Display elements and display devices

Abstract

The display device combines a black PDL and an optical film to reduce surface reflectance and suppress dimming of OLED output. The display device integrates organic light-emitting diodes (OLEDs), each consisting of an anode, an organic light-emitting layer, and a cathode, on a substrate. The display device also includes partition walls (PDLs) made of a black material that surround the organic light-emitting diodes, and an optical film that covers the organic light-emitting diodes and the partition walls.

Description

[Technical Field]

[0001] This disclosure relates to a display element, and more particularly to a display element having an organic light-emitting layer and arranged in a matrix to constitute a display device. [Background technology]

[0002] In display devices containing multiple pixels, which are display elements having organic light-emitting diodes (OLEDs), polarizing plates are installed to obtain high contrast. Therefore, since the polarizing plate reduces the OLED output by approximately 60%, the power consumption of the display element increases in order to obtain a given amount of light. This increase in power consumption shortens the lifespan of the OLED.

[0003] The polyimide substrate used in top-emission OLEDs has a surface reflectivity of approximately 10% or more, and when an anode electrode made of silver (or a silver alloy) is used to increase the external quantum efficiency (EQE), the surface reflectivity is approximately 90% or more. Therefore, OLED display elements without polarizers have high reflectivity, and visibility is significantly reduced, especially under sunlight.

[0004] To address these problems, a light-shielding film is provided in contact with the anode electrode, or a light-shielding film is used on the pixel-defining layer (PDL) that defines the OLED (see, for example, Patent Documents 1-3). When the aperture ratio of each RGB color OLED is 40%, the surface reflectance of the polyimide substrate is 10%, and the reflectance of the anode electrode is 90%, the average surface reflectance is calculated to be approximately 45%. By providing a light-shielding film, the surface reflectance of the polyimide substrate can be reduced by approximately 5% or more, resulting in an average surface reflectance of approximately 35%, demonstrating an improvement of about 10% in average surface reflectance. However, the reflectance is still high for a practical display element, and in reality, a polarizing plate is required.

[0005] Currently, flexible or foldable display elements are becoming increasingly common. However, polarizers are necessary to reduce reflectivity. Polarizers are generally rigid, prone to cracking when bent, and the orientation of liquid crystal molecules is affected by bending, making them unsuitable for use in flexible display devices. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2002-033185 [Patent Document 2] Japanese Patent Publication No. 2011-034884 [Patent Document 3] Japanese Patent Publication No. 2015-008036 [Overview of the project]

[0007] The object of the present invention is to provide a display element that reduces surface reflectivity by combining a black PDL and an optical film, thereby suppressing the attenuation of OLED output.

[0008] To achieve the objectives of this disclosure, one embodiment of this disclosure is a display element in which an organic light-emitting diode (OLED) is integrated, wherein an anode, an organic light-emitting layer, and a cathode are fabricated on a substrate, and the element comprises a partition made of a black material surrounding the organic light-emitting diode, and an optical film covering the organic light-emitting diode and the partition.

[0009] According to this embodiment, by combining a black partition with an optical film having a predetermined range of polarization degrees, the average surface reflectivity of the OLED display element can be reduced, and an improvement in EQE can be expected, thereby suppressing the attenuation of OLED output.

[0010] The surface resistivity of the partition wall is 10 14 Ω / cm 2 The above is true, and the volume resistivity is 10 14It is preferably above Ω / cm.

[0011] According to this form, leakage current can be suppressed and surface reflection can be suppressed at a high optical density.

[0012] The optical density of the partition is preferably 1.0 or more.

[0013] According to this form, leakage light to an adjacent OLED can be reduced.

[0014] The optical film can be a polarizing film with a polarization degree of 60 - 90%.

[0015] According to this form, it can satisfy the requirements for application to an OLED display element, that is, a surface reflectance of 12.5% or less and an expected EQE improvement rate of 10% or more. <000007@>

[0016] The optical film can be an ND filter with an optical density of 0.15 - 0.26.

[0017] According to this form, it can satisfy the requirements for application to an OLED display element, that is, a surface reflectance of 12.5% or less and an expected EQE improvement rate of 10% or more.

