the 1/2 wave plate may be disposed adjacent to the polarizer compared to the 1/4 wave plate.

The optical compensation layer may include a cholesteric liquid crystal layer (hereinafter, may be abbreviated as a CLC layer). The CLC layer may include a cholesterically aligned liquid crystal region (hereinafter, may be abbreviated as a CLC region). The CLC region may be a liquid crystal region having a helical structure in which directors of liquid crystal molecules are twisted along a helical axis to form a layer and are aligned.

Referring to FIG. 4, CLC has a helical structure in which directors of liquid crystal molecules (n in FIG. 4) are twisted along a spiral axis (H in FIG. 4) to form a layer and align. In the structure of the CLC, the distance (P in FIG. 4) until the director of the liquid crystal molecules completes the rotation of 360 degrees is referred to as "pitch". In the present specification, the term "CLC area" may mean an area in which the director of the CLC completes a 360 degree rotation. The director of the liquid crystal molecule may mean a slow axis direction. For example, the director of the liquid crystal molecule may mean a normal direction of a disk in case of a discotic liquid crystal, and may mean a direction of a long axis of a rod shape in case of a bar-shaped liquid crystal.

CLC can selectively reflect light of circularly polarized light. The wavelength of light reflected by CLC depends on the refractive index and pitch of the liquid crystal. The helical distortion of the optical axis of the CLC results in a spatially periodic deformation in the material's dielectric tensor, which causes wavelength-selective reflection of light. In general, in CLC, for light propagating along a spiral axis, Bragg reflection occurs when the wavelength λ is in the range of the following General Formula 1.

[General Formula 1]

N _o P <λ <N _e P

In the general formula 1, P is the pitch of the CLC region, N _e represents the refractive index of CLC for light polarized parallel to the director of the CLC, and N _o is the light polarized perpendicular to the director of the CLC. Refractive index of CLC is shown.

In addition, the center wavelength λ ₀ of the wavelength range of light reflected by the CLC can be approximated by the following General Formula 2.

[General Formula 2]

λ _o = 0.5(N _o +N _e )P

In the general formula 2, P, N _e and N _o are as defined in the general formula 1.

In addition, the spectral width Δλ ₀ of light reflected by the CLC can be approximated by the following general formula (3).

[General Formula 3]

△λ ₀ =2λ _o (N _e -N _o )/ (N _o +N _e ) = P(N _e -N _o )

In the general formula 3, P, N _e and N _o are as defined in the general formula 1.

The CLC layer may include a CLC region formed such that a helical axis of the CLC region is parallel to the thickness direction of the CLC layer. In this specification, the CLC region in which the spiral axis is oriented parallel to the thickness direction of the CLC layer as described above may be referred to as a planar-oriented CLC region.

In the present specification, the term "thickness direction of a CLC layer" may mean a direction parallel to an imaginary line connecting one main surface of the CLC layer and a main surface opposite to the main surface of the CLC layer with the shortest distance.

The cholesteric liquid crystal layer may include a liquid crystal polymer. An exemplary method for producing a CLC layer is to coat a CLC composition containing a crosslinkable or polymerizable liquid crystal compound and a chiral agent, and polymerize or crosslink the composition in a state in which a helical pitch is induced by the chiral agent. In this case, the CLC layer may include a crosslinked or polymerized liquid crystal polymer. In the above, the chiral agent may be crosslinkable or polymerizable, or may be non-crosslinkable or non-polymerizable. The liquid crystal compound may be, for example, a nematic liquid crystal compound. The composition may further include a photoinitiator if necessary.

The cholesteric liquid crystal layer may have a reflection band within a range of 420 nm to 530 nm. In one example, the cholesteric liquid crystal layer may have a reflection band in the range of 420 nm to 530 nm. The cholesteric liquid crystal layer tends to shift toward a wavelength whose reflection band at the side is lower. Since the cholesteric liquid crystal layer can recycle blue light, the luminance of blue light can be improved, and the lifespan can be improved through low power driving.

The optical compensation layer may not include a cholesteric liquid crystal layer having a reflection band other than the cholesteric liquid crystal layer having the reflection band in the range of 420 nm to 530 nm. When the optical compensation layer includes a cholesteric liquid crystal layer having a different reflection band, reflection may be increased by increasing luminance by recycling light of a color other than blue light, which is not weak in lifespan.

