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
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
  • H01J1/54—Screens on or from which an image or pattern is formed, picked-up, converted, or stored; Luminescent coatings on vessels
  • H01J1/62—Luminescent screens; Selection of materials for luminescent coatings on vessels
• • 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
  • H05B33/10—Apparatus or processes specially adapted to the manufacture of electroluminescent light sources
• • 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
• • 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
  • H10K2102/311—Flexible OLED
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K77/00—Constructional details of devices covered by this subclass and not covered by groups H10K10/80, H10K30/80, H10K50/80 or H10K59/80
  • H10K77/10—Substrates, e.g. flexible substrates
  • H10K77/111—Flexible substrates
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/30—Coordination compounds
  • H10K85/321—Metal complexes comprising a group IIIA element, e.g. Tris (8-hydroxyquinoline) gallium [Gaq3]
  • H10K85/324—Metal complexes comprising a group IIIA element, e.g. Tris (8-hydroxyquinoline) gallium [Gaq3] comprising aluminium, e.g. Alq3
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/60—Organic compounds having low molecular weight
  • H10K85/631—Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine

Definitions

• the subject invention is directed to flexible organic light emitting devices (OLED's) including a hole transporting layer and/or an electron transporting layer comprised of a vacuum- deposited, non-polymeric material.
• organic material is placed between a layer of conductive material that can inject electrons and a layer of conductive material that can inject holes.
• a voltage of proper polarity is applied between the outer layers of conductive material, electrons from one layer combine with holes from the other so as to release energy as light that is, to produce electroluminescence (EL) .
• EL electroluminescence
• OLED's organic light emitting devices
• OLED's have been constructed from polymers so as to have a highly advantageous flexibility that enables them to be used for light weight, portable, roll-up displays or to be used for conformable displays wnich can be readily attached to windows, windshields or instrument panels that may have curved surfaces; "The Plastic LED: A Flexible Ligh -Emitting Device Using a Polyanilme Transparent Electrode” oy G. Gustafsson et al in "Synthetic Metals", 55-57 4123-4227 (1993).
• a flexible OLED using small molecule based heterostructure of organic material in which the hole transporting layer, the electron transporting layer, and/or the emissive layer, f separately present, includes a non-polymeric material, that is, a layer comprised of small molecules.
• small molecules is used herein to refer to molecules which are small in the sense that such molecules are not made up of a plurality of repeating molecular nits such as are present in a polymeric material
• the term “small molecule” is intended to oe used intercnangeably with the term “non-polymeric ' In ract, the term “small molecules” may embrace relatively large molecules such as are typically used m the hole transporting layer, the electron transporting layer and/or the emissive layer that is present in an OLED.
• the subject invention is furtner directed to a method of fabricating flexible OLED' s wherein the nole transporting layer, the electron transporting layer and/or the emissive layer, .tf present, may oe prepared using vacuum deposition techniques, rather than using the less convenient fabrication technique such as employed by Gustafsson et al, tnat is, rather than spin coating a layer of polymer, such as polyamlme onto the flexible substrate
• Sucn vacuum deposition methods are particularly suitaole for use m fabricating the OLED's of tne subject invention since tr.e other layers of the OLED are also typically prepared using vacuum deposition tecnniques Integration of all the vacuum deposition steps into a single overall sequence of steps for fabricating the OLED, without requiring the use of solvents or removing the air sensitive layers from a vacuum chamber and exposing them to ambient conditions provides an additional especially beneficial advantage.
