WO2005109541A1 - Dispositif electroluminescent emettant de la lumiere blanche a couleur reglable - Google Patents

Dispositif electroluminescent emettant de la lumiere blanche a couleur reglable Download PDF

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Publication number
WO2005109541A1
WO2005109541A1 PCT/IB2005/051461 IB2005051461W WO2005109541A1 WO 2005109541 A1 WO2005109541 A1 WO 2005109541A1 IB 2005051461 W IB2005051461 W IB 2005051461W WO 2005109541 A1 WO2005109541 A1 WO 2005109541A1
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WO
WIPO (PCT)
Prior art keywords
color
electroluminescent
light
compound
emitting
Prior art date
Application number
PCT/IB2005/051461
Other languages
English (en)
Inventor
Simone I. E. Vulto
Klemens Brunner
Rene T. Wegh
Original Assignee
Koninklijke Philips Electronics N.V.
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 Koninklijke Philips Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2005109541A1 publication Critical patent/WO2005109541A1/fr

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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]
    • H10K50/11—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
    • H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
    • H10K71/841—Applying alternating current [AC] during manufacturing or treatment

Definitions

  • the present invention relates to a color tunable electroluminescent device emitting white light, as well as to a method for tuning the color of a white light emitting electroluminescent device.
  • Electroluminescent devices are devices, which emit light when a suitable voltage is impressed on its electrodes. Electroluminescent devices are generally used in display applications. As a consequence of the rapid developments of light-emitting polymers with respect to lifetime and efficiency, electroluminescent devices emitting white light may be used for non-display applications such as lighting.
  • a very interesting feature in lighting is "color tuning", i.e. the ability to alter the emitted white color, depending on the desired atmosphere in the house, shop etc. This is also referred to as "emotional lighting”.
  • White light emitting electroluminescent devices have been known per se. In the most simple device structure of a white light emitting electroluminescent device the electroluminescent compound comprises a white polymer. However, with this kind of device color tuning is not possible. It is also known to use RGB matrix devices. With these types of devices all colors can be made. However, the use of a matrix display as light-source is disadvantageous because of the complexity of such a device.
  • a color-tunable white light emitting diode device is described wherein the emitted color is voltage controlled.
  • the device comprises an electroluminescent layer comprising a blend of conjugated polymers having a different band gap. The emitted color depends on the applied voltage.
  • the object of the present invention is, inter alia, to provide a color tunable electroluminescent device emitting white light, which also can be used for non-display applications such as lighting.
  • an electroluminescent device comprising a first and a second electrode and an electroluminescent layer disposed there between, said layer comprising a first electroluminescent compound for emitting light of a first color and a second electroluminescent compound for emitting light of a second color, different from the first color, wherein the electroluminescent layer emits light of the first color when the device is electrically biased in one direction and wherein the electroluminescent layer emits light of the second color when the device is electrically biased in another direction opposite the one direction, said device further comprising means for controlling the relative amounts of power in both directions such that said device emits white light having a predetermined color temperature.
  • the electroluminescent device of the invention while comprising one electroluminescent layer thus is capable of emitting two different colors, i.e. the device when electrically biased in one direction emits light of a first (non-white) color and when biased in another direction opposite to the one direction, emits light of a second (non- white) color different from the first color.
  • the relative amounts of power in both directions i.e. the voltage or current
  • the relative amounts of emission of the first and second color are controlled, such that the device emits light which is perceived by a viewer as white light.
  • the white light can be "tuned" by varying the power in one or both directions, for example by varying the voltage amplitude.
  • the light-emitting layer does not have to be structured.
  • the first and second electroluminescent compounds preferably are homogeneously distributed in the electroluminescent layer.
