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WO1997008919A1 - Systeme stratifie electroluminescent - Google Patents

Systeme stratifie electroluminescent Download PDF

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Publication number
WO1997008919A1
WO1997008919A1 PCT/DE1996/001036 DE9601036W WO9708919A1 WO 1997008919 A1 WO1997008919 A1 WO 1997008919A1 DE 9601036 W DE9601036 W DE 9601036W WO 9708919 A1 WO9708919 A1 WO 9708919A1
Authority
WO
WIPO (PCT)
Prior art keywords
electrode
electron
alloy
work function
layer system
Prior art date
Application number
PCT/DE1996/001036
Other languages
German (de)
English (en)
Inventor
Wolfgang Grothe
Martin Hueppauff
Claus Schmidt
Original Assignee
Robert Bosch Gmbh
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 Robert Bosch Gmbh filed Critical Robert Bosch Gmbh
Publication of WO1997008919A1 publication Critical patent/WO1997008919A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
    • H05B33/26—Light sources with substantially two-dimensional radiating surfaces characterised by the composition or arrangement of the conductive material used as an electrode
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/80—Constructional details
    • H10K50/805—Electrodes
    • H10K50/82—Cathodes

Definitions

  • the invention relates to an electroluminescent layer system according to the preamble of claim 1.
  • Electroluminescent layer systems are known. In these, either inorganic or organic substances are used which can be excited by means of an electrical voltage to emit light rays.
  • the light-emitting substances are arranged, for example, between planar electrodes, with a first electrode being a hole-injecting electrode and a second electrode being an electron-injecting electrode. If the light-emitting substance is formed from an organic material, the excitation can take place via a DC voltage source.
  • the hole-injecting electrode with the positive pole of the DC voltage source and the electron injecting electrode connected to the negative pole of the direct voltage source.
  • Such an electroluminescent layer system is known for example from EP 0 278 757 A2.
  • the electron-injecting electrode (cathode) consists of an alloy, alkali metals being excluded as alloy components.
  • An electron work function of the electron-injecting electrode is less than 4 eV.
  • Alkali metals are excluded as alloying constituents since they are known to be very unstable against corrosion and oxidation. From "Organic EL Cells with High Luminous Efficiency", International Symposium of Inorganic and Organic Electroluminescence 1994, Hamamatsu, Japan (Oct. 5-6, 1994) 1994, pages 77 to 79, it is known that the electron-injecting electrode is made of an aluminum-lithium alloy. In this case, the maximum lithium content is 0.1% by weight, since otherwise the cathode becomes unstable.
  • the electroluminescent layer system according to the invention with the features mentioned in claim 1 offers the advantage that a cathode containing an alkali metal is stable against corrosion and oxidation.
  • the electron-injecting electrode consists of an alloy which, as an alloying component, contains at least one alkali metal with an electron work function of less than 3.5 eV and an alkaline earth metal with an electron work function of greater than 3.5 eV, it is advantageously achieved that the electron-injecting electrode has a desirable low electron work function and is at the same time stable against corrosion and oxidation.
  • the electron-injecting electrode consists of a magnesium-lithium alloy, the lithium content preferably being between 0.1 and 40% by weight. In this way, it is very advantageously achieved that the electron work function of the electron-injecting electrode is determined by the lithium component, while the magnesium component ensures the stability of the electrode.
  • the only figure shows an electroluminescent layer system, generally designated 10.
  • the representation schematically shows a section Section through the layer system 10.
  • the layer system 10 has a light-emitting material 12 which is arranged between a first electrode 14 and a second electrode 16.
  • the electrodes 14 and 16 are flat, so that the light-emitting material 12 located between the electrodes 14 and 16 is also flat.
  • the electrodes 14 and 16 are connected to a voltage source 18, for example a DC voltage source.
  • the electrode 14 is connected to the positive pole of the voltage source 18 and the electrode 16 to the negative pole.
  • the layer system 10 also has a carrier layer 20, which serves, for example, to mechanically stabilize the layer system 10.
  • the light-emitting material 12 has at least one organic substance which is capable of emitting light when the DC voltage is applied.
  • the color of the emitted light is determined by the chemical structure of the organic substance used.
  • suitable light-emitting organic substances are polymers, low molecular weight organic compounds, monomers, mixtures of polymeric and low molecular weight organic compounds or of vapor-deposited, low molecular weight organic compounds. Additional layers can be arranged between the electrodes 14 and 16, which also serve for light emission or for charge carrier transport to the light-emitting material 12.
  • the first electrode 14 consists of a material with a high electron work function. This can consist, for example, of an oxidic material, for example indium tin oxide.
  • the electrode 14 By connecting the electrode 14 to the voltage source 18, the latter is connected as an anode, and due to the high electron work function, which is, for example, greater than 4 eV, it injects holes that are transported as charge carriers into the organic material 12.
  • the electrode 14 is resistant to corrosion due to its high electron work function.
  • the electrode 14 and the carrier layer 20 advantageously consist of an optically transparent or semi-transparent material, so that the light emitted by the light-emitting material can be emitted by the layer system 10.
  • the second electrode 16 consists of an alloy which has at least one alkali metal and one alkaline earth metal as an alloy component.
  • the electrode 16 consists of a magnesium-lithium alloy (MgLi).
  • the lithium content can vary between 0.1 and 40% by weight.
  • Lithium has an electron work function that is lower than 3.5 eV.
  • the further alloy component formed by an alkaline earth metal, here magnesium has an electron work function which is greater than 3.5 eV.
  • the stability of the electrode 16 against corrosion and oxidation is determined by the alloy component with the higher electron work function, in this case the magnesium. Overall, the electrode 16 has a low electron work function and is at the same time stable. According to further exemplary embodiments, the electrode 16 can contain further alloy components which further increase the stability of the electrode 16.
  • the additional components can be a metal whose electron work function is greater than or equal to that of aluminum (4.28 eV). This can be aluminum, nickel, silver, chrome, for example.
  • Advantageous alloys for the electrode 16 are, for example, a magnesium-lithium alloy, a magnesium-lithium-silver alloy, a magnesium-lithium-aluminum alloy
  • Magnesium-lithium-calcium alloy a magnesium-lithium-calcium-silver alloy.
  • Other alloy compositions are also possible if at least one alloy component is an alkali metal and one alloy component is an alkaline earth metal.
  • the electrode 14 By connecting the electrode 14 to the positive pole of the voltage source 18 and the electrode 16 to the negative pole of the voltage source, the latter acts as a cathode and injects electrons into the light-emitting organic material 12. This results in a current flow between the anode in the light-emitting organic material 12 14 and the cathode 16, so that the organic substances are excited to generate light quanta.
  • the electroluminescent layer system 10 can thus be used as a light source.
  • the electrode 16 consists of a stable material which at the same time has a low electron work function means that it can be operated with high efficiency, that is to say with a good ratio of the light yield to the excitation current, and at the same time it remains stable over the life of the layer system 10 against oxidation and corrosion.

