Display devices and display apparatus

Abstract

A display device is provided that reduces surface reflectivity through a combination of a black PDL and an optical film, thereby suppressing a decrease in OLED output. The display device includes each organic light-emitting diode (OLED) having an anode, an organic light-emitting layer, and a cathode fabricated on a substrate, the display device comprising a partition wall (PDL) made of a black material surrounding the organic light-emitting diode; and an optical film covering the organic light-emitting diode and the partition wall.

Description

Technical Field

[0001] This disclosure relates to display devices, and more specifically, to display devices in which each element has an organic light-emitting layer and is arranged in a matrix to constitute a display device. Background Technology

[0002] In display devices comprising multiple pixels, these pixels are organic light-emitting diodes (OLEDs), and polarizers are installed to achieve high contrast. Since polarizers reduce OLED output by approximately 60%, the power consumption of the display device becomes very high to obtain a given amount of light. This increased power consumption shortens the lifespan of the OLED.

[0003] The surface reflectivity of the polyimide substrate used in top-emitting OLEDs is approximately 10% or higher. When an anode electrode made of silver (or a silver alloy) is used to improve external quantum efficiency (EQE), the surface reflectivity of the OLED can reach approximately 90% or higher. Therefore, OLED displays without polarizers exhibit high reflectivity and suffer from significantly reduced visibility, especially in sunlight.

[0004] To address this issue, a light-shielding film is provided that contacts the anode electrode, or the light-shielding film is used as a separator (PDL: pixel defining layer) defining the OLED (see, for example, Patent Documents 1 to 3). When the aperture ratio of each RGB color OLED is 40%, the surface reflectivity of the polyimide substrate is 10%, and the reflectivity of the anode electrode is 90%, the calculated average surface reflectivity is approximately 45%. Although the light-shielding film reduces the surface reflectivity of the polyimide substrate by more than 5%, and the average surface reflectivity is reduced to approximately 35%, it can be seen that the average surface reflectivity is improved by about 10%. However, for practical display devices, the reflectivity is still high, and polarizers are practically required.

[0005] Flexible or foldable display devices are becoming increasingly popular. However, polarizers are still needed to reduce reflectivity. Because polarizers are typically rigid and easily bent, the orientation of liquid crystal molecules will be affected, therefore polarizers cannot be used in flexible display devices.

[0006] Citation List

[0007] Patent documents

[0008] PTL 1: Japanese Patent Publication No. 2002-033185

[0009] PTL 2: Japanese Patent Publication No. 2011-034884

[0010] PTL 3: Japanese Patent Publication No. 2015-008036 Summary of the Invention

[0011] The purpose of this invention is to provide a display device that reduces surface reflectivity through a combination of black PDL and an optical film, thereby suppressing the attenuation of light output from the OLED.

[0012] To achieve the purpose of this disclosure, one embodiment of the disclosure features a display device in which each organic light-emitting diode (OLED) has an anode, an organic light-emitting layer and a cathode fabricated on a substrate, including: a partition wall made of a black material surrounding the OLED; and an optical film covering the OLED and the partition wall.

[0013] According to this embodiment, combining a black separator wall with an optical film having polarization efficiency within a predetermined range can reduce the average surface reflectivity of the OLED display device and bring about the expected effect of improving EQE, thereby suppressing the attenuation of light output from the OLED.

[0014] The surface resistivity of the partition wall is preferably 10. 14 Ω / cm 2 Or higher, with a volume resistivity preferably of 10. 14 Ω / cm 2 Or higher.

[0015] This embodiment can suppress leakage current, thereby reducing surface reflection with high optical density.

[0016] The partition wall should ideally have a light density of 1.0 or higher.

[0017] This embodiment can reduce light leakage to adjacent OLEDs.

[0018] The optical film can be a polarizing film with a polarization efficiency of 60% to 90%.

[0019] This embodiment can meet the requirements for application in OLED display devices, namely a surface reflectance of 12.5% ​​or lower and an expected EQE improvement rate of 10% or higher.

