GB2549490A - Light emitting device with tuned cathode layer optical properties - Google Patents
Light emitting device with tuned cathode layer optical properties Download PDFInfo
- Publication number
- GB2549490A GB2549490A GB1606768.8A GB201606768A GB2549490A GB 2549490 A GB2549490 A GB 2549490A GB 201606768 A GB201606768 A GB 201606768A GB 2549490 A GB2549490 A GB 2549490A
- Authority
- GB
- United Kingdom
- Prior art keywords
- light
- emitting device
- light emitting
- electrode
- absorbing layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 230000003287 optical effect Effects 0.000 title description 16
- 230000008033 biological extinction Effects 0.000 claims abstract description 47
- 239000002245 particle Substances 0.000 claims abstract description 37
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 25
- 229910052709 silver Inorganic materials 0.000 claims abstract description 24
- 239000004332 silver Substances 0.000 claims abstract description 24
- 229920001940 conductive polymer Polymers 0.000 claims abstract description 14
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000010949 copper Substances 0.000 claims abstract description 8
- 229910052802 copper Inorganic materials 0.000 claims abstract description 8
- 229910044991 metal oxide Inorganic materials 0.000 claims abstract description 4
- 150000004706 metal oxides Chemical class 0.000 claims abstract description 4
- 239000000463 material Substances 0.000 claims description 20
- 239000000203 mixture Substances 0.000 claims description 20
- 229910052751 metal Inorganic materials 0.000 claims description 7
- 239000002184 metal Substances 0.000 claims description 7
- 239000010931 gold Substances 0.000 claims description 5
- 239000002070 nanowire Substances 0.000 claims description 5
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 4
- 229910052737 gold Inorganic materials 0.000 claims description 4
- 238000002310 reflectometry Methods 0.000 abstract description 18
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 abstract description 8
- 229920000642 polymer Polymers 0.000 abstract description 8
- 239000000084 colloidal system Substances 0.000 abstract description 6
- NIHNNTQXNPWCJQ-UHFFFAOYSA-N fluorene Chemical compound C1=CC=C2CC3=CC=CC=C3C2=C1 NIHNNTQXNPWCJQ-UHFFFAOYSA-N 0.000 abstract description 6
- 239000004417 polycarbonate Substances 0.000 abstract description 5
- 229920000515 polycarbonate Polymers 0.000 abstract description 5
- YTPLMLYBLZKORZ-UHFFFAOYSA-N Thiophene Chemical compound C=1C=CSC=1 YTPLMLYBLZKORZ-UHFFFAOYSA-N 0.000 abstract description 4
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 abstract description 4
- 239000011787 zinc oxide Substances 0.000 abstract description 3
- 229920000144 PEDOT:PSS Polymers 0.000 abstract description 2
- 229930192474 thiophene Natural products 0.000 abstract description 2
- 229920001577 copolymer Polymers 0.000 abstract 2
- 239000013528 metallic particle Substances 0.000 abstract 2
- 239000010410 layer Substances 0.000 description 47
- 239000000758 substrate Substances 0.000 description 11
- 238000000034 method Methods 0.000 description 8
- 239000000243 solution Substances 0.000 description 8
- 235000009508 confectionery Nutrition 0.000 description 5
- 238000013461 design Methods 0.000 description 5
- 230000028161 membrane depolarization Effects 0.000 description 5
- 239000000470 constituent Substances 0.000 description 4
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 241001247986 Calotropis procera Species 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 3
- 238000006731 degradation reaction Methods 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 238000004768 lowest unoccupied molecular orbital Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000006096 absorbing agent Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000003086 colorant Substances 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 230000001066 destructive effect Effects 0.000 description 2
- 239000007772 electrode material Substances 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 150000003384 small molecules Chemical class 0.000 description 2
- 229920001621 AMOLED Polymers 0.000 description 1
- 229910001316 Ag alloy Inorganic materials 0.000 description 1
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 229910019015 Mg-Ag Inorganic materials 0.000 description 1
- 241000206607 Porphyra umbilicalis Species 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- UPGUYPUREGXCCQ-UHFFFAOYSA-N cerium(3+) indium(3+) oxygen(2-) Chemical compound [O--].[O--].[O--].[In+3].[Ce+3] UPGUYPUREGXCCQ-UHFFFAOYSA-N 0.000 description 1
- 230000001010 compromised effect Effects 0.000 description 1
- 239000011370 conductive nanoparticle Substances 0.000 description 1
- 239000000412 dendrimer Substances 0.000 description 1
- 229920000736 dendritic polymer Polymers 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000004770 highest occupied molecular orbital Methods 0.000 description 1
- 230000005525 hole transport Effects 0.000 description 1
- 238000007641 inkjet printing Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- SJCKRGFTWFGHGZ-UHFFFAOYSA-N magnesium silver Chemical compound [Mg].[Ag] SJCKRGFTWFGHGZ-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012044 organic layer Substances 0.000 description 1
- 125000002524 organometallic group Chemical group 0.000 description 1
- 239000002952 polymeric resin Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000012552 review Methods 0.000 description 1
- 238000004528 spin coating Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- YVTHLONGBIQYBO-UHFFFAOYSA-N zinc indium(3+) oxygen(2-) Chemical compound [O--].[Zn++].[In+3] YVTHLONGBIQYBO-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/36—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes
- H01L33/40—Materials therefor
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B33/00—Electroluminescent light sources
- H05B33/12—Light sources with substantially two-dimensional radiating surfaces
- H05B33/26—Light sources with substantially two-dimensional radiating surfaces characterised by the composition or arrangement of the conductive material used as an electrode
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/80—Constructional details
- H10K59/805—Electrodes
- H10K59/8052—Cathodes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/06—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances
- H01B1/08—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances oxides
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/06—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances
- H01B1/12—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances organic substances
- H01B1/124—Intrinsically conductive polymers
Abstract
A light emitting device 300 comprising: a light transmissive first electrode 304; a light emitting layer 306; and a second electrode 308 comprising a light absorbing layer layer with a complex refractive index RI = n + i.k, where the value of n (the refractive index) lies between 1.3 and 2.2 and the value of k (the extinction coefficient) lies between 0.05 and 0.5. The second electrode 308 may be light absorbing layer or the light absorbing layer may be a further layer disposed on a separate second electrode 308. The light absorbing layer may comprise a combination of metallic particles and a host, where the metallic particles may be silver or copper and where the host may be a metal oxide, such as zinc oxide or indium tin oxide; or a conductive polymer, such as a fluorene polymer or copolymer, PEDOT:PSS or thiophene polymer or copolymer (e.g. F8-BT). The silver particles may be part of a silver colloid having a ratio of 3:7 silver to polycarbonate. The second electrode 308 may be a cathode and have a reflectivity of less than 2%.
