WO2016063871A1 - 表示装置 - Google Patents
表示装置 Download PDFInfo
- Publication number
- WO2016063871A1 WO2016063871A1 PCT/JP2015/079578 JP2015079578W WO2016063871A1 WO 2016063871 A1 WO2016063871 A1 WO 2016063871A1 JP 2015079578 W JP2015079578 W JP 2015079578W WO 2016063871 A1 WO2016063871 A1 WO 2016063871A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- light emitting
- light
- layer
- emitting unit
- electrode
- Prior art date
Links
Images
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K50/00—Organic light-emitting devices
- H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
- H10K50/17—Carrier injection layers
- H10K50/171—Electron injection layers
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133602—Direct backlight
- G02F1/133603—Direct backlight with LEDs
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133621—Illuminating devices providing coloured light
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
- G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K50/00—Organic light-emitting devices
- H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
- H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
- H10K50/125—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers specially adapted for multicolour light emission, e.g. for emitting white light
-
- 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
- H10K59/30—Devices specially adapted for multicolour light emission
- H10K59/32—Stacked devices having two or more layers, each emitting at different wavelengths
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/03—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect
- G02F1/0305—Constructional arrangements
- G02F1/0316—Electrodes
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133602—Direct backlight
- G02F1/133613—Direct backlight characterized by the sequence of light sources
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133621—Illuminating devices providing coloured light
- G02F1/133622—Colour sequential illumination
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K50/00—Organic light-emitting devices
- H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
- H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K50/00—Organic light-emitting devices
- H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
- H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
- H10K50/125—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers specially adapted for multicolour light emission, e.g. for emitting white light
- H10K50/13—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers specially adapted for multicolour light emission, e.g. for emitting white light comprising stacked EL layers within one EL unit
- H10K50/131—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers specially adapted for multicolour light emission, e.g. for emitting white light comprising stacked EL layers within one EL unit with spacer layers between the electroluminescent layers
Definitions
- the present invention relates to a field sequential display device including an organic electroluminescence element (organic EL element) as a light source.
- organic EL element organic electroluminescence element
- the field sequential method is a color display method using a color mixture by “time division”.
- organic electroluminescence (EL) elements have been proposed as direct-type or side-edge type backlights instead of LEDs (see, for example, Patent Document 1 and Patent Document 2).
- any one of red (R), green (G), and blue (B) constituting the backlight can be emitted and continuously displayed for each field.
- Each color is switched (time-division) to emit light, and an arbitrary color light is obtained by sufficiently increasing the switching speed.
- a color field is divided into an R field, a G field, and a B field, and each RGB field is caused to emit light with a time difference in order, and one color field is displayed on the display panel.
- the backlight emission is red (R)
- the backlight emission is blue (B)
- the G field is displayed.
- the backlight emission is green (G).
- a color moving image can be displayed by displaying each of the three color fields that are time-divided in this manner while continuously changing the emission color.
- the field sequential display device has no light loss due to absorption and does not use an expensive color filter compared to a method using a color filter, so the number of members can be reduced, which is a great advantage for cost reduction.
- a backlight formed by dividing three types of organic EL elements is used. As described above, when an organic EL element formed by dividing three colors of red, green, and blue is used as a backlight, the portion that emits each color on the substrate is substantially 1/3, and the aperture ratio is low. turn into.
- a stack in which light emitting layers emitting red (R), green (G), and blue (B) are stacked in a light emitting direction on a substrate In the field sequential liquid crystal display device described in Patent Document 2, a stack in which light emitting layers emitting red (R), green (G), and blue (B) are stacked in a light emitting direction on a substrate.
- An organic EL element having a structure is used for a backlight.
- the light generated in the light emitting layer disposed farthest from the light emitting surface is other than that provided between the light emitting layer and the light emitting surface. It is affected by absorption and reflection by the light emitting layer and electrodes.
- the light extraction efficiency of the light emitting layer disposed at the farthest position from the light emitting surface is lower than that of the light emitting layer disposed on the light emitting surface side. This causes an increase in power consumption in the backlight of the field sequential display device, and thus the power consumption of the field sequential display device increases.
- the present invention provides a display device capable of reducing power consumption.
- the display device of the present invention is a display device comprising a backlight and a field sequential display panel, wherein the light emitting portion of the backlight is composed of organic electroluminescence elements, and the organic electroluminescence elements are of different colors.
- a plurality of light emitting units that emit light are stacked, and a light emitting unit capable of emitting white light or yellow light is provided on the most light emission surface side.
- FIG. 1 is a schematic configuration diagram of a field sequential display device.
- the field sequential display device shown in FIG. 1 includes a display panel 200 and a backlight 100 made of an organic electroluminescence element (organic EL element).
- organic EL element organic electroluminescence element
- the display panel 200 is a liquid-sequential liquid crystal display panel that is driven at a high speed by a TFT (Thin Film Transistor) method.
- the display panel 200 has a well-known configuration in the TFT system, and the display panel 200 has a liquid crystal layer 206 between two transparent substrates 202 (for example, a glass substrate or a transparent film substrate) provided with a polarizing plate 201 on the outer surface side. Is sandwiched.
- a pixel electrode 204 and a thin film transistor (TFT) 203 are formed on the lower transparent substrate 202. Further, data lines 210 and scanning lines (not shown) are arranged in a matrix on the transparent substrate 202 with an insulating layer 207 interposed therebetween. A TFT 203 and a pixel electrode 204 are disposed at the intersection of the data line 210 and the scanning line.
- TFT thin film transistor
- a liquid crystal layer 206 capable of high-speed response sandwiched by the alignment film 205 is formed.
- a spacer 208, a seal 209, and a pair of alignment films 205 form a space that encloses the liquid crystal layer 206.
- the display panel 200 is required to be capable of high-speed response in order to display a full-color image by a field sequential method.
- a liquid crystal display panel capable of high-speed response using a known ferroelectric liquid crystal or antiferroelectric liquid crystal. Is preferably used.
- an OCB (Optically Compensated Bend, Optically Compensated Birefringence) type liquid crystal panel or a MEMS (Micro Electro Mechanical Systems) type liquid crystal panel may be used. Note that since the display panel 200 is applied to a field sequential display device, a color filter is not provided.
- the light emitting part of the backlight 100 is composed of a stacked organic EL element.
- the organic EL element constituting the light emitting portion of the backlight 100 has a so-called four-layer stack structure in which four layers of light emitting units are stacked in the thickness direction (light emission direction). ing. Further, the organic EL element is continuously formed on the entire surface of the region where the light emitting portion of the backlight 100 is provided.
- the organic EL element constituting the backlight 100 includes a first electrode 102, a first light emitting unit 103, a first intermediate electrode 104, a second light emitting unit 105, The second intermediate electrode 106, the third light emitting unit 107, the third intermediate electrode 108, the fourth light emitting unit 109, and the second electrode 110 are stacked in this order.
- the organic EL element includes a first light emitting unit 103 and a second light emitting element sandwiched between the first electrode 102, the first intermediate electrode 104, the second intermediate electrode 106, the third intermediate electrode 108, and the second electrode 110, respectively.
- One of the unit 105, the third light emitting unit 107, and the fourth light emitting unit 109 functions as a cathode, and the other functions as an anode.