[0020] The optical film can be an ND filter with an optical density of 0.15 to 0.26.

[0021] This embodiment can meet the requirements for application in OLED display devices, namely a surface reflectance of 12.5% ​​or lower and an expected EQE improvement rate of 10% or higher.

[0022] The portion of the substrate other than the partition wall surrounding the organic light-emitting diode is covered with a black material, and an opening is formed in a part of the covered portion.

[0023] This embodiment can provide an OLED with improved transmittance and contrast through black PDL. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the configuration of an OLED according to an embodiment of the present disclosure;

[0025] Figure 2 This is a schematic diagram illustrating the pixel structure of a display device using the OLED of this embodiment;

[0026] Figure 3 This is a schematic diagram showing the structure of conventional polyimide PDL;

[0027] Figure 4 This is a schematic diagram illustrating the structure of the black PDL in this embodiment;

[0028] Figure 5 This is a schematic diagram illustrating an example of the relationship between optical density and surface reflectivity of PDL;

[0029] Figure 6 This is a schematic diagram showing the structure of the optical film used in the OLED of this embodiment;

[0030] Figure 7 This is a schematic diagram illustrating an example of the characteristics of a low polarization efficiency (LPE) film according to this embodiment;

[0031] Figure 8 This is a schematic diagram showing the output spectrum of a display device using the OLED of this embodiment;

[0032] Figure 9 This is a schematic diagram illustrating the improved OLED output demonstrated by the LPE film of this embodiment compared to a conventional polarizer; and

[0033] Figure 10 This is a schematic diagram illustrating an example of the characteristics of the ND filter in this embodiment. Detailed Implementation

[0034] The embodiments of this disclosure are described in detail below with reference to the accompanying drawings.

[0035] Figure 1 This is a diagram illustrating the configuration of an OLED according to an embodiment of the present disclosure. Figure 1This is a cross-sectional view of OLED 100, with the emission direction of OLED 100 (the display surface of the OLED display device) as the top side, and the layer structure is schematically shown. OLED 100 has a back barrier 110, a substrate 121, a backplate 122, a front panel 130, and a thin film encapsulation (TFE) 140 stacked in sequence.

[0036] The back barrier 110 has a first inorganic barrier layer 111 of silicon nitride (SiNx), silicon oxynitride (SiNxOy) or silicon oxide (SiOx) stacked in sequence, an organic barrier layer 112 of organic resin, and a second inorganic barrier layer 113 of SiNx or SiOx, and prevents O2 and H2O from penetrating from the opposite side of the emission direction, i.e., the back side.

[0037] The backplane 122 on substrate 121 has driving circuitry for thin-film transistors (TFTs) directly buried beneath each pixel to apply voltage or current to selected pixels for individual pixel operation. The TFTs and wiring on substrate 121 are buried in resin to planarize the backplane 122.

[0038] The front panel 130 has a series of stacked layers, including an anode 131, a light-emitting layer comprising 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, an electron transport layer (ETL) 136, and a cathode 137.

[0039] TFE 140 has a first inorganic barrier layer 141 of SiNx / SiOx with a thickness of about 0.5 to 1 μm, an organic barrier layer 142 with a thickness of about 7.5 to 15 μm, and a SiNx / SiOx layer with a thickness of about 0.5 to 1 μm, stacked sequentially. x The second inorganic barrier layer 143. Note that the thickness of each layer constituting TFE 140 can be appropriately set according to suitable light extraction conditions in the optical design and the manufacturing structure of the OLED formed under TFE 140, and is not uniquely determined, but rather determined by the panel design of the OLED display device. TFE 140 prevents O2 and H2O from penetrating from the display surface of the OLED display device.

[0040] OLED 100 is a top-emitting OLED that extracts light from the cathode 137 side opposite the substrate 121, when holes injected from the anode 131 and electrons injected from the cathode 137 recombine in the organic light-emitting layer 134.