Description
LIGHT EMITTING DEVICE WITH TUNED CATHODE LAYER OPTICAL PROPERTIES
[0001] This invention reiates to iight emitting devices, such as an organic iight-emitting device (OLED). More specificaiiy, various embodiments of the disciosure reiate to a iight emitting device with tuned cathode iayer opticai properties.
BACKGROUND
[0002] The past decade has witnessed substantiai usage of active organic materiais in dispiay screens of high-end eiectronic devices. Exampies of such eiectronic devices may inciude, but not iimited to, an organic iight-emitting diodes (OLED) device and an organic photoresponsive device. The usage of active organic materiais in such eiectronic devices may offer various benefits, such as iow weight, iow power consumption, and high fiexibiiity. Various soiution processing techniques, such as inkjet printing or spin-coating, may be used to manufacture such eiectronic devices that contain the active organic materiais.
[0003] Typicaiiy, an OLED comprises a substrate, an anode, a cathode, and one or more organic iight-emitting iayers sandwiched between the anode and the cathode. Hoies are injected from the anode and eiectrons are injected from the cathode into an organic iight-emitting iayer, during the operation of the OLED device, in the organic iight-emitting iayer, hoies injected into the highest occupied moiecuiar orbitai (HOMO) and eiectrons injected into the iowest unoccupied moiecuiar orbitai (LUMO) combine to form an exciton that reieases its energy in the form of iight on recombination.
[0004] in certain scenarios, the cathode of the OLED device may reflect the internaiiy generated iight towards the substrate to improve the brightness of the emission of internaiiy generated iight through the substrate, in such scenarios, the cathode aiso reflects ambient iight when the OLED device is used in an outdoor appiication or in the bright iight conditions that may iead to degradation of the visuaiiy perceived contrast of the cathode. Consequentiy, the sharpness and coiors of images dispiayed on the OLED device may aiso get compromised. To overcome the above-mentioned probiems, various techniques for antireflection coatings, black absorbers, and circular polarizers, may be used in such an OLED device to reduce the reflection of ambient light. Such techniques may maintain high contrast under bright light conditions, but, may lead to reduced power efficiency and increased design complexity as well as overall manufacturing cost of the OLED device.
[0005] W02008028611A2 discloses an organic light-emitting component, particularly an organic light-emitting diode, in which an arrangement is formed that comprises a bottom electrode, a top electrode, and an organic layer region. The bottom electrode is a cathode that is formed from a dispersion as a structured, binder-free, and optically transparent bottom electrode layer made of a bottom electrode material by means of a wet chemical application process. The bottom electrode material is an optically transparent, electrically conductive oxide.
[0006] W02001008240A1 discloses an organic electroluminescent device having an optical interference member that reduces the overall reflectance from the device by causing a destructive optical interference of ambient light incident on the display.
[0007] WO2013053517A1 discloses a light-emitting component that includes a first electrode, which may be a cathode, formed from a network composed of metallic nanowires combined with conductive polymers.
[0008] US7804238B2 discloses a functional thin-film element that includes first and second electrodes comprising electro-conductive nanoparticles, and a transparent polymer resin.
[0009] Therefore, there is a need of an OLED device that can overcome the aforesaid limitations. Further limitations and disadvantages of conventional and traditional approaches will become apparent to those skilled in the art, through the comparison of described systems with some aspects of the present disclosure, as set forth in the remainder of the present application and with reference to the drawings.
SUMMARY OF THE INVENTION
[0010] A light emitting device with a cathode layer having tuned optical constants is provided as shown in, and / or described in connection with, at least one of the figures, as set forth more completely in the claims. In accordance with an embodiment of the present disclosure, a light emitting device is disclosed, as claimed in claim 1. The light emitting device includes a light transmissive first electrode, a second electrode, and a light emissive layer. The light emitting device may have additional optional electron or hole transporting layers. The light emissive layer is located between the light transmissive first electrode and the second electrode. The second electrode includes a light absorbing layer that has a complex refractive index Rl = n + i.k, wherein the value of n (the refractive index) lies between 1.3 and 2.2 and the value of k (the extinction coefficient) lies between 0.05 and 0.5.
[0011] In accordance with an embodiment, the second electrode further includes a layer that comprises a metal layer, the light absorbing layer being located between the metal layer and the light emissive layer. The light transmissive first electrode is an anode and the second electrode is a cathode. In accordance with an embodiment, a display may be formed by use of plurality of light emitting devices.
[0012] In accordance with an embodiment, the light absorbing layer comprises a mixture of conductive particles and a host material. In accordance with an embodiment, the conductive particles are silver particles, gold particles, or copper particles. In accordance with an embodiment the conductive particles are nanowires. The host material may comprise a conductive polymer. The host material may further comprise a metal oxide.
