PIXEL ARRANGEMENT COMPRISING A PEROVSKITE LIGHT EMITTING DIODE
20210242418 · 2021-08-05
Inventors
Cpc classification
H10K50/852
ELECTRICITY
H10K59/38
ELECTRICITY
Y02P70/50
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
H10K50/115
ELECTRICITY
International classification
Abstract
A pixel arrangement for a display is provided. The pixel arrangement comprises a plurality of sub-pixels. At least one sub-pixel comprises a perovskite light emitting diode. In one embodiment, a first sub-pixel is configured to emit a first colour of light, and includes a perovskite light emitting diode. A second sub-pixel is configured to emit a second colour of light that is different from the first colour, and a third sub-pixel is configured to emit a third colour of light that is different from the first and second colour. The second sub-pixel comprises a perovskite light emitting diode, an organic light emitting diode or a quantum dot light emitting diode. The third sub-pixel comprises a perovskite light emitting diode, an organic light emitting diode or a quantum dot light emitting diode.
Claims
1. A pixel arrangement for a display, the arrangement comprising a plurality of pixels, each pixel comprising: a first sub-pixel configured to emit a first colour of light, the first sub-pixel comprising a perovskite light emitting diode; a second sub-pixel configured to emit a second colour of light that is different from the first colour of light; and a third sub-pixel configured to emit a third colour of light that is different from the first and second colour of light, wherein the second sub-pixel comprises a perovskite light emitting diode (PeLED), an organic light emitting diode (OLED) or a quantum dot light emitting diode (QLED), and the third sub-pixel comprises a PeLED, an OLED or a QLED.
2. The pixel arrangement of claim 1, wherein the second sub-pixel comprises a PeLED and the third sub-pixel comprises a PeLED.
3. The pixel arrangement of claim 1, wherein at least one of the second sub-pixel and the third sub-pixel comprises an OLED or a QLED.
4. The pixel arrangement of claim 1, wherein the second sub-pixel comprises a PeLED and the third sub-pixel comprises an OLED or a QLED.
5. The pixel arrangement of claim 3, wherein the second sub-pixel comprises a PeLED or an OLED, and the third sub-pixel comprises a PeLED or an OLED, and at least one of the second sub-pixel and the third sub-pixel comprises an OLED.
6. The pixel arrangement of claim 5, wherein the second sub-pixel comprises a PeLED and the third sub-pixel comprises an OLED.
7. The pixel arrangement of claim 5, wherein the second sub-pixel comprises an OLED, and the third sub-pixel comprises an OLED.
8. The pixel arrangement of claim 3, wherein the second sub-pixel comprises a PeLED or a QLED, and the third sub-pixel comprises a PeLED or a QLED, and at least one of the second sub-pixel and the third sub-pixel comprises a QLED.
9. The pixel arrangement of claim 8, wherein the second sub-pixel comprises a PeLED and the third sub-pixel comprises a QLED.
10. The pixel arrangement of claim 8, wherein the second sub-pixel comprises a QLED, and the third sub-pixel comprises a QLED.
11. The pixel arrangement of claim 3, wherein the second sub-pixel comprises an OLED and the third sub-pixel comprises a QLED.
12. The pixel arrangement of any one of the preceding claims, wherein one of the first, second and third sub-pixels emits red light; one of the first, second and third sub-pixels emits green light; and one of the first, second and third pixels emits blue light.
13. The pixel arrangement of claim 12, wherein one of the first, second and third sub-pixels emits red light with CIE 1931 x coordinate greater than or equal to 0.680; one of the first, second and third sub-pixels emits green light with CIE 1931 y coordinate greater than or equal to 0.690; and one of the first, second and third sub-pixels emits blue light with CIE 1931 y coordinate less than or equal to 0.060.
14. The pixel arrangement of claim 12, wherein one of the first, second and third sub-pixels emits red light with CIE 1931 x coordinate greater than or equal to 0.708; one of the first, second and third sub-pixels emits green light with CIE 1931 y coordinate greater than or equal to 0.797; and one of the first, second and third sub-pixels emits blue light with CIE 1931 y coordinate less than or equal to 0.046.
15. The pixel arrangement of any one of the preceding claims, wherein each of the first, second and third sub-pixels have the same surface area.
16. The pixel arrangement of any one of claims 1 to 14, wherein at least one of the first, second and third sub-pixels has a surface area different from another of the first, second and third sub-pixels.
17. The pixel arrangement of any one of the preceding claims, wherein the pixel arrangement further comprises a fourth sub-pixel configured to emit a fourth colour of light that is different from the first, second and third colour of light, the fourth sub-pixel comprising a PeLED, an OLED or a QLED.
18. The pixel arrangement of any one of the preceding claims, wherein one or more of the PeLEDs comprise organic metal halide light-emitting perovskite material.
19. The pixel arrangement of any one of the preceding claims, wherein one or more of the PeLEDs comprise inorganic metal halide light-emitting perovskite material.
20. A display comprising the pixel arrangement of any one of the preceding claims.
21. The display of claim 20, wherein each of the sub-pixels include a microcavity structure.
22. The display of claim 20, wherein at least one of sub-pixels includes a microcavity structure.
23. The display of any one of claims 20 to 22, wherein each of the sub-pixels include a colour altering layer.
24. The display of any one of claims 20 to 22, wherein at least one of the sub-pixels includes a colour altering layer.
25. The display of any one of claims 20 to 24, wherein the display is a flexible structure.
26. The display of any one of claims 20 to 25, wherein the display is part of a consumer product.
27. The display of any one of claims 20 to 26, wherein the display is capable of rendering the DCI-P3 colour gamut.
28. The display of any one of claims 20 to 26, wherein the display is capable of rendering the Rec. 2020 colour gamut.
Description
[0037] In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing. Embodiments of the present disclosure will now be described, by way of example only, with reference to the following:
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DESCRIPTION OF EMBODIMENTS
[0051] General device architectures and operating principles for PeLEDs are substantially similar to those for OLEDs and QLEDs. Each of these types of light emitting devices comprises at least one emissive layer disposed between and electrically connected to an anode and a cathode. For a PeLED, the emissive layer comprises perovskite light emitting material. For an OLED, the emissive layer comprises organic light emitting material. For a QLED, the emissive layer comprises quantum dot light emitting material. For each of these light emitting devices, when a current is applied, the anode injects holes and the cathode injects electrons into the emissive layer(s). The injected holes and electrons each migrate towards the oppositely charged electrode. When an electron and a hole localize, an exciton, which is a localized electron-hole pair having an excited energy state, may be formed. Light is emitted if the exciton relaxes via a photo-emissive mechanism. Non-radiative mechanisms, such as thermal radiation and/or Auger recombination may also occur, but are generally considered undesirable. Substantial similarity between device architectures and working principles required for PeLEDs, OLEDs and QLEDs, facilitates the combination of these light emitting devices in a single device, such as a display.
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[0054] The simple layered structures illustrated in
[0055] PeLEDs, OLEDs and QLEDs are generally intended to emit light through at least one of the electrodes, and one or more transparent electrodes may be useful in such optoelectronic devices. For example, a transparent electrode material, such as indium tin oxide (ITO), may be used for the bottom electrode, while a transparent electrode material, such as a thin metallic layer of a blend of magnesium and silver (Mg:Ag), may be used for the top electrode. For a device intended to emit light only through the bottom electrode, the top electrode does not need to be transparent, and may be comprised of an opaque and/or reflective layer, such as a metal layer having a high reflectivity. Similarly, for a device intended only to emit light through the top electrode, the bottom electrode may be opaque and/or reflective, such as a metal layer having a high reflectivity. Where an electrode does not need to be transparent, using a thicker layer may provide better conductivity and may reduce voltage drop and/or Joule heating in the device, and using a reflective electrode may increase the amount of light emitted through the other electrode by reflecting light back towards the transparent electrode. A fully transparent device may also be fabricated, where both electrodes are transparent.