[0018] A portion other than the partition (PDL) surrounding the organic light-emitting diode on the substrate is coated with the black material, and an opening is formed in a part of the coated portion.

[0019] According to this form, an OLED with high transmittance and improved contrast by a black PDL can be provided.

Brief Description of Drawings

[0020] [Figure 1] It is a diagram showing the structure of an OLED according to an embodiment of the present disclosure. [Figure 2] It is a diagram showing the pixel structure of a display element using the OLED of this embodiment. [Figure 3] This is a diagram showing the structure of a conventional polyimide PDL. [Figure 4] This is a diagram showing the structure of the black PDL of the present embodiment. [Figure 5] This is a diagram showing an example of the relationship between the optical density and the surface reflectance of the PDL. [Figure 6] This is a diagram showing the structure of an optical film applied to the OLED of the present embodiment. [Figure 7] This is a diagram showing an example of the characteristics of the LPE film of the present embodiment. [Figure 8] This is a diagram showing the output spectrum of a display element using the OLED of the present embodiment. [Figure 9] This is a diagram showing the improvement effect of the OLED output by the LPE film of the present embodiment on a conventional polarizing plate. [Figure 10] This is a diagram showing an example of the characteristics of the ND filter of the present embodiment.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0022] FIG. 1 shows the structure of an OLED according to an embodiment of the present invention. FIG. 1 is a cross-sectional view with the emission direction (display surface of the OLED display element) of the OLED 100 on the upper side of the figure, and is a diagram schematically showing the layer structure. The OLED 100 has a backside barrier 110, a substrate 121, a backplane 122, a frontplane 130, and a thin film encapsulant (TFE) 140 laminated in this order.

[0023] The backside barrier 110 has a first inorganic barrier layer 111 such as silicon nitride (SiNx), silicon oxynitride (SiNxOy), or silicon oxide (SiOx), an organic barrier layer 112 of an organic resin, and a second inorganic barrier layer 113 of SiNx or SiOx laminated in this order, and prevents the intrusion of O2 and H2O from the opposite side of the emission direction, that is, the backside. [[ID= forty]]

[0024] On the backplane 122 on the substrate 121, a driving circuit for thin-film transistors (TFTs) is embedded directly beneath each pixel to apply voltage or current to selected pixels for individual operation. The backplane 122 is planarized by embedding the TFTs and wiring on the substrate 121 with resin.

[0025] The front plane 130 is constructed by sequentially stacking an anode 131, an emissive layer including a hole injection layer (HIL) 132, a hole transport layer (HTL) 133, an organic light-emitting layer (EML) 134, a hole block layer (HBL) 135, and an electron transport layer (ETL) 136, and a cathode 137.

[0026] TFE140 consists of a first inorganic barrier layer 141 of SiNx / SiOx with a thickness of approximately 0.5 μm-1 μm, an organic barrier layer 142 with a thickness of approximately 7.5 μm-15 μm, and a second inorganic barrier layer 143 of SiNx / SiOx with a thickness of approximately 0.5 μm-1 μm, which are stacked in sequence. The thickness of each component of TFE140 can be arbitrarily set according to the optimal light extraction conditions for optical design in conjunction with the stacked structure of the OLED configured below, and is determined by the panel design of the OLED display element, so it is not uniquely determined. TFE140 prevents the intrusion of O2 and H2O from the display surface of the OLED display element.

[0027] OLED100 is a top-emission type OLED in which light generated when holes injected from the anode 131 and electrons injected from the cathode 137 recombine within the organic light-emitting layer 134 is extracted from the cathode 137 side, which is opposite to the substrate 121.

[0028] The substrate 121 is a support on which multiple OLEDs 100 are arranged and formed on its upper surface. For example, quartz, glass, metal foil, or a resin film or sheet can be used. If the substrate 121 is made of resin, the material can be polyesters such as polybutylene naphthalate (PBN), methacrylic resins represented by polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide, polyamide (PA), or polycarbonate resin.