[0041] The substrate 121 is a support on which multiple OLEDs 100 are arranged and formed. For example, films or sheets made of quartz, glass, metal foil, or resin are used. When the substrate 121 is made of resin, polyesters such as polybutylene naphthalate (PBN) and methacrylic resins such as polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide, polyamide (PA), or polycarbonate resins can be used as materials for the substrate 121.

[0042] To effectively inject holes into the light-emitting layer, for example, the anode 131 can be made of an electrode material with a large work function at the vacuum level. Specifically, the electrode material can be made of a single metal or alloy, such as chromium (Cr), gold (Au), platinum (Pt), nickel (Ni), copper (Cu), tungsten (W), or silver (silver). Furthermore, the anode 131 can have a sputtered or evaporated structure of a metal layer made of the aforementioned single metal or alloy, and a transparent conductive layer made of indium tin oxide (ITO), indium zinc oxide (InZnO), or an alloy of zinc oxide (ZnO) and aluminum (Al), or similar materials.

[0043] Specifically, in the case of top-emitting display devices, the electrode of the OLED 100 with high reflectivity is used as the anode 131. Therefore, due to interference and high reflectivity effects, the efficiency of light extraction to the outside is improved. For example, the anode 131 uses a sputtered or evaporated structure with a first layer having excellent light reflectivity and a second layer disposed on top of the first layer, having light transmittance and a large work function. The first layer can be made of an alloy mainly composed of Al or Ag with high reflectivity, and as an auxiliary component, it also contains a material with a relatively small work function compared to Al, which is the main component. Any lanthanide element series material can be used as such an auxiliary component. Although the work function of any lanthanide element series material is not large, any of these materials, when included in the auxiliary component, can improve the stability of the anode 131 and meet the hole injection performance of the anode 131. In addition to any lanthanide element series material, materials such as silicon (Si) or copper (Cu) can also be used as auxiliary components of the first layer.

[0044] The second layer can be made of oxides of aluminum alloys, oxides of molybdenum (Mo), oxides of zirconium (Zr), oxides of chromium (Cr), or oxides of tantalum (Ta). For example, when the second layer is composed of an oxide layer of aluminum alloy (including a natural oxide film) containing any lanthanide element as an auxiliary component, the transmittance of the second layer containing any lanthanide element as an auxiliary component is excellent because oxides of any lanthanide element have high transmittance. As a result, the reflectivity on the surface of the first layer remains at a high level. In addition, the electron injection performance of the anode 131 is enhanced by using a transparent conductive layer made of ITO or the like in the second layer. It should be noted that since ITO or the like has a large work function, using ITO or the like on the side in contact with the substrate 121, i.e., in the first layer, can improve the carrier injection efficiency and also enhance the adhesion between the anode 131 and the substrate 121.

[0045] It should be noted that when the method used to drive a display device including OLED 100 is an active matrix method, each pixel portion is patterned with a pixel defining layer (PDL) to connect the anode 131 to the TFT for driving after the anode 131 is formed.

[0046] HIL 132, HTL 133, EML 134, HBL 135, and ETL 136, included in the light-emitting layer, are organic layers. These organic layers are composed of materials described later, in addition to acrylic compounds and hexamethyldisiloxane (HMDSO). The organic layers are formed using, for example, an inkjet printer. While there are no particular limitations on the thickness of the individual layers constituting the organic layers, the constituent materials, etc., some examples will be described below.

[0047] HIL 132 is a buffer layer used to enhance the efficiency of hole injection into EML 134 and prevent the generation of leakage current. The thickness of HIL 132 is set in the range of 5 to 200 nm, more preferably in the range of 8 to 150 nm. The material used for HIL 132 can be appropriately selected based on the materials of the electrodes and adjacent layers. Examples of materials include, for example, polyaniline and its derivatives, polythiophene and its derivatives, polypyrrole and its derivatives, polyphenylenevinylene and its derivatives, polyquinoline and its derivatives, polyquinoxaline and its derivatives, conductive polymers (e.g., polymers containing aromatic amine structures in their main chain or side chains, metal phthalocyanines (e.g., copper phthalocyanine)), and carbon. Specific examples of conductive polymers include aniline oligomers and polydioxophenes, such as poly(3,4-ethylenedioxophene) (PEDOT).