The optical compensation layer may have a retardation value in the thickness direction of light having a wavelength of 550 nm greater than 0 nm. In one example, the optical compensation layer may have a retardation value in the thickness direction of light having a wavelength of 550 nm of 25 nm to 650 nm. As will be described later, the optical compensation layer may have a single-layer structure of a cholesteric liquid crystal layer or a stacked structure of a cholesteric liquid crystal layer and another phase difference layer. The retardation value in the thickness direction of the optical compensation layer may mean a retardation value in the thickness direction of the cholesteric liquid crystal layer when the optical compensation layer has a single-layer structure of a cholesteric liquid crystal layer. The retardation value in the thickness direction of the optical compensation layer is a retardation value in the thickness direction of the cholesteric liquid crystal layer and a retardation value in the thickness direction of the other retardation layer when the optical compensation layer is a stacked structure of a cholesteric liquid crystal layer and another retardation layer. It can be the sum of When the retardation in the thickness direction of the optical compensation layer is within the above range, the optical anisotropy of the polymer can be compensated in the application to an organic light emitting device including a polymer substrate to be described later, so that the anti-reflection property at a viewing angle can be improved.

The optical compensation layer may include a discotic cholesteric liquid crystal layer or a rod-shaped cholesteric liquid crystal layer as the cholesteric liquid crystal layer.

In one example, the optical compensation layer may have a single layer structure of the discotic cholesteric liquid crystal layer 301 having a reflection band in the range of 420 nm to 530 nm, as shown in FIG. 5.

The retardation in the thickness direction of the light having a wavelength of 550 nm of the discotic cholesteric liquid crystal layer may be in a range of 25 nm to 650 nm. The retardation in the thickness direction may be specifically 25 nm or more or 50 nm or more, and may be 650 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, or 250 nm or less. The discotic cholesteric liquid crystal layer may have optical anisotropy similar to the +C plate in a wavelength band other than the reflection band in the cholesteric alignment state due to the refractive index structure of the discotic liquid crystal. That is, the discotic cholesteric liquid crystal layer may have a positive thickness direction retardation value in a wavelength band other than the reflection band.

The thickness, pitch, and birefringence values of the discotic cholesteric liquid crystal layer may be appropriately selected in consideration of a reflection band and a retardation value in the thickness direction. The discotic cholesteric liquid crystal layer may have a thickness of, for example, 0.5 μm to 12 μm. The pitch of the discotic cholesteric liquid crystal layer may be, for example, 250 nm to 400 nm. The birefringence (n) value of the discotic cholesteric liquid crystal layer may be 0.02 to 0.20. In one example, as the thickness of the cholesteric liquid crystal layer increases, it may be more advantageous to improve the brightness of blue light.

In the present specification, the birefringence value of the liquid crystal layer may mean a difference (ne-no) between an extraordinary refractive index (ne) and an ordinary refractive index (no). The ideal refractive index means a refractive index in a direction in which the polarization direction of light is horizontal to the optical axis of the liquid crystal layer, and the normal refractive index means the refractive index in a direction in which the polarization direction of light is perpendicular to the optical axis of the liquid crystal layer. The optical axis of the liquid crystal layer may mean a slow axis.

In another example, the optical compensation layer, as shown in FIG. 6, has a stacked structure of a rod-shaped cholesteric liquid crystal layer 302 and a +C plate 303 in a reflection band of 420 nm to 530 nm. I can.

The retardation of the +C plate in the thickness direction with respect to the light having a wavelength of 550 nm may be 100 nm to 950 nm. The retardation in the thickness direction may be specifically 100 nm or more, 200 nm or more, 250 nm or more, or 270 nm or more, and may be 950 nm or 910 nm or less. The sum of the retardation in the thickness direction of the light having a wavelength of 550 nm of the rod-shaped cholesteric liquid crystal layer of the optical compensation layer and the retardation in the thickness direction of the light having the wavelength of 550 nm of the +C plate may be 25 nm to 650 nm. The sum of the retardation in the thickness direction may be specifically 25 nm or more, 50 nm or more, 100 nm or more, or 200 nm or more, and may be 650 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, or 350 nm or less.