[0029] The anode 131 can be, for example, one with a large work function from the vacuum level of the electrode material in order to efficiently inject holes into the light-emitting layer. Specifically, the electrode material can be a single metal or alloy such as chromium (Cr), gold (Au), platinum (Pt), nickel (Ni), copper (Cu), tungsten (W), or silver (Ag). The anode 131 may also have a sputtered or evaporated layered structure of a metal film made of these single metals or alloys and a transparent conductive film such as indium tin oxide (ITO), indium zinc oxide (InZnO), or an alloy of zinc oxide (ZnO) and aluminum (Al).

[0030] In particular, in the case of a top-emission type display element, the anode 131 uses an electrode of the highly reflective OLED 100, thereby improving the efficiency of light extraction to the outside due to interference effects and high reflectivity effects. For example, the anode 131 uses a structure in which a first layer with excellent light reflectivity and a second layer with light transmittance and a large work function, provided above it, are sputtered or deposited. The first layer can mainly use an alloy with Al or Ag as the main component, and as a minor component, a material with a work function relatively smaller than Al, the main component with high reflectivity, is used. Lanthanide series elements can be used as such minor components. Although the work functions of lanthanide series elements are not large, the inclusion of these elements improves the stability of the anode 131 and also satisfies the hole injection properties of the anode 131. In addition to lanthanide series elements, elements such as silicon (Si) and copper (Cu) may also be used as minor components.

[0031] The second layer can be made of aluminum alloy oxide, molybdenum (Mo) oxide, zirconium (Zr) oxide, chromium oxide, or tantalum (Ta) oxide. For example, if the second layer is an aluminum alloy oxide layer (including native oxide film) containing lanthanide series elements as minor components, the transmittance of the second layer containing these elements will be good because lanthanide series elements have high transmittance. This will maintain a high reflectance on the surface of the first layer. Furthermore, the properties of the anode 131 can be improved by using a transparent conductive layer such as ITO in the second layer. Because ITO has a large work function, using it on the side in contact with the substrate 121, i.e., in the first layer, can increase carrier injection efficiency and improve adhesion between the anode 131 and the substrate 121.

[0032] Furthermore, if the driving method for the display element configured using the OLED 100 is an active matrix method, after forming the anode 131, the pixel portion is patterned with a pixel definition layer (PDL), and the anode 131 is connected to a driving TFT provided on the substrate 121.

[0033] HIL132, HTL133, EML134, HBL135, and ETL136, which are contained in the light-emitting layer, are organic layers. These organic layers are composed of acrylic compounds and hexamethyldisiloxane (HMDSO), as well as other materials described later. The organic layers are formed, for example, by an inkjet printer. The film thickness and constituent materials of each layer that makes up the organic layer are not particularly limited, but an example is shown below.

[0034] HIL132 is a buffer layer that enhances hole injection efficiency into EML134 and prevents leakage. The thickness of HIL132 is, for example, 5 nm to 200 nm, and more preferably in the range of 8 nm to 150 nm. The constituent material of HIL132 can be appropriately selected in relation to the materials of the electrodes and adjacent layers, and includes, for example, conductive polymers such as polyaniline, polythiophene, polypyrrole, polyphenylene vinylene, polythienylene vinylene, polyquinoline, polyquinoxaline and their derivatives, polymers containing aromatic amine structures in the main chain or side chains, metal phthalocyanines (such as copper phthalocyanine), and carbon. Specific examples of conductive polymers include oligoaniline and polydioxythiophenes such as poly(3,4-ethylenedioxythiophene) (PEDOT).

[0035] HTL133 is an organic layer designed to enhance hole transport efficiency to EML134. The thickness of HTL133 can be set in the range of 5nm-200nm, depending on the overall configuration of the device. If necessary, the thickness of HTL133 can be set in the range of 8nm-150nm. As materials for constituting HTL133, luminescent materials soluble in organic solvents can be used, such as polyvinylcarbazole, polyfluorene, polyaniline, polysilane or derivatives thereof, polysiloxane derivatives having aromatic amines in the side chain or main chain, polythiophene and its derivatives, polypyrrole or triphenylamine derivatives, etc.