- the organic EL element is configured as a bottom emission type in which generated light is extracted at least from the transparent substrate 101 side.
- the first light emitting unit 103 provided on the most substrate side is a light emitting unit having a white (W) emission color.
- the second light emitting unit 105 is a light emitting unit having a red (R) emission color.
- the third light emitting unit 107 is a light emitting unit having a green (G) emission color.
- the fourth light emitting unit 109 is a light emitting unit having a blue (B) emission color.
- the emission colors of the second light emitting unit 105, the third light emitting unit 107, and the fourth light emitting unit 109 are red, green, and blue. Any may be sufficient and the lamination
- White (W) has a color temperature in the range of 2000K to 12000K.
- Each electrode is connected to a drive control unit for controlling light emission of each light emitting unit.
- Driving control of each light emitting unit of the organic EL element is performed by controlling the driving voltage to the electrodes sandwiching each light emitting unit by the drive control unit.
- the first light emitting unit 103, the second light emitting unit 105, the third light emitting unit 107, and the fourth light emitting color for each of R, G, B, and W emission colors are individually driven. Further, the light emission time and light emission luminance for each light emitting unit are controlled by drive control.
- the emission color of the organic EL element is switched and light is emitted by time division driving.
- light emission lights of four colors R, G, B, and W are obtained from the four light emission units. For this reason, in order to perform time-division driving of the organic EL element having the above-described configuration and display one color per field, it is necessary to divide at least one frame into four. That is, it is necessary to drive the organic EL element in a time-division manner at least about 1/240 seconds or less (about 4 milliseconds or less).
- the color field is time-divided into 1/3. Then, R, G, and B are sequentially emitted. For example, the color field is divided into an R field, a G field, and a B field on the display panel side.
- the R, G, and B fields are made to emit light with a time difference in order. At this time, when the R field is displayed, the backlight emission is red (R), and when the B field is displayed, the backlight emission is blue (B), and the G field is displayed. At this time, the light emission of the backlight is set to green (G).
- a field of one color is displayed by displaying each of the three color fields divided in time in this way while switching the emission color. For example, when it is desired to display white (W) in the color field in this display device, the R field, the G field, and the R field are obtained by sequentially emitting R, G, and B that are emitted in a time-sharing manner sequentially. The field and B field are continuously displayed to synthesize white light.
- W white
- the R field, the G field, and the R field are obtained by sequentially emitting R, G, and B that are emitted in a time-sharing manner sequentially.
- the field and B field are continuously displayed to synthesize white light.
- the light emission from the light emitting unit formed on the light emitting surface side and the light emitted from the light emitting unit laminated on the opposite side of the light emitting surface have different extraction efficiencies.
- the light extraction efficiency is lower in the light emitted from the light emitting units laminated on the side opposite to the light emitting surface. That is, the light emission efficiency of the light emitting unit formed on the light emission surface side is high, and the light emission efficiency of the light emission unit formed on the side opposite to the light emission surface is low.
- the organic EL element having the above-described stack structure when it is desired to increase the luminance, it is necessary to increase the voltage applied to each light emitting unit and increase the light emitting luminance of each light emitting layer. For this reason, power consumption increases.
- a light emitting unit laminated on the side opposite to the light emitting surface with low light extraction efficiency needs to be applied with a higher driving voltage in order to increase the luminance in accordance with the light emitting unit formed on the light emitting surface side. Become. For this reason, in this light emitting unit, the increase in power consumption due to the low light emission efficiency becomes remarkable.
- the organic EL element of the present embodiment has a light emitting unit having a W emission color in the first light emitting unit arranged on the most light emission surface side.
- a light emitting unit having a light emitting color of W absorption due to a laminated structure, etc.
- white light is obtained by synthesizing light of three colors R, G, and B from a light emitting unit of three layers It is hard to be affected by the decrease in brightness.
- the light emitting unit having the W emission color on the most light extraction side, the emission of white light is not inhibited by the other light emitting units, and higher luminance can be obtained. Accordingly, the light emission efficiency of the organic EL element is improved.
- the light emission efficiency of the light emission unit having the W emission color is higher than that of the R, G, and B light emission units, this effect becomes remarkable.
- it is intended to increase the luminance of the organic EL element by providing a white light emitting layer with high luminous efficiency it is only necessary to increase the luminance of the white light emitting layer, and it is necessary to increase the luminance of the RGB layer with low luminous efficiency. Disappear. For this reason, by providing the white light emitting layer, the light emission efficiency of the backlight is improved, and the power consumption can be reduced.
- the light emitting unit that emits white light is disposed closest to the light emitting surface, and the arrangement of the R, G, and B light emitting units can be arbitrarily configured.
- the light emitting units other than the light emitting units that emit white light are not limited to the light emitting units of the three primary colors of R, G, and B, and may be a combination of other light emitting colors.
- a configuration including a light emitting unit capable of emitting a complementary color of yellow, cyan, or magenta or a configuration combining a light emitting unit that emits one of the three primary colors and a light emitting unit that emits one of the complementary colors. Also good.
- the light emitting unit that emits white light includes, for example, a laminated structure of a light emitting layer that emits B and a light emitting layer that emits yellow (YL), or a dopant for B emission and a YL light emitting dopant in the light emitting layer. It can be configured. As described above, the light emitting unit that emits white light may have a single light emitting layer or a plurality of light emitting layers. The same applies to the other R, G, and B light emitting units.
- the light emitting layers may be directly stacked, or a non-light emitting intermediate connector layer may be provided between the light emitting layers.
- the intermediate connector layer is also commonly referred to as an intermediate electrode, intermediate conductive layer, charge generation layer, electron extraction layer, connection layer, or intermediate insulating layer. Electrons are transferred to the anode side adjacent layer and holes are connected to the cathode side adjacent layer.
- a known material structure can be used as long as the layer has a function of supplying. For example, a configuration similar to an intermediate electrode described later can be used.
- each structure of the organic EL element which comprises the light emission part of a backlight is demonstrated.
- the first electrode 102, the first intermediate electrode 104, the second intermediate electrode 106, and the third intermediate electrode 108 are configured as translucent electrodes.
- the details of these components will be described.
- Examples of the transparent substrate 101 of the organic EL element include, but are not limited to, glass and plastic.
- Examples of the transparent substrate 101 preferably used include glass, quartz, and a transparent resin film.
- polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate ( CAP), cellulose esters such as cellulose acetate phthalate, cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by J
- the 1st electrode 102 is a transparent electrode in an organic EL element, and is a conductive layer comprised using silver or the alloy which has silver as a main component.
- the main component refers to a component having the highest component ratio among the components constituting the first electrode 102.
- Examples of the alloy mainly composed of silver (Ag) constituting the first electrode 102 include silver magnesium (AgMg), silver copper (AgCu), silver palladium (AgPd), silver palladium copper (AgPdCu), and silver indium ( AgIn) and the like.