  • Such device can for example be made by spin-coating the electroluminescent layer comprising the mixture of electroluminescent compounds on the electrode. Due to this simple device structure the device of the present invention can be used for large surfaces, such as may be desired in lighting applications.
  • an electroluminescent compound is a compound, which is capable of emitting light when a layer comprising such compound is sandwiched between suitable electrodes and is subjected to a suitable voltage.
  • It may also be a combination of a charge transporting compound and a luminescent compound which is adapted to receive charges from the charge transporting compound to effect light emission.
  • said compound in order to be electroluminescent said compound is capable of accepting and/or transporting holes and/or electrons and emit light having a certain emission spectrum, which is characteristic for the compound.
  • an electroluminescent compound accepts electrons and holes, which may recombine to cause emission of a light photon.
  • the electroluminescent compound may be capable of exhibiting electro luminescence without assistance of charge transporting and light emission compounds in which case the electroluminescent compound accepts and/or transports holes and electrons which may recombine to cause light emission.
  • the first electroluminescent compound may be an organic conjugated compound of low molecular weight or a conjugated polymer.
  • Organic conjugated compounds of low molecular weight known in the art as such may be used, such as Ci-Cioo homonuclear or heteronuclear aromatic compounds capable of forming thin films by means of evaporation in vacuo.
  • a conjugated polymer may be used.
  • the conjugated polymer may be a cross-linked polymer, star polymer, dendrimer or linear chain polymer. In the context of the invention the term polymer includes oligomer and copolymers, terpolymers and higher-order mers.
  • the linear chain polymer may be a side-chain polymer having electroluminescent moieties as pendant side-groups or a conjugated polymer having electroluminescent structural units in the main chain.
  • the first electroluminescent compound is a blue light emitting compound
  • the second electroluminescent compound is a yellow light-emitting compound.
  • the blue light-emitting compound may for example be a blue light emitting polymer, which may be doped with a yellow phosphorescent dopant. Examples of blue light-emitting polymers are polyspirofluorenes, polyfluorenes, dibenzothiophene units, and dibenzofuran units.
  • the device comprises means for controlling the relative amounts of power in both directions such that said device emits white light having a predetermined color temperature.
  • said means comprise at least one structured electrode such that power is sent in both directions through said device and means for controlling the power amplitude through the electrodes.
  • the relative amounts of emission of said first and second color are controlled by having at least one of the electrodes structured, such that, in operation, when a voltage is applied over the electroluminescent layer between the electrodes, part of the electroluminescent layer is biased in one direction leading to light emission of the first color from the first compound, while the second part of the layer is simultaneously biased in another direction opposite to the one direction leading to light of the second color from the second compound.
  • Figure 2A the emitted first and second color are "spatially resolved".
  • the perceived white color can be varied, i.e. "tuned".
  • the color may thus be tuned from for example a bluish white to a yellowish white, that is, the color temperature of the emitted white light can be adjusted (from about 4000 to 14000 K) ( Figure 3).
  • the said means comprise means for providing an alternating power through the device and means for controlling the ratio of said power in both directions.
  • the relative amounts of emission of said first and second color are controlled by having the device alternately biased in the one direction and the other direction opposite to the one direction, that is, by rapidly switching the direction of the applied voltage from the one direction to the other opposite direction.
  • the device In the one direction the device thus may emit yellow light and in the other direction opposite the one direction, the device may emit blue light.
  • the emitted color of the device By rapidly switching the direction of the bias, the emitted color of the device will rapidly change between blue and yellow, such that the viewer sees white light.
  • This configuration of the electroluminescent device of the invention is represented in Figure 2B.
  • the white light thus is generated by "temporarily resolving" the colors.
  • the pulse intensity and/or pulse width of the applied power By varying the pulse intensity and/or pulse width of the applied power the brightness of the individual colors, and thus the color temperature of the perceived white light, can be varied.