The rod-shaped cholesteric liquid crystal layer may have an optical anisotropy similar to the -C plate in a wavelength band other than the reflection band in the cholesteric alignment state due to the refractive index structure of the rod-shaped liquid crystal. That is, the rod-shaped cholesteric liquid crystal layer may have a negative thickness direction retardation value in a wavelength band other than the reflection band. In one example, the retardation in the thickness direction at a wavelength of 550 nm of the rod-shaped cholesteric liquid crystal layer may be in the range of -25 nm to -650 nm or -50 nm to -600 nm. Therefore, in order to implement the retardation value in the thickness direction of the optical compensation layer in the above-described range, it is preferable that a +C plate is additionally included in the bar-shaped cholesteric liquid crystal layer.

The thickness, pitch, and birefringence values of the rod-shaped cholesteric liquid crystal layer may be appropriately selected in consideration of a reflection band and a retardation value in the thickness direction. The thickness of the rod-shaped cholesteric liquid crystal layer may be, for example, 0.5 μm to 12 μm. The pitch of the rod-shaped cholesteric liquid crystal layer may be, for example, 250 nm to 400 nm. The bar-shaped cholesteric liquid crystal layer may have a birefringence (n) value of 0.02 to 0.20. In one example, as the thickness of the cholesteric liquid crystal layer increases, it may be more advantageous to improve the brightness of blue light.

The thickness of the +C plate may be appropriately selected in consideration of a retardation value in the thickness direction. The thickness of the +C plate may be, for example, 0.5 μm to 7 μm.

The polarizing plate may have excellent antireflection performance at a viewing angle. The polarizing plate may have a reflectance of 25% or less, 20% or less, 15% or less, 10% or less, 9% or less, 8% or less, 7% or less, or 6% or less at an inclination angle of 60 degrees. The reflectance may be a reflectance for light of any one wavelength in the visible light region, for example, a reflectance for light of any one wavelength in the range of 380 nm to 780 nm, or a reflectance for light in the entire visible light region, or an average reflectance. have. The reflectance may be, for example, a reflectance measured from the polarizer side of the polarizing plate. The reflectance may mean a reflectance measured at a specific azimuth angle of an inclination angle of 60 degrees or a predetermined range of azimuth angles, or a reflectance measured for all azimuth angles at an inclination angle of 60 degrees or an average reflectance measured for all azimuth angles at an inclination angle of 60 degrees. , Can be measured in the manner described in the evaluation examples described later.

The polarizing plate may exhibit excellent blue light luminance characteristics. The polarizing plate may have a relative luminance of 103% or more, 105% or more, 110% or more, 115% or more, or 120% or more of blue light, for example. In the present specification, the term ``relative luminance of blue light'' refers to the ratio of the blue light luminance (I _W ) in the polarizing plate including the optical compensation layer to the blue light luminance (I _O ) in the polarizing plate not including the optical compensation layer. can do. The blue light may mean light in a wavelength range of 380 nm to 500 nm, for example, and the relative luminance of the blue light may be measured in the manner described in the evaluation examples described later.

The polarizing plate may further include a pressure-sensitive adhesive layer provided on one surface of the optical compensation layer. In one example, the pressure-sensitive adhesive layer 40 may be provided on an opposite surface of the optical compensation layer on which the retardation layer is provided, as shown in FIG. 7. The pressure-sensitive adhesive layer may be used for attaching the polarizing plate to a substrate of an organic light-emitting device. As the pressure-sensitive adhesive layer, a known pressure-sensitive adhesive layer used for attaching an optical element may be used.

The polarizing plate may further include an antireflection layer provided on one surface of the polarizer. In one example, the antireflection layer 50 may be provided on an opposite surface of the polarizer on which the retardation layer is provided, as shown in FIG. 8. As the antireflection layer, a low reflective layer having a reflectance of 0.3% to 1.5% for light having a wavelength of 550 nm may be used. As the antireflection layer, a low refractive index layer having a refractive index of 1.2 to 1.45 or a laminate of two or more layers having different refractive indexes may be used, but the present invention is not limited thereto.

Each of the 1/4 wave plate, the 1/2 wave plate, or the +C plate may be a polymer film or a liquid crystal film. Examples of the polymer film include polyolefins such as PC (polycarbonate), norbonene resin, PVA (poly(vinyl alcohol)), PS (polystyrene), PMMA (poly(methyl methacrylate)), and PP (polypropylene), A film including Par (poly(arylate)), PA (polyamide), PET (poly(ethylene terephthalate)), or PS (polysulfone) may be used. The polymer film may be stretched or contracted under appropriate conditions to impart birefringence, and thus may be used as the 1/4 wave plate, 1/2 wave plate, or +C plate. The liquid crystal film may include liquid crystal molecules aligned and polymerized. The liquid crystal molecule may be a polymerizable liquid crystal molecule. In the present specification, a polymerizable liquid crystal molecule may refer to a molecule including a site capable of showing liquid crystallinity, for example, a mesogen skeleton, and including one or more polymerizable functional groups. In addition, the inclusion of the polymerizable liquid crystal molecules in a polymerized form may mean a state in which the liquid crystal molecules are polymerized to form a skeleton such as a main chain or side chain of a liquid crystal polymer in a liquid crystal film.