- the first electrode 102 may have a configuration in which silver or an alloy layer mainly containing silver is divided into a plurality of layers as necessary. Further, the layer thickness of the first electrode 102 is preferably in the range of 2 to 15 nm, more preferably in the range of 3 to 12 nm, and particularly preferably in the range of 4 to 9 nm. When the layer thickness is less than 15 nm, the absorption component or reflection component of the layer is small, and the light transmittance of the first electrode 102 is increased. Further, when the layer thickness is thicker than 2 nm, the conductivity of the layer can be sufficiently ensured.
- a wet process such as a coating method, an ink jet method, a coating method, a dip method, a dry method such as a vapor deposition method (resistance heating, EB method, etc.), a sputtering method, a CVD method, or the like is used. Examples include a method using a process. Among these, the vapor deposition method is preferably applied.
- the 1st electrode 102 comprised using the alloy which has silver or silver as a main component is formed on the following base layer.
- the foundation layer is a layer provided on the transparent substrate 101 side of the first electrode 102.
- the material constituting the underlayer is not particularly limited.
- a nitrogen atom or a sulfur atom that can suppress aggregation of silver is used.
- the upper limit of the layer thickness needs to be less than 50 nm, preferably less than 30 nm, and preferably less than 10 nm. More preferably, it is particularly preferably less than 5 nm.
- the lower limit of the layer thickness is required to be 0.05 nm or more, preferably 0.1 nm or more, and particularly preferably 0.3 nm or more.
- the upper limit of the layer thickness is not particularly limited, and the lower limit of the layer thickness is the same as that of the low refractive index material. .
- the layer is formed with a necessary layer thickness that allows uniform film formation.
- the thickness thereof is preferably set to a thickness that does not hinder the light transmittance of the organic EL element, for example, 5 nm or less.
- the base layer needs to have a thickness that can ensure the film uniformity of the first electrode 102.
- the metal layer has one or more atomic layers in the underlayer.
- the underlayer is preferably a continuous film. Note that even if there is a defect in the continuous phase of the layer containing the metal serving as the silver growth nucleus in the underlayer, the film of the first electrode 102 is sufficient if the defect is smaller than the Ag atoms constituting the first electrode 102. Uniformity can be ensured.
- the compound containing a nitrogen atom constituting the underlayer is not particularly limited as long as it is a compound containing a nitrogen atom in the molecule, but is preferably a compound having a heterocycle having a nitrogen atom as a heteroatom.
- the heterocycle having a nitrogen atom as a hetero atom include aziridine, azirine, azetidine, azeto, azolidine, azole, azinane, pyridine, azepan, azepine, imidazole, pyrazole, oxazole, thiazole, imidazoline, pyrazine, morpholine, thiazine, indole, Examples include isoindole, benzimidazole, purine, quinoline, isoquinoline, quinoxaline, cinnoline, pteridine, acridine, carbazole, benzo-C-cinnoline, porphyrin, chlorin, choline and
- a method using a wet process such as a coating method, an inkjet method, a coating method, a dip method, a vacuum deposition method (resistance heating, EB method, etc.), a sputtering method, an ion plating method, plasma
- a method using a dry process such as a CVD method or a thermal CVD method.
- assist such as IAD (ion assist) in order to increase the film density.
- the layer containing zinc oxide (zinc oxide-containing layer) constituting the base layer contains zinc oxide (ZnO) as a main component.
- the main component in the zinc oxide-containing layer is a component having the highest constituent ratio among constituent components, and is preferably 50 atomic% or more.
- the zinc oxide-containing layer may contain materials other than zinc oxide.
- the dielectric material or the oxide semiconductor material may be an insulating material or a conductive material.
- Examples of the dielectric material or oxide semiconductor material contained in the zinc oxide-containing layer include TiO 2 , ITO (indium tin oxide), ZnS, Nb 2 O 5 , ZrO 2 , CeO 2 , and Ta 2 O 5.
- the zinc oxide-containing layer may contain only one type of dielectric material or oxide semiconductor material, and may contain two or more types.
- the dielectric material or the oxide semiconductor material is particularly preferably ZnS, TiO 2 , GZO, ITO.
- the zinc oxide-containing layer may contain MgF 2 , SiO 2 or the like in addition to the dielectric material and the oxide semiconductor material.
- MgF 2 MgF 2
- SiO 2 SiO 2
- the zinc oxide-containing layer is likely to be amorphous, and the flexibility of the organic EL element is likely to be enhanced.
- the zinc oxide-containing layer contains zinc oxide as a main component from the viewpoint of suppressing the aggregation of silver during film formation of the first electrode 102 and obtaining the first electrode 102 that is thin but has a uniform thickness. It is preferable.
- the amount of zinc atoms contained in the zinc oxide-containing layer is preferably 0.1 to 50 at%, more preferably 0.5 to 50 at%, based on the total number of atoms constituting the zinc oxide-containing layer. .
- the amount of zinc atoms is excessive, uniform film formation of the zinc oxide-containing layer becomes difficult and transparency may be lowered.
- the kind and content of each atom contained in the first electrode 102 are specified by, for example, the XPS method.
- the thickness of the zinc oxide-containing layer is usually preferably 3 to 35 nm, more preferably 5 to 25 nm.
- the thickness of the zinc oxide-containing layer is 3 nm or more, the film formability of the first electrode 102 is sufficiently improved.
- the thickness of the zinc oxide-containing layer is 35 nm or less, the influence on the optical characteristics of the organic EL element is small, and the light transmittance of the organic EL element is hardly lowered.
- the thickness of the zinc oxide-containing layer is measured with an ellipsometer or the like.
- the first electrode 102 is formed on the base layer, and is sufficiently conductive even without a high-temperature annealing treatment after the first electrode 102 is formed.
- the film may be subjected to high-temperature annealing after film formation.
- the Ag atom adhering to a base material produces
- a metal such as Pd, Al, Ti, Pt, or Mo
- the first electrode 102 made of silver or an alloy containing silver as a main component may be provided on an underlayer formed using a compound containing nitrogen atoms.
- the silver atoms constituting the first electrode 102 interact with the compound containing nitrogen atoms constituting the underlayer, and The diffusion distance on the surface of the formation is reduced and silver aggregation is suppressed.
- the zinc atom contained in the zinc oxide-containing layer has a high affinity with the silver of the first electrode 102. For this reason, at the time of forming the first electrode 102, the silver constituting the first electrode 102 is less likely to aggregate on the zinc oxide-containing layer, and the first electrode 102 having a thin and uniform thickness can be formed. Furthermore, since zinc atoms have a high affinity with silver contained in the first electrode 102, aggregation of silver due to moisture and corrosion of silver can be suppressed in a high humidity environment.
- the first electrode 102 made of silver or an alloy containing silver as a main component has a thinner layer and the conductivity is ensured, so that the conductivity of the first electrode 102 can be improved and light can be transmitted. It becomes possible to aim at coexistence with improvement of property.
- Intermediate electrode In the organic EL element, between the first light emitting unit 103, the second light emitting unit 105, the third light emitting unit 107, and the fourth light emitting unit 109, the first intermediate electrode 104, the second intermediate electrode 106, and the second light emitting unit 109 are provided. An intermediate electrode by three intermediate electrodes 108 is provided. These intermediate electrodes preferably have a small light absorption component and reflection component, and a high light transmittance.
- the intermediate electrode for example, a configuration similar to that of the first electrode 102 described above can be applied.