[0056] Devices fabricated in accordance with embodiments of the present invention may optionally comprise a substrate 110. The substrate 110 may comprise any suitable material that provides the desired structural and optical properties. The substrate 110 may be rigid or flexible. The substrate 110 may be flat or curved. The substrate 110 may be transparent, translucent or opaque. Preferred substrate materials are glass, plastic and metal foils. Other substrates, such as fabric and paper may be used. The material and thickness of the substrate 110 may be chosen to obtain desired structural and optical properties. Substantial similarity between substrate properties required for PeLEDs, OLEDs and QLEDs facilitates the combination of these light emitting devices in a single device, such as a display.
[0057] Devices fabricated in accordance with embodiments of the present invention may optionally comprise an anode 115. The anode 115 may comprise any suitable material or combination of materials known to the art, such that the anode 115 is capable of conducting holes and injecting them into the layers of the device. Preferred anode 115 materials include conductive metal oxides, such as indium tin oxide (ITO), indium zinc oxide (IZO) and aluminum zinc oxide (AlZnO), metals such as silver (Ag), aluminum (Al), aluminum-neodymium (Al:Nd), gold (Au) and alloys thereof, or a combination thereof. Other preferred anode 115 materials include graphene, carbon nanotubes, nanowires or nanoparticles, silver nanowires or nanoparticles, organic materials, such as poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and derivatives thereof, or a combination thereof. Compound anodes comprising one or more anode materials in a single layer may be preferred for some devices. Multilayer anodes comprising one or more anode materials in one or more layers may be preferred for some devices. One example of a multilayer anode is ITO/Ag/ITO. In a standard device architecture for PeLEDs, OLEDs and QLEDs, the anode 115 may be sufficiently transparent to create a bottom-emitting device, where light is emitted through the substrate. One example of a transparent anode commonly used in a standard device architecture is a layer of ITO. Another example of a transparent anode commonly used in a standard device architecture is ITO/Ag/ITO, where the Ag thickness is less than approximately 25 nm. By including a layer of silver of thickness less than approximately 25 nm, the anode may be transparent as well as partially reflective. When such a transparent and partially reflective anode is used in combination with a reflective cathode, such as LiF/Al, this may have the advantage of creating a microcavity effect within the device. A microcavity may provide one or more of the following advantages: an increased total amount of light emitted from device, and therefore higher efficiency and brightness; an increased proportion of light emitted in the forward direction, and therefore increased apparent brightness at normal incidence; and spectral narrowing of the emission spectrum, resulting in light emission with increased colour saturation. The anode 115 may be opaque and/or reflective. In a standard device architecture for PeLEDs, OLEDs and QLEDs, a reflective anode 115 may be preferred for some top-emitting devices to increase the amount of light emitted from the top of the device. One example of a reflective anode commonly used in a standard device architecture is a multilayer anode of ITO/Ag/ITO, where the Ag thickness is greater than approximately 80 nm. When such a reflective anode is used in combination with a transparent and partially reflective cathode, such as Mg:Ag, this may have the advantage of creating a microcavity effect within the device. A microcavity may provide one or more of the following advantages: an increased total amount of light emitted from device, and therefore higher efficiency and brightness; an increased proportion of light emitted in the forward direction, and therefore increased apparent brightness at normal incidence; and spectral narrowing of the emission spectrum, resulting in light emission with increased colour saturation. The material and thickness of the anode 115 may be chosen to obtain desired conductive and optical properties. Where the anode 115 is transparent, there may be a range of thicknesses for a particular material that is thick enough to provide the desired conductivity, yet thin enough to provide the desired degree of transparency. Other materials and structures may be used. Substantial similarity between anode properties required for PeLEDs, OLEDs and QLEDs facilitates the combination of these light emitting devices in a single device, such as a display.
[0058] Devices fabricated in accordance with embodiments of the present invention may optionally comprise a hole transport layer 125. The hole transport layer 125 may include a material capable of transporting holes. The hole transport layer 125 may be deposited by a solution process or by a vacuum deposition process. The hole transport layer 125 may be doped or undoped. Doping may be used to enhance conductivity.
[0059] Examples of undoped hole transport layers are N,N′-Di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPD), poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl) diphenylamine (TFB), poly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)-benzidine] (poly-TPD), poly(9-vinylcarbazole) (PVK), 4,4′-Bis(N-carbazolyl)-1,1′-biphenyl (CBP), Spiro-OMeTAD and molybdenum oxide (MoO.sub.3). One example of a doped hole transport layer is 4,4′,4″-Tris[phenyl(m-tolyl)amino]triphenylamine (m-MTDATA) doped with F.sub.4-TCNQ at a molar ratio of 50:1. One example of a solution-processed hole transport layer is PEDOT:PSS. Other hole transport layers and structures may be used. The preceding examples of hole transport materials are all especially well-suited to application in PeLEDs. However, these materials may also be implemented effectively in OLEDs and QLEDs. Substantial similarity between hole transport layer properties required for PeLEDs, OLEDs and QLEDs facilitates the combination of these light emitting devices in a single device, such as a display.
[0060] Devices fabricated in accordance with embodiments of the present invention may optionally comprise an emissive layer 135. The emissive layer 135 may include material capable of emitting light when a current is passed between anode 115 and cathode 155. Device architectures and operating principles are substantially similar for PeLEDs, OLEDs and QLEDs. However, these light emitting devices may be distinguished by differences in their respective emissive layers. The emissive layer of a PeLED may comprise perovskite light emitting material. The emissive layer of an OLED may comprise organic light emitting material. The emissive layer of a QLED may comprise quantum dot light emitting material.