[0013] In accordance with an embodiment, the light absorbing layer comprises a conductive polymer. In accordance with an embodiment, the volume percentage of the conductive particles in the light absorbing layer is between 2% and 10%.
[0014] In accordance with another aspect of the disclosure, a light absorbing layer of a light emitting device is disclosed, as claimed in claim 13. The light absorbing layer has a complex refractive index Rl = n + i.k, wherein the value of n (the refractive index) lies between 1.3 and 2.2 and the value of k (the extinction coefficient) lies between 0.05 and 0.5. The light absorbing layer corresponds to a cathode of the light emitting device.
[0015] These and other features and advantages of the present disclosure may be appreciated from a review of the following detailed description of the present disclosure, along with the accompanying figures in which like reference numerals refer to like parts throughout.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the principles of the disclosure. In the drawings: [0017] FIG. 1 is a schematic cross-sectional view of a prior art standard light emitting device, such as an organic light-emitting diode (OLED); [0018] FIG. 2 shows a prior art computer modelled graphical plot of refractive index and extinction coefficient versus the wavelength of the emitted light from the prior art light emitting device; [0019] FIG. 3 is a schematic cross-sectional view that illustrates an exemplary light emitting device such as an OLED, in accordance with an embodiment of the present disclosure; [0020] FIG. 4 shows a computer modelled graphical plot of reflectivity versus an extinction coefficient for the light emitting device, in accordance with an embodiment of the present disclosure; [0021] FIG. 5A shows a first exemplary computer modelled graphical plot of refractive index and extinction coefficient versus the wavelength of the emitted light from the light emitting device, in accordance with an embodiment of the present disclosure; [0022] FIG. 5B shows a second exemplary computer modelled graphical plot of the refractive index and extinction coefficient versus the wavelength of the emitted light from the light emitting device, in accordance with an embodiment of the present disclosure; [0023] FIG. 5C shows a third exemplary computer modelled graphical plot of the refractive index and extinction coefficient versus the wavelength of the emitted light from the light emitting device, in accordance with an embodiment of the present disclosure; and [0024] FIG. 5D shows a fourth exemplary computer modelled graphical plot of the refractive index and extinction coefficient versus the wavelength of the emitted light from the light emitting device, in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0025] Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings.
[0026] FIG. 1 is a schematic cross-sectional view of a prior art standard light emitting device such as an organic light-emitting diode (OLED). With reference to FIG. 1, there is shown a prior art light emitting device 100, such as an OLED device. The prior art light emitting device 100 that comprises a substrate 102 (such as glass), an anode 104 (typically made of indium-tin-oxide), an organic light-emitting layer 106, an electron injection layer 108, and a cathode 110 (such as metal colloid of gold (Au), silver (Ag), aluminium (Al), or alloys, such as magnesium-silver alloy (Mg-Ag) or lithium fluoride / aluminum alloy (LiF / Al), which may be reflective in nature). There is further shown an electrical potential difference from a power supply 112 applied between the anode 104 and the cathode 110. The cathode 110 may be associated with a complex refractive index, which comprises a real component and an imaginary component, is given by a mathematical expression (1), as follows: complex refractive index = n+ ik (1) where, “n” is the real component that corresponds to a refractive index, and “k” is the imaginary component that corresponds to an extinction coefficient. Typically, the refractive index indicates how light propagates through the cathode 110 and the extinction coefficient indicates an amount of attenuation when the light propagates through the cathode 110.
[0027] During the operation of the prior art light emitting device 100, holes are injected from the anode 104 and electrons are injected from the cathode 110 and the electron injection layer 108 into the organic light-emitting layer 106. In the organic light-emitting layer 106, the holes and the electrons may combine to form excitons. The excitons have high energy and are unstable. Thus, when the unstable excitons recombine, the energy is released in the form of light with a specific wavelength range.
[0028] In the prior art, the cathode 110 of the prior art light emitting device 100 may reflect the internally generated light towards the substrate 102 to improve the brightness of the emission of internally generated light. However, the cathode 110 may reflect ambient light when the prior art light emitting device 100 is used in bright light conditions. This may lead to degradation of the visually perceived contrast of the cathode 110 and the sharpness and colors of images displayed by the prior art light emitting device 100. An exemplary graphical plot of the refractive index and the extinction coefficient of the cathode 110, versus the wavelength of the emitted light from the prior art light emitting device 100, has been illustrated in FIG. 2.
[0029] In the prior art, an optical interference member (not shown) may be disposed in between any two consecutive layers of the prior art light emitting device 100 that may reduce the overall reflection of the prior art light emitting device 100. Such an optical interference member may cause a destructive optical interference of the ambient light incident on the prior art light emitting device 100. Various techniques for antireflection coatings, black absorbers, and circular polarizers are known in the prior art and may be used to reduce the reflection of the ambient light from the cathode 110 of the prior art light emitting device 100.
[0030] Such optical interference member and above-mentioned techniques do maintain a high contrast under bright light conditions, but reduce power efficiency and increase design complexity and the overall manufacturing cost of the prior art light emitting device 100.
[0031] FIG. 2 shows a prior art computer modelled graphical plot of refractive index and extinction coefficient versus the wavelength of the emitted light from the prior art light emitting device. FIG. 2 has been described in conjunction with the operation of the prior art light emitting device 100 in FIG. 1. It may be understood that the prior art light emitting device 100 includes a silver colloid, such as “30% silver (Ag) particles in polycarbonate (PC), and a Bruggeman depolarization factor (0.1)”, as the cathode 110 of the prior art light emitting device 100, as an exemplary embodiment.