The polarizer, the retardation layer, the cholesteric liquid crystal layer to the +C plate of the polarizing plate may be attached to each other through an adhesive or an adhesive, or may be laminated to each other by direct coating. As the pressure-sensitive adhesive or adhesive, an optically transparent pressure-sensitive adhesive or adhesive may be used.

Since the polarizing plate is applied to the organic light emitting device to prevent reflection of external light, the visibility of the organic light emitting device may be improved. Incident unpolarized light (hereinafter referred to as "external light") incident from the outside passes through the polarizer, and only one of the two polarization orthogonal components, that is, the first polarization orthogonal component, is transmitted. The resulting light may be converted into circularly polarized light while passing through the retardation layer. The circularly polarized light is reflected from an organic light emitting device including a substrate and an electrode, and the rotation direction of the circularly polarized light is changed. As the circularly polarized light passes through the retardation layer again, the other polarization orthogonal component of the two polarization orthogonal components That is, it is converted into a second polarization orthogonal component. Since the second polarization orthogonal component does not pass through the polarizer and does not emit light to the outside, it may have an effect of preventing reflection of external light.

Since the polarizing plate can effectively prevent reflection of external light incident from the side, the side visibility of the organic light emitting device can be improved. For example, reflection of external light incident from the side can be effectively prevented through the viewing angle polarization compensation principle.

This application relates to an organic light emitting device. An exemplary organic light emitting device may include the polarizing plate. As shown in FIG. 9, the organic light-emitting device is provided in order on the organic light-emitting panel 60 and one surface of the organic light-emitting panel, the absorption type polarizer 10, the retardation layer 20, and the optical compensation layer 30 It may include a polarizing plate including ). As shown in FIG. 10, the organic light emitting panel 60 may sequentially include a substrate 601, a color filter layer 602, a first electrode layer 603, an organic light emitting layer 604, and a second electrode layer 605. I can.

The organic light-emitting device may include a substrate, a color filter layer sequentially provided on a first surface of the substrate, a first electrode layer, an organic emission layer, and a second electrode layer, and may include the polarizing plate provided on the second surface of the substrate. have. The optical compensation layer of the polarizing plate may be disposed adjacent to the substrate compared to the polarizer.

The substrate may include a polymer. Such an organic light emitting device may be advantageous in implementing a rollable, flexible, or bendable organic light emitting device.

Examples of the polymer include polyimide, polyamic acid, polyethylene naphthalate, polyether ether ketone, polycarbonate, polyethylene terephthalate, polyether sulfide, polysulfone, or acrylic polymer. In one example, in terms of process temperature or light extraction performance, a polyimide-based substrate having excellent high-temperature durability may be used as the substrate.

As the substrate, a light-transmitting substrate may be used. The translucent substrate may have a transmittance of 50% or more, 80% or more, or 90% or more of light in the visible light region.

The retardation value in the thickness direction of the substrate may be less than 0 nm. In one example, the retardation value in the thickness direction of the light having a wavelength of 550 nm of the substrate may be in the range of -5 nm to -250 nm. The retardation value in the thickness direction of the substrate may be specifically -100nm to -250nm, or -150nm to -250nm.

The substrate may include, for example, polyimide, cyclo-olefin polymer (COP), tri-acetyl-cellulose (TAC), polycarbonate (PC), or an acrylic polymer. In one example, when a polyimide-based substrate is used as the substrate, it may be advantageous in terms of process temperature. The substrate may exhibit a negative thickness direction retardation value. In this case, by applying a polarizer including an optical compensation layer having a positive thickness direction retardation value, the optical anisotropy of the substrate can be compensated, so that the anti-reflection property at a viewing angle can be improved.