[0061] Examples of perovskite light-emitting materials include 3D perovskite materials, such as methylammonium lead iodide (CH.sub.3NH.sub.3Pbl.sub.3), methylammonium lead bromide (CH.sub.3NH.sub.3PbBr.sub.3), methylammonium lead chloride (CH.sub.3NH.sub.3PbCl.sub.3), formamidinium lead iodide (CH(NH.sub.2).sub.2Pbl.sub.3), formamidinium lead bromide (CH(NH.sub.2).sub.2PbBr.sub.3), formamidinium lead chloride (CH(NH.sub.2).sub.2PbCl.sub.3), caesium lead iodide (CsPbl.sub.3), caesium lead bromide (CsPbBr.sub.3) and caesium lead chloride (CsPbCl.sub.3). Examples of perovskite light-emitting materials further include 3D perovskite materials with mixed halides, such as CH.sub.3NH.sub.3Pbl.sub.3-xCl.sub.x, CH.sub.3NH.sub.3Pbl.sub.3-x(Br.sub.x, CH.sub.3NH.sub.3PbCl.sub.3-xBr.sub.x, CH(NH.sub.2).sub.2Pbl.sub.3-xBr.sub.x, CH(NH.sub.2).sub.2Pbl.sub.3-xCl.sub.x, CH(NH.sub.2).sub.2PbCl.sub.3-xBr.sub.x, CsPbl.sub.3-xCl.sub.x, CsPbl.sub.3-x(Br.sub.x and CsPbCl.sub.3-xBr.sub.x, where x is in the range of 0-3. Examples of perovskite light-emitting materials further include 2D perovskite materials such as (C.sub.10H.sub.7CH.sub.2NH.sub.3).sub.2Pbl.sub.4, (C.sub.10H.sub.7CH.sub.2NH.sub.3).sub.2PbBr.sub.4, (C.sub.10H.sub.7CH.sub.2NH.sub.3).sub.2PbCl.sub.4, (C.sub.6H.sub.5C.sub.2H.sub.4NH.sub.3).sub.2Pbl.sub.4, (C.sub.6H.sub.5C.sub.2H.sub.4NH.sub.3).sub.2PbBr.sub.4 and (C.sub.6H.sub.5C.sub.2H.sub.4NH.sub.3).sub.2PbCl.sub.4, 2D perovskite materials with mixed halides, such as (C.sub.10H.sub.7CH.sub.2NH.sub.3).sub.2Pbl.sub.3-xCl.sub.x, (C.sub.10H.sub.7CH.sub.2NH.sub.3).sub.2Pbl.sub.3-xBr.sub.x, (C.sub.10H.sub.7CH.sub.2NH.sub.3).sub.2PbCl.sub.3-xBr.sub.x, (C.sub.6H.sub.5C.sub.2H.sub.4NH.sub.3).sub.2Pbl.sub.3-xCl.sub.x, (C.sub.6H.sub.5C.sub.2H.sub.4NH.sub.3).sub.2Pbl.sub.3-xBr.sub.x and (C.sub.6H.sub.5C.sub.2H.sub.4NH.sub.3).sub.2PbCl.sub.3-xBr.sub.x, where x is in the range of 0-3. Examples of perovskite light-emitting materials further include Quasi-2D perovskite materials, such as (C.sub.6H.sub.5C.sub.2H.sub.4NH.sub.3).sub.2(CH(NH.sub.2).sub.2PbBr.sub.3).sub.n-1Pbl.sub.4, (C.sub.6H.sub.5C.sub.2H.sub.4NH.sub.3).sub.2(CH(NH.sub.2).sub.2PbBr.sub.3).sub.n-1PbBr.sub.4, (C.sub.6H.sub.5C.sub.2H.sub.4NH.sub.3).sub.2(CH(NH.sub.2).sub.2PbBr.sub.3).sub.n-1PbCl.sub.4, (C.sub.10H.sub.7CH.sub.2NH.sub.3).sub.2(CH.sub.3NH.sub.3Pbl.sub.2Br).sub.n-1Pbl.sub.4, (C.sub.10H.sub.7CH.sub.2NH.sub.3).sub.2(CH.sub.3NH.sub.3Pbl.sub.2Br).sub.n-1PbBr.sub.4 and (C.sub.10H.sub.7CH.sub.2NH.sub.3).sub.2(CH.sub.3NH.sub.3Pbl.sub.2Br).sub.n-1PbCl.sub.4, where n is the number of layers, and, optionally, n may be in the range of about 2-10. Examples of perovskite light-emitting materials further include Quasi-2D perovskite materials with mixed halides, such as (C.sub.6H.sub.5C.sub.2H.sub.4NH.sub.3).sub.2(CH(NH.sub.2).sub.2PbBr.sub.3).sub.n-1Pbl.sub.3-xCl.sub.x, (C.sub.6H.sub.5C.sub.2H.sub.4NH.sub.3).sub.2(CH(NH.sub.2).sub.2PbBr.sub.3).sub.n-1Pbl.sub.3-xBr.sub.x, (C.sub.6H.sub.5C.sub.2H.sub.4NH.sub.3).sub.2(CH(NH.sub.2).sub.2PbBr.sub.3).sub.n-1PbCl.sub.3-xBr.sub.x, (C.sub.10H.sub.7CH.sub.2NH.sub.3).sub.2(CH.sub.3NH.sub.3Pbl.sub.2Br).sub.n-1Pbl.sub.3-xCl.sub.x, (C.sub.10H.sub.7CH.sub.2NH.sub.3).sub.2(CH.sub.3NH.sub.3Pbl.sub.2Br).sub.n-1Pbl.sub.3-xBr.sub.x and (C.sub.10H.sub.7CH.sub.2NH.sub.3).sub.2(CH.sub.3NH.sub.3Pbl.sub.2Br).sub.n-1PbCl.sub.3-xBr.sub.x, where n is the number of layers, and, optionally, n may be in the range of about 2-10, and x is in the range of 0-3. Examples of perovskite light-emitting materials further include any of the aforementioned examples, where the divalent metal cation lead (Pb.sup.+) may be replaced with tin (Sn.sup.+), copper (Cu.sup.+) or europium (Eu.sup.+). Examples of perovskite light-emitting materials further include perovskite light-emitting nanocrystals with structures that closely resemble Quasi-2D perovskite materials.
[0062] Perovskite light emitting material may comprise organic metal halide perovskite material, such as methylammonium lead iodide (CH.sub.3NH.sub.3Pbl.sub.3), methylammonium lead bromide (CH.sub.3NH.sub.3PbBr.sub.3), methylammonium lead chloride (CH.sub.3NH.sub.3PbCl.sub.3), where the materials comprises an organic cation. Perovskite light emitting material may comprise inorganic metal halide perovskite material, such as caesium lead iodide (CsPbl.sub.3), caesium lead bromide (CsPbBr.sub.3) and caesium lead chloride (CsPbCl.sub.3), where the material comprises an inorganic cation. Furthermore, perovskite light emitting material may comprise perovskite light emitting material where there is a combination of organic and inorganic cations. The choice of an organic or inorganic cation may be determined by several factors, including desired emission colour, efficiency of electroluminescence, stability of electroluminescence and ease of processing. Inorganic metal halide perovskite material may be particularly well-suited to perovskite light-emitting materials with a nanocrystal structure, such as those depicted in
[0063] Perovskite light emitting material may be included in the emissive layer 135 in a number of ways. For example, the emissive layer may comprise 2D perovskite light-emitting material, Quasi-2D perovskite light-emitting material or 3D perovskite light-emitting material, or a combination thereof. Optionally, the emissive layer may comprise perovskite light emitting nanocrystals. Optionally, the emissive layer 135 may comprise an ensemble of Quasi-2D perovskite light emitting materials, where Quasi-2D perovskite light emitting materials in the ensemble comprise a different number of layers. An ensemble of Quasi-2D perovskite light emitting materials may be preferred because there may be energy transfer from Quasi-2D perovskite light emitting materials with a smaller number of layers and a larger energy band gap to Quasi-2D perovskite light emitting materials with a larger number of layers and a lower energy band gap. This energy funnel may efficiently confine excitons in a PeLED device, and may improve device performance. Optionally, the emissive layer 135 may comprise perovskite light emitting nanocrystal materials. Perovskite light emitting nanocrystal materials may be preferred because nanocrystal boundaries may be used to confine excitons in a PeLED device, and surface cations may be used to passivate the nanocrystal boundaries. This exciton confinement and surface passivation may improve device performance. Other emissive layer materials and structures may be used.
[0064] Organic light emitting materials may be fluorescent or phosphorescent or may emit light through mechanisms such as triplet-triplet annihilation (TTA) or thermally activated delayed fluorescence (TADF). Several examples of fluorescent organic light emitting materials are described in European patent EP 0423283 B1. Several examples of phosphorescent organic light emitting materials are described in U.S. Pat. No. 6,303,238 B1 and U.S. Pat. No. 7,279,704 B2. Several examples of organic light emitting materials that emit through a TADF mechanism are described in Uoyama et al. All of these citations are included herein by reference in their entirety.
[0065] Quantum dot light emitting materials may be photoluminescent or electroluminescent. As used herein, the term “quantum dot light emitting materials” refers exclusively to electroluminescent quantum dot light emitting materials. Wherever “quantum dot light emitting materials” are referred to in the text, it should be understood that reference is being made to electroluminescent quantum dot light emitting materials. Several examples of quantum dot light emitting materials are described in Kathirgamanathan et al. (1), which is included herein by reference in its entirety.