- silver of 2 to 15 nm or an alloy containing silver as a main component can be used.
- silver or an alloy containing silver as a main component is formed as the intermediate electrode, it may be formed on the above-described underlayer. Or you may form directly on organic material layers, such as an electron carrying layer which comprises a light emitting unit.
- the intermediate electrode for example, aluminum of 5 nm to 20 nm can be used. Furthermore, it can also be set as the structure which laminated
- ITO indium / tin oxide
- IZO indium / zinc oxide
- ZnO 2 TiN, ZrN, HfN, TiO x , VO x , CuI, InN, GaN, CuAlO 2 , CuGaO 2 2
- conductive inorganic compound layers such as SrCu 2 O 2 , LaB 6 , and RuO 2
- two-layer films such as Au / Bi 2 O 3 , SnO 2 / Ag / SnO 2 , ZnO / Ag / ZnO, Bi 2 Multilayer films such as O 3 / Au / Bi 2 O 3 , TiO 2 / TiN / TiO 2 , TiO 2 / ZrN / TiO 2 , fullerenes such as C 60
- conductive organic layers such as oligothiophene, metal phthalocyanines
- conductive organic compound layers such as metal-free phthalocyanines, metal porphyr
- the second electrode 110 has a function of supplying, for example, electrons to the fourth light emitting unit 109, and is an electrode film that serves as a counter electrode with respect to the third intermediate electrode 108 that is a transparent electrode.
- the second electrode 110 is made of a metal having a small work function (4 eV or less) (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material.
- the sheet resistance as the second electrode 110 is several ⁇ / sq.
- the film thickness is usually selected from the range of 10 nm to 5 ⁇ m, preferably 50 to 200 nm.
- Electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al 2 O 3 ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like.
- a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, A magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al 2 O 3 ) mixture, a lithium / aluminum mixture, aluminum, or the like is preferable.
- the second electrode 110 can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering.
- the first light-emitting unit 103, the second light-emitting unit 105, the third light-emitting unit 107, and the fourth light-emitting unit 109 include at least light-emitting organic materials and emit light that emits light in white, red, green, or blue colors. It may have a layer, and may further include another layer between the light emitting layer and the electrode.
- the following configurations can be raised, but are not limited thereto. is not.
- Anode / light emitting layer / cathode (2) Anode / light emitting layer / electron transport layer / cathode (3) Anode / hole transport layer / light emitting layer / cathode (4) Anode / hole transport layer / light emitting layer / electron Transport layer / cathode (5) anode / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode (6) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / cathode ( 7) Anode / hole injection layer / hole transport layer / (electron blocking layer /) luminescent layer / (hole blocking layer /) electron transport layer / electron injection layer / cathode Among the above, the configuration of (7) is preferable. Although used, it is not limited to this. In the above-described typical element configuration, the layer excluding the anode and the cathode is a light
- the light emitting layer is formed of a single layer or a plurality of layers.
- a non-light emitting intermediate layer may be provided between the light emitting layers.
- a hole blocking layer hole blocking layer
- an electron injection layer cathode buffer layer
- An electron blocking layer electron barrier layer
- a hole injection layer anode buffer layer
- the electron transport layer is a layer having a function of transporting electrons.
- the electron transport layer includes an electron injection layer and a hole blocking layer in a broad sense.
- the electron transport layer may be composed of a plurality of layers.
- the hole transport layer is a layer having a function of transporting holes.
- the hole transport layer includes a hole injection layer and an electron blocking layer in a broad sense.
- the hole transport layer may be composed of a plurality of layers.
- the light emitting layer preferably contains a phosphorescent compound as a light emitting material.
- the light emitting layer may be a mixture of a plurality of light emitting materials, or a phosphorescent light emitting material and a fluorescent light emitting material (fluorescent dopant, fluorescent compound) may be mixed and used in the same light emitting layer.
- a host compound such as a light emitting host
- a light emitting material light emitting dopant
- the light emitting layer can be formed by forming a light emitting material or a host compound by a known thin film forming method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, or an ink jet method.
- the light emitting layer is not particularly limited in its configuration as long as the light emitting material included satisfies the light emission requirements.
- the light emitting layer is a layer that emits light by recombination of electrons injected from the electrode or the electron transport layer and holes injected from the hole transport layer, and the light emitting portion is in the layer of the light emitting layer. Alternatively, it may be an interface between the light emitting layer and an adjacent layer. Moreover, there may be a plurality of layers having the same emission spectrum and emission maximum wavelength. In this case, a non-light emitting auxiliary layer may be provided between the light emitting layers.
- the total thickness of the light emitting layers is preferably in the range of 1 to 100 nm, and more preferably in the range of 1 to 30 nm because a lower driving voltage can be obtained.
- the thickness of each light emitting layer is preferably adjusted in the range of 1 to 50 nm, more preferably in the range of 1 to 20 nm. Note that the sum of the thicknesses of the light emitting layers is a layer thickness including the intermediate layers when a non-light emitting intermediate layer exists between the light emitting layers.
- Host compound As the host compound contained in the light emitting layer, a compound having a phosphorescence quantum yield of phosphorescence emission at room temperature (25 ° C) of less than 0.1 is preferable. More preferably, the phosphorescence quantum yield is less than 0.01. Moreover, it is preferable that the volume ratio in the layer is 50% or more among the compounds contained in a light emitting layer.
- a known host compound may be used alone, or a plurality of types may be used.
- a plurality of types of host compounds it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient.
- a plurality of kinds of light emitting materials described later it is possible to mix different light emission, thereby obtaining an arbitrary light emission color.
- Luminescent material examples include phosphorescent compounds (phosphorescent compounds, phosphorescent luminescent materials) and fluorescent compounds (fluorescent compounds, fluorescent luminescent materials).
- a phosphorescent compound is a compound in which light emission from an excited triplet is observed. Specifically, it is a compound that emits phosphorescence at room temperature (25 ° C.), and the phosphorescence quantum yield is 0 at 25 ° C. A preferred phosphorescence quantum yield is 0.1 or more, although it is defined as 0.01 or more compounds.
- the phosphorescent quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition.
- the phosphorescence quantum yield in solution can be measured using various solvents, but when using a phosphorescent compound, the above phosphorescence quantum yield (0.01 or more) can be achieved in any solvent. That's fine.
- the phosphorescent compound can be appropriately selected from known compounds used for the light emitting layer of the organic EL device.
- it is a complex compound containing a group 8-10 metal in the periodic table of elements, more preferably an iridium compound, an osmium compound, a platinum compound (platinum complex compound) or a rare earth complex, and most preferred among them.
- the at least one light emitting layer may contain two or more phosphorescent compounds, and the concentration ratio of the phosphorescent compound in the light emitting layer may vary in the thickness direction of the light emitting layer.
- the phosphorescent compound is 0.1 volume% or more and less than 30 volume% with respect to the total amount of the light emitting layer.
- Fluorescent compounds include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes, stilbene dyes. System dyes, polythiophene dyes, rare earth complex phosphors, and the like.
- injection layer hole injection layer, electron injection layer
- the injection layer is a layer provided between the electrode and the light-emitting layer in order to lower the driving voltage and improve the light emission luminance.