One of the first electrode and the second electrode may be an anode and the other may be a cathode. The anode is an electrode into which holes are injected and may be made of a conductive material having a high work function, and the cathode is an electrode into which electrons are injected and may be made of a conductive material having a low work function. In one example, the first electrode may be an anode, and the second electrode may be a cathode. In one example, the anode may be a transparent electrode, and the cathode may be a reflective electrode. The anode may include a transparent metal oxide, for example, ITO, IZO, AZO, GZO, ATO or SnO ₂ . The cathode may include a metal electrode, for example, Ag, Au, Al, or the like.

The organic emission layer may include an organic material capable of emitting light when power is applied to the first electrode layer and the second electrode layer. In a structure called a bottom emitting device, the first electrode layer may be formed as a transparent electrode layer, and the second electrode layer may be formed as a reflective electrode layer. In addition, in a structure called a top emitting device, the first electrode layer may be formed as a reflective electrode layer, and the second electrode layer may be formed as a transparent electrode layer. Light may be generated by recombination of electrons and holes injected by the electrode layer in the emission layer existing in the organic layer. The light may be emitted toward the substrate in the bottom emission type device and toward the second electrode layer in the top emission type device.

The organic emission layer may include a red emission layer, a green emission layer, and a blue emission layer. The emission layer may include a known organic material emitting the color. In one example, the organic light-emitting device is driven in a manner in which three primary colors of light emitting layers each emit different colors to form one pixel (dot, pixel), or by stacking the three primary colors of light emitting layers to emit white light. After configuring a pixel of, it can be driven in a manner of implementing various colors by disposing a color filter on the front surface of the white light emitting layer.

An auxiliary layer may be further included between the first electrode and the organic emission layer and between the second electrode and the organic emission layer. The auxiliary layer may include a hole transporting layer, a hole injecting layer, an electron injecting layer, and an electron transporting layer for balancing electrons and holes. However, it is not limited thereto. The encapsulation substrate may be made of glass, metal and/or polymer, and the first electrode, the organic emission layer, and the second electrode may be encapsulated to prevent moisture and/or oxygen from flowing from the outside.

The polarizing plate may be disposed on the side where light is emitted from the organic light emitting device. For example, in the case of a bottom emission structure emitting light toward the substrate, it may be disposed outside the substrate, and in the case of a top emission structure emitting light toward the encapsulation substrate, it may be disposed outside the encapsulation substrate. The polarizing plate can improve display characteristics of the organic light-emitting device by preventing external light from being reflected by a reflective layer made of metal such as electrodes and wirings of the organic light-emitting device and coming out of the organic light-emitting device. In addition, as described above, the polarizing plate can exhibit an anti-reflection effect not only from the front side but also from the side, thereby improving side visibility.

The present application can provide a polarizing plate for an organic light emitting device and an organic light emitting device having an effect of improving the lifespan through low power driving by improving the luminance of blue light, and having excellent antireflection properties at a viewing angle.

1 to 3 exemplarily show a polarizing plate.
4 shows an exemplary cholesteric alignment liquid crystal layer.
5 to 8 exemplarily show a polarizing plate.
9 exemplarily shows an organic light emitting device.
10 shows an organic light emitting panel as an example.

The present application will be described in detail through the following examples, but the scope of the present application is not limited by the following examples.

Comparative example One

An organic light-emitting device was prepared by placing a polarizing plate including a low reflective layer, an absorption type polarizer, and a 1/4 wavelength plate sequentially on one side of the substrate of the OLED panel. The absorption type polarizer has an absorption axis in one direction and a single transmittance (Ts) of 42.5%. In the 1/4 wave plate, the slow axis is 45 degrees with the absorption axis of the polarizer, the R(450)/R(550) value is 0.86, and the Rin(550) value is 140 nm. The OLED panel (OLED55B7K, LG Electronics) includes a substrate, a color filter layer, a transparent electrode, an organic light emitting layer, and a reflective electrode, and has a reflectance of 44%. The reflectance of the OLED panel is an average reflectance for a wavelength of 380 nm to 780 nm measured from the front side. The substrate is a polyimide substrate having a retardation value of -200 nm in the thickness direction. The low reflection layer has a refractive index of 1.36 for light having a wavelength of 550 nm and a thickness of 100 nm.

Comparative example 2

An organic light-emitting device was prepared by placing a polarizing plate including a low reflective layer, an absorption type polarizer, a 1/2 wavelength plate, and a 1/4 wavelength plate sequentially on one side of the substrate of the OLED panel.