[0066] Devices fabricated in accordance with embodiments of the present invention may optionally comprise an electron transport layer 145. The electron transport layer 145 may include any material capable of transporting electrons. The electron transport layer 145 may be deposited by a solution process or by a vacuum deposition process. The electron transport layer 145 may be doped or undoped. Doping may be used to enhance conductivity.
[0067] Examples of undoped electron transport layers are tris(8-hydroxyquinolinato)aluminum (Alq.sub.3), 2,2′,2″-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi), 2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), zinc oxide (ZnO) and titanium dioxide (TiO.sub.3). One example of a doped electron transport layer is 4,7-diphenyl-1,10-phenanthroline (BPhen) doped with lithium (Li) at a molar ratio of 1:1. One example of a solution-processed electron transport layer is [6,6]-Phenyl C61 butyric acid methyl ester (PCBM). Other electron transport layers and structures may be used. The preceding examples of electron transport materials are all especially well-suited to application in PeLEDs. However, these materials may also be implemented effectively in OLEDs and QLEDs. Substantial similarity between electron transport layer properties required for PeLEDs, OLEDs and QLEDs facilitates the combination of these light emitting devices in a single device, such as a display.
[0068] Devices fabricated in accordance with embodiments of the present invention may optionally comprise a cathode 155. The cathode 155 may comprise any suitable material or combination of materials known to the art, such that the cathode 155 is capable of conducting electronics and injecting them into the layers of the device. Preferred cathode 155 materials include metal oxides, such as indium tin oxide (ITO), indium zinc oxide (IZO) and fluorine tin oxide (FTO), metals, such as calcium (Ca), barium (Ba), magnesium (Mg) and ytterbium (Yb) or a combination thereof. Other preferred cathode 155 materials include metals such as silver (Ag), aluminum (Al), aluminum-neodymium (Al:Nd), gold (Au) and alloys thereof, or a combination thereof. Compound cathodes comprising one or more cathode materials in a single layer may be preferred from some devices. One example of a compound cathode is Mg:Ag. Multilayer cathodes comprising one or more cathode materials in one or more layers may be preferred for some devices. One example of a multilayer cathode is Ba/Al. In a standard device architecture for PeLEDs, OLEDs and QLEDs, the cathode 155 may be sufficiently transparent to create a top-emitting device, where light is emitted from the top of the device. One example of a transparent cathode commonly used in a standard device architecture is a compound layer of Mg:Ag. By using a compound of Mg:Ag, the cathode may be transparent as well as partially reflective. When such a transparent and partially reflective cathode is used in combination with a reflective anode, such as ITO/Ag/ITO, where the Ag thickness is greater than approximately 80 nm, this may have the advantage of creating a microcavity effect within the device. A microcavity may provide one or more of the following advantages: an increased total amount of light emitted from device, and therefore higher efficiency and brightness; an increased proportion of light emitted in the forward direction, and therefore increased apparent brightness at normal incidence; and spectral narrowing of the emission spectrum, resulting in light emission with increased colour saturation. The cathode 155 may be opaque and/or reflective. In a standard device architecture for PeLEDs, OLEDs and QLEDs, a reflective cathode 155 may be preferred for some bottom-emitting devices to increase the amount of light emitted through the substrate from the bottom of the device. One example of a reflective cathode commonly used in a standard device architecture is a multilayer cathode of LiF/Al. When such a reflective cathode is used in combination with a transparent and partially reflective anode, such as ITO/Ag/ITO, where the Ag thickness is less than approximately 25 nm, this may have the advantage of creating a microcavity effect within the device. A microcavity may provide one or more of the following advantages: an increased total amount of light emitted from device, and therefore higher efficiency and brightness; an increased proportion of light emitted in the forward direction, and therefore increased apparent brightness at normal incidence; and spectral narrowing of the emission spectrum, resulting in light emission with increased colour saturation.
[0069] The material and thickness of the cathode 155 may be chosen to obtain desired conductive and optical properties. Where the cathode 155 is transparent, there may be a range of thicknesses for a particular material that is thick enough to provide the desired conductivity, yet thin enough to provide the desired degree of transparency. Other materials and structures may be used. Substantial similarity between cathode properties required for PeLEDs, OLEDs and QLEDs facilitates the combination of these light emitting devices in a single device, such as a display.
[0070] Devices fabricated in accordance with embodiments of the present invention may optionally comprise one or more blocking layers. Blocking layers may be used to reduce the number of charge carriers (electrons or holes) and/or excitons exiting the emissive layer. An electron blocking layer 130 may be disposed between the emissive layer 135 and the hole transport layer 125 to block electrons from leaving the emissive layer 135 in the direction of the hole transport layer 125. Similarly, a hole blocking layer 140 may be disposed between the emissive layer 135 and the electron transport layer 145 to block holes from leaving the emissive layer 135 in the direction of the electron transport layer 145. Blocking layers may also be used to block excitons from diffusing from the emissive layer. As used herein, and as would be understood by one skilled in the art, the term “blocking layer” means that the layer provides a barrier that significantly inhibits transport of charge carriers and/or excitons, without suggesting that the layer completely blocks the charge carriers and/or excitons. The presence of such a blocking layer in a device may result in substantially higher efficiencies as compared to a similar device lacking a blocking layer. A blocking layer may also be used to confine emission to a desired region of a device. Substantial similarity between blocking layer properties required for PeLEDs, OLEDs and QLEDs facilitates the combination of these light emitting devices in a single device, such as a display.
[0071] Devices fabricated in accordance with embodiments of the present invention may optionally comprise one or more injection layers. Generally, injection layers are comprised of one or more materials that may improve the injection of charge carriers from one layer, such as an electrode, into an adjacent layer. Injection layers may also perform a charge transport function.
[0072] In device 100, the hole injection layer 120 may be any layer that improves the injection of holes from the anode 115 into the hole transport layer 125. Examples of materials that may be used as a hole injection layer are Copper(II)phthalocyanine (CuPc) and 1,4,5,8,9,11-Hexaazatriphenylenehexacarbonitrile (HATCN), which may be vapor deposited, and polymers, such as PEDOT:PSS, which may be deposited from solution. Another example of a material that may be used as a hole injection layer is molybdenum oxide (MoO.sub.3). The preceding examples of hole injection materials are all especially well-suited to application in PeLEDs. However, these materials may also be implemented effectively in OLEDs and QLEDs. Substantial similarity between hole injection layer properties required for PeLEDs, OLEDs and QLEDs facilitates the combination of these light emitting devices in a single device, such as a display.
[0073] A hole injection layer (HIL) 120 may comprise a charge carrying component having HOMO energy level that favourably matches, as defined by their herein-described relative IP energies, with the adjacent anode layer on one side of the HIL, and the hole transporting layer on the opposite side of the HIL. The “charge carrying component” is the material responsible for the HOMO energy level that actually transports the holes. This material may be the base material of the HIL, or it may be a dopant. Using a doped HIL allows the dopant to be selected for its electrical properties, and the host to be selected for morphological properties, such as ease of deposition, wetting, flexibility, toughness, and others. Preferred properties of the HIL material are such that holes can be efficiently injected from the anode into the HIL material. The charge carrying component of the HIL 120 preferably has an IP not more than about 0.5 eV greater than the IP of the anode material. Similar conditions apply to any layer into which holes are being injected. HIL materials are further distinguished from conventional hole transporting materials that are typically used in the hole transporting layer of a PeLED, OLED or QLED in that such HIL materials may have a hole conductivity that is substantially less than the hole conductivity of conventional hole transporting materials. The thickness of the HIL 120 of the present invention may be thick enough to planarize the anode and enable efficient hole injection, but thin enough not to hinder transportation of holes. For example, an HIL thickness of as little as 10 nm may be acceptable. However, for some devices, an HIL thickness of up to 50 nm may be preferred.
