EP1034559A1 - Diode electroluminescente organique a matrice active pourvue d'une couche organique dopee a epaisseur augmentee - Google Patents

Diode electroluminescente organique a matrice active pourvue d'une couche organique dopee a epaisseur augmentee

Info

Publication number
EP1034559A1
EP1034559A1 EP99951561A EP99951561A EP1034559A1 EP 1034559 A1 EP1034559 A1 EP 1034559A1 EP 99951561 A EP99951561 A EP 99951561A EP 99951561 A EP99951561 A EP 99951561A EP 1034559 A1 EP1034559 A1 EP 1034559A1
Authority
EP
European Patent Office
Prior art keywords
organic layer
doped
light emitting
layer
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.)
Withdrawn
Application number
EP99951561A
Other languages
German (de)
English (en)
Inventor
Karl Pichler
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.)
eMagin Corp
Original Assignee
FED Corp USA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by FED Corp USA filed Critical FED Corp USA
Publication of EP1034559A1 publication Critical patent/EP1034559A1/fr
Withdrawn legal-status Critical Current

Links

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]
    • H10K50/14—Carrier transporting layers
    • H10K50/15—Hole transporting layers
    • H10K50/155—Hole transporting layers comprising dopants
    • 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]
    • H10K50/14—Carrier transporting layers
    • H10K50/16—Electron transporting layers
    • H10K50/165—Electron transporting layers comprising dopants
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2101/00—Properties of the organic materials covered by group H10K85/00
    • H10K2101/80—Composition varying spatially, e.g. having a spatial gradient
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/80—Constructional details
    • H10K59/805—Electrodes