  • An advantage of this embodiment is that none of the layers, i.e. neither the light-emitting layer, nor the electrodes, needs to be structured.
  • the first and second electrodes may be both formed of a stable high work function material.
  • Suitable electrode materials are conducting inorganic oxides (particularly preferred because they are optically transparent) such as indium tin oxide (ITO), zinc indium oxide, gallium indium oxide, or conducting polymers such as polyethylenedioxythiophene and polyanilline, and metals such as gold, aluminium or silver or other conductive thin metal films.
  • ITO indium tin oxide
  • zinc indium oxide gallium indium oxide
  • conducting polymers such as polyethylenedioxythiophene and polyanilline
  • metals such as gold, aluminium or silver or other conductive thin metal films.
  • Such high work function electrode materials are air-stable in contrast to the low work function materials normally employed in organic light emitting diodes (LED).
  • the electroluminescent device may suitably include one or more additional layers such as hole-transporting, hole-injecting, electron- injecting, electron-transporting, hole-blocking and exciton-blocking layers, being known in the art.
  • the present invention further relates to a method for tuning the color of a white light emitting electroluminescent device, comprising a first and a second electrode and an electroluminescent layer disposed there between, said layer comprising a first electroluminescent compound for emitting light of a first color and a second electroluminescent compound for emitting light of a second color, different from the first color, wherein the electroluminescent layer emits light of a first color when the electroluminescent device is electrically biased in one direction and wherein the electroluminescent layer emits light of a second color, different from said first color, when electrically biased in another direction opposite the one direction, said method comprising controlling the relative amounts of power in both directions such that said device emits white light having a predetermined color temperature.
  • the device is alternately electrically biased in the one and the opposite direction such that said device emits white light having a predetermined color temperature, as described above.
  • the device thus is driven in a pulsed mode.
  • the relative amounts of emission of said first color and second color may be adjusted by for example varying the pulse height and/or pulse width of the applied pulses.
  • the color-tunable electroluminescent device 1 preferably comprises a first electrode 2 which applied on a substrate 3, a second electrode 4 and an electroluminescent layer 5 disposed there between.
  • the electroluminescent device further includes an additional layer 6, which for example is a hole- transporting, hole-injecting, electron-injecting, electron-transporting, hole-blocking or exciton-blocking layer being known in the art.
  • said electroluminescent layer 6 preferably comprises a first electroluminescent compound for emitting light of a first color and a second electroluminescent compound for emitting light of a second color, different from said first color, which are homogeneously distributed throughout the electroluminescent layer 6.
  • Said layer 6 emits light of the first color 7 when the electroluminescent device is electrically biased in one direction and the electroluminescent layer 6 emits light of the second color 8 when electrically biased in another direction opposite the one direction.
  • the device further comprises means for controlling the relative amounts of power in both directions such that said device emits white light, which may for example comprise at least one structured electrode such that power is sent in both directions through said device, or means for providing an alternating power through the device and means for controlling the ratio of said power in both directions (not shown).
  • white light is generated with a blue light-emitting compound 7 doped with a yellow light-emitting phosphorescent complex 8 by simultaneously biasing the device in opposite directions, thus addressing different parts of a structured electrode (not shown).
  • the white color can be tuned, i.e. the color temperature can be varied.
  • the white light is generated with a blue light-emitting single compound doped with a yellow light-emitting phosphorescent complex 8 by alternately biasing the device in one direction and another direction opposite to the one direction.
  • the emitted color of the device will rapidly change between blue and yellow, such that the viewer sees white light.
  • Figure 3 by changing the mutual intensity of the blue and yellow compound all colors, including a large amount of whitish color, on the line between the blue and yellow color points, can be made.