[0074] In device 100, the electron injection layer 150 may be any layer that improves the injection of electrons from the cathode 155 into the electron transport layer 145. Examples of materials that may be used as an electron injection layer are inorganic salts, such as lithium fluoride (LiF), sodium fluoride (NaF), barium fluoride (BaF) and caesium fluoride (CsF), and caesium carbonate (CsCO.sub.3). Other examples of materials that may be used as an electron injection layer are metal oxides, such as zinc oxide (ZnO) and titanium oxide (TiO.sub.2) and metals, such as calcium (Ca), barium (Ba), magnesium (Mg) and ytterbium (Yb). Other materials of combinations of materials may be used for injection layers. Depending on the configuration of a particular device, injection layers may be disposed at location different than those shown in device 100. The preceding examples of electron injection materials are all especially well-suited to application in PeLEDs. However, these materials may also be implemented effectively in OLEDs and QLEDs. Substantial similarity between electron injection layer properties required for PeLEDs, OLEDs and QLEDs facilitates the combination of these light emitting devices in a single device, such as a display.
[0075] Devices fabricated in accordance with embodiments of the present invention may optionally comprise a capping layer 160. The capping layer 160 may include any material capable of enhancing light extraction from the device. Preferably, the capping layer 160 is disposed over the top electrode in a top-emitting device architecture. Preferably, the capping layer 160 has a refractive index of at least 1.7, and is configured to enhance passage of light from the emissive layer 135 through the top electrode and out of the device, thereby enhancing device efficiency. Examples of materials that may be used for the capping layer 160 are 4,4′-Bis(N-carbazolyl)-1,1′-biphenyl (CBP), Alq.sub.3, and more generally, triamines and arylenediamines. The capping layer 160 may comprise a single layer or multiple layers. Other capping layer materials and structures may be used. Substantial similarity between capping layer properties required for PeLEDs, OLEDs and QLEDs, facilitates the combination of these light emitting devices in a single device, such as a display.
[0076] Devices fabricated in accordance with embodiments of the present invention may optionally comprise a barrier layer 165. One purpose of the barrier layer 165 is to protect device layers from damaging species in the environment, including moisture, vapour and/or gasses. Optionally, the barrier layer 165 may be deposited over, under or next to the substrate, electrode, or any other parts of the device, including an edge. Optionally, the barrier layer 165 may be a bulk material such as glass or metal, and the bulk material may be affixed over, under of next to the substrate, electrode, or any other parts of the device. Optionally, the barrier layer 165 may be deposited onto a film, and the film may be affixed over, under of next to the substrate, electrode, or any other parts of the device. Where the barrier layer 165 is deposited onto a film, preferred film materials comprise glass, plastics, such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) and metal foils. Where the barrier layer 165 is a bulk material or deposited onto a film, preferred materials used to affix the film or bulk material to the device include thermal or UV-curable adhesives, hot-melt adhesives and pressure sensitive adhesives.
[0077] The barrier layer 165 may be a bulk material or formed by various known deposition techniques, including sputtering, vacuum thermal evaporation, electron-beam deposition and chemical vapour deposition (CVD) techniques, such as plasma-enhanced chemical vapour deposition (PECVD) and atomic layer deposition (ALD). The barrier layer 165 may include compositions having a single phase as well as compositions having multiple phases. Any suitable material or combination of materials may be used for the barrier layer 165. The barrier layer 165 may incorporate organic or inorganic compounds or both. Preferred inorganic barrier layer materials include aluminum oxides such as Al.sub.2O.sub.3, silicon oxides such SiO.sub.2, silicon nitrides such as SiN.sub.x and bulk materials such as glasses and metals. Preferred organic barrier layer materials include polymers. The barrier layer 165 may comprise a single layer or multiple layers. Multilayer barriers comprising one or more barrier materials in one or more layers may be preferred for some devices. One preferred example of a multilayer barrier is a barrier comprising alternating layers of SiN.sub.x and a polymer, such as in the multilayer barrier SiN.sub.x/polymer/SiN.sub.x. Substantial similarity between barrier layer properties required for PeLEDs, OLEDs and QLEDs facilitates the combination of these light emitting devices in a single device, such as a display.
[0078] Unless otherwise specified, any one of the layers of the various embodiments may be deposited by any suitable method. Methods include vacuum thermal evaporation, sputtering, electron beam physical vapour deposition, organic vapor phase deposition and organic vapour jet printing. Other suitable methods include spincoating and other solution-based processes. Substantially similar processes can be used to deposit PeLEDs, OLEDs and QLEDs, which facilitates the combination of these light emitting devices in a single device, such as a display.
[0079] Devices fabricated in accordance with embodiments of the invention may be incorporated into a wide range of consumer products. Optionally, devices may be used in displays for televisions, computer monitors, tablets, laptop computers, smart phones, cell phones, digital cameras, video recorders, smartwatches, fitness trackers, personal digital assistants, vehicle displays and other electronic devices. Optionally, devices may be used for micro-displays or heads-up displays. Optionally, devices may be used in light sources for interior or exterior illumination and/or signaling, in smart packaging or in billboards.
[0080] Optionally, various control mechanisms may be used to control PeLED, OLED and QLED devices fabricated in accordance with the present invention, including passive matrix and active matrix address schemes.
[0081] The materials and structures described herein may have applications in devices other than light emitting devices. For example, other optoelectronic devices such as solar cells, photodetectors, transistors or lasers may employ the materials and structures.
[0082] Layers, materials, regions and devices may be described herein in reference to the colour of light they emit. As used herein, a “red” layer, material, region or device, refers to one that emits light that has an emission spectrum with a peak wavelength in the range of about 580-780 nm; a “green” layer, material, region or device, refers to one that emits light that has an emission spectrum with a peak wavelength in the range of about 500-580 nm; a “blue” layer, material, region or device, refers to one that emits light that has an emission spectrum with a peak wavelength in the range of about 380-500 nm; a “light blue” layer, material, region or device, refers to one that emits light that has an emission spectrum with a peak wavelength in the range of about 460-500 nm; and a “yellow” layer, material, region or device, refers to one that emits light that has an emission spectrum with a peak wavelength in the range of about 540-600 nm. Preferred ranges include a peak wavelength in the range of about 600-640 nm for red, about 510-550 nm for green, about 440-465 nm for blue, about 465-480 nm for light blue, and about 550-580 nm for yellow.
[0083] Similarly, any reference to a colour altering layer refers to a layer that converts or modifies another colour of light to light having a wavelength as specified for that colour. For example, a “red” color filter refers to a filter that results in light having an emission spectrum with a peak wavelength in the range of about 580-780 nm. In general, there are two classes of colour altering layers: colour filters that modify a spectrum by removing unwanted wavelengths of light, and colour changing layers that convert photons of higher energy to photons of lower energy.
[0084] Display technology is rapidly evolving, with recent innovations enabling thinner and lighter displays with higher resolution, improved frame rate and enhanced contrast ratio. However, one area where significant improvement is still required is colour gamut. Digital displays are currently incapable of producing many of the colours the average person experiences in day-to-day life. To unify and guide the industry towards improved colour gamut, two industry standards have been defined, DCI-P3 and Rec. 2020, with DCI-P3 often seen as a stepping stone towards Rec. 2020.