Definitions

  • the present invention relates to an organic light emitting device (OLED).
  • OLED organic light emitting device
  • the present invention relates to an OLED display device having a doped organic layer with increased thickness and conductivity.
  • OLED displays typically include multiple layers of organic compounds which are insulating or high band gap pure semiconductors. These organic layers have high resistance.
  • the individual organic layers are typically very thin ( ⁇ 0.1 ⁇ m) and the total organic layer stack thickness is typically less than 0.2 ⁇ m in order to keep the drive voltage low and the power efficiency high.
  • the use of the extremely thin layers makes the OLEDs more susceptible to shorting and other defects. Furthermore, manufacturing with high uniformity and yield is more difficult.
  • the prior art contains OLED's having a wide range of organic layer thickness.
  • the key point of the present invention is to dope at least one or part of one organic layer to increase its conductivity to be able to increase the thickness of the layer without a significant increase in the OLED drive voltage.
  • the present invention is directed to an improved organic light emitting device display device.
  • the device includes a substrate, a first conductor, at least one organic layer and a second conductor.
  • at least one of the organic layers is a doped organic layer to increase its electrical conductivity.
  • the doped organic layer includes a concentration of dopant.
  • the concentration of dopant of the doped organic layer may be uniform throughout the layer. It is also contemplated and preferred that the concentration of the dopant may increase.
  • the concentration of dopant increases adjacent the second conductor. There may be uniform increase in concentration. Alternatively, there may be a stepwise increase in concentration.
  • the organic light emitting device may also include an undoped organic layer.
  • the doped organic layer may have a thickness greater that the thickness of the undoped organic layer.
  • the concentration of dopant in the doped organic layer may be uniform.
  • the concentration of dopant in the doped organic layer may increase from the undoped organic layer to the second conductor.
  • Fig. 1 illustrates an organic light emitting device according to an embodiment of the present invention
  • Fig. 2 illustrates another organic light emitting device according to another embodiment of the present invention.
  • the present invention is directed to an OLED 10, shown in Fig. 1.
  • the OLED 10 includes a substrate and a first electrode layer 11.
  • the first electrode may be formed on the substrate.
  • the first electrode may be an anode.
  • the substrate is preferably a CMOS silicon substrate. Other suitable substrates including but not limited to glass, quartz, plastic and silicon, however, are considered to be well within the realm of the present invention.
  • the substrate is preferably an active matrix Si chip.
  • the active matrix Si chip includes drive electronics formed thereon and patterned pixel electrodes.
  • the OLED 10 has one common electrode.
  • the OLED may be up-emitting or down-emitting active matrix OLED on glass, quartz, plastic or silicon.
  • the active matrix OLED may be formed using amorphous, poly- crystalline or single-crystalline silicon active matric circuitry. Non-silicon technology may also be used.
  • a stack of organic layers 12-17 is formed on the substrate electrode layer 11.
  • An injector layer 12 is formed on the substrate electrode layer 11.
  • the injector layer 12 is preferably formed from CuPc (copper pthalocyanine). It, however, is contemplated by the inventor of the present invention that other suitable materials having similar properties may be used to form layer 12.
  • a hole transporter layer 13 is formed on the injector layer 12.
  • the hole transporter layer 13 is preferably formed fromNPB (4,4'-bis[N-(l -naphthyl)-N-phenyl- amino]-biphenyl). It, however, is contemplated that other suitable materials may be used to form the hole transporter layer 13.
  • An emitter doped Alq 3 layer 14 is formed on top of the hole transporter layer 13.
  • a thin undoped Alq 3 layer 15 is formed on the emitter doped Alq 3 layer 14.
  • a doped Alq 3 layer 16 that is more conductive is formed on the layer 15. It is preferred that the doping in layer 16 gradually increase such that the greatest concentration of dopant is located adjacent an electrode layer 17.
  • the conductivity of the layer 16 increases as the dopant concentration increases.
  • the layer 16 may be formed from an n-type doped Alq 3 .
  • the layer 16 may be formed by co-evaporation.
  • the electrode 17 is positioned above the layer 16. In a preferred embodiment, the electrode 17 is a cathode. Furthermore, it is preferred that the electrode 17 is formed from a transparent material or a material that permits the transmission of light therethrough.
  • the doped layer may have a thickness greater than the thickness of the other organic layers. A thickness, however, less than the thickness of the other organic layers is also contemplated.
  • a typical OLED (without the doped organic layer of the invention) may have a total organic layer thickness of x to give optimized light output, low voltage, high power efficiency, etc. With the present invention, the total organic layer thickness will be larger than x but with possible improvements on light output, low voltage, high power efficiency. However, the doped organic layer of the present invention may have a very wide range of thicknesses (absolute and relative) to the total organic layer thickness x. The total thickness of the organic layer thickness increase by at least 10% but preferably 30% and better still 50% compared to the "undoped case" but the total OLED drive voltage of the doped case would not be more than 10% larger than that of the undoped case.
  • An organic light emitting device 20 includes a substrate and electrode layer 21.
  • the layer 21 is similar to the layer 11 , described above.
  • An inj ector layer 22 is formed on the substrate electrode layer 21.
  • a hole transporter layer 23 is formed on the layer 22.
  • An emitter doped Alq 3 layer 24 is formed on top of the hole transporter layer 23.
  • a second doped Alq 3 layer 25 is formed on the doped Alq 3 layer 24.
  • the layer 25 may uniformly doped. It is preferred, however, that the doping in layer 25 gradually increase such that the greatest concentration of dopant is located adjacent the common cathode 26, which is formed on top of the layer 25.
  • the thickness of at least one of the organic layers (e.g., layers 16 and 25) in the OLED 10 and 20 is made thicker when compared to the prior art.
  • the consideration of such thicker layers without strongly increasing the overall OLED drive voltage is permitted and accomplished by doping the organic layer to increase its electrical conductivity.
  • the use of a thicker organic layers 16 and 25 improves the reliability of manufacture of larger area displays.
  • the displays are also more reliable and less sensitive to defects and unevenness on the substrate.
  • the displays exhibit low drive voltage and high power efficiency. It is contemplated that the present invention may be used with active matrix-driven
  • the common electrode may be either the anode or the cathode of the OLED.
  • the organic layers can be doped according to the present invention to make it more conductive. Conductive organic layers tend to show significantly reduced photo luminescents efficiency.
  • the present invention uses a multi-layer and/or gradual doping design to keep the emission zone highly (electro/photo) luminescent.
  • the active matrix OLEDs 10 and 20 may have one common electrode.
  • the doped layer is preferably adjacent the common electrode.
  • the active matrix OLED preferably has pixelated anode bottom electrodes and a transparent or semi-transparent top common electrode.
  • the doped layer is a doped electron injection transporting layer.
  • the preferred thickness for the doped organic layer(s) of the invention is in the range of 50 to 500 nm. It, however, is contemplated that other-thicknesses are within the scope of the present invention. The optimum thickness depends on the requirements for making the OLED more "robust" by increasing the organic layer thickness, the achievably conductivity range for the doped organic layer, is conductivity-transparency relationship, interference and/or output-coupling effects, etc.
  • a typical yellow-green emitting state-of-the-art OLED takes about 5 mA/cm 3 at voltages between 5 and 10 V to achieve a light output of several hundred CD/m 2 .
  • the organic doped layer needs to have a minimum conductivity of about 2xl0 "7 S/cm to assure that the additional voltage drop across the doped organic layer stays below 0.5 V. Therefore, taking thicknesses of the doped organic layer between 50 and 500 nm and a maximum allowed additional voltage increase of 0.5 V into account, the organic layer needs to have values in the 10 "7 and 10 "8 S/cm conductivity decades/range. This can easily be achieved with low levels of doping.
  • the doping concentration and doped layer thickness can be reduced.
  • the doping profile of the doped organic layer is not uniform but changes from low doping (conductivity) closer to the emissive zone of the OLED to higher doping (conductivities) closer to the top electrode and thus the conductivity of the doped organic layer may have a profile ranging from 10 "5 S/cm close to the top electrode to less than 10 "10 S/cm close to the emissive zone.
  • the change in concentration may be uniform. It, however, is contemplated that a nonuniform (i.e., stepwise) change in concentration of dopant is well within the scope of the present invention.
  • TTF-TCNQ an organic charge transfer crystal - in which one molecule is an acceptor and another molecule is a donor; the acceptor may be used as acceptor dopant in a holeOijnecting and/or hole-transporting doped layer of the present invention or the donor part may be used as the donor dopant in an electron-injecting and/or electron-transporting doped layer of the present invention
  • DDQ various other n-type dopants that have suitable mobility and molecule sublimation properties, as well as, suitable thermal and current/voltage stress stability.
  • the dopant needs to have the ability to increase the conductivity of the host layer by way of example, a charge transfer reaction in which the dopant accepts charge carriers from the host (donates charge carriers to the host) to increase the hole (electron) current in the layer.
  • a charge transfer reaction in which the dopant accepts charge carriers from the host (donates charge carriers to the host) to increase the hole (electron) current in the layer.
  • Alkali and earth-alkaline metals are potential dopants fort the electron transporting/injecting layer of the present invention under the cathode.
  • the hole transport layer 13 and 23 may be doped to make the layer thicker.
  • the top emitting electrode should have the highest possible transparency. Therefore the electrically- doped organic layer must also be transparent, or at least as much as possible. Therefore, the doping of the organic layer must be such that the doped organic layer stays predominantly transparent. It is possible to slightly dope organic layers, whereby the conductivity increases substantially but by retaining most of its transmission. A key point in this respect is also that the doped organic layer of the present invention does not have to be highly conductive to keep the drive voltage low.
  • the preferred embodiments of the invention as set forth herein are intended to be illustrative, not limiting.
  • the present invention is particularly applicable to OLEDs that have one of the two electrodes as a common electrode such as active-matrix OLEDS.
  • the inventio may also be used in low and high resolution segmented and passive-matrix displays provided that action is taken to reduce or avoid lateral current spending/leakage between the electrode elements adjacent to the doped layer of the invention.
  • One possible way to do this is to pattern the layer of the present invention to render portions of it less conductive.
  • Another way would be to use spacer structures to separate the top electrode elements such as described, for example, in Hosakara et al., SID Digest 1998, Vol. XXIX.