[0036] In EML134, recombination of electrons and holes occurs when an electric field is applied, resulting in light emission. The thickness of EML134 depends on the overall configuration of the device, but can be set to, for example, 10nm-200nm. If necessary, the thickness of EML134 can be 20nm-150nm. Each EML134 may have a single-layer or multi-layer structure.

[0037] The materials constituting EML134 can be any material corresponding to the respective emission color, such as (poly)paraphenylene vinylene derivatives, polyfluorene polymer derivatives, polyphenylene derivatives, polyvinylcarbazole derivatives, polythiophene derivatives, perylene dyes, coumarin dyes, rhodamine dyes, triphenylamine derivatives, or polymers doped with organic EL materials. Examples of doping materials include rubrene, perylene, 9,10-diphenylanthracene, tetraphenylbutadiene, Nile Red, coumarin 6, and triphenylamine derivatives. The materials constituting EML134 may be a mixture of two or more of the above materials. Furthermore, the materials for the organic light-emitting layer 134 are not limited to the high molecular weight materials mentioned above, but may also be a combination of low molecular weight materials. Examples of low molecular weight materials include anthracene, benzine, styrylamine, triphenylamine, porphyrin, triphenylene, azatriphenylene, tetracyanoquinodimethane, triazole, imidazole, oxadiazole, polyarylalkane, phenylenediamine, arylamine, oxazole, fluorenone, hydrazone, stilbene or their triphenylamine derivatives, or heterocyclic conjugated monomers or oligomers such as polysilane compounds, vinylcarbazole compounds, thiophene compounds, or aniline compounds.

[0038] In addition to the materials mentioned above, EML134 can be composed of other materials that have high luminescence efficiency, such as low molecular weight fluorescent materials, phosphorescent dyes, or metal complexes, as luminescent guest materials. EML134 may also be a hole-transporting organic luminescent layer that also functions as the HTL133 described above, or an electron-transporting organic luminescent layer that also functions as the ETL136 described later.

[0039] HBL135 prevents the inflow of holes into cathode 137, and for example, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) can be used. The thickness of HBL135 can be, for example, 0.1 nm to 100 nm.

[0040] ETL136 is an organic layer designed to enhance electron transport efficiency to EML134. The thickness of ETL136 can be set to, for example, 5nm-200nm, depending on the overall configuration of the device. If necessary, the thickness of ETL136 can be set to 10nm-180nm. It is preferable to use an organic material with excellent electron transport ability as the material for ETL136. By increasing the transport efficiency to EML134, the change in emission color due to electric field strength, as described later, is suppressed. Specifically, it is preferable to use arylpyridine derivatives, benzimidazole derivatives, etc. This maintains high electron supply efficiency even at low drive voltages. Other examples include alkali metals, alkaline earth metals, rare earth metals and their oxides, composite oxides, fluorides, carbonates, etc.

[0041] ETL136 has electron donor properties, and as its material, for example, an electron transport material doped with an n-type dopant, specifically the materials listed above, can be used. Examples of n-type doped materials include alkali metals, alkaline earth metals, or their oxides, composite oxides, fluorides, and organic complexes. In particular, when the electron mobility of ETL136 is relatively large, materials with low electronegativity and excellent electron donor properties are preferred. Among these, materials with low light absorption in the visible light region in the film state are preferred. Specifically, examples include alkali metals such as Li, Na, K, Rb, and Cs, or alkaline earth metals such as Be, Mg, Ca, Sr, Ba, and Ra, and lanthanide metals such as Sm, Yb, Ga, and La, which have low electronegativity.

[0042] The cathode 137 is, for example, made of a material with a thickness of about 10 nm, good light transmittance, and a low work function. Light extraction can also be ensured by forming a transparent conductive film using an oxide. In this case, ZnO, ITO, InZnO, InSnZnO, etc., can be used. Furthermore, the cathode 137 may be a single layer, or it may be a structure in which multiple layers are stacked sequentially from the anode 131 side. The cathode 137 may also be a mixed layer containing organic light-emitting materials such as aluminum quinoline complexes, styrylamine derivatives, and phthalocyanine derivatives. In this case, it may also have Al-Li and Mg-Ag layers. The cathode 137 can be configured in an optimal combination and stacked structure depending on the structure of the fabricated device.