[0032] With reference to FIG. 2, there is shown a prior art computer modelled graphical plot 200 depicting the values of the refractive index, “n”, and the extinction coefficient, “k”, on y-axis. The prior art computer modelled graphical plot 200 further depicts the values of the wavelength, “Wavelength (nm)”, of the emitted light from the prior art light emitting device 100 on x-axis. There are further shown graphical curves 202 and 204 that represent the variation of the refractive index, “n”, and the extinction coefficient, “k”, respectively, versus the wavelength, “Wavelength (nm)”.
[0033] From the prior art computer modelled graphical plot 200, it is observed that the graphical curve 202 that represents the variation of the refractive index, “n”, versus the wavelength, “Wavelength (nm)”, is substantially deviating from a first desired range, represented by a target “n” range 206. Similarly, the graphical curve 204 that represents the variation of the extinction coefficient, “k”, versus the wavelength, “Wavelength (nm)”, is substantially deviating from a second desired range, represented by a target “k” range 208. Such a deviation of the graphical curves 202 and 204 from the first desired target range and the second desired target range, respectively, may result in the degradation of the visually perceived contrast of the prior art light emitting device 100, as the reflectivity of the cathode 110 is undesirably high.
[0034] FIG. 3 is a schematic cross-sectional view that illustrates an exemplary light emitting device such as an OLED, in accordance with an embodiment of the present disclosure. With reference to FIG. 3, there is shown a light emitting device 300, such as an OLED device. The light emitting device 300 includes a substrate 302, a light transmissive first electrode 304, a light emissive layer 306, and a second electrode 308. There is further shown an electrical potential difference from a power supply 310 applied between the light transmissive first electrode 304 and the second electrode 308. The light transmissive first electrode 304 may be disposed on the substrate 302. The light emissive layer 306 may be disposed on the light transmissive first electrode 304. The second electrode 308 may be disposed on the light emissive layer 306. In accordance with an embodiment, the light emitting device 300 may include additional optional electron or hole transport layers. In accordance with an embodiment, a plurality of light emitting devices, such as the light emitting device 300, may be utilized to realize a display of a display device.
Display [0035] The display may comprise a suitable logic, circuitry, interfaces, and / or a code that may be configured to present digital and / or multimedia content on a user interface rendered at the display (in other words, the display screen) of the display device. In accordance with an embodiment, the display may be a touch-screen display. Example of the display may include, but not limited to, an electroluminescent display (ELD), a light-emitting diode display (LED), and / or an organic light-emitting diode (OLED) display. Examples of the display device may include, but not limited to, a television screen, a computer monitor, a portable system (such as a mobile phone), or a handheld game console.
Light emitting device [0036] The light emitting device 300, such as an OLED, may correspond to a light-emitting diode (included in the display of the display device) that emits light in response to an electric current applied across the electrodes. The light emitting device 300 may correspond to one of the following types that depend on the type of material used for the formation of the light-emitting layer, such as a layer of non-polymeric small molecules or polymers. Adding mobile ions to the light emitting device 300 creates a light-emitting electrochemical cell (LEG), which has a slightly different mode of operation. The display of the light emitting device 300 can use either passive-matrix (PMOLED) or active-matrix (AMOLED) addressing schemes.
Substrate [0037] The substrate 302 is light transmissive, preferably transparent.
Light Transmissive First Electrode [0038] The light transmissive first electrode 304 corresponds to an anode that is deposited directly on the substrate 302. The holes are injected from the light transmissive first electrode 304 into the light emissive layer 306 when the electrical potential difference from the power supply 310 is applied between the light transmissive first electrode 304 and the second electrode 308. The light transmissive first electrode 304 may be made of transparent conductive material oxides, such as indium tin oxide (ITO), indium zinc oxide (IZO), indium cerium oxide (ICO), and / or the like. It may be understood to a person having ordinary skill in the art that similar transparent conductive material oxides other than the ones mentioned above, may be used to form the light transmissive first electrode 304, without deviating from the scope of the disclosure.
Light Emissive Laver [0039] The light emissive layer 306 may correspond to an organic light-emitting layer that is located between the light transmissive first electrode 304 and the second electrode 308. During the operation of the light emitting device 300, electrons injected from the second electrode 308 and holes injected from the light transmissive first electrode 304 may be recombined to form excitons in the light emissive layer 306. The thickness of the light emissive layer 306 may depend on the material used according to the color of light emission. The light emissive layer 306 may be made of organic molecules, such as light emitting polymers, or polymer hosts with a light emitting dopant, organometallic chelates (for example Alqs), fluorescent and phosphorescent polymers or organic non-polymeric small molecule materials, conjugated dendrimers, and / or the like. It may be understood to a person having ordinary skiii in the art that simiiar materiais other than the ones mentioned above, may be used to form the iight emissive iayer 306, without deviating from the scope of the disciosure.
Second Eiectrode [0040] The second eiectrode 308 corresponds to a cathode that is deposited on top of the iight emissive iayer 306 by using soiution processing techniques, known in the art. The second eiectrode 308 inciudes a iight absorbing iayer that has a compiex refractive index simiiar to the equation (1), as given above. The vaiue of the refractive index “n” iies in the range between 1.3 and 2.2 and the vaiue of the extinction coefficient “k” iies in the range between 0.05 and 0.5. The composition of the iight absorbing iayer in the second eiectrode 308 inciudes a host materiai and conductive particies biended in the host materiai. The host materiai may be a metai oxide or a conductive poiymer. The metai oxide may be one of the zinc oxide or indium tin oxide. The conductive poiymer may be one of the fiuorene poiymers and co-poiymers, PEDOT:PSS, and thiophene poiymers and co-poiymers (for exampie F8-BT). Specificaiiy, the refractive index of the host materiai is seiected to iie in the range, Ί .3 to 2.2”, preferabiy Ί .8 to 2.0”. The conductive metai particies may be seiected from one of the siiver particies, goid particies, or copper particies. The conductive particies may be nanowires.