[0085] DCI-P3 was defined by the Digital Cinema Initiatives (DCI) organization and published by the Society of Motion Picture and Television Engineers (SMPTE). Rec. 2020 (more formally known as ITU-R Recommendation BT. 2020) was developed by the International Telecommunication Union to set targets, including improved colour gamut, for various aspects of ultra-high-definition televisions.
[0086] The CIE 1931 (x, y) chromaticity diagram was created by the Commission Internationale de l′Eclairage (CIE) in 1931 to define all colour sensations that an average person can experience. Mathematical relationships describe the location of each colour within the chromaticity diagram. The CIE 1931 (x, y) chromaticity diagram may be used to quantify the colour gamut of displays. The white point (D65) is at the centre, while colours become increasingly saturated (deeper) towards the extremities of the diagram.
[0087] OLED displays can successfully render the DCI-P3 colour gamut. For example, smartphones with OLED displays such as the iPhone X (Apple), Galaxy S9 (Samsung) and OnePlus 5 (OnePlus) can all render the DCI-P3 gamut. Commercial liquid crystal displays (LCDs) can also successfully render the DCI-P3 colour gamut. For example, LCDs in the Surface Studio (Microsoft), Mac Book Pro and iMac Pro (both Apple) can all render the DCI-P3 gamut. In addition, electroluminescent and photoluminescent quantum dot technology has also been used to demonstrate electroluminescent and photoluminescent QLED displays with wide colour gamut. However, until now, no display has been demonstrated that can render the Rec. 2020 colour gamut.
[0088] Here we disclose a novel pixel arrangement for application in a display. In various embodiments, when implemented in a display, the pixel arrangement can enable the display to render the DCI-P3 colour gamut. In various embodiments, when implemented in a display, the pixel arrangement can enable the display to render the Rec. 2020 colour gamut.
[0089] The novel pixel arrangement comprises a plurality of pixels, each pixel comprising a first sub-pixel configured to emit a first colour of light, the first sub-pixel comprising a PeLED; a second sub-pixel configured to emit a second colour of light that is different from the first colour of light; and a third sub-pixel configured to emit a third colour of light that is different from the first and second colour of light, wherein the second sub-pixel comprises a PeLED, an OLED or a QLED, and the third sub-pixel comprises a PeLED, an OLED or a QLED.
[0090] Until now, no display has been demonstrated that comprises a PeLED. We demonstrate that by including one or more PeLEDs within a pixel arrangement for application in a display, the colour gamut of the display can be extended. We further demonstrate that colour gamut can be further extended by combining PeLEDs with OLED and/or QLEDs in a pixel arrangement.
[0091] A pixel arrangement for application in a display is provided herein.
[0092] In one embodiment of the pixel arrangement, the first sub-pixel 310 comprises a PeLED, the second sub-pixel 320 comprises a PeLED and the third sub-pixel 330 comprises a PeLED.
[0093] In one embodiment of the pixel arrangement, the first sub-pixel 310 comprises a PeLED, and at least one of the second sub-pixel 320 and the third sub-pixel 330 comprises an OLED or a QLED. Such a pixel arrangement may be advantageous because the combination of different light emitting diodes may enable the optimum type of light emitting diode to be selected for each sub-pixel within the pixel arrangement, thereby enhancing performance beyond that which could be achieved from a pixel arrangement comprising a single type of light emitting diode, such as only PeLEDs, only OLEDs or only QLEDs.
[0094] In one embodiment of the pixel arrangement, the first sub-pixel 310 comprises a PeLED, the second sub-pixel 320 comprises a PeLED and the third sub-pixel 330 comprises an OLED or a QLED.
[0095] In one embodiment of the pixel arrangement, the first sub-pixel 310 comprises a PeLED, the second sub-pixel 320 comprises a PeLED or an OLED and the third sub-pixel 330 comprises a PeLED or an OLED, wherein at least one of the second sub-pixel and the third sub-pixel comprises an OLED.
[0096] Such a pixel arrangement may be advantageous because a PeLED device architecture may be preferred for the first sub-pixel of a display, but the performance of the display may be enhanced if an OLED device architecture is used for the second and/or third sub-pixel of the display. For example, the colour gamut, electroluminescence efficiency and/or electroluminescence stability of the display may be enhanced. In one embodiment, the first sub-pixel may comprise a PeLED that emits green light, the second sub-pixel may comprise an OLED that emits red light, and the third sub-pixel may comprise an OLED that emits blue light. Such a pixel arrangement may enhance the colour gamut of a display. Combination of PeLED device architectures with OLED device architectures within the pixel arrangement of a display may be particularly advantageous because advanced OLED performance already available in commercial products may be complemented and enhanced where required by PeLED device performance.
[0097] In one embodiment of the pixel arrangement, the first sub-pixel 310 comprises a PeLED, the second sub-pixel 320 comprises a PeLED and the third sub-pixel 330 comprises an OLED.
[0098] In one embodiment of the pixel arrangement, the first sub-pixel 310 comprises a PeLED, the second sub-pixel 320 comprises a PeLED or a QLED and the third sub-pixel 330 comprises a PeLED or a QLED, wherein at least one of the second sub-pixel and the third sub-pixel comprises a QLED.
[0099] Such a pixel arrangement may be advantageous because a PeLED device architecture may be preferred for the first sub-pixel of a display, but the performance of the display may be enhanced if a QLED device architecture is used for the second and/or third sub-pixel of the display. For example, the colour gamut, electroluminescence efficiency and/or electroluminescence stability of the display may be enhanced. In one embodiment, the first sub-pixel may comprise a PeLED that emits green light, the second sub-pixel may comprise a QLED that emits red light, and the third sub-pixel may comprise a PeLED that emits blue light. Such a pixel arrangement may enhance the colour gamut of a display. Combination of PeLED device architectures with QLED device architectures within the pixel arrangement of a display may be particularly advantageous because the similarity of structure of perovskite light-emitting materials and quantum dot light-emitting materials may allow these device architectures to be manufactured together with little or no added complexity. For example, in the case of solution-process manufacturing, common solvents may be used to process perovskite light-emitting materials and quantum dot light-emitting materials.
[0100] In one embodiment of the pixel arrangement, the first sub-pixel 310 comprises a PeLED, the second sub-pixel 320 comprises a PeLED and the third sub-pixel 330 comprises a QLED.
[0101] In one embodiment of the pixel arrangement, the first sub-pixel 310 comprises a PeLED, the second sub-pixel 320 comprises an OLED and the third sub-pixel 330 comprises an OLED.
[0102] In one embodiment of the pixel arrangement, the first sub-pixel 310 comprises a PeLED, the second sub-pixel 320 comprises a QLED and the third sub-pixel 330 comprises a QLED.
[0103] In one embodiment of the pixel arrangement, the first sub-pixel 310 comprises a PeLED, the second sub-pixel 320 comprises an OLED and the third sub-pixel 330 comprises a QLED.
[0104] The pixel arrangements 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080 and 1090 may be of advantage in that by including at least one PeLED in at least one sub-pixel, the colour gamut of the pixel arrangement may be extended. The pixel arrangements 1000, 1020, 1030, 1040, 1050, 1060, 1070, 1080 and 1090 may be of further advantage in that one or more PeLEDs may be combined with one or more OLEDs and/or QLEDs to further extend the colour gamut of the pixel arrangement. When such pixel arrangements are implemented in a display, the colour gamut of the display may be extended. Such a combination of PeLED, OLED and/or QLED devices may be demonstrated in practice because substantial similarity between device architectures and processing techniques facilitates their combination within a pixel arrangement. Combination of different light emitting diodes enables the optimum type of light emitting diode to be selected for each sub-pixel within the pixel arrangement, thereby enhancing performance beyond that which could be expected from a pixel arrangement comprising a single type of light emitting diode, such as only PeLEDs, only OLEDs, or only QLEDs. Enhancement in performance may be through extended colour gamut, increased efficiency, increased brightness, extended operation lifetime, reduced voltage, reduced costs or other enhancements.