- the injection layer can be provided as necessary. If it is a hole injection layer, it may exist between the anode (anode) and the light emitting layer or hole transport layer, and if it is an electron injection layer, it may exist between the cathode (cathode) and the light emitting layer or electron transport layer. .
- the electron injection layer is preferably a very thin layer, and the layer thickness is preferably in the range of 1 nm to 10 ⁇ m, depending on the material.
- the hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer.
- the hole transport layer can be provided as a single layer or a plurality of layers. Further, the hole transport layer may have a single layer structure made of one kind or two or more kinds of materials.
- the layer thickness of the hole transport layer is not particularly limited, but is usually about 5 nm to 5 ⁇ m, preferably 5 to 200 nm.
- the hole transport material has any of hole injection or transport and electron barrier properties, and may be either organic or inorganic.
- the hole transport layer material can be doped with impurities to increase the p property. It is preferable to increase the p property of the hole transport layer because an element with lower power consumption can be manufactured.
- the hole transport layer is formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. Can do.
- the electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer (not shown) are also included in the electron transport layer.
- the electron transport layer can be provided as a single layer structure or a stacked structure of a plurality of layers.
- the electron transport layer may have a single-layer structure made of one kind or two or more kinds of materials.
- the thickness of the electron transport layer is not particularly limited, but is usually about 5 nm to 5 ⁇ m, preferably 5 to 200 nm.
- the electron transport layer having a single-layer structure and the electron transport layer having a multilayer structure as an electron transport material (also serving as a hole blocking material) constituting a layer portion adjacent to the light emitting layer, electrons injected from the cathode are emitted from the light emitting layer. It suffices to have a function of transmitting to the network. As such a material, any one of conventionally known compounds can be selected and used.
- the material for the electron transport layer (electron transport compound)
- a compound containing a nitrogen atom constituting the above-described underlayer may be used. This is the same for the electron transport layer that also serves as the electron injection layer, and the same material as that for the above-described underlayer may be used.
- the electron transport layer can be formed by thinning the above material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method.
- Blocking layer hole blocking layer, electron blocking layer
- the blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film. For example, as described in JP-A Nos. 11-204258 and 11-204359 and “Organic EL elements and the forefront of industrialization (published by NTT Corporation on November 30, 1998)”. There is a hole blocking layer.
- the hole blocking layer has a function of an electron transport layer in a broad sense.
- the hole blocking layer is made of a hole blocking material that has a function of transporting electrons but has a very small ability to transport holes, and recombines electrons and holes by blocking holes while transporting electrons. Probability can be improved.
- the structure of an electron carrying layer can be used as a hole-blocking layer as needed.
- the hole blocking layer is preferably provided adjacent to the light emitting layer.
- the electron blocking layer has a function of a hole transport layer in a broad sense.
- the electron blocking layer is made of a material that has a function of transporting holes but has a very small ability to transport electrons. By blocking holes while transporting holes, the electron recombination probability is improved. Can be made.
- the structure of a positive hole transport layer can be used as an electron blocking layer as needed.
- the thickness of the hole blocking layer is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.
- Second Embodiment of Display Device> a second embodiment of the field sequential display device will be described.
- the second embodiment is different from the first embodiment only in the configuration of the organic EL element of the backlight. For this reason, in the following description, only the configuration of the organic EL element will be described, and the description of the configuration of the display panel and the like and the overlapping description in each configuration will be omitted.
- FIG. 2 shows a schematic configuration diagram of a field sequential display device according to the second embodiment.
- the field sequential display device shown in FIG. 2 includes a display panel 200 and a backlight 100A made of an organic electroluminescence element (organic EL element).
- organic EL element organic electroluminescence element
- a so-called four-layer stack in which the organic EL elements constituting the light-emitting portion of the backlight 100A are stacked in four layers in the thickness direction (light emission direction). It has a structure.
- the first light emitting unit 103A is a light emitting unit having a yellow (YL) emission color.
- YL yellow
- the first electrode 102, the first intermediate electrode 104, the second light emitting unit 105, the second intermediate electrode 106, the third light emitting unit 107, the third intermediate electrode 108, the fourth light emitting unit 109, and the second electrode 110 about a structure, it is the same structure as the above-mentioned 1st Embodiment.
- the first light emitting unit 103A arranged closest to the light emitting surface is provided with a YL light emitting unit, the same effect as in the first embodiment in which the first light emitting unit is provided with a W light emitting unit is obtained. be able to.
- the first light emitting unit 103A By arranging the first light emitting unit 103A, compared to the case where YL is obtained by synthesizing R and G, the first light emitting unit 103A is less susceptible to luminance reduction such as absorption due to the laminated structure. For this reason, YL emission by other light emitting units is not hindered, and higher luminance can be obtained.
- the emission of YL light is not inhibited by other light emitting units, and higher luminance can be obtained. Accordingly, the light emission efficiency of the organic EL element is improved. For this reason, by providing the first light emitting unit 103A having the YL emission color, the light emission efficiency of the backlight is improved, and the power consumption can be reduced.
- the light emitting unit that emits YL light is disposed closest to the light emission surface, and the arrangement of the R, G, and B light emitting units can be arbitrarily configured.
- the detailed configurations of the R, G, B, and YL first light emitting units 103A, the second light emitting units 105, the third light emitting units 107, and the fourth light emitting units 109 are described in the first embodiment. The same configuration as each of the light emitting units can be applied.
- FIG. 3 shows an equivalent circuit diagram and a timing chart of the organic EL element.
- a pair of electrodes (the first electrode 102 and the first intermediate electrode shown in FIG. 1 or 2) sandwiching the first light emitting unit 103, the second light emitting unit 105, the third light emitting unit 107, and the fourth light emitting unit 109, respectively.
- 104, the second intermediate electrode 106, the third intermediate electrode 108, and the second electrode 110) are connected in parallel.
- the first light emitting unit 103 is white (W) or yellow (YL)
- the second light emitting unit 105 is red (R)
- the third light emitting unit 107 is blue (B)
- the fourth light emitting unit 109 is green.
- a case of emitting (G) will be described.
- the timing chart shown in FIG. 3 is a diagram showing the drive timing of the display panel and the light emission timing of each light emitting unit of the organic EL element of the backlight.
- drive pulses of Vr, Vg, Vb, Vw (or Vyl) when the R, G, B, and W (or YL) fields are sequentially driven to form one frame.
- a timing chart is shown.
- the light emitting unit sequentially divides each color of R, G, B, and W (YL), and emits each color by, for example, dividing one frame into four equal parts (1/4 frame).
- the display panel shields the light emitted by the time division in synchronization with each of the three primary colors, so that the time-division field images of each color [R field, G field, B field, W (YL) field] Are sequentially formed. Then, one frame image is formed by temporal color mixing of the time-division field images of the respective colors.
- the ratio of the light emission period of each light emitting unit of each R, G, B, and W (YL) is the same. It is also possible to change arbitrarily.
- the life of the backlight can be extended by adjusting the light emission periods of R, G, B, and W (YL) according to the life of each light emitting unit.
- the light emission period of the light emitting unit having relatively large deterioration with time (short lifetime) is longer than that of the other light emitting units.