[0041] in accordance with the present disciosure, various design ruies are described to achieve the iowest possibie reflectivity by tuning the opticai properties, thickness, and intermixing with eiectron injection iayer (EiL) (not shown) of the second eiectrode 308. Such design ruies may be appiicabie to both iayers deposited by evaporation and soiution-processing techniques. The design ruies may correspond to determining and setting the desirabie vaiues / ranges of the opticai properties and thickness of the second eiectrode 308, as foiiows.
[0042] in accordance with an embodiment, the voiume percentage of the conductive particies in the iight absorbing iayer is between 2% and 10%. Based on the composition of the second eiectrode 308, as described above, a piuraiity of opticai properties, such as the compiex refractive index (simiiar to the given equation (1)), of the second eiectrode 308 may be tuned in such a manner that the second electrode 308 shows a reflectivity of less than “2%”. Due to such a low reflectivity, the second electrode 308 appears to be nearly black in presence of bright ambient light conditions. In accordance with an embodiment, the second electrode 308 further includes a layer comprising a metal layer, the light absorbing layer being located between the metal layer and the light emissive layer 306. An exemplary graphical plot of the reflectivity of the second electrode 308, versus the extinction coefficient of the second electrode 308, has been illustrated in FIG. 4.
[0043] In accordance with an embodiment, the thickness of the second electrode 308 may be inversely proportional to the extinction coefficient, as given by a mathematical expression (2), as follows:
Thickness = ~ 0.5/k pm (2) where “k” indicates the extinction coefficient of the second electrode 308. In an exemplary instance, when the extinction coefficient, “k”, is “0.5”, the thickness of the second electrode 308 may be calculated as “one pm”, based on the mathematical expression (2). In another exemplary instance, when the extinction coefficient, “k”, is less than “0.3”, the thickness of the second electrode 308 may be calculated to be greater than one pm (“1.6 microns” in the present example), based on the mathematical expression (2). In yet another exemplary instance, when the extinction coefficient, “k”, is “0.05”, the thickness of the second electrode 308 may be calculated as “10 pm”, based on the mathematical expression (2).
[0044] During the operation of the light emitting device 300, when the electrical potential difference from the power supply 310 is applied between the light transmissive first electrode 304 and the second electrode 308, the light transmissive first electrode 304 and the second electrode 308 will inject holes and electrons, respectively, in the light emissive layer 306. The excess holes in the highest occupied molecular orbital (HOMO) and excess electrons in the lowest unoccupied molecular orbital (LUMO) may combine to form excitons that releases their energy in the form of light with a specific wavelength.
[0045] In accordance with an embodiment, the second electrode 308 may correspond to a mixture of silver particles and zinc oxide deposited from a colloidal liquid. In accordance with another embodiment, the second electrode 308 may be deposited from a solution of silver particles and a conductive polymer, such as fluorene polymers. In accordance with another embodiment, the second electrode 308 may be deposited from a solution of silver particles and a host material with a refractive index “n=2”. In accordance with another embodiment, the second electrode 308 may correspond to a mixture of copper particles and a conductive polymer, such as fluorene polymers. In accordance with another embodiment, the second electrode 308 may correspond to a mixture of non-ideal cathode materials and the EIL. All such blends of the second electrode 308 tune the optical properties, as described above. Exemplary graphical plots of the refractive indices and the extinction coefficients of the second electrode 308, versus the wavelengths of the emitted light from the light emitting device 300, have been illustrated in FIGs. 5A to 5D.
[0046] In accordance with an embodiment, the second electrode 308 of the light emitting device 300 reflects the internally generated light towards the substrate 302 exhibiting a reflectivity of less than “2%”, due to the disclosed composition and tuned optical properties, as described above. Thus, the brightness of the emission of internally generated light is considerably increased, thereby enhancing the visually perceived contrast of the second electrode 308. Further, the sharpness and colors of images displayed by the light emitting device 300 are also improved under bright light conditions. Furthermore, the disclosed composition of the second electrode 308 of the light emitting device 300 aids in enhancement of the display contrast of the light emitting device 300 with less impact on the overall manufacturing cost and efficiency of the light emitting device 300.
[0047] It may be understood by a person having ordinary skill in the art that the disclosed composition described above for the second electrode 308 may be also implemented as a separate absorption layer, which may be sandwiched between two consecutive layers, preferably between the cathode and the organic light-emitting layer of an exemplary light emitting device such as an OLED, without deviating from the scope of the disclosure.
[0048] FIG. 4 shows a computer modelled graphical plot of reflectivity versus an extinction coefficient for the light emitting device 300, in accordance with an embodiment of the present disclosure. FIG. 4 has been described in conjunction with FIG. 2. With reference to FIG. 4, there is shown a graphical plot 400 depicting the values of the reflectivity, on y-axis. The graphical plot 400 further depicts the values of the extinction coefficient, “k”, of the second electrode 308 on x-axis. Further, there are graphical curves 402 to 412 that represent the variation of the reflectivity, versus the extinction coefficient, “k”. The graphical curves 402 to 406 correspond to different values of refractive index, such as “0.1”, “1”, and “2.3”, respectively, exhibited by an exemplary second electrode, such as the cathode 110 (as described in FIG. 1), fabricated via different evaporation or solution processed materials, such as colloidal silver. The graphical curves 408 to 412 correspond to the different values of refractive index, such as “2.2”, “1.3”, and “1.65”, respectively, exhibited by the second electrode 308 with the disclosed composition, as described in FIG. 3.