[0043] Figure 2 shows the pixel structure of the display element using OLEDs according to this embodiment. It shows one pixel in which OLEDs of each RGB color are integrated. A front plane 130 is formed on the back plane 122, and PDL 180a-180d are patterned to define the front planes 130a-130c of each RGB color. The anode 131 of the front plane 130 is connected to the wiring on the back plane 122.

[0044] TFE 140 (first inorganic barrier layer 141, organic barrier layer 142, and inorganic barrier layer 143) is laminated to cover the front planes 130a-130c and PDL 180a-180d, thereby encapsulating the OLED. Furthermore, the optical film 160 of this embodiment, described below, is laminated via an adhesive layer 150.

[0045] By replacing conventional polyimide PDL with black PDL, the black PDL directly absorbs ambient light from the outside (Figure 2A), or absorbs a portion of the light reflected by the anode 131 (Figure 2B). Furthermore, it can also absorb light leaking from adjacent OLEDs (Figure 2C). Therefore , Next-generation polyimide PDL A black PDL that replaced it. Therefore, it can be suppressed at high optical density (OD). Also, as will be discussed later, leakage current can be suppressed by using black material.

[0046] Figure 3 shows the configuration of a conventional polyimide PDL. It shows an example of one pixel 201 in which four OLEDs with R=1, G=2, and B=1 are integrated. In addition to the partition wall surrounding the OLED, for example, the upper part 202 of the backplane 122 into which the TFTs and wiring are embedded, a black material is used to reduce reflection from the front. 200 It is desirable that the area be covered with the same material as the black PDL. In other words, to improve contrast, it is generally preferable that the area other than the aperture region where the pixel 201 is located is covered with the same material as the black PDL. However, if it is desirable to increase the transmittance of the OLED display element itself, it is preferable to provide a region that is not covered with the said material.

[0047] Figure 4 shows the configuration of the black PDL of this embodiment. In this embodiment, the black PDL material 210 The pattern is created, and an opening is made in a part of the area other than the black PDL surrounding the OLED of pixel 211, for example, in the area 212 where the TFT and wiring of the backplane 122 are embedded. 213It is formed. As a result, an OLED with high transmittance and improved contrast by the black PDL can be provided. Furthermore, since it can be a transparent OLED, it becomes possible to install a sensor or a camera below the OLED display element.

[0048] The black material has a low resistivity, which can cause leakage current from adjacent pixels or dust from carbon particles added to add conductivity, becoming a cause of defects. For many black materials, the surface resistivity (sheet resistance) of black materials such as carbon is about 10 16 Ω / cm 2 or less. On the other hand, the surface resistivity of the PDL of the OLED needs to be 10 14 Ω / cm 2 or more. Thereby, the black material can be applied, and the leakage current can be suppressed by the black PDL. The volume resistivity (electrical resistivity, specific resistance) of the black material is about 10 16 Ω / cm or less. In an OLED, 10 14 Ω / cm or more is sufficient, and the volume resistivity is also sufficient.

[0049] Specific examples of the black material include at least one of carbon black, acetylene black, lamp black, manganese ferrite, or an acrylic group-containing resin, a polyimide group-containing resin, a silicone group-containing resin, a fluorine group-containing resin, a urethane group-containing resin, and an epoxy group-containing resin. A material containing at least one of manganese ferrite, bone black, graphite, iron black, aniline black, cyanine black, titanium black, aniline black, or iron oxide black pigment may be used as the black material.

[0050] Examples of base materials for black materials include acrylic group-containing resins, polyimide group-containing resins, silicone group-containing resins, fluorine group-containing resins, urethane group-containing resins, and epoxy group-containing resins. It is preferable to use a mixture of two or more resins as the base material. Furthermore, a black material may be used as a coloring substance mixed with the base material. Examples of black coloring materials include manganese ferrite, carbon black, acetylene black, lamp black, bone black, graphite, iron black, aniline black, cyanine black, titanium black, and iron oxide black pigment.