Landscapes

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

Abstract

L'invention concerne un dispositif électroluminescent organique (10) pourvu d'une couche organique dopée (16) à épaisseur et à conductivité augmentées. La couche organique dopée permet de fabriquer des écrans à large surface fiables.
EP99951561A 1998-09-24 1999-09-23 Diode electroluminescente organique a matrice active pourvue d'une couche organique dopee a epaisseur augmentee Withdrawn EP1034559A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US10168398P 1998-09-24 1998-09-24
US101683P 1998-09-24
PCT/US1999/022000 WO2000017911A1 (fr) 1998-09-24 1999-09-23 Diode electroluminescente organique a matrice active pourvue d'une couche organique dopee a epaisseur augmentee

Publications (1)

Publication Number Publication Date
EP1034559A1 true EP1034559A1 (fr) 2000-09-13

Family

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Family Applications (1)

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EP99951561A Withdrawn EP1034559A1 (fr) 1998-09-24 1999-09-23 Diode electroluminescente organique a matrice active pourvue d'une couche organique dopee a epaisseur augmentee

Country Status (2)

Country Link
EP (1) EP1034559A1 (fr)
WO (1) WO2000017911A1 (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6814642B2 (en) 2001-04-04 2004-11-09 Eastman Kodak Company Touch screen display and method of manufacture
US20040004433A1 (en) 2002-06-26 2004-01-08 3M Innovative Properties Company Buffer layers for organic electroluminescent devices and methods of manufacture and use
US7193291B2 (en) 2004-03-25 2007-03-20 3M Innovative Properties Company Organic Schottky diode
JP4915544B2 (ja) 2005-05-11 2012-04-11 パナソニック株式会社 有機エレクトロルミネッセンス素子
DE102006005926B4 (de) * 2006-02-06 2011-04-14 Samsung Mobile Display Co. Ltd., Suwon Organische Lumineszenzvorrichtung und Verfahren zu deren Herstellung
FR2992097B1 (fr) 2012-06-18 2015-03-27 Astron Fiamm Safety Diode electroluminescente organique de type pin
CN119789678A (zh) * 2025-01-02 2025-04-08 京东方科技集团股份有限公司 有机发光器件、显示面板及显示装置

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2998268B2 (ja) * 1991-04-19 2000-01-11 三菱化学株式会社 有機電界発光素子
JP3276745B2 (ja) * 1993-11-15 2002-04-22 株式会社日立製作所 可変波長発光素子とその制御方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0017911A1 *

Also Published As

Publication number Publication date
WO2000017911A1 (fr) 2000-03-30

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