[0049] From the graphical plot 400, it is observed that the reflectivity indicated by the graphical curves 402 to 406 is greater than “2%”, which is undesirable, as the visually perceived contrast of an exemplary display device, such as the prior art light emitting device 100, is degraded. On the contrary, the reflectivity indicated by the graphical curves 408 to 412 is less than “2%”, which is desirable, as the visually perceived contrast of the light emitting device 300, is enhanced. The graphical curves 408 to 412 exist in an ideal range, as depicted by a region 414, which may be referred as the “sweet spot” for an ideal black cathode, such as the second electrode 308. Various desirable ranges of the optical properties are “1.3<n<2.2”, and “0.05<k<0.5”, where “n” indicates the refractive index, and “k” indicates the extinction coefficient of the second electrode 308. Further, the desirable range of the reflectivity “R” is less than “2%” and thickness is greater than “0.5/k pm”.
[0050] In accordance with an embodiment, the refractive index, “n”, lies within the desired range, however, the extinction coefficient, “k”, does not lie within the desired range. With reference to FIG. 4, the refractive index “n” of the second electrode 308 lies in the region 414, but the extinction coefficient “k” of the second electrode 308 does not lie in the region 414. In such a case, the light emissive layer 306 may be doped to make it sufficiently conductive and polaron absorption may be used so that the extinction coefficient “k” is adjusted. Alternatively, SO -> S1 absorption, known in the art, may be used from the light emissive layer 306 so that the extinction coefficient “k” is adjusted.
[0051] FIG. 5A shows a first exemplary computer modelled graphical plot of the refractive index and the extinction coefficient versus the wavelength of the emitted light from the light emitting device 300, in accordance with an embodiment of the present disclosure. FIG. 5A has been described in conjunction with the operation of the light emitting device 300 in FIG. 3. It may be understood that the light emitting device 300 may include blend of a silver particles and zinc oxide (ZnO) in the volume ratio of 15:85 as the second electrode 308 of the light emitting device 300, as an exemplary embodiment. Such a composition may be modeled as per the effective medium approximations (EMA) or effective medium theory (EMT), such as Bruggeman's model (known in the art) that corresponds to the analytical or theoretical modeling of composite materials, such as the second electrode 308. For example, the blend of a silver colloid and zinc oxide (ZnO) may be modelled as an effective medium using the optical constants of the constituent materials, their volume ratio (for example 15:85), and a Bruggeman depolarization factor (for example 0.1). The silver colloid may correspond to a mixture of silver particles and polycarbonate. Typically, the silver colloid comprises approximately 30% by volume of silver particles and the remaining approximately 70% of polycarbonate. Thus, the volume ratio (for example 15:85) may correspond to 4.5% silver particles by volume (30% of 15%) and 10.5% polycarbonate by volume (70% of 15%).
[0052] With reference to FIG. 5A, there is shown a computer modelled graphical plot 500A depicting the values of the refractive index, “n”, and the extinction coefficient, “k”, on y-axis. The computer modelled graphical plot 500A further depicts the values of the wavelength, “Wavelength (nm)”, of the emitted light from the light emitting device 300 on x-axis. There are further shown graphical curves 502 and 504 that represent the variation of the refractive index, “n”, and the extinction coefficient, “k”, respectively, versus the wavelength, “Wavelength (nm)”.
[0053] From the computer modelled graphical plot 500A, it is observed that the graphical curve 502 that represents the variation of the refractive index, “n”, versus the wavelength, “Wavelength (nm)”, is traversing through a first desired range, represented by a target “n” range 506. Similarly, the graphical curve 504 that represents the variation of the extinction coefficient, “k”, versus the wavelength, “Wavelength (nm)”, is traversing through a second desired range, represented by a target “k” range 508. It may be noted that the target ranges 506 and 508 correspond to the target ranges 206 and 208, respectively (as described in FIG.2). Such a traversal of the graphical curves 502 and 504 from the first desired target range and the second desired target range, respectively, may result in the enhancement of the visually perceived contrast of the light emitting device 300. Further, the reflectivity of the second electrode 308 is less than “2%” that corresponds to the region 414 (as described in FIG. 4), referred to as the “sweet spot” of the second electrode 308.
[0054] FIG. 5B shows a second exemplary computer modelled graphical plot of the refractive index and the extinction coefficient versus the wavelength of the emitted light from the light emitting device 300, in accordance with an embodiment of the present disclosure. FIG. 5B has been described in conjunction with the operation of the light emitting device 300 in FIG. 3. It may be understood that the light emitting device 300 may include a solution of silver particles and conductive polymer in the volume ratio of 5:95 as the second electrode 308 of the light emitting device 300, as an exemplary embodiment. Such a composition of the solution may be modeled as per the effective medium approximations (EMA) or effective medium theory (EMT), such as Bruggeman's model (known in the art) that corresponds to analytical or theoretical modeling of composite materials, such as the second electrode 308. For example, the solution of silver particles and conductive polymer may be modelled as an effective medium using the optical constants of the constituent materials, their volume ratio (for example 5:95), and a Bruggeman depolarization factor (for example 0.1).
[0055] With reference to FIG. 5B, there is shown a computer modelled graphical plot 500B having an x-axis and a y-axis similar to the ones shown in computer modelled graphical plot 500A (as described in FIG. 5A). There are further shown graphical curves 510 and 512 that represent the variation of the refractive index, “n”, and the extinction coefficient, “k”, respectively, versus the wavelength, “Wavelength (nm)”.