[0048] HTL 133 is an organic layer designed to enhance the efficiency of hole transport to EML 134. The thickness of HTL 133, depending on the overall device structure, can be set in the range of, for example, 5 to 200 nm. Optionally, the thickness of HTL 133 can be in the range of 8 to 150 nm. Light-emitting materials soluble in organic solvents, such as polyvinylcarbazole and its derivatives, polyfluorene and its derivatives, polyaniline and its derivatives, polysilane and its derivatives, polysiloxane derivatives having aromatic amines in the side chain or main chain, polythiophene and its derivatives, polypyrrole, triphenylamine derivatives, etc., can be used as materials for HTL 133.

[0049] In EML 134, the application of an electric field causes electrons and holes to recombine and emit light. The thickness of the EML 134, depending on the overall device structure, can be set in, for example, the range of 10 to 200 nm. Alternatively, the thickness of the EML 134 can be in the range of 20 to 150 nm. The EML 134 can have a single-layer or multi-layer structure.

[0050] The material used for EML 134 should be selected according to the corresponding emission color. For example, available materials for EML 134 include (poly)paraphenylenevinylene derivatives, polyfluorene polymer derivatives, polyphenylene derivatives, polyvinylcarbazole derivatives, polythiophene derivatives, dinaphthalene pigments, coumarin pigments, rhodamine pigments, triphenylamine derivatives, and materials obtained by doping the above-mentioned polymers with organic EL materials. For example, rubrene, dinaphthalene, 9,10-diphenylanthracene, tetraphenylbutadiene, Nile red, coumarin 6, triphenylamine derivatives, etc., can be used as doping materials. Note that materials for EML 134 can be obtained by mixing two or more of the above-mentioned materials. Furthermore, the materials used for organic light-emitting layer 134 are not limited to the above-mentioned polymers and can be combinations of low-molecular-weight materials. Examples of such low-molecular-weight materials include anthracene, benzene, styreneamine, triphenylamine, porphyrin, triphenylene, azirtriphenylene, tetracyano-p-benzoquinone dimethyl ether, triazole, imidazole, oxadiazole, polyaromatic hydrocarbons, phenylenediamine, aromatic amines, oxazole, fluorenone, hydrazone, stilbene, triphenylamine derivatives, heterocyclic conjugated monomers or oligomers of polysilane compounds, vinylcarbazole compounds, thiophene compounds, aniline compounds, etc.

[0051] In addition to the materials mentioned above, materials with high luminous efficiency, such as organic light-emitting materials, low-molecular-weight fluorescent materials, phosphorescent pigments, or metal complexes, can be used as materials for EML 134. It should be noted that EML 134 can be, for example, an organic light-emitting layer with hole transport properties used as an HTL 133, and an organic light-emitting layer with electron transport properties used as an ETL 136, which will be described later.

[0052] HBL 135 is used to suppress hole inflow into cathode 137 and can be made of, for example, BCP (BCP(2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline)). The thickness of HBL 135 can be set, for example, in the range of 0.1 nm to 100 nm.

[0053] ETL 136 is an organic layer designed to enhance the efficiency of electron transport to EML 134. The thickness of ETL 136, depending on the overall device structure, can be set, for example, from 5 to 200 nm. Alternatively, the thickness of ETL 136 can range from 10 to 180 nm. Organic materials with excellent electron transport capabilities are preferred as the material for ETL 136. The improved efficiency of electron transport to EML 134 suppresses changes in emission color due to electric field strength, which will be described later. Specifically, arylpyridine derivatives, benzimidazole derivatives, etc., are preferred, for example. As a result, high electron supply efficiency is maintained even at low drive voltages. Other examples of such organic materials include alkali metals and their oxides, their complex oxides, fluorides and their carbonates, alkaline earth metals and their oxides, their complex oxides, fluorides and their carbonates, rare earth metals and their oxides, their complex oxides, fluorides and carbonates.