Landscapes

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

Abstract

L'invention concerne un système stratifié électroluminescent contenant un matériau organique électroluminescent situé entre deux électrodes connectables à une source de tension continue. Une première électrode injecte des trous (anode) et une deuxième électrode injecte des électrons (cathode), cette dernière étant constituée d'un alliage. L'électrode (16) injectrice d'électrons est constituée d'un alliage présentant au moins un constituant métallique alcalin avec une énergie d'extraction d'électrons inférieure à 3,5 eV et un métal alcalino-terreux avec une énergie d'extraction d'électrons supérieure à 3,5 eV.
PCT/DE1996/001036 1995-08-31 1996-06-13 Systeme stratifie electroluminescent WO1997008919A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19532064A DE19532064A1 (de) 1995-08-31 1995-08-31 Elektrolumineszierendes Schichtsystem
DE19532064.6 1995-08-31

Publications (1)

Publication Number Publication Date
WO1997008919A1 true WO1997008919A1 (fr) 1997-03-06

Family

ID=7770858

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DE1996/001036 WO1997008919A1 (fr) 1995-08-31 1996-06-13 Systeme stratifie electroluminescent

Country Status (2)

Country Link
DE (1) DE19532064A1 (fr)
WO (1) WO1997008919A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6541790B1 (en) 1996-05-03 2003-04-01 Cambridge Display Technology Limited Organic light-emitting device and method of fabricating the same
US6707248B1 (en) 1999-02-12 2004-03-16 Cambridge Display Technology Ltd. Opto-electrical devices

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2123773C1 (ru) * 1998-04-20 1998-12-20 Некоммерческое партнерство "Полимерная электроника" Электролюминесцентное устройство и способ его изготовления
RU2126610C1 (ru) * 1998-08-07 1999-02-20 "Некоммерческое партнерство "Полимерная электроника" Электролюминесцентное устройство и способ его изготовления

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04212287A (ja) * 1990-05-29 1992-08-03 Toppan Printing Co Ltd 有機薄膜ｅｌ素子
JPH06306357A (ja) * 1993-04-23 1994-11-01 Pioneer Electron Corp 有機エレクトロルミネッセンス素子

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4885211A (en) * 1987-02-11 1989-12-05 Eastman Kodak Company Electroluminescent device with improved cathode
KR950000111B1 (ko) * 1988-11-21 1995-01-09 미쓰이도오아쓰가가꾸 가부시끼가이샤 발광소자(Luminescence element)
EP0563009B1 (fr) * 1992-03-23 1998-05-13 Ciba SC Holding AG Elément électroluminescent organique
EP0605739A4 (fr) * 1992-07-23 1994-11-30 Idemitsu Kosan Co Dispositif electroluminescent organique.

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04212287A (ja) * 1990-05-29 1992-08-03 Toppan Printing Co Ltd 有機薄膜ｅｌ素子
JPH06306357A (ja) * 1993-04-23 1994-11-01 Pioneer Electron Corp 有機エレクトロルミネッセンス素子

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Section Ch Week 9237, Derwent World Patents Index; Class L03, AN 92-305139, XP002012810 *
PATENT ABSTRACTS OF JAPAN vol. 94, no. 011 *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6541790B1 (en) 1996-05-03 2003-04-01 Cambridge Display Technology Limited Organic light-emitting device and method of fabricating the same
US6881598B2 (en) 1996-05-03 2005-04-19 Cambridge Display Technology Ltd. Organic light-emitting device and method of fabricating the same
US7394093B2 (en) 1996-05-03 2008-07-01 Cambridge Display Technology Ltd. Organic light-emitting device and method of fabricating the same
US7786474B2 (en) 1996-05-03 2010-08-31 Cambridge Display Technology Limited Organic light-emitting device and method of fabricating the same
US6707248B1 (en) 1999-02-12 2004-03-16 Cambridge Display Technology Ltd. Opto-electrical devices
US6765350B1 (en) 1999-02-12 2004-07-20 Cambridge Display Technology Ltd. Opto-electrical devices
US6992438B2 (en) 1999-02-12 2006-01-31 Cambridge Display Technology Limited Opto-electrical devices
US7071612B2 (en) 1999-02-12 2006-07-04 Cambridge Display Technology Limited Opto-electrical devices

Also Published As

Publication number Publication date
DE19532064A1 (de) 1997-03-06

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