- the method for generating the W video signal is as follows. If the smallest video signal among the R, G, and B video signals is M gradation, the W video signal is ⁇ ⁇ M ( ⁇ is a multiplier of 0 to 1). The constant ⁇ is the lowest power consumption when it is 1, but is a value of about 0.8 from the viewpoint of appearance and the like. Similarly, in the case of YL, if the smallest video signal among the R and G video signals is N tone, the YL video signal is ⁇ ⁇ N ( ⁇ is a multiplier of 0 to 1). The constant ⁇ is the lowest power consumption when it is 1, but is a value of about 0.8 from the viewpoint of appearance and the like.
- the first light emitting unit arranged closest to the light emission surface side has a light emitting unit having a light emission color of W or YL. is doing.
- a light emitting unit having a light emission color of W or YL it is less likely to receive absorption or the like due to the laminated structure, compared to the case of using only R, G, and B light emission. For this reason, higher luminance can be obtained. Therefore, the light emission efficiency of the organic EL element is improved, and the power consumption of the backlight can be reduced. In addition, the power consumption of the field sequential display device can be reduced.
Abstract
Description
このように時分割された3色のカラーの各フィールドを、発光色を切り替えながら連続して表示することにより、カラーの動画を表示できる。
なお、説明は以下の順序で行う。
1.表示装置の第1実施形態
2.表示装置の第2実施形態
3.タイミングチャート
図1に、フィールドシーケンシャル方式の表示装置の概略構成図を示す。図1に示すフィールドシーケンシャル方式の表示装置は、表示パネル200と、有機エレクトロルミネッセンス素子(有機EL素子)からなるバックライト100とを備える。
表示パネル200は、TFT(Thin Film Transistor)方式により高速駆動されるフィールシーケンシャル方式用の液晶表示パネルである。表示パネル200は、TFT方式における周知の構成であり、表示パネル200は、偏光板201を外面側に備えた2枚の透明基板202(例えば、ガラス基板若しくは透明フィルム基板)の間に液晶層206が挟まれている。
次に、図1に示すフィールドシーケンシャル方式に用いられるバックライト100について説明する。バックライト100の発光部は、積層型の有機EL素子からなる。
このように時分割された3色のカラーの各フィールドを、発光色を切り替えながら連続して表示することにより、一つのカラーのフィールドを表示する。例えば、この表示装置においてカラーのフィールドに白色(W)を表示したい場合には、時分割して発光させたR、G、Bを順次、連続して発光させることにより、Rのフィールド、Gのフィールド及びBのフィールドを連続的に表示して白色光を合成する。
なお、白色光を発光する発光ユニット以外の発光ユニットは、R、G、Bの3原色の各発光ユニットに限らず、他の発光色の組み合わせとしてもよい。例えば、イエロー、シアン、マゼンダのいずれかの補色を発光可能な発光ユニットを備える構成や、3原色のいずれかを発光する発光ユニットと、補色のいずれかを発光する発光ユニットとを組み合わせた構成としてもよい。
次に、バックライトの発光部を構成する有機EL素子の各構成について説明する。有機EL素子において、第1電極102、第1中間電極104、第2中間電極106、及び、第3中間電極108が、透光性の電極として構成されている。また、第1電極102、第1中間電極104、第2中間電極106、第3中間電極108、及び、第2電極110によって挟持されている部分の第1発光ユニット103、第2発光ユニット105、及び、第3発光ユニット107のみが、有機EL素子における発光領域である。以下、これら各構成の詳細について説明する。
有機EL素子の透明基板101としては、例えばガラス、プラスチック等を挙げることができるが、これらに限定されない。好ましく用いられる透明基板101としては、ガラス、石英、透明樹脂フィルムを挙げることができる。
第1電極102は、有機EL素子における透明電極であり、銀又は銀を主成分とした合金を用いて構成された導電層である。ここで、主成分とは、第1電極102を構成する成分のうち、構成比率が最も高い成分をいう。
さらに、この第1電極102の層厚は、2~15nmの範囲内にあることが好ましく、3~12nmの範囲内にあることがより好ましく、4~9nmの範囲内にあることが特に好ましい。層厚が15nmより薄い場合には、層の吸収成分又は反射成分が少なく、第1電極102の光透過率が大きくなる。また、層厚が2nmより厚い場合には、層の導電性を十分に確保することができる。
また、銀又は銀を主成分とした合金を用いて構成された第1電極102は、下記の下地層上に形成さることが好ましい。下地層は、第1電極102の透明基板101側に設けられる層である。
下地層を構成する材料としては、特に限定されるものではなく、例えば、銀又は銀を主成分とする合金からなる第1電極102の成膜に際し、銀の凝集を抑制できる窒素原子や硫黄原子を含んだ化合物等や、銀を成膜する際に成長核となるPd、Al、Ti、Pt、Mo等の金属を含む層、及び、酸化亜鉛を含む層が挙げられる。
下地層が、高屈折率材料(屈折率1.7以上)からなる場合、その層厚の上限としては特に制限はなく、層厚の下限としては上記低屈折率材料からなる場合と同様である。
ただし、単なる下地層の機能としては、均一な成膜が得られる必要層厚で形成されれば十分である。
一方、亜鉛原子の量が過剰であると、酸化亜鉛含有層の均一な成膜が難しくなり、透明性が低下する場合がある。第1電極102に含まれる各原子の種類や、その含有量は、例えばXPS法等で特定される。
有機EL素子において、第1発光ユニット103、第2発光ユニット105、第3発光ユニット107、及び、第4発光ユニット109の間には、第1中間電極104、第2中間電極106、及び、第3中間電極108による中間電極が設けられる。これら中間電極は、層の吸収成分及び反射成分が少なく、光透過率が大きいことが好ましい。
第2電極110は、第4発光ユニット109に、例えば電子を供給する機能を有し、透明電極である第3中間電極108に対して対向電極となる電極膜である。例えば、第2電極110は、仕事関数の小さい(4eV以下)金属(電子注入性金属と称する)、合金、電気伝導性化合物及びこれらの混合物を電極物質とするものが用いられる。
第2電極110としてのシート抵抗は数Ω/sq.以下が好ましく、膜厚は通常10nm~5μmの範囲内、好ましくは50~200nmの範囲内で選ばれる。
これらの中で、電子注入性及び酸化等に対する耐久性の点から、電子注入性金属とこれより仕事関数の値が大きく安定な金属である第二金属との混合物、例えば、マグネシウム/銀混合物、マグネシウム/アルミニウム混合物、マグネシウム/インジウム混合物、アルミニウム/酸化アルミニウム(Al2O3)混合物、リチウム/アルミニウム混合物やアルミニウム等が好適である。
第2電極110は、蒸着やスパッタリング等の方法によりこれらの電極物質の薄膜を形成することにより、作製することができる。
第1発光ユニット103、第2発光ユニット105、第3発光ユニット107、及び、第4発光ユニット109は、少なくとも発光性を有する有機材料を含み、白、赤、緑又は青の各色に発光する発光層を有し、さらに、発光層と電極との間に他の層を備えていてもよい。
(1)陽極/発光層/陰極
(2)陽極/発光層/電子輸送層/陰極
(3)陽極/正孔輸送層/発光層/陰極
(4)陽極/正孔輸送層/発光層/電子輸送層/陰極
(5)陽極/正孔輸送層/発光層/電子輸送層/電子注入層/陰極
(6)陽極/正孔注入層/正孔輸送層/発光層/電子輸送層/陰極
(7)陽極/正孔注入層/正孔輸送層/(電子阻止層/)発光層/(正孔阻止層/)電子輸送層/電子注入層/陰極
上記の中で(7)の構成が好ましく用いられるが、これに限定されるものではない。
上記の代表的な素子構成において、陽極と陰極を除く層が、発光性を有する発光ユニットである。
上記構成において、発光層は、単層または複数層で構成される。発光層が複数の場合は、各発光層の間に非発光性の中間層を設けてもよい。
また、必要に応じて、発光層と陰極との間に正孔阻止層(正孔障壁層)や電子注入層(陰極バッファー層)等を設けてもよく、また、発光層と陽極との間に電子阻止層(電子障壁層)や正孔注入層(陽極バッファー層)等を設けてもよい。
電子輸送層は、電子を輸送する機能を有する層である。電子輸送層には、広い意味で電子注入層、及び、正孔阻止層も含まれる。また、電子輸送層は、複数層で構成されていてもよい。
正孔輸送層は、正孔を輸送する機能を有する層である。正孔輸送層には、広い意味で正孔注入層、及び、電子阻止層も含まれる。また、正孔輸送層は、複数層で構成されていてもよい。
発光層には、発光材料としてリン光発光化合物が含有されていることが好ましい。また、発光層は、複数の発光材料を混合してもよく、また、リン光発光材料と蛍光発光材料(蛍光ドーパント、蛍光性化合物)とを同一発光層中に混合して用いてもよい。発光層の構成として、ホスト化合物(発光ホスト等)、発光材料(発光ドーパント)を含有し、発光材料より発光させることが好ましい。発光層は、発光材料やホスト化合物を、例えば、真空蒸着法、スピンコート法、キャスト法、LB法、インクジェット法等の公知の薄膜形成方法により成膜して形成することができる。
発光層に含有されるホスト化合物としては、室温(25℃)におけるリン光発光のリン光量子収率が0.1未満の化合物が好ましい。さらに好ましくはリン光量子収率が0.01未満である。また、発光層に含有される化合物の中で、その層中での体積比が50%以上であることが好ましい。
発光材料としては、リン光発光性化合物(リン光性化合物、リン光発光材料)と蛍光発光性化合物(蛍光性化合物、蛍光発光材料)が挙げられる。
リン光発光性化合物とは、励起三重項からの発光が観測される化合物であり、具体的には室温(25℃)にてリン光発光する化合物であり、リン光量子収率が25℃において0.01以上の化合物であると定義されるが、好ましいリン光量子収率は0.1以上である。
蛍光発光性化合物としては、クマリン系色素、ピラン系色素、シアニン系色素、クロコニウム系色素、スクアリウム系色素、オキソベンツアントラセン系色素、フルオレセイン系色素、ローダミン系色素、ピリリウム系色素、ペリレン系色素、スチルベン系色素、ポリチオフェン系色素、又は希土類錯体系蛍光体等が挙げられる。
注入層とは、駆動電圧低下や発光輝度向上のために、電極と発光層との間に設けられる層のことで、「有機EL素子とその工業化最前線(1998年11月30日エヌ・ティー・エス社発行)」の第2編第2章「電極材料」(123~166頁)に詳細に記載されており、正孔注入層と電子注入層とがある。
電子注入層はごく薄い膜からなる層であることが望ましく、素材にもよるがその層厚は1nm~10μmの範囲内であることが好ましい。
正孔輸送層は、正孔を輸送する機能を有する正孔輸送材料からなり、広い意味で正孔注入層、電子阻止層も正孔輸送層に含まれる。正孔輸送層は、単層又は複数層設けることができる。また、正孔輸送層は、1種又は2種以上の材料からなる一層構造であってもよい。正孔輸送層の層厚については特に制限はないが、通常は5nm~5μm程度、好ましくは5~200nmの範囲内である。
電子輸送層は、電子を輸送する機能を有する材料からなり、広い意味で電子注入層、正孔阻止層(図示略)も電子輸送層に含まれる。電子輸送層は、単層構造又は複数層の積層構造として設けることができる。また、電子輸送層は、1種又は2種以上の材料からなる1層構造であってもよい。電子輸送層の層厚については特に制限はないが、通常は5nm~5μm程度、好ましくは5~200nmの範囲内である。
阻止層は、上記のように、有機化合物薄膜の基本構成層の他に、必要に応じて設けられるものである。例えば、特開平11-204258号公報、同11-204359号公報及び「有機EL素子とその工業化最前線(1998年11月30日エヌ・ティー・エス社発行)」の237頁等に記載されている正孔阻止(ホールブロック)層がある。
次に、フィールドシーケンシャル方式の表示装置の第2実施形態について説明する。第2実施形態は、バックライトの有機EL素子の構成のみが上述の第1実施形態と異なる。このため、以下の説明では、有機EL素子の構成のみを説明し、表示パネル等の構成、及び、各構成において重複する説明は省略する。
次に、図3に有機EL素子の等価回路図とタイミングチャートを示す。
第1発光ユニット103、第2発光ユニット105、第3発光ユニット107、及び、第4発光ユニット109を、それぞれ挟む1組の電極(図1又は図2に示す第1電極102、第1中間電極104、第2中間電極106、第3中間電極108、及び、第2電極110)が並列に接続されている。ここでは一例として、第1発光ユニット103が白(W)若しくは黄(YL)、第2発光ユニット105が赤(R)、第3発光ユニット107が青(B)、第4発光ユニット109が緑(G)を発光する場合について説明する。
発光ユニットがR、G、B、W(YL)の各色を順次時分割して、例えば1フレームを4等分(1/4フレーム)して各色を発光する。そして、この時分割して発光した光を、表示パネルが三原色毎に同期させて遮光することにより、時分割された各色のフィールド画像[Rフィールド、Gフィールド、Bフィールド、W(YL)フィールド]が順次形成される。
そして、時分割された各色のフィールド画像の時間的な混色により、一つのフレーム画像が形成される。
特に、各発光ユニットの寿命に応じて、各R、G、B、及びW(YL)の発光期間を調整することで、バックライトの長寿命化を実現することができる。その際、相対的に経時劣化が大きい(寿命が短い)発光ユニットの発光期間を、他の発光ユニットよりも長くすることが好ましい。例えば、最も寿命の短い発光ユニットの発光期間の比率を、最も長くすることが好ましい。これにより、経時劣化によるバックライトの輝度の低下や、色度の変化を抑制することができ、表示装置の信頼性が向上する。
R、G、Bの映像信号の内、最も小さい映像信号をM諧調とすると、Wの映像信号は、α×M(αは0以上1以下の乗数)となる。定数αは、1の場合に最も低消費電力となるが、見栄え等の観点から0.8程度の値となる。
YLの場合も同様に、R、Gの映像信号の内、最も小さい映像信号をN諧調とすると、YLの映像信号は、β×N(βは0以上1以下の乗数)となる。定数βは、1の場合に最も低消費電力となるが、見栄え等の観点から0.8程度の値となる。
上述の第1実施形態及び第2実施形態のフィールドシーケンシャル方式の表示装置においては、最も光射出面側に配置された第1発光ユニットに、W、又は、YLの発光色を有する発光ユニットを有している。W、又は、YLの発光色を有する発光ユニットを備えることにより、R、G、Bの3色の発光光のみを用いる場合に比べて、積層構造に起因する吸収等を受けにくい。このため、より高い輝度を得ることができる。従って、有機EL素子の発光効率が向上し、バックライトの低消費電力化が可能となる。そして、フィールドシーケンシャル方式の表示装置の低消費電力化が可能となる。
Claims (8)
- バックライトと、フィールドシーケンシャル方式の表示パネルと、を備える表示装置であって、
前記バックライトの発光部が、有機エレクトロルミネッセンス素子からなり、
前記有機エレクトロルミネッセンス素子は、異なる色の光を発光する発光ユニットが複数積層され、
白色光、又は、黄色光を発光可能な発光ユニットが、最も光射出面側に設けられている
表示装置。 - 赤色光を発光する発光ユニット、緑色光を発光する発光ユニット、及び、青色光を発光する発光ユニットを備える請求項1に記載の表示装置。
- 白色光、又は、黄色光を発光可能な前記発光ユニットは、赤色光を発光する前記発光ユニット、緑色光を発光する前記発光ユニット、及び、青色光を発光する前記発光ユニットよりも発光効率が高い請求項1に記載の表示装置。
- 前記有機エレクトロルミネッセンス素子の少なくとも1つの電極が、Ag又はAgを主成分として含む合金からなる請求項1に記載の表示装置。
- 最も前記表示パネル側に形成される前記電極がAg又はAgを主成分として含む合金からなる請求項4に記載の表示装置。
- Ag又はAgを主成分として含む合金からなる前記電極が、窒素原子を含む化合物からなる下地層上に形成されている請求項4に記載の表示装置。
- 前記発光ユニットが積層された前記有機エレクトロルミネッセンス素子において、積層された前記発光ユニットの間に形成される中間電極が、Ag又はAgを主成分として含む合金からなる請求項4に記載の表示装置。
- 白色光、又は、黄色光の映像信号の諧調データが、赤色光、緑色光、及び、青色光の映像信号の内、最も小さい映像信号をM諧調したとき、α×M(但し、αは0以上1以下)となる請求項2に記載の表示装置。
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2016555232A JPWO2016063871A1 (ja) | 2014-10-21 | 2015-10-20 | 表示装置 |
US15/518,419 US20170309860A1 (en) | 2014-10-21 | 2015-10-20 | Display device |
CN201580056973.XA CN107077029A (zh) | 2014-10-21 | 2015-10-20 | 显示装置 |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2014-214826 | 2014-10-21 | ||
JP2014214826 | 2014-10-21 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2016063871A1 true WO2016063871A1 (ja) | 2016-04-28 |
Family
ID=55760904
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2015/079578 WO2016063871A1 (ja) | 2014-10-21 | 2015-10-20 | 表示装置 |
Country Status (4)
Country | Link |
---|---|
US (1) | US20170309860A1 (ja) |
JP (1) | JPWO2016063871A1 (ja) |
CN (1) | CN107077029A (ja) |
WO (1) | WO2016063871A1 (ja) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006269100A (ja) * | 2005-03-22 | 2006-10-05 | Fuji Photo Film Co Ltd | 表示装置 |
WO2013141057A1 (ja) * | 2012-03-21 | 2013-09-26 | コニカミノルタ株式会社 | 有機電界発光素子 |
JP2013229218A (ja) * | 2012-04-26 | 2013-11-07 | Konica Minolta Inc | 表示装置 |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102945928A (zh) * | 2012-12-06 | 2013-02-27 | 吉林大学 | 一种光谱可调且色坐标稳定的白光有机电致发光器件 |
-
2015
- 2015-10-20 WO PCT/JP2015/079578 patent/WO2016063871A1/ja active Application Filing
- 2015-10-20 CN CN201580056973.XA patent/CN107077029A/zh active Pending
- 2015-10-20 US US15/518,419 patent/US20170309860A1/en not_active Abandoned
- 2015-10-20 JP JP2016555232A patent/JPWO2016063871A1/ja active Pending
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006269100A (ja) * | 2005-03-22 | 2006-10-05 | Fuji Photo Film Co Ltd | 表示装置 |
WO2013141057A1 (ja) * | 2012-03-21 | 2013-09-26 | コニカミノルタ株式会社 | 有機電界発光素子 |
JP2013229218A (ja) * | 2012-04-26 | 2013-11-07 | Konica Minolta Inc | 表示装置 |
Also Published As
Publication number | Publication date |
---|---|
CN107077029A (zh) | 2017-08-18 |
US20170309860A1 (en) | 2017-10-26 |
JPWO2016063871A1 (ja) | 2017-09-07 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US9786720B2 (en) | Organic light emitting display device | |
CN105960717B (zh) | 包括电致变色器件和有机电致发光器件的智能窗 | |
US8405098B2 (en) | Organic light emitting device, display unit including the same, and illuminating device including the same | |
JP2007265763A (ja) | フルカラー有機elパネル | |
KR20150076740A (ko) | 유기전계발광 표시장치 | |
CN102916030A (zh) | 有机电致发光显示元件以及其制造方法 | |
JP2006302874A (ja) | 表示装置 | |
WO2022166306A1 (zh) | 显示基板及其制备方法、显示装置 | |
AU2017341162A1 (en) | Organic light emitting device, display apparatus, method of controlling color temperature of light emitted from organic light emitting device, and method of fabricating organic light emitting device | |
KR20140032628A (ko) | 유기 발광 표시 장치 및 이의 제조 방법 | |
KR102116414B1 (ko) | 유기전계발광 표시장치 | |
JP2009158140A (ja) | エレクトロルミネッセンス素子及びこれを用いた表示装置並びに照明装置 | |
KR20160134918A (ko) | 유기 발광 표시 장치 | |
JP2013207010A (ja) | 発光素子、発光素子の製造方法、表示装置および照明装置 | |
WO2017056682A1 (ja) | 有機エレクトロルミネッセンスパネル | |
WO2017056684A1 (ja) | 有機エレクトロルミネッセンスパネル及びその製造方法 | |
CN105226197A (zh) | 一种oled结构 | |
WO2016063870A1 (ja) | 表示装置 | |
WO2016063871A1 (ja) | 表示装置 | |
JP4912210B2 (ja) | 表示装置 | |
KR101862605B1 (ko) | 유기 전계 발광 표시 패널 및 그의 제조 방법 | |
US20060273734A1 (en) | Light-emitting device using organic electroluminescent element | |
KR102113609B1 (ko) | 유기 발광 표시 장치 및 그의 제조 방법 | |
JP6881566B2 (ja) | 面発光装置 | |
CN105336874B (zh) | 有机发光二极管及其驱动方法、有机发光显示屏 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 15852625 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2016555232 Country of ref document: JP Kind code of ref document: A |
|
WWE | Wipo information: entry into national phase |
Ref document number: 15518419 Country of ref document: US |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 15852625 Country of ref document: EP Kind code of ref document: A1 |