[0054] ETL 136 exhibits electron-donating properties; for example, electron transport materials doped with n-type dopants can be used, specifically the aforementioned materials used in ETL 136. Examples of n-type doped materials include alkali metals or their oxides, complex oxides thereof, their fluorides and their organic complexes, alkaline earth metals or their oxides, complex oxides thereof, fluorides and their organic complexes. In particular, when the electron mobility of ETL 136 is relatively high, materials with low electronegativity and excellent electron-donating properties can be used. Among these materials, those with low light absorption in the visible light region are preferred. Specifically, metallic materials with low electronegativity, such as alkali metals like Li, Na, K, Rb, and Cs, alkaline earth metals like Be, Mg, Ca, Sr, Ba, and Ra, or lanthanides like Sm, Yb, Ga, and La, are examples of such materials.

[0055] The cathode 137 is made of a material, for example, about 10 nm thick, with excellent light transmittance and a small work function. Furthermore, light extraction can be ensured even when a transparent conductive film is formed using oxides. In this case, ZnO, ITO, InZnO, InSnZnO, etc., can be used. Moreover, although the cathode 137 can be a single layer, it can also have a structure in which multiple layers are sequentially stacked from the anode 131 side. The cathode 137 can also be composed of a mixed layer containing organic light-emitting materials such as aluminum quinoline complexes, styrene amine derivatives, or phthalocyanine derivatives. In this case, the cathode 137 can further have an Al-Li layer or a Mg-Ag layer. Additionally, the cathode 137 should adopt the optimal combination and optimal multilayer structure according to the construction of the device to be fabricated.

[0056] Figure 2 The pixel structure of a display device using an OLED according to this embodiment is shown. Figure 2A single pixel is displayed, which integrates various RGB colors of the OLED. PDLs 180a to 180d are patterned to define front panels 130a to 130c for each RGB color. The anode 131 of the front panel 130 is connected to wiring in the back panel 122.

[0057] A TFE 140 (a first inorganic barrier layer 141, an organic barrier layer 142, and an inorganic barrier layer 143) is stacked to cover the front panels 130a to 130c and the PDLs 180a to 180d, thereby sealing the OLED. Furthermore, the optical film 160 of this embodiment, described below, is stacked via an adhesive layer 150.

[0058] Black PDL is used instead of conventional polyimide PDL, and the black PDL directly absorbs ambient light from the outside. Figure 2 (A) or absorbs a portion of the light reflected by anode 131. Figure 2 (B in the text). Additionally, it can absorb leaked light from adjacent OLEDs (…). Figure 2 (C in the text). Therefore, conventional polyimide PDL with black PDL can suppress surface reflection at high optical density (OD). Additionally, as described below, leakage current can be suppressed by black PDL.

[0059] Figure 3 The structure of conventional polyimide PDL is shown. Figure 3 An example of a pixel 201 is shown, which integrates four OLEDs with R=1, G=2, and B=1. Ideally, to reduce reflections from the front side, a portion other than the partition walls surrounding the OLEDs, such as the upper part of the TFTs and wiring portion 202 buried in the backplane 122, is covered with a black material. That is, to improve contrast, it is generally preferable to cover the area outside the opening region where pixel 201 is arranged with the same material as the black PDL. However, to improve the transmittance of the OLED display device itself, it is preferable to leave areas uncovered by this material.