The slow axis of the 1/2 wave plate is 15 degrees with the absorption axis of the polarizer, the R(450)/R(550) value is 1.1, and the Rin(550) value is 257 nm. The slow axis of the 1/4 wave plate is 75 degrees with the absorption axis of the polarizer, the R(450)/R(550) value is 1.1, and the Rin(550) value is 128 nm. The low reflective layer, the polarizer, and the OLED panel are the same as in Comparative Example 1.

Example One

An organic light emitting device was prepared by disposing a polarizing plate including a low reflective layer, an absorption type polarizer, a quarter wave plate, and a discotic cholesteric liquid crystal layer sequentially on one side of a substrate of an OLED panel.

The maximum reflection wavelength of the discotic cholesteric liquid crystal layer is 465 nm, and the thickness and thickness direction retardation values are adjusted as shown in Table 2 below. The low reflection layer, the polarizer, the 1/4 wavelength plate, and the OLED panel are the same as in Comparative Example 1.

Example 2

An organic light-emitting device was prepared by placing a polarizing plate including a low reflective layer, an absorption type polarizer, a 1/2 wave plate, a 1/4 wave plate, and a discotic cholesteric liquid crystal layer sequentially on one side of the substrate of the OLED panel. .

The maximum reflection wavelength of the discotic cholesteric liquid crystal layer is 465 nm, and the thickness and the retardation in the thickness direction are adjusted as shown in Table 3 below. The low reflective layer, polarizer, 1/2 wave plate, 1/4 wave plate, and OLED panel are the same as in Comparative Example 2.

Example 3

An organic light-emitting device was prepared by placing a polarizing plate sequentially including a low reflective layer, an absorption type polarizer, a 1/4 wave plate, a rod-shaped cholesteric liquid crystal layer, and a +C plate on one side of the substrate of the OLED panel.

The maximum reflection wavelength of the rod-shaped cholesteric liquid crystal layer is 465 nm, the thickness and thickness direction retardation values are adjusted as shown in Table 4 below, and the thickness direction retardation value of the +C plate is also adjusted as shown in Table 4 below. The low reflection layer, the polarizer, the 1/4 wavelength plate, and the OLED panel are the same as in Comparative Example 1.

Example 4

A polarizing plate including a low reflective layer, an absorption polarizer, a 1/2 wave plate, a 1/4 wave plate, a rod-shaped cholesteric liquid crystal layer and a +C plate in sequence is placed on one surface of the OLED panel A light emitting device was prepared.

The maximum reflection wavelength of the rod-shaped cholesteric liquid crystal layer is 465 nm, the thickness and thickness direction retardation values are adjusted as shown in Table 5 below, and the thickness direction retardation value of the +C plate is also adjusted as shown in Table 5 below. The low reflective layer, polarizer, 1/2 wave plate, 1/4 wave plate, and OLED panel are the same as in Comparative Example 2.

Evaluation example 1 Reflectance evaluation

For Examples and Comparative Examples, reflectance was simulated (Techwiz 1D plus, man system) in the lateral direction of 60 degrees from the front and the front according to the azimuth angles from 0 to 360 degrees, and the results are summarized in Tables 1 to 5. Reflectance (%) is calculated as a ratio (R _I / R _O) of the intensity _(I R) reflection for the incident light (R _O), it means the average reflectance of the 380nm to 780nm wavelength. In Tables 1 to 5, the average reflectance refers to the average value of the reflectance at an azimuth angle of 0 to 360 degrees, and the maximum reflectance refers to the highest reflectance among the reflectivity at an azimuth angle of 0 to 360 degrees. From Tables 1 to 5, it can be seen that Examples 1 to 4 have similar or better anti-reflective properties compared to Comparative Examples 1 to 2.

Evaluation example 2 Blue light luminance evaluation

For the Examples and Comparative Examples, the blue light luminance for the front characteristics was simulated ((Techwiz 1D plus, Menai System), and the results are summarized in Tables 1 to 5. Specifically, a blue image (Blue) in an OLED panel image), and the luminance was measured from the emission spectrum generated when a polarizing plate was applied to an OLED panel (OLED55B7K, LG Electronics) as in Examples and Comparative Examples. , G, B]=[0, 0, 255], where 255 is the maximum value that can be realized as a digital image, and the luminance of the blue image was evaluated as the blue light luminance, Examples 1 and 3 were comparative examples. Values for the case where the blue light luminance of 1 is 100%, and Examples 2 and 4 are values for the case of 100% of the blue light luminance of Comparative Example 2. Examples 1 to 4 from Tables 1 to 5 It can be seen that the blue light luminance is higher compared to Comparative Examples 1 to 2.