[0056] From the computer modelled graphical plot 500B, it is observed that the graphical curve 510 that represents the variation of the refractive index, “n”, versus the wavelength, “Wavelength (nm)”, is traversing through the target “n” range 506 (as described in FIG. 5A). Similarly, the graphical curve 512 that represents the variation of the extinction coefficient, “k”, versus the wavelength, “Wavelength (nm)”, is traversing through the target “k” range 508 (as described in FIG. 5A). It may be noted that the target ranges 506 and 508 correspond to the target ranges 206 and 208, respectively, as described in (FIG.2). Such a traversal of the graphical curves 510 and 512 from the target ranges 506 and 508, respectively, may result in the enhancement of the visually perceived contrast of the light emitting device 300. Further, the reflectivity of the second electrode 308 is less than “2%” that corresponds to the region 414 (as described in FIG. 4), referred to as the “sweet spot” of the second electrode 308.
[0057] FIG. 5C shows a third exemplary computer modelled graphical plot of the refractive index and the extinction coefficient versus the wavelength of the emitted light from the light emitting device 300, in accordance with an embodiment of the present disclosure. FIG. 5C has been described in conjunction with the operation of the light emitting device 300 in FIG. 3. It may be understood that the light emitting device 300 may include a solution of silver particles and a host material with a value “2” of the refractive index “n” in the volume ratio of 10:90 as the second electrode 308 of the light emitting device 300, as an exemplary embodiment. As described above, the solution of silver particles and the host material with a value “2” of the refractive index “n” may be modelled as an effective medium using the optical constants of the constituent materials, their volume ratio (for example 10:90), and a Bruggeman depolarization factor (for example 0.1).
[0058] With reference to FIG. 5C, there is shown a computer modelled graphical plot 500C having an x-axis and a y-axis similar to the ones shown in computer modelled graphical plot 500A (as described in FIG. 5A). There are further shown graphical curves 514 and 516 that represent the variation of the refractive index, “n”, and the extinction coefficient, “k”, respectively, versus the wavelength, “Wavelength (nm)”.
[0059] From the computer modelled graphical plot 500C, it is observed that the graphical curve 514 that represents the variation of the refractive index, “n”, versus the wavelength, “Wavelength (nm)”, is traversing through the target “n” range 506 (as described in FIG. 5A). Similarly, the graphical curve 516 that represents the variation of the extinction coefficient, “k”, versus the wavelength, “Wavelength (nm)”, is traversing through the target “k” range 508 (as described in FIG. 5A). It may be noted that the target ranges 506 and 508 correspond to the target ranges 206 and 208, respectively (as described in FIG.2). Such a traversal of the graphical curves 514 and 516 from the target ranges 506 and 508, respectively, may result in the enhancement of the visually perceived contrast of the light emitting device 300. Further, the reflectivity of the second electrode 308 is less than “2%” that corresponds to the region 414 (as described in FIG. 4), referred to the “sweet spot” of the second electrode 308.
[0060] FIG. 5D shows a fourth exemplary computer modelled graphical plot of the refractive index and the extinction coefficient versus the wavelength of the emitted light from the light emitting device 300, in accordance with an embodiment of the present disclosure. FIG. 5D has been described in conjunction with the operation of the light emitting device 300 in FIG. 3. It may be understood that the light emitting device 300 may include a blend of copper particles and conductive polymer in the volume ratio of 5:95 as the second electrode 308 of the light emitting device 300, as an exemplary embodiment. As described above, the blend of copper particles and conductive polymer may be modelled as an effective medium using the optical constants of the constituent materials, their volume ratio (for example 5:95), and a Bruggeman depolarization factor (for example 0.1).
[0061] With reference to FIG. 5D, there is shown a computer modelled graphical plot 500D having an x-axis and a y-axis similar to the ones shown in computer modelled graphical plot 500A (as described in FIG. 5A). There are further shown graphical curves 518 and 520 that represent the variation of the refractive index, “n”, and the extinction coefficient, “k”, respectively, versus the wavelength, “Wavelength (nm)”.
[0062] From the computer modelled graphical plot 500D, it is observed that the graphical curve 518 that represents the variation of the refractive index, “n”, versus the wavelength, “Wavelength (nm)”, is traversing through the target “n” range 506 (as described in FIG. 5A). Similarly, the graphical curve 520 that represents the variation of the extinction coefficient, “k”, versus the wavelength, “Wavelength (nm)”, is traversing through the target “k” range 508 (as described in FIG. 5A). It may be noted that the target ranges 506 and 508 correspond to the target ranges 206 and 208, respectively (as described in FIG.2). Such a traversal of the graphical curves 518 and 520 from the target ranges 506 and 508, respectively, may result in the enhancement of the visually perceived contrast of the light emitting device 300. Further, the reflectivity of the second electrode 308 is less than “2%” that corresponds to the region 414 (as described in FIG. 4), referred to the “sweet spot” of the second electrode 308.
[0063] Although the present invention has been described in terms of specific exemplary embodiments, it will be appreciated that various modifications, alterations and / or combinations of features disclosed herein will be apparent to those skilled in the art without departing from the scope of the invention as set forth in the following claims.
Claims (20)
1. A light emitting device comprising: a light transmissive first electrode; a second electrode; and a light emissive layer located between the light transmissive first electrode and the second electrode, characterized in that the second electrode comprises a light absorbing layer having a complex refractive index Rl = n + i.k wherein the value of n (the refractive index) lies between 1.3 and 2.2 and the value of k (the extinction coefficient) lies between 0.05 and 0.5.
2. The light emitting device as claimed in claim 1 in which the light absorbing layer comprises a mixture of conductive particles and a host material.
3. The light emitting device as claimed in claim 1 or claim 2 in which the light absorbing layer comprises a conductive polymer.
4. The light emitting device as claimed in claim 2 in which the host material comprises a conductive polymer.
5. The light emitting device as claimed in claim 2 in which the host material comprises a metal oxide.
6. The light emitting device as claimed in claims 2, 4 or 5 in which the volume percentage of the conductive particles in the light absorbing layer is between 2% and 10%.