[0060] Figure 4 The construction of a black PDL according to this embodiment is shown. In this embodiment, the material for the black PDL is patterned, and an opening is formed in a portion of the OLED surrounding pixel 211, other than the black PDL, such as an area like portion 212, where the TFTs and wiring of the backplane 122 are buried. This can provide an OLED with high transmittance and improved contrast due to the black PDL. Furthermore, the OLED can be made transparent, allowing sensors or cameras to be mounted under the OLED display device.

[0061] The disadvantages of black materials are that leakage current can occur between adjacent pixels due to their low resistivity, and the addition of carbon particles to provide conductivity can generate dust, which may lead to defects. Although many black materials have low resistivity compared to conventional polyimides, the surface resistivity (thin-film resistance) of black materials such as carbon is approximately 10. 16 Ω / cm 2 Or even smaller. On the other hand, the surface resistivity of the PDL in OLEDs needs to exceed 10. 14 Ω / cm 2 Therefore, a black material can be applied, and the black PDL can suppress leakage current. The volume resistivity (resistivity, specific resistance) of the black material is approximately 10. 16 Below Ω / cm. In OLEDs, 10 14 A value above Ω / cm is sufficient, thus its volume resistivity is adequate.

[0062] Specific examples of black materials include at least one of carbon black, acetylene black, lamp black, manganese ferrite, or resins containing acrylic groups, resins containing polyimide groups, resins containing silicon groups, resins containing fluorine groups, resins containing urethane groups, and resins containing epoxy groups. Materials comprising at least one black coloring material selected from manganese ferrite, bone black, graphite, iron black, aniline black, anthocyanin black, titanium black, aniline black, or iron oxide black pigments can be used as black materials.

[0063] Examples of substrates for black materials include resins containing acrylic groups, resins containing polyimide groups, resins containing silicon groups, resins containing fluorine groups, resins containing urethane groups, resins containing epoxy groups, etc. It is preferable to use a mixture of two or more resins as the substrate. Alternatively, a black coloring material to be mixed with the substrate can be used as the black material. Examples of black coloring materials include manganese ferrite, carbon black, acetylene black, lampblack, bone black, graphite, iron black, aniline black, anthocyanin black, titanium black, aniline black, and iron oxide black pigments.

[0064] The coloring substance mixed in the above-mentioned substrate can be not only the black substance mentioned above, but also a mixture of coloring substances of different colors that have the same light-blocking properties as the black substance. For example, the colorants include Victoria Pure Blue (42595), Auramine O (41000), Kachiron Brilliant Yellow (Basic 13), Rhodamine 6GCP (45160), Rhodamine B (45170), Crocin OK 70:100 (50240), Elio-Glasin X (42080), No.120 / Lionol Yellow (21090), Lonor Yellow GRO (21090), Shimla Fast Yellow 8GF (21105), Benzidine Yellow 4T-564D (21095), Shimler Fast Red 4015 (12355), Lionol Red 7B4401 (15850), Fastgen Blue TGR-L (74160), and Lionol Blue SM (26150). Examples of adaptive CI (Color Index) include CII yellow pigments 20, 24, 86, 93, 109, 110, 117, 125, 137, 138, 147, 148, 150, 153, 154, 166; CI orange pigments 36, 43, 51, 55, 59, 61; and CI red pigments 9, 97, 122, 123, 149, 168, 177. 180, 192, 215, 216, 217, 220, 224, 226, 227, 228, 240, 254, CI purple pigment 19, 23, 29, 30, 37, 40, 50, CII blue pigment 15, 15:1, 15:4, 15:6, 22, 60, 64, CII green pigment 7, 36 and CI brown pigment 23, 25, 26.

[0065] Optical density (OD), which is used as an indicator of PDL, is a logarithmic expression of the medium opacity and has the following relationship with transmittance T.

[0066] OD = log10(1 / T)

[0067] For example, when T = 0.1 (10%), OD = 1; when T = 0.01 (1%), OD = 2. When OD is large, T is small.