[0105] One or more advantages of including at least one PeLED in at least one sub-pixel of a pixel arrangement, and/or combining one or more PeLEDs with one or more OLEDs and/or QLEDs in a pixel arrangement, may be demonstrated using the data shown in Table 1 and
[0106]
TABLE-US-00001 TABLE 1 CIE 1931 (x, y) colour coordinates for exemplary PeLED, OLED and QLED devices. Also included are colour coordinates for DCI-P3 and Rec. 2020 colour gamut standards. Red Green Blue CIE x CIE y CIE x CIE y CIE x CIE y DCI-P3 0.680 0.320 0.265 0.690 0.150 0.060 Rec. 2020 0.708 0.292 0.170 0.797 0.131 0.046 Commercial OLED 0.680 0.320 0.265 0.690 0.150 0.060 R&D PeLED 0.720 0.280 0.100 0.810 0.166 0.079 R&D OLED — — — — 0.146 0.045 R&D QLED 0.712 0.288 — — — —
[0107] The CIE 1931 (x, y) colour coordinate data reported for red, green and blue PeLED, OLED and QLED devices in Table 1 are exemplary. Commercial OLED data are taken from the Apple iPhone X, which fully supports the DCI-P3 colour gamut. This data set is available from Raymond Soneira at DisplayMate Technologies Corporation (Soneira et al.). Data for R&D PeLED, R&D OLED and R&D QLED devices are taken from a selection of peer-reviewed scientific journals: Red R&D PeLED data are taken from Wang et al. (1). Red R&D QLED data are taken from Kathirgamanathan et al. (2). Green R&D PeLED data are taken from Hirose et al. Blue R&D PeLED data are taken from Kumar et al. Blue R&D OLED data is taken from Takita et al. Data from these sources is used by way of example, and should be considered non-limiting. Data from other peer-reviewed scientific journals, simulated data and/or experimental data collected from laboratory devices may also be used to demonstrate the aforementioned advantages of the claimed pixel arrangement.
[0108] As can be seen from Table 1 and
[0109] Table 1 and
[0110] Optionally, by including a PeLED device in a sub-pixel of the pixel arrangement, the sub-pixel may emit green light with CIE 1931 (x, y)=(0.100, 0.810), which as can be seen from
[0111] However, colour gamut is only one metric by which the performance of a display may be measured. Other performance parameters, such as efficiency, brightness, operational lifetime, voltage, process conditions and cost must also be considered in design of a pixel arrangement. It may be advantageous under some circumstances to combine one or more sub-pixels comprising one or more PeLEDs with one or more sub-pixels comprising one or more OLEDs and/or one or more QLEDs in a pixel arrangement.
[0112] Optionally, by including a QLED device in a sub-pixel of the pixel arrangement, the sub-pixel may emit red light with CIE 1931 (x, y)=(0.712, 0.288), which as can be seen from
[0113] Optionally, by including an OLED device in a sub-pixel of the pixel arrangement, the sub-pixel may emit blue light with CIE 1931 (x, y)=(0.146, 0.045), which as can be seen from
[0114] Optionally, by combining one or more sub-pixels comprising one or more PeLEDs with one or more sub-pixels comprising one or more OLEDs and/or one or more QLEDs, a pixel arrangement that may render the DCI-P3 colour gamut may be demonstrated. In one embodiment, one of the first, second and third sub-pixels may emit red light with CIE 1931 x coordinate greater than or equal to 0.680; one of the first, second and third sub-pixels may emit green light with CIE 1931 y coordinate greater than or equal to 0.690; and one of the first, second and third sub-pixels may emit blue light with CIE 1931 y coordinate less than or equal to 0.060. Such a pixel arrangement may be of advantage in that it fulfills colour gamut requirements of the DCI-P3 display standard. Such a pixel arrangement may be of advantage in that when implemented in a display, the display may render a broader range of colours experienced in everyday life, thereby improving functionality and user experience.
[0115] Optionally, by combining one or more sub-pixels comprising one or more PeLEDs with one or more sub-pixels comprising one or more OLEDs and/or one or more QLEDs, a pixel arrangement that may render the Rec. 2020 colour gamut may be demonstrated. In one embodiment, one of the first, second and third sub-pixels may emit red light with CIE 1931 x coordinate greater than or equal to 0.708; one of the first, second and third sub-pixels may emit green light with CIE 1931 y coordinate greater than or equal to 0.797; and one of the first, second and third sub-pixels may emit blue light with CIE 1931 y coordinate less than or equal to 0.046. Such a pixel arrangement may be of advantage in that it fulfills colour gamut requirements of the Rec. 2020 display standard. Such a pixel arrangement may be of advantage in that when implemented in a display, the display may render a broader range of colours experienced in everyday life, thereby improving functionality and user experience.
[0116] Optionally, the pixel arrangement may comprise a plurality of pixels, each pixel comprising a first sub-pixel configured to emit red light, the first sub-pixel comprising a PeLED, a second sub-pixel configured to emit green light, the second sub-pixel comprising a PeLED, and a third sub-pixel configured to emit blue light, the third sub-pixel comprising an OLED.
[0117] Optionally, the pixel arrangement may comprise a plurality of pixels, each pixel comprising a first sub-pixel configured to emit red light, the first sub-pixel comprising a QLED, a second sub-pixel configured to emit green light, the second sub-pixel comprising a PeLED, and a third sub-pixel configured to emit blue light, the third sub-pixel comprising an OLED.
[0118] In one embodiment, the first, second and third sub-pixels of the pixel arrangement may have the same surface area.
[0119] In one embodiment, at least one of the first, second and third sub-pixels has a surface area different from another of the first, second and third sub-pixels.
[0120] Optionally, and as depicted in pixel arrangement 1110, the surface area of the sub-pixel configured to emit blue light (sub pixel 430 in pixel arrangement 1110) may be substantially greater than the surface area of the sub-pixel configured to emit red light (sub pixel 410 in pixel arrangement 1110). Optionally, and as depicted in pixel arrangement 1110, the surface area of the sub-pixel configured to emit blue light (sub pixel 430 in pixel arrangement 1110) may be substantially greater than the surface area of the sub-pixel configured to emit green light (sub pixel 420 in pixel arrangement 1110).
[0121] Such a pixel arrangement may be of advantage in that it may extend the operational lifetime of a display into which it is incorporated. One reason for this may be that the light-emitting materials used in the sub-pixel that emits blue light may have shorter operational lifetime compared to the light-emitting materials used in the sub-pixels that emit red and green light. This effect may be seen in PeLED, OLED and QLED devices, and may be a result of the higher energy associated with blue light compared to red and green light. The higher energy associated with blue light means that the energy band gap between HOMO and LUMO levels is necessarily greater, which may result in the exciton state being more difficult to stabilize, and therefore shorter operational lifetime may result. By increasing the surface area of the sub-pixel that emits blue light, it may be possible to generate the same total light output from the sub-pixel at a lower luminance. For example, if the surface area of the sub-pixel is increased by a factor of two, the luminance may be reduced by a factor of two, and the same total light output may still be achieved. It is well understood in the art that by reducing luminance, operation lifetime for PeLED, OLED and QLED devices may be extended. Therefore, by increasing the surface area of the sub-pixel that emits blue light to be greater than the surface area of each of the sub-pixels that emit red and green light, the operational lifetime of the red, green and blue sub-pixels may be more evenly balanced, and the operational lifetime of a display into which such a pixel arrangement is incorporated may be extended.