CLC layer Front reflectance (%) Reflectance (%)
(60 degree side) Blue light
Luminance (%) Comparative Example 1 none 1.3 17 100 Comparative Example 2 none 1.23 18.1 100

Example 1 Discotic CLC Floor Front reflectance (%) Average reflectance (%)
(60 degrees side) Reflectance (%)
(60 degrees side) Blue light
Luminance (%) thickness
(㎛) Rth
(nm) One 0.5 25 1.64 16.1 17.8 103.8 2 One 50 1.78 13.9 16.6 109.6 3 2 100 1.86 10.9 13.1 117.9 4 4 200 1.88 5.75 6.1 121.4 5 5 250 1.89 6.4 7.4 121.9 6 10 500 1.95 17.6 19.7 121.8 7 12 600 1.95 22.6 23.6 121.1

Example 2 Discotic CLC Floor Front reflectance (%) Average reflectance (%)
(60 degrees side) Reflectance (%)
(60 degrees side) Blue light
Luminance (%) thickness
(㎛) Rth
(nm) One 0.5 25 1.5% 17.1 19.9 104.4 2 One 50 1.66 15.6 17.9 110.1 3 2 100 1.76 12.6 15.4 117.7 4 4 200 1.81 7.5 8.8 120.3 5 5 250 1.81 6.4 7.18 122.1 6 10 500 1.82 16.6 19.1 122.7 7 12 600 1.83 21.6 23.1 122.9

Example 3 Rod-shaped CLC layer +C plate Front reflectance (%) Average reflectance (%)
(60 degrees side) Reflectance (%)
(60 degrees side) Blue light
Luminance (%) thickness
(㎛) Rth
(nm) Rth
(nm) One 0.5 -25 250 1.68 5.8 6.2 107 2 One -50 290 1.76 5.85 6.45 115.7 3 2 -100 340 1.84 5.8 6.22 121.8 4 4 -200 460 1.91 6.15 6.75 121.7 5 6 -300 570 1.91 6.25 6.95 122.4 6 10 -500 790 1.91 6.65 7.35 122.9 7 12 -600 910 1.91 6.7 7.6 123.2

Example 4 Rod-shaped CLC layer +C plate Front reflectance (%) Average reflectance (%)
(60 degrees side) Reflectance (%)
(60 degrees side) Blue light
Luminance (%) thickness
(㎛) Rth
(nm) Rth
(nm) One 0.5 -25 270 1.65 6.3 7.1 104.1 2 One -50 300 1.68 6.2 6.9 107.5 3 2 -100 340 1.78 6.5 7.3 118.5 4 4 -200 460 1.81 6.6 7.4 121.3 5 6 -300 570 1.83 7.7 8.7 121.9 6 10 -500 780 1.83 7.8 8.8 121.8 7 12 -600 910 1.82 8.5 9.8 122.3

10: absorption polarizer, 20: retardation layer, 201: 1/4 wave plate, 202: 1/2 wave plate, 203: 1/4 wave plate, 30: optical compensation layer, 301: discotic cholesteric liquid crystal layer , 302: rod-shaped cholesteric liquid crystal layer, 303: +C plate, 40: adhesive layer, 50: antireflection layer, 60: organic light emitting panel, 601: substrate, 602: color filter layer, 601: first electrode layer, 602 : Organic emission layer, 602: second electrode layer

Claims (16)