[0068] Figure 5An example of the relationship between the OD (Optical Dispersion) of a PDL and its surface reflectivity is shown. According to this example, if the OD of the PDL is greater than 1, it can be seen that the surface reflectivity is saturated at 6%. Surface reflectivity is an optical parameter determined by the general structure, and the absolute value of surface reflectivity will not saturate to 6%. However, due to the definition of OD, the saturation trend of OD shows this relative relationship, regardless of the structure used. Therefore, the PDL of this embodiment can reduce light leakage to adjacent OLEDs by using materials with an OD of 1 or higher.

[0069] However, a portion of the light reflected by anode 131 is still emitted to the outside. Furthermore, to reduce surface reflectivity, a high-OD optical film can be attached to the display surface of the OLED display device. However, this further reduces the OLED's output, and consequently increases the power consumption of the OLED display device to obtain a given amount of light. Although color filters (CFs) can be added, it is necessary to match the CF transmission spectrum in the visible light range with the OLED's output spectrum. Even after matching, approximately 7% surface reflectivity is retained, which is not very effective in reducing manufacturing costs. Although electrode materials with low reflectivity can be used for anode 131, efficiency is reduced in top-emitting OLEDs, and the microcavity effect is also reduced at low reflectivity.

[0070] Therefore, as Figure 2 As shown, in this embodiment, an optical film 160 is added to reduce surface reflectivity. In the general application of polarizers, a high polarized efficiency (PE) is preferred. For example, it is desirable for the PE to be close to 100%. On the other hand, in this embodiment, when the combination with a black PDL allows the optical film 160 to have a PE within a predetermined range, the average surface reflectivity of the OLED display device can be set to 10% or less. Furthermore, since an improved EQE effect can be expected in the optical film 160 with a low PE, a reduction in OLED output can be suppressed.

[0071] (Example 1)

[0072] Figure 6 The structure of the optical film used in the OLED of this embodiment is shown. Specifically, an LPE (low polarization efficiency) film with PE content of 65% to 80% is used. Figure 6This is a cross-sectional view of OLED 100, where the emission direction of OLED 100 (the display surface of the OLED display device) is at the top side of the figure. The optical film 160 includes, sequentially arranged 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, taking a liquid crystal polarizer with a so-called liquid crystal coating as an example, a polarizing film with PE within a predetermined range is obtained by adjusting the concentration of the dichroic dye.

[0073] Figure 7 An example of the characteristics of the LPE film of this embodiment is shown. The solid line represents the expected rate of EQE improvement provided by the optical film with low PE, shown on the left vertical scale, and the dashed line represents the surface reflectance, shown on the right vertical scale. Assuming that the requirements for OLED display devices are 10% or less surface reflectance and 20% or more expected rate of EQE improvement, the PE of optical film 160 falls in the range of 65% to 80%. Furthermore, assuming that the actual requirements for OLED display devices are relaxed to 12.5% ​​or less surface reflectance and 10% or more expected rate of EQE improvement, the PE of optical film 160 falls in the range of 60% to 90%.

[0074] Figure 8 The output spectrum of a display device using the OLED of this embodiment is shown. It is the output spectrum of an OLED display device equipped with an OLED for each RGB color. The solid line shows the application of optical film 160 with an expected rate of improvement of 75% PE, 5.8% reflectivity and 30% EQE; the dashed line shows the application of a conventional polarizer (PE = 99.96%). Figure 9 The improved OLED output resulting from the LPE film of this embodiment compared to a conventional polarizer is shown. It has been demonstrated that the LPE film of this embodiment enhances EQE and increases OLED output across the entire visible light region.

[0075] (Example 2)

[0076] Iodine polarizers, in which iodine compound molecules are adsorbed and aligned in polyvinyl alcohol (PVA), can also be used instead of liquid crystal polarizers. By adjusting the iodine concentration, PE with a surface reflectance of 10% or less can be obtained within a predetermined range.