[0122] In one embodiment, the pixel arrangement may further comprise a fourth sub-pixel configured to emit a fourth colour of light that is different from the first, second and third colour of light, the fourth sub-pixel comprising a PeLED, an OLED or a QLED. Such a pixel arrangement may be of advantage in that a fourth sub-pixel may broaden the colour gamut of a display into which it is incorporated.
[0123] In one embodiment, the first, second, third and fourth sub-pixels of the pixel arrangement may have the same surface area. In one embodiment, at least one of the first, second, third and fourth sub-pixels has a surface area different from another of the first, second, third and fourth sub-pixels.
[0124]
[0125] In one embodiment, the pixel arrangement may comprise a fourth sub-pixel that emits light blue light.
[0126] In one embodiment, the pixel arrangement may be included in a display. Optionally, the display may be incorporated into a wide range of consumer products. Optionally, the display may be used in televisions, computer monitors, tablets, laptop computers, smart phones, cell phones, digital cameras, video recorders, smartwatches, fitness trackers, personal digital assistants, vehicle displays and other electronic devices. Optionally, the display may be used for micro-displays or heads-up displays. Optionally, the display may be used in light sources for interior or exterior illumination and/or signaling, in smart packaging or in billboards.
[0127] In one embodiment, the display is a flexible structure. Optionally, the display may be flexible with a flexural rigidity in the range of 0.1 Nm to 0.00001 Nm. Such a flexible display may be of advantage in that it may be less likely to suffer failure when subject to mechanical stress, when compared to an equivalent rigid structure. Such a flexible display may also be implemented more effectively in applications where curvature of the structure is required.
[0128] In one embodiment, at least one of the sub-pixels of the display includes a microcavity structure. In one embodiment, each of the sub-pixels of the display include a microcavity structure. Optionally, as described herein, a microcavity structure may be created where a transparent and partially reflective electrode is used in combination with an opposing reflective electrode. Optionally, in a standard device architecture, a bottom-emission microcavity structure may be created using a transparent and partially reflective multilayer anode such as ITO/Ag/ITO, where the Ag thickness is less than approximately 25 nm, in combination with a reflective multilayer cathode such as LiF/Al. In this architecture, light emission is through the anode. Optionally, in a standard device architecture, a top-emission microcavity structure may be created using a transparent and partially reflective compound cathode such as Mg:Ag in combination with a reflective multilayer anode such as ITO/Ag/ITO, where the Ag thickness is greater than approximately 80 nm. In this architecture, light emission is through the cathode.
[0129] Such a display may be of advantage in that one or more microcavity structures may increase the total amount of light emitted from one or more sub-pixels to which they are applied, thereby increasing the efficiency and brightness of the display. Such a display may further be of advantage in that one or more microcavity structures may increase the proportion of light emitted in the forward direction from one or more sub-pixels to which they are applied, thereby increasing the apparent brightness of the display to a user positioned at normal incidence. Such a display may further be of advantage in that one or more microcavity structures may narrow the spectrum of emitted light from one or more sub-pixels to which they are applied, thereby increasing the colour saturation of the emitted light and the colour gamut of the display. Application of one or more microcavity structures may thereby enable the display to render the DCI-P3 colour gamut. Application of one or more microcavity structures may thereby enable the display to render the Rec. 2020 colour gamut. Substantial similarity between anode and cathode properties required for PeLEDs, OLEDs and QLEDs facilitates the combination of these light emitting devices in a single device, such as a display.
[0130] In one embodiment, each of the sub-pixels of the display include a colour altering layer. In one embodiment, at least one of the sub-pixels of the display includes a colour altering layer. As described herein, there are in general two classes of colour altering layers: colour filters that modify a spectrum by removing unwanted wavelengths of light, and colour changing layers that convert photons of higher energy to photons of lower energy.
[0131]
[0132] Optionally, the one or more colour altering layers may comprise one or more colour filters. Optionally, the one or more colour altering layers may comprise one or more colour changing layers. Optionally, the first, second and third sub-pixels of display 1300 may have the same surface area. Optionally, at least one of the first 620, second 630 and third 640 sub-pixels has a surface area different from another of the first, second and third sub-pixels. Optionally, display 1300 may comprise further sub-pixels, such as a fourth sub-pixel, which may further comprise a fourth colour altering layer.
[0133]
[0134] Optionally, the one or more colour altering layers may comprise one or more colour filters. Optionally, the one or more colour altering layers may comprise one or more colour changing layers. Optionally, the first, second and third sub-pixels of display 1310 may have the same surface area. Optionally, at least one of the first 620, second 630 and third 640 sub-pixels has a surface area different from another of the first, second and third sub-pixels. Optionally, display 1310 may comprise further sub-pixels, such as a fourth sub-pixel, which may further comprise a fourth colour altering layer.
[0135] Such displays as depicted in
[0136] In one embodiment, the display is capable of rendering the DCI-P3 colour gamut. That is to say that in one embodiment, one of the first, second and third sub-pixels of the display emits red light; one of the first, second and third sub-pixels of the display emits green light; and one of the first, second and third sub-pixels of the display emits blue light. In one embodiment, one of the first, second and third sub-pixels of the display emits red light with CIE 1931 x coordinate greater than or equal to 0.680; one of the first, second and third sub-pixels of the display emits green light with CIE 1931 y coordinate greater than or equal to 0.690; and one of the first, second and third sub-pixels of the display emits blue light with CIE 1931 y coordinate less than or equal to 0.060.
[0137] Such a display may be of advantage in that it fulfills colour gamut requirements of the DCI-P3 display standard. Such a display may be of advantage in that it may render a broader range of colours experienced in everyday life, thereby improving functionality and user experience.
[0138] In one embodiment, the display is capable of rendering the Rec. 2020 colour gamut. That is to say that in one embodiment, one of the first, second and third sub-pixels of the display emits red light; one of the first, second and third sub-pixels of the display emits green light; and one of the first, second and third sub-pixels of the display emits blue light. In one embodiment, one of the first, second and third sub-pixels of the display emits red light with CIE 1931 x coordinate greater than or equal to 0.708; one of the first, second and third sub-pixels of the display emits green light with CIE 1931 y coordinate greater than or equal to 0.797; and one of the first, second and third sub-pixels of the display emits blue light with CIE 1931 y coordinate less than or equal to 0.046.
[0139] Such a display may be of advantage in that it fulfills colour gamut requirements of the Rec. 2020 display standard. Such a display may be of advantage in that it may render a broader range of colours experienced in everyday life, thereby improving functionality and user experience.
[0140] A person skilled in the art will understand that only a few examples of use are described, but that they are in no way limiting.
[0141] Modifications to embodiments of the invention described in the foregoing are possible without departing from the scope of the invention as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “consisting of”, “have”, “is” used to describe and claim the present invention are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural. Any numerals included within parentheses in the accompanying claims are intended to assist understanding of the claims and should not be construed in any way to limit subject matter claimed by these claims.
PATENT REFERENCES
[0142] U.S. Pat. No. 8,773,013 B2, Rajan et al., Three Dimensional OLED Lamps [0143] EP 0423283 B1, Friend et al., Electroluminescent Devices [0144] U.S. Pat. No. 6,303,238 B1, Thompson et al., OLEDs Doped with Phosphorescent Compounds [0145] U.S. Pat. No. 7,279,704 B2, Walters et al., Complexes with Tridentate Ligands
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