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

Abstract

Dispositif électroluminescent (1) à couleur réglable et procédé servant à régler la couleur de ce dispositif électroluminescent émettant de la lumière blanche. Ce dispositif (1) est composé d'une première électrode (2) et d'une deuxième électrode (2) entre lesquelles vient s'intercaler une couche électroluminescente (5). Cette couche (5) contient un premier composé électroluminescent servant à émettre de la lumière d'une première couleur et un deuxième composé électroluminescent servant à émettre de la lumière d'une deuxième couleur différente de ladite première couleur. La couche électroluminescente émet de la lumière de la première couleur quand le dispositif électroluminescent est polarisé dans un sens et la couche électroluminescente émet de la lumière de la deuxième couleur quand elle est polarisée dans un autre sens contraire au premier sens. Ledit dispositif comprend également des moyens servant à contrôler les niveaux relatifs de puissance dans les deux sens, de sorte que ce dispositif émet de la lumière blanche.
PCT/IB2005/051461 2004-05-11 2005-05-04 Dispositif electroluminescent emettant de la lumiere blanche a couleur reglable WO2005109541A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP04102022.3 2004-05-11
EP04102022 2004-05-11

Publications (1)

Publication Number Publication Date
WO2005109541A1 true WO2005109541A1 (fr) 2005-11-17

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TW (1) TW200621081A (fr)
WO (1) WO2005109541A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010033153A1 (fr) 2008-09-16 2010-03-25 Global Oled Technology Llc. Oled blanche en tandem à température de couleur élevée
JP2015040961A (ja) * 2013-08-21 2015-03-02 株式会社ジャパンディスプレイ 有機ｅｌ表示装置の駆動方法、及び有機ｅｌ表示装置
WO2019147479A1 (fr) 2018-01-25 2019-08-01 OLEDWorks LLC Procédé de dépôt et de fabrication d'oled sans masque

Citations (6)

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Publication number Priority date Publication date Assignee Title
JPH09297560A (ja) * 1996-05-07 1997-11-18 Kouha:Kk 発光表示装置
EP0942407A1 (fr) * 1997-02-17 1999-09-15 Seiko Epson Corporation Afficheur emissif pilote par le courant, procede de pilotage de cet afficheur, et procede de fabrication
US5982345A (en) * 1996-02-09 1999-11-09 Tdk Corporation Organic electroluminescent image display device
US20020190661A1 (en) * 2000-01-27 2002-12-19 General Electric Company AC powered oled device
US20030094612A1 (en) * 2001-11-22 2003-05-22 Semiconductor Energy Light emitting device and manufacturing method thereof
WO2005015640A1 (fr) * 2003-08-12 2005-02-17 Philips Intellectual Property & Standards Gmbh Agencement de circuits de commande a courant alternatif de diodes organiques

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5982345A (en) * 1996-02-09 1999-11-09 Tdk Corporation Organic electroluminescent image display device
JPH09297560A (ja) * 1996-05-07 1997-11-18 Kouha:Kk 発光表示装置
EP0942407A1 (fr) * 1997-02-17 1999-09-15 Seiko Epson Corporation Afficheur emissif pilote par le courant, procede de pilotage de cet afficheur, et procede de fabrication
US20020190661A1 (en) * 2000-01-27 2002-12-19 General Electric Company AC powered oled device
US20030094612A1 (en) * 2001-11-22 2003-05-22 Semiconductor Energy Light emitting device and manufacturing method thereof
WO2005015640A1 (fr) * 2003-08-12 2005-02-17 Philips Intellectual Property & Standards Gmbh Agencement de circuits de commande a courant alternatif de diodes organiques

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 1998, no. 03 27 February 1998 (1998-02-27) *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010033153A1 (fr) 2008-09-16 2010-03-25 Global Oled Technology Llc. Oled blanche en tandem à température de couleur élevée
US7977872B2 (en) 2008-09-16 2011-07-12 Global Oled Technology Llc High-color-temperature tandem white OLED
JP2015040961A (ja) * 2013-08-21 2015-03-02 株式会社ジャパンディスプレイ 有機ｅｌ表示装置の駆動方法、及び有機ｅｌ表示装置
WO2019147479A1 (fr) 2018-01-25 2019-08-01 OLEDWorks LLC Procédé de dépôt et de fabrication d'oled sans masque
US10923689B2 (en) 2018-01-25 2021-02-16 OLEDWorks LLC Method for mask-free OLED deposition and manufacture

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