7. The light emitting device as claimed in claims 2, 4 or 5 in which the conductive particles are silver particles, gold particles, or copper particles.
8. The light emitting device as claimed in claim 2 or claim 7 in which the conductive particles are nanowires.
9. The light emitting device as claimed in any preceding claim in which the second electrode further includes a layer comprising a metal layer, the light absorbing layer being located between the metal layer and the light emissive layer.
10. The light emitting device as claimed in any preceding claim in which the second electrode is a cathode and the light transmissive first electrode is an anode.
11. A display comprising a plurality of light emitting devices as claimed in any preceding claim.
12. A light absorbing layer of a light emitting device having a complex refractive index Rl = n + i.k wherein the value of n (the refractive index) lies between 1.3 and 2.2 and the value of k (the extinction coefficient) lies between 0.05 and 0.5.
13. The light absorbing layer as claimed in claim 12 comprises a mixture of conductive particles and a host material.
14. The light absorbing layer as claimed in claim 12 or claim 13 comprises a conductive polymer.
15. The light absorbing layer as claimed in claim 13 in which the host material comprises a conductive polymer.
16. The light absorbing layer as claimed in claim 13 in which the host material comprises a metal oxide.
17. The light absorbing layer as claimed in claims 13, 15 or 16 in which the volume percentage of the conductive particles is between 2% and 10%.
18. The light absorbing layer as claimed in claims 13, 15 or 16 in which the conductive particles are silver particles, gold particles, or copper particles.
19. The light absorbing layer as claimed in claim 13 or claim 18 in which the conductive particles are nanowires.
20. The light absorbing layer as claimed in any preceding claim in which the light absorbing layer corresponds to a cathode of the light emitting device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1606768.8A GB2549490A (en) | 2016-04-19 | 2016-04-19 | Light emitting device with tuned cathode layer optical properties |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1606768.8A GB2549490A (en) | 2016-04-19 | 2016-04-19 | Light emitting device with tuned cathode layer optical properties |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2549490A true GB2549490A (en) | 2017-10-25 |
Family
ID=59958369
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1606768.8A Withdrawn GB2549490A (en) | 2016-04-19 | 2016-04-19 | Light emitting device with tuned cathode layer optical properties |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2549490A (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040256983A1 (en) * | 2003-06-17 | 2004-12-23 | Liang-Sun Hung | Organic light-emitting device with reduction of ambient-light-reflection by disposing a multilayer structure over a semi-transparent cathode |
| GB2426627A (en) * | 2005-05-20 | 2006-11-29 | Lg Philips Lcd Co Ltd | Display devices with light absorbing metal nanoparticle layers |
| US20070222922A1 (en) * | 2006-03-22 | 2007-09-27 | Eastman Kodak Company | Graded contrast enhancing layer for use in displays |
-
2016
- 2016-04-19 GB GB1606768.8A patent/GB2549490A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040256983A1 (en) * | 2003-06-17 | 2004-12-23 | Liang-Sun Hung | Organic light-emitting device with reduction of ambient-light-reflection by disposing a multilayer structure over a semi-transparent cathode |
| GB2426627A (en) * | 2005-05-20 | 2006-11-29 | Lg Philips Lcd Co Ltd | Display devices with light absorbing metal nanoparticle layers |
| US20070222922A1 (en) * | 2006-03-22 | 2007-09-27 | Eastman Kodak Company | Graded contrast enhancing layer for use in displays |
Non-Patent Citations (1)
| Title |
|---|
| Chiu, T-L et al.; Journal of Physics D: Applied Physics; 2011; vol. 44; no. 9; page 95102. * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US10114257B2 (en) | Conducting film or electrode with improved optical and electrical performance for display and lighting devices and solar cells | |
| CN106953020B (en) | Organic light-emitting display device and organic light-emitting display device | |
| JP4111729B2 (en) | Organic light emitting device | |
| TWI448195B (en) | Organic electroluminescence device, display device including the same, and method of manufacturing an organic electroluminescence device | |
| US7982396B2 (en) | Light-emitting device with light-scattering particles and method of making the same | |
| US7851995B2 (en) | Electroluminescent device having improved light output | |
| US9130196B2 (en) | Light-emitting component and method for producing a light-emitting component | |
| US20040239240A1 (en) | Electroluminescence display | |
| JP2008533655A (en) | Transparent light emitting parts | |
| US20190372042A1 (en) | Organic light-emitting display panel and display device | |
| CN109301082A (en) | Display panel and display device | |
| TWI506836B (en) | Transparent conducting film and organic light emitting device comprising the same | |
| US10062862B2 (en) | Organic light-emitting diode (OLED) display panel, electronic device and manufacturing method | |
| JP7201442B2 (en) | Display panel and its manufacturing method, electroluminescence device and display device | |
| US9941486B2 (en) | Component and method for producing a component | |
| CN104106310B (en) | Organic electroluminescent device | |
| JP2010056211A (en) | Organic el device and process of reproducing the same | |
| US7564181B2 (en) | Performance enhancement layer for OLED devices | |
| Chang et al. | Bi‐directional organic light‐emitting diodes with nanoparticle‐enhanced light outcoupling | |
| KR102317267B1 (en) | Organic light emitting diode | |
| CN113437241A (en) | Display substrate, display device and preparation method of display substrate | |
| GB2549490A (en) | Light emitting device with tuned cathode layer optical properties | |
| CN105409024B (en) | Opto-electronic device, the method for manufacturing opto-electronic device and mirror device | |
| CN104471738A (en) | Transparent supporting electrode for OLED | |
| KR102477831B1 (en) | Organic light emitting device including nano-island structures and manufacturing method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |