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WO2000057446A1 - Electrodes haute efficacite pour dispositifs organiques a diodes electroluminescentes - Google Patents

Electrodes haute efficacite pour dispositifs organiques a diodes electroluminescentes Download PDF

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Publication number
WO2000057446A1
WO2000057446A1 PCT/US2000/006929 US0006929W WO0057446A1 WO 2000057446 A1 WO2000057446 A1 WO 2000057446A1 US 0006929 W US0006929 W US 0006929W WO 0057446 A1 WO0057446 A1 WO 0057446A1
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WO
WIPO (PCT)
Prior art keywords
conductor
layer
light emitting
dielectric material
organic light
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.)
Ceased
Application number
PCT/US2000/006929
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English (en)
Inventor
Gary W. Jones
Munisamy Anandan
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
FED Corp
eMagin Corp
Original Assignee
FED Corp
FED Corp USA
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Filing date
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Publication of WO2000057446A1 publication Critical patent/WO2000057446A1/fr
Anticipated expiration legal-status Critical
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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
    • 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
    • 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
    • H10K50/80—Constructional details
    • H10K50/805—Electrodes
    • H10K50/81—Anodes
    • H10K50/816—Multilayers, e.g. transparent multilayers
    • 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
    • H10K50/80—Constructional details
    • H10K50/805—Electrodes
    • H10K50/82—Cathodes
    • H10K50/828—Transparent cathodes, e.g. comprising thin metal layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2102/00—Constructional details relating to the organic devices covered by this subclass
    • H10K2102/301—Details of OLEDs
    • H10K2102/302—Details of OLEDs of OLED structures
    • H10K2102/3023—Direction of light emission
    • H10K2102/3026—Top emission

Definitions

  • the present invention relates to organic light emitting diode (“OLED") devices.
  • OLED organic light emitting diode
  • the present invention relates to the use of doped conductors in organic light emitting devices.
  • OLED devices have been known for approximately two decades. All OLEDs work on the same general principles.
  • An OLED is typically a thin filmed structure formed on a substrate.
  • a light-emitting layer of a luminescent organic solid, as well as adjacent semiconductor layers, are sandwiched between a cathode and an anode.
  • the semiconductor layers may be hole-injecting or electron-injecting layers.
  • the light-emitting layer may be selected from any of a multitude of fluorescent organic solids.
  • the light-emitting layer may consist of multiple sublayers.
  • the color of light emitted from the OLED device can be controlled by the selection of the organic material.
  • White light is produced by generating and mixing blue, red and green lights simultaneously.
  • the precise color of the light emitted by a particular structure can be controlled both by the selection of the organic material, as well as by the selection of dopants.
  • either the cathode or the anode is transparent.
  • the cathode is typically constructed of a low work function material.
  • the holes are typically injected from a high work function anode material into the organic material via a hole transport layer.
  • the devices operate with a DC bias of 2 to 30 volts.
  • the films may be formed by evaporation, spin casting or other appropriate polymer film-forming techniques, or chemical self-assembly. Thicknesses typically range from a few mono layers to about 1 to 2.000 angstroms. OLEDs typically work best when operated in a current mode. The light output is much more stable for constant current drive than for a constant voltage drive. This is in contrast to many other display technologies, which are typically operated in a voltage mode.
  • An active matrix display using OLED technology therefore, requires a specific pixel architecture to provide for a current mode of operation.
  • numerous OLEDs are formed on a single substrate and arranged in groups in a regular grid pattern.
  • Several OLED groups forming a column of the grid may share a common cathode, or cathode line.
  • Several OLED groups forming a row of the grid may share a common anode, or anode line.
  • the individual OLEDs in a given group emit light when their cathode line and anode line are activated at the same time.
  • OLEDs have a number of beneficial characteristics. These include a low activation voltage (about 5 volts), fast response when formed with a thin light-emitting layer, and high brightness in proportion to the injected electric current. OLEDs also provide high visibility due to self-emission, as well as superior impact resistance, and ease of handling of the solid state devices in which they are used. OLEDs have practical application in television, graphic display systems, and digital printing.
  • Li lithium fluoride
  • Alternatives that employ an Al:Li alloy (0.1 % Li) have been used to fabricate efficient and stable OLEDs. These devices, however, are difficult to reproduce because the Li content in Al is difficult to control during the co-evaporation process.
  • Other alternatives employ a thin insulating film such as lithium fluoride (LiF), deposited between the organic layer and the Al cathode. These OLED devices are easier to reproduce, but do not produce the desired efficiency.
  • LiF lithium fluoride
  • other materials such as silicon dioxide, magnesium fluoride, calcium fluoride, sodium chloride, hexatriacontane. cesium carbonate, etc., have been used as insulating layers in OLEDs fabrication.
  • OLEDs provide no better enhancement in device performance and stability than devices that include a LiF buffer layer.
  • More recent developments in OLEDS include employing a co-deposited composite cathode of AhLiF as disclosed in Jabbour et. al, "Aluminum based cathode structure for enhanced electron injection in electroluminescent organic devices," 73 Applied Physics Letters 1 185 (1998).
  • the OLEDs employ only a small percentage of dielectric material (alkali fluorides e.g. LiF) in the cathode, typically 1 to 3 percent. These OLEDs are down emitting and employ non transparent cathodes.
  • the present invention provides a solution to the current problems by increasing the luminous efficiency for OLED devices that include substrates formed from silicon integrated circuits or metal foil.
  • the present invention is directed to an organic light emitting diode device having a substrate, a first conductor formed on the substrate, an organic stack formed on the first conductor, and a second conductor formed on the organic stack.
  • at least one of the first conductor and the second conductor includes a thin layer of dielectric material, and a conducting layer.
  • the first conductor may include the thin layer of dielectric material, and the conducting layer.
  • the second conductor may include the thin layer of dielectric material, and the conducting layer.
  • each of the first conductor and the second conductor includes the thin layer of dielectric material, and the conducting layer.
  • the second conducting layer may be either a cathode or an anode.
  • the conducting layer may be transparent.
  • the thin layer of dielectric material may include a doped dielectric material.
  • the doped dielectric material may include between 5% and 50% of a conducting material.
  • the conducting material may include one of Mg, Ca. Ce, Ba, Al, Sn, Ga and
  • the thin layer of dielectric material may include one of lithium fluoride, cesium fluoride and silicon monoxide.
  • the present invention is also directed to a conductor layer for an organic light emitting diode display.
  • the conductor layer includes a thin layer of dielectric material, and a conducting layer.
  • the conducting layer may be transparent.
  • the thin layer of dielectric material may include a doped dielectric material.
  • the doped dielectric material may include between 5% and 50% of a conducting material.
  • the conducting material may include one of Mg. Ca. Ce, Ba. Al, Sn, Ga and In.
  • the thin layer of dielectric material may include one of lithium fluoride, cesium fluoride and silicon monoxide.
  • the present invention is also directed to a method of fabricating an organic light emitting diode device.
  • the method includes the steps of providing a substrate, forming a first conductor layer on the substrate, forming an organic stack on the first conductor layer, and forming a second conductor layer on the organic stack.
  • one of the step of forming the first conductor layer and the step of forming the second conductor layer includes the steps of forming a doped dielectric material layer and forming a layer of conducting material such that the doped dielectric material layer is located adjacent the organic stack.
  • the step of forming a doped dielectric material layer may include the step of co-evaporating a transparent dielectric material with a conducting material.
  • Fig. 1 is a cross-sectional side view of a conventional OLED device
  • Fig. 2 is a cross-sectional side view of an OLED device according to the present invention
  • Fig. 3 is a cross-sectional side view of an OLED device according to another embodiment of the present invention.
  • Fig. 4 is a cross-sectional side view of an OLED device according to another embodiment of the present invention.
  • Fig. 1 discloses the basic structure of an organic light emitting device ("OLED").
  • OLED organic light emitting device
  • a substrate 100 Overlying the substrate 100 is a first conductor 200. Overlying the first conductor 200 is a second conductor 400. Sandwiched between the conductor layers is a layer or a stack of layers of light emitting organic material 300.
  • the substrate 100 is substantially planar and underlies and provides support for the entire OLED structure.
  • the first and second conductors 200 and 400 function as either electron injecting or hole injecting layers. When the positive and negative charges from the conductors meet in the layer of organic material 300, light is emitted. OLED 15 may emit light through either the second conductor 400 or the substrate 100.
  • the substrate 100 may be formed from silicon or a metal foil. Furthermore, the substrate 100 may include integrated circuitry for operating the OLED device 10.
  • the OLED device 10 further includes a first conductor 200 and an organic stack 300.
  • the second conductor 400 of the up-emitting OLED device 10 includes a conducting layer 420 and a layer of dielectric material 410.
  • the layer of dielectric material 410 is located between the conducting layer 420 and the organic stack 300.
  • the organic material 300 may include multiple layers of materials (e.g. A1Q/A1Q + dopant/NPB/CuPc). It is contemplated that polymers, small molecule organics or combinations thereof may be employed in the layers of organic material 300.
  • the dielectric layer 410 is preferably formed of a thin film ( ⁇ 50nm) of transparent dielectric.
  • the transparent dielectric may be formed of lithium fluoride, cesium fluoride, or silicon monoxide. It is contemplated that other suitable materials having similar electrical and physical properties may be used to form the transparent dielectric.
  • the dielectric 410 is preferably doped to include between 5 and 50 percent of conducting material.
  • the conducting material may include, for example, Mg, Ca, Ce, Ba, Al, Sn, Ga, or In. The conducting material serves to insure vertical conduction and to enhance carrier injection.
  • the conductor doping of the dielectric layer 410 also minimizes the need for precise thickness control of the dielectric layer 410 and provides a barrier for damage during subsequent sputter depositions of the transparent top conductor cathode 420 (e.g., sputtered ITO, IAO, or IZO).
  • Thin metal layers e.g., ⁇ 20nm
  • Thin metal layers are not preferred for most applications since they are more opaque than the intrinsically transparent conductors.
  • the second conductor 400 may serve as either the anode or cathode in accordance with embodiments of the present invention. It is contemplated that other suitable dielectric host and conductor dopant materials having suitable electrical and physical properties are considered to be well within the scope of the present invention.
  • the selection of both the dielectric material and the doping material determines the improvement of carrier injection into the OLED device. For example, selecting CsF doped with Ca or Mg works well when second conductor 400 serves a cathode, and selecting either LiF or SiO doped with Al or Sn works well when second conductor 400 functions as an anode.
  • the preferred material selections for anode contacts also work reasonablv well as cathode contacts and the reverse is generally true with the preferred materials for cathode contacts.
  • Below the organic material 300 is the bottom conductor 200.
  • the conductor 200 is preferably formed from 20nm Mo over 40nm Cr.
  • the present invention may also can be used to increase the effective light emitting active area on active matrix substrates.
  • the present invention improves the up-emitting characteristics of the
  • OLED device 10 thereby permitting the OLED device to be constructed over the substrate transistors.
  • OLED devices were required to emit between the transistors. The improvement increases increasing peak luminance or life.
  • the process of forming an OLED device 10 utilizing a conductor in accordance with the present invention will now be described.
  • the basic OLED device stacked structure is constructed by first forming the first conductor 200 on the substrate 100 using conventional techniques.
  • the organic stack 300 is then deposited in layers on the first conductor 200. This includes depositing a final layer of organic light emitting material (e.g., preferably an electron transport layer including Alq 3 ).
  • a final layer of organic light emitting material e.g., preferably an electron transport layer including Alq 3
  • the process of forming the second conductor 400 as a cathode will now be described.
  • a layer of doped dielectric material 410 is then co-evaporated on the final layer of the organic stack 300.
  • a thin layer of 5nm is formed from the co-evaporation in a vacuum of CsF with 30wt% Mg through a shadow mask opening onto the planned cathode area of the device.
  • the co- evaporation of the dielectric layer 410 may begin with a higher dopant concentration such as up to 98% conductor for the first 0.5-3nm before increasing the conductor deposition rate to reach a less than 50 percent conductor concentration overall.
  • the conductor-dielectric concentration change may be abrupt or gradual.
  • the transparent conductor 420 is then deposited over doped dielectric layer 410.
  • the conductor 420 is preferably formed from indium-tin oxide (ITO) that is sputter deposited in a very low pressure argon and ⁇ 1% oxygen atmosphere.
  • ITO indium-tin oxide
  • the doped dielectric material 410 is preferably formed by co-evaporating a thin layer (approximately 5nm) of LiF or SiO with 30 wt% In or Sn through a shadow mask opening onto to the planned anode area of the device.
  • the transparent conductor 420 is then deposited over doped dielectric layer 410.
  • the dielectric material may be placed under the organic stack 300, as shown in Fig. 3.
  • Fig. 3 discloses an OLED device 20 in accordance with another embodiment of the present invention.
  • the first conductor 200 includes a conductor layer 210 and a layer of doped dielectric material 220.
  • This composite layer can be under or on top of the stack of light emitting organic material 300 depending on the desired current direction through the device.
  • the dielectric material 220 is placed under the organic material 300 and on top of a conducting electrode 210, then the bottom conductor or electrode 210 does not have to be formed from a transparent material (i.e., ITO) because an up- emitting OLED does not require a transparent first conductor 200.
  • ITO transparent material
  • a semi-transparent OLED device can be formed if transparent conductors (e.g., ITO) are used on both sides of the organic material 300. It is further contemplated that in accordance with the present invention, the dielectric material may be placed on both sides of the organic stack 300, as shown in Fig. 4.
  • Fig. 4 discloses an OLED device 30 in accordance with another embodiment of the present invention. In the OLED device 30, doped dielectric layers 220, 410 are formed on both sides of the light emitting organic material 300.
  • an OLED may include a top cover overlying the conductors and the organic material.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Electroluminescent Light Sources (AREA)

Abstract

Cette invention concerne un dispositif organique à diodes électroluminescentes (10) comprenant un substrat (100), un premier conducteur (200) formé sur le substrat, un empilement organique (300) formé sur le premier conducteur et un second conducteur (400) formé sur l'empilement organique. Selon cette invention, l'un au moins du premier (200) et du second (400) conducteur comprend une mince couche de matériau diélectrique (410), et une couche conductrice (420). Cette couche conductrice (420) peut être transparente. La mince couche de matériau diélectrique peut renfermer un matériau diélectrique dopé. Ce matériau diélectrique dopé peut renfermer un matériau conducteur à raison de 5 % à 50 %. Ce matériau peut comprendre l'un des éléments suivants : Mg, Ca, Ce, Ba, Al, Sn, Ga et In. Conformément à cette invention, la mince couche de matériau diélectrique peur renfermer un composé pris les suivants, à savoir fluorure de lithium, fluorure de césium et monoxyde de silicium.
PCT/US2000/006929 1999-03-19 2000-03-17 Electrodes haute efficacite pour dispositifs organiques a diodes electroluminescentes Ceased WO2000057446A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US12523999P 1999-03-19 1999-03-19
US60/125,239 1999-03-19

Publications (1)

Publication Number Publication Date
WO2000057446A1 true WO2000057446A1 (fr) 2000-09-28

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006016153A1 (fr) * 2004-08-10 2006-02-16 Cambridge Display Technology Limited Dispositif d’émission lumineuse
EP1873845A1 (fr) * 2006-06-08 2008-01-02 Toppoly Optoelectronics Corp. Dispositif d'affichage
US7915059B2 (en) 2007-05-11 2011-03-29 Chimei Innolux Corporation Method for fabricating organic light emitting diode with fluorine-ion-doped electrode
EP1610397A3 (fr) * 2004-06-22 2011-08-24 General Electric Company Électrodes multicouches contentant un compose métallique et un métal pour dispositif électronique organique
CN102468448A (zh) * 2010-11-09 2012-05-23 三星移动显示器株式会社 有机发光装置和用于有机发光装置的阴极
EP2525628A4 (fr) * 2010-01-15 2014-04-02 Sumitomo Chemical Co Élément luminescent macromoléculaire
EP3343660A4 (fr) * 2015-08-28 2019-05-15 Boe Technology Group Co. Ltd. Composant électroluminescent organique et son procédé de fabrication ainsi que dispositif d'affichage

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5314759A (en) * 1990-07-18 1994-05-24 Planar International Oy Phosphor layer of an electroluminescent component
US5674217A (en) * 1993-10-01 1997-10-07 Wahlstrom; Dale A. Heart synchronized extractor for an implanted object

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5314759A (en) * 1990-07-18 1994-05-24 Planar International Oy Phosphor layer of an electroluminescent component
US5674217A (en) * 1993-10-01 1997-10-07 Wahlstrom; Dale A. Heart synchronized extractor for an implanted object

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1610397A3 (fr) * 2004-06-22 2011-08-24 General Electric Company Électrodes multicouches contentant un compose métallique et un métal pour dispositif électronique organique
JP2008509537A (ja) * 2004-08-10 2008-03-27 ケンブリッジ ディスプレイ テクノロジー リミテッド 発光装置
WO2006016153A1 (fr) * 2004-08-10 2006-02-16 Cambridge Display Technology Limited Dispositif d’émission lumineuse
GB2431292B (en) * 2004-08-10 2009-09-30 Cambridge Display Tech Ltd Light Emissive Device
GB2431292A (en) * 2004-08-10 2007-04-18 Cambridge Display Tech Ltd Light Emissive Device
US8049408B2 (en) 2004-08-10 2011-11-01 Cambridge Display Technology Limited Light emissive device having electrode comprising a metal and a material which is codepositable with the metal
US8415875B2 (en) 2004-08-10 2013-04-09 Cambridge Display Technology Limited Light emissive device having cathode comprising a codeposited mixed layer
EP1873845A1 (fr) * 2006-06-08 2008-01-02 Toppoly Optoelectronics Corp. Dispositif d'affichage
US7915059B2 (en) 2007-05-11 2011-03-29 Chimei Innolux Corporation Method for fabricating organic light emitting diode with fluorine-ion-doped electrode
EP2525628A4 (fr) * 2010-01-15 2014-04-02 Sumitomo Chemical Co Élément luminescent macromoléculaire
CN102468448A (zh) * 2010-11-09 2012-05-23 三星移动显示器株式会社 有机发光装置和用于有机发光装置的阴极
EP3343660A4 (fr) * 2015-08-28 2019-05-15 Boe Technology Group Co. Ltd. Composant électroluminescent organique et son procédé de fabrication ainsi que dispositif d'affichage
US10566565B2 (en) 2015-08-28 2020-02-18 Boe Technology Group Co., Ltd. Organic light emitting device and method of fabricating the same, and display device

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