[0051] The coloring substance mixed with the aforementioned substrate may be not only the black substance mentioned above, but also a mixture of coloring substances of different colors having light-shielding properties equivalent to those of the black substance. For example, such coloring substances include Victoria Pure Blue (42595), Auramine O (41000), Catiron Brilliant Flavin (Basic 13), Rhodamine 6 GCP (45160), Rhodamine B (45170), Safranin OK 70:100 (50240), Elio Glauzan X (42080), No.120 / Lionol Yellow (21090), Loner Yellow GRO (21090), Simler Fast Yellow 8GF (21105), Benzidine Yellow 4T-564D (21095), Simler Fast Red 4015 (12355), Lionol Red 7B4401 (15850), Fastogen Blue TGR-L (74160), Lionol Blue SM (26150), etc. Examples of applicable pigment CI (color index) are: CII Yellow pigment 20, 24, 86, 93, 109, 110, 117, 125, 137, 138, 147, 148, 150, 153, 154, 166; CI Orange pigment 36, 43, 51, 55, 59, 61; CI Red pigment 9, 97, 122, 123, 149, 168, 177, 180, 192, 215, 216, 217, 220, 224, 226, 227, 228, 240, 254; CI Violet pigment 19, 23, 29, 30, 37, 40, 50; CI Blue pigment 15, 15:1, 15:4, 15:6, 22, 60, 64; CI Green pigment 7, 36, CI Contains brown pigments 23, 25, and 26.

[0052] Optical density (OD), used as an indicator to identify PDL, is the logarithmic representation of the opacity of the medium and has the following relationship with transmittance T. OD = log10(1 / T) For example, when T=0.1 (10%), OD=1, and when T=0.01 (1%), OD=2. If OD is large, T is small.

[0053] Figure 5 shows the PDL optical densityAn example of the relationship between (OD) and surface reflectance is shown. According to this example, if the OD of the PDL is 1 or greater, it can be seen that the surface reflectance is saturated at 6%. Surface reflectance is an optical parameter determined by the overall configuration, and its absolute value does not uniquely saturate at 6%, but the saturation tendency with respect to OD is such that the relative relationship is as shown, depending on the definition of OD for any configuration. Therefore, in this embodiment, by using a material with an OD of 1 or greater, it is possible to reduce light leakage to adjacent OLEDs.

[0054] However, some of the light reflected by the anode 131 is still emitted to the outside. Furthermore, to reduce surface reflectivity, it is conceivable to add an optical film with a high OD (Optical Diode) to the display surface of the OLED display element. However, this would further reduce the OLED output, and the power consumption of the OLED display element would increase further to obtain a given amount of light. Adding a color filter (CF) is also conceivable, but it is necessary to match the output spectrum of the OLED with the transmission spectrum of the CF across the visible light range. Even after matching, a surface reflectivity of about 7% remains, and the effect is not worth the increase in manufacturing cost. It is also conceivable to use a low-reflectivity electrode material for the anode 131, but this would reduce the efficiency of top-emission type OLEDs, and the microcavity effect would also be diminished with low reflectivity.

[0055] Therefore, in this embodiment, as shown in Figure 2, an optical film 160 that reduces surface reflectance is added. In the general use of polarizers, a higher degree of polarization (PE) is desirable, for example, a PE close to 100% is preferable. On the other hand, in this embodiment, by combining it with a black PDL, if the optical film 160 has a predetermined range of PE, the average surface reflectance of the OLED display element can be reduced to 10% or less. Furthermore, since an improvement in EQE can be expected with the optical film 160 with a low PE, the attenuation of OLED output can be suppressed.

[0056] (Example 1) Figure 6 shows the structure of the optical film applied to the OLED of this embodiment. Specifically, an LPE (low polarized efficiency) film with PE = 65-80% is applied. Figure 6 is a cross-sectional view with the emission direction of the OLED 100 (display surface of the OLED display element) as the upper side of the figure. The optical film 160 is composed of, from top to bottom, a protective layer (TAC) 161 with a thickness of approximately 25 μm, a polarizing coating 162 with a thickness of approximately 4 μm, an adhesive layer (PSA) 163 with a thickness of approximately 5 μm, a quarter-wave plate 164 with a thickness of approximately 2 μm, and an adhesive layer (PSA) 165 with a thickness of approximately 15 μm. In Example 1, as an example, a liquid crystal polarizing plate with a so-called liquid crystal coating is used, and a polarizing film having a predetermined range of PE is obtained by adjusting the concentration of the dichroic dye.