[0077] (Example 3)

[0078] An ND (neutral density) filter can be used instead of the polarizer mentioned above. Figure 10The characteristics of the neutral density (ND) filter added to the OLED in this embodiment are illustrated. The solid line represents the expected rate of EQE improvement provided by the optical film with low PE, shown on the left vertical scale, and the dashed line represents the surface reflectance, shown on the right vertical scale. Assuming that the requirement for the OLED display device is 10% or less surface reflectance and 20% or more expected rate of EQE improvement, the transmittance of the ND filter falls in the range of 60% to 65%. At this time, the OD of the ND filter is 0.22 to 0.18. As mentioned above, when the surface reflectance decreases to 12.5% ​​or less and the expected rate of EQE improvement decreases to 10% or more, the transmittance of the ND filter is in the range of 55% to 70%, and the OD becomes 0.26 to 0.15.

[0079] Will Figure 7 and Figure 10 The comparison shows that the ND filter has a lower expected rate of EQE improvement within the expected range of PE, and the ND filter has a narrower range of applicability.

[0080] (Example 4)

[0081] In addition to Examples 1 to 3, the following can be applied: Figure 4 The structure of the black PDL is shown. This can provide an OLED with high transmittance and improved contrast through the black PDL and optical film.

Claims

1.A display device in which each organic light emitting diode (OLED) has an anode, an organic light emitting layer, and a cathode manufactured on a substrate, the display device comprising: a partition wall made of a black material surrounding the organic light emitting diode, the partition wall having an optical density of 1.0 or more, the partition wall being patterned to define a front panel for each of the OLEDs, the front panel including the anode, a hole injection layer, a hole transport layer, the organic light emitting layer, a hole blocking layer, an emitting layer of an electron transport layer, and the cathode stacked in order, a first inorganic barrier layer in a thin film encapsulation (TFE) being overlaid on an upper portion of the partition wall and in contact with the partition wall; and an optical film covering the organic light emitting diode and the partition wall, the optical film being a polarizing film having a polarization efficiency of 60% to 90%; an upper portion of a portion in which a thin film transistor (TFT) and a wiring of a backplane are buried in another portion of the substrate other than the partition wall of the organic light emitting diode being covered with a black material, an opening being formed in a portion other than the portion in which the buried TFT and wiring of the backplane are formed in the another portion, a lower portion of the opening being mounted with a sensor or a camera, the opening allowing the display device to have a light transmittance. 2.The display device of claim 1, wherein the optical film is a polarizing film having a polarization efficiency of 70% to 90%. 3.The display device of claim 1, wherein the optical film is a polarizing film having a polarization efficiency of 80% to 90%. 4.The display device of claim 1, wherein the optical film is a polarizing film having a polarization efficiency of 60% to 70%. 5.The display device of claim 1, wherein the optical film is a polarizing film having a polarization efficiency of 70% to 80%. 6.The display device of claim 1, wherein the optical film is a polarizing film having a polarization efficiency of 80% to 90%. 7.The display device of claim 1, wherein the optical film is a polarizing film having a polarization efficiency of 60% to 70%. 8.The display device of claim 1, wherein the optical film is a polarizing film having a polarization efficiency of 70% to 80%. 9.The display device of claim 1, wherein the optical film is a polarizing film having a polarization efficiency of 60% to 80%. 10.The display device of claim 1, wherein the optical film is a polarizing film having a polarization efficiency of 80% to 90%. 11.The display device of claim 1, wherein the optical film is a polarizing film having a polarization efficiency of 60% to 90%. 12.The display device of claim 1, wherein the optical film is a polarizing film having a polarization efficiency of 60% to 80%. 13.The display device of claim 1, wherein the optical film is a polarizing film having a polarization efficiency of 60% to 70%. 14.The display device of claim 1, wherein the optical film is a polarizing film having a polarization efficiency of 70% to 80%. 15.The display device of claim 2. The display device of claim 1, wherein, The surface resistivity of the partition wall is 10 14 Ω / cm 2 or more, and the volume resistivity is 10 14 Ω / cm 2 or more.

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