An absorption polarizer, a retardation layer for converting circularly polarized light into linearly polarized light or linearly polarized light into circularly polarized light, and an optical compensation layer, wherein the optical compensation layer includes a cholesteric liquid crystal layer having a reflection band in the range of 420nm to 530nm, , The optical compensation layer has a retardation value in the thickness direction for light having a wavelength of 550 nm in the range of 10 nm to 650 nm,
The retardation value in the thickness direction of the optical compensation layer means a retardation value in the thickness direction of the cholesteric liquid crystal layer when the optical compensation layer has a single-layer structure of a cholesteric liquid crystal layer, and the optical compensation layer is different from the cholesteric liquid crystal layer. In the case of a laminated structure of retardation layers, it means the sum of the retardation value in the thickness direction of the cholesteric liquid crystal layer and the retardation value in the thickness direction of the other retardation layer, and the retardation in the thickness direction of the cholesteric liquid crystal layer or the retardation layer (Rth ) Is a polarizing plate for an organic light emitting device calculated by Equation 4:
[Equation 4]
Rth = d × (nz-ny)
In Equation 4, Rth is the retardation in the thickness direction, d is the thickness of the cholesteric liquid crystal layer or the retardation layer, the refractive index of the ny cholesteric liquid crystal layer or the retardation layer in the plane fast axis direction, and nz is the cholesteric liquid crystal layer or It is the refractive index in the thickness direction of the retardation layer. The polarizing plate of claim 1, wherein the retardation layer has a reverse wavelength dispersion characteristic. The polarizing plate of claim 1, wherein the retardation layer has a single-layer structure of a 1/4 wave plate, and an angle formed by a slow axis of the 1/4 wave plate and an absorption axis of the absorption type polarizer is 40 degrees to 50 degrees. . The method of claim 1, wherein the retardation layer is a stacked structure of a 1/2 wave plate and a 1/4 wave plate, and an angle formed by a slow axis of the 1/2 wave plate and an absorption axis of the absorption polarizer is 10 degrees to 80 degrees. Degrees, the slow axis of the 1/4 wave plate satisfies the following Equation 8 when the angle of the slow axis of the 1/2 wave plate is more than 0 degrees, and the following Equation 9 when the angle of the slow axis of the 1/2 wave plate is less than 0 degrees Polarizing plate for organic light emitting device satisfying:
[Equation 8]
H×2 + 35 ≤ Q ≤ H×2 + 55
[Equation 9]
H×2-55 ≤ Q ≤ H×2-35
In Equations 8 and 9, H is the angle of the slow axis of the 1/2 wave plate, Q is the angle of the slow axis of the 1/4 wave plate, and the angles of the slow axis of the 1/4 wave plate and the 1/2 wave plate are respectively This is the angle for the case where the absorption axis of the absorption type polarizer is set to 0 degrees, and if the angle is clockwise relative to the absorption axis, the angle exceeds 0 degrees, and if the angle is counterclockwise to the absorption axis, the angle is less than 0 degrees. Have. The polarizing plate of claim 1, wherein the cholesteric liquid crystal layer has a reflection band in the front surface of 420 nm to 530 nm. The polarizing plate according to claim 1, wherein the optical compensation layer does not include a cholesteric liquid crystal layer having a reflection band other than the cholesteric liquid crystal layer having the reflection band in the range of 420 nm to 530 nm. The polarizing plate of claim 1, wherein the optical compensation layer has a single layer structure of a discotic cholesteric liquid crystal layer having a reflection band in the range of 420 nm to 530 nm. The polarizing plate for an organic light emitting device according to claim 7, wherein the discotic cholesteric liquid crystal layer has a retardation in the thickness direction of light having a wavelength of 550 nm in a range of 25 nm to 650 nm. The polarizing plate according to claim 1, wherein the optical compensation layer has a lamination structure of a rod-shaped cholesteric liquid crystal layer and a +C plate having a reflection band in the range of 420 nm to 530 nm. The polarizing plate of claim 9, wherein the +C plate has a retardation in the thickness direction of light having a wavelength of 550 nm of 100 nm to 950 nm. The polarizing plate of claim 9, wherein a sum of the retardation in the thickness direction of the rod-shaped cholesteric liquid crystal layer of the optical compensation layer and the retardation in the thickness direction of the +C plate is 100 nm to 400 nm for light having a wavelength of 550 nm. The polarizing plate of claim 1, further comprising an adhesive layer on one surface of the optical compensation layer. The polarizing plate of claim 1, further comprising an antireflection layer on one surface of the polarizer. A substrate, a color filter layer sequentially provided on the first surface of the substrate, a first electrode layer, an organic emission layer, and a second electrode layer, and the polarizing plate of claim 1 provided on the second surface of the substrate, An organic light emitting device in which an optical compensation layer is disposed adjacent to the substrate compared to a polarizer. 15. The organic light-emitting device of claim 14, wherein the substrate comprises polyimide, cyclo-olefin polymer (COP), tri-acetyl-cellulose (TAC), polycarbonate (PC), or an acrylic polymer. The organic light-emitting device of claim 14, wherein the retardation in the thickness direction of the substrate is in the range of -5nm to -250nm.

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