[0057] Figure 7 shows an example of the characteristics of the LPE film of this embodiment. The solid line represents the expected EQE improvement rate by the optical film with low PE, shown on the left vertical axis scale, and the dashed line represents the surface reflectance, shown on the right vertical axis scale. If the requirements for the OLED display element are a surface reflectance of 10% or less and an expected EQE improvement rate of 20% or more, the PE of the optical film 160 will be in the range of 65%-80%. Furthermore, if the requirements for the practical OLED display element are relaxed to a surface reflectance of 12.5% ​​or less and an expected EQE improvement rate of 10% or more, the PE of the optical film 160 will be in the range of 60%-90%.

[0058] Figure 8 shows the output spectrum of a display element using OLED according to this embodiment. This is the output spectrum of an OLED display element equipped with OLEDs of each RGB color. The solid line represents the case when optical film 160 with PE=75%, reflectance 5.8%, and expected EQE improvement rate of 30% is applied, while the dashed line represents the case when a conventional polarizer (PE=99.96%) is applied. Figure 9 shows the improvement effect of the LPE film of this embodiment on OLED output compared to a conventional polarizer. It can be seen that with the LPE film of this embodiment, EQE is improved and OLED output is increased across the entire visible light range.

[0059] (Example 2) Instead of liquid crystal polarizers, iodine polarizers can be used, which are made by adsorbing and oriented iodine compound molecules onto polyvinyl alcohol (PVA). By adjusting the iodine concentration, PE (polyethylene) with a surface reflectance of 10% or less can be obtained within a predetermined range.

[0060] (Example 3) Instead of the polarizing plate mentioned above, an ND (Neutral Density) filter can also be applied. Figure 10 shows the characteristics of the neutral density (ND) filter added to the OLED in this embodiment. The solid line represents the expected EQE improvement rate by the low PE optical film and is shown on the left vertical axis scale, while the dashed line represents the surface reflectance and is shown on the right vertical axis scale. If the requirements for the OLED display element are a surface reflectance of 10% or less and an expected EQE improvement rate of 20% or more, the transmittance of the ND filter will be in the range of 60-65%. In this case, the OD of the ND filter will be 0.22-0.18. As mentioned above, if the requirements are relaxed to a surface reflectance of 12.5% ​​or less and an expected EQE improvement rate of 10% or more, the transmittance of the ND filter will be in the range of 55-70%, and the OD will be 0.26-0.15.

[0061] Comparing Figure 7 and Figure 10, it can be seen that ND filters have a low probability of improving EQE within the desired PE range, indicating a narrow range of applicability. (Example 4) In addition to Examples 1-3, the black PDL configuration shown in Figure 4 can also be applied. This makes it possible to provide an OLED with high transmittance and improved contrast due to the black PDL and optical film.

Claims

1. In a display element in which an organic light-emitting diode (OLED) is integrated, having an anode, an organic light-emitting layer, and a cathode stacked on a substrate, A partition made of a black material surrounding the organic light-emitting diode, wherein a thin film encapsulant (TFE) is laminated to cover the partition, and the TFE is adjacent to the partition, and the partition and The organic light-emitting diode and the optical film covering the partition wall. A display element comprising the above, wherein the optical film is a polarizing film with a polarization degree of 60-90%.

2. The surface resistivity of the partition wall is 10 14 Ω / cm 2 The above is true, and the volume resistivity is 10 14 The display element according to claim 1, characterized in that it is Ω / cm or greater.

3. The display element according to claim 1 or 2, characterized in that the optical density of the partition wall is 1.0 or greater.

4. The display element according to any one of claims 1 to 3, characterized in that the optical film is a neutral density (ND) filter with an optical density of 0.15-0.

26.

5. The display element according to any one of claims 1 to 4, characterized in that the portion of the substrate other than the partition wall surrounding the organic light-emitting diode is covered with the black material, and an opening is formed in a part of the covered portion.

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