• the subject invention is directed to a method, wnerein the nole transporting, electron transporting, and/or separate emissive layer, if present, may be prepared using vacuum deposition steps BRIEF DESCRIPTION OF THE DRAWINGS Fig 1 is a cross section of one emjoodiment of a flexible OLED constructed in accor ⁇ ance with this invention,
• Fig 2 contains graphs illustrating the current vs voltage characteristic of an OLED sucn as shown in Fig. 1 before and after repeated bending and the current vs voltage characteristic of a prior art OLED having a glass substrate in place of the flexible polyester substrate and
• Fig 3 contains grapns illustrating the optical power vs current characteristics of an OLED such as shown in Fig 1 before and after repeated bending and the current vs voltage characteristic of a prior art OLED used m a glass substrate in place of the flexiole polyester substrate
• Fig 4 shows atomic force microscope (AFM) images of a typical ITO-coated polyester substrate film wherein (a) snows t.ne ITO (top) substrate and (b) snows the polyester (bottom) suostrate surface Tne height range of the images was -50 nm (nanometers)
• Fig 5 shows a photograph of an array of nine unpackaged 1 cm 2 vacuum-deposited, non-polymeric flexible OLED's One device in contact with the probe arm is shown operating in air in a well-iilummated room at normal video display brightness (-100 cd/m 2 )
• the sub j ect OLED's may be incorporated into a single heterostructure or in a double heterostructure .
• the materials, methods and apparatus for preparing the single and double heterostructures are disclosed, for example, in U.S. Patent No.
• a single heterostructural OLED of the subject invention includes a flexible substrate, which is preferably transparent, a first electrode, which may typically be an indium tin oxide (ITO) anode layer, a hole transporting layer, an electron transporting layer, a second electrode layer, for example, a metal cathode layer of Mg.Ag, and a metal protective layer, for example, made of a layer of Ag, for protecting tne Mg Ag cathode layer from atmospheric oxidation
• ITO indium tin oxide
• a second electrode layer for example, a metal cathode layer of Mg.Ag
• a metal protective layer for example, made of a layer of Ag, for protecting tne Mg Ag cathode layer from atmospheric oxidation
• a double heterostructure would also include an additional layer containing an emissive material This additional layer is herein referred to as a "separate emissive layer" so as to distinguish it from tne otner layers, since
• the molecular bonds responsible for the mechanical properties of the thin films comprising the OLED needs to be reasonably tolerant of the stress applied to the structure on oending, and, second, the substrates needs to be sufficiently flat and uniform such that mechanical defects are not formed during growth or flexing
• the subject devices grown on flexible substrates were found to have efficiencies comparable with conventional vacuum-deposited OLED's grown on glass and, furthermore, such devices were found to be mechanically robust .
• a flexible substrate 2 for the device is comprised of any suitable flexible polymer sheet such as a polyester.
• the flexible substrate is capable of being bent to a radius of curvature down to 0.5 cm or less.
• the flexible substrate 2 is precoated with a thin film 4 of indium tin oxide, ITO, such as is available from Southwall Technologies, Inc., 1029 Corporation Way, Palo Alto, Calif., 943C3, Part No. 903-6011.
• the hole transport layer 6 was comprised of N,N'- diphenyl-N,N " ' -bis (3 - ethylpheny) l-l ' b ⁇ phenyl-4 , 4 'diamine (TPD)
• the electron transporting layer 8 was comprised of tris- (8 -hydroxyqumoline) aluminum (Alq 3 )
• Other non-polymeric materials such as known m the art for preparing hole transporting layers, electron transporting layers and emissive layers may also be used
• the hole conducting layer 6 of TPD is formed on top of tne hole injecting ITO layer 4, and a light emitting layer 8 of Alq, is formed on the layer 6.
• a single layer can be used in place of the layers 6 and 8 in which TPD and Alq 3 are combined
• a layer 10 of Mg-Ag is formed on the Alq 3 layer 8
• a power supply 14 is connected between the Ag layer 12 and the precoated ITO layer 4
• the layers could have different thicknesses than those shown in the table below, the thicknesses shown produced the characteristics illustrated by the graphs of F gs 2 and 3.
• the light emitting device of Fig. 1 may be fabricated- as follows.
• the thickness of the flexible substrate may be either substantially tnicker or thinner depending on the needs of the particular application which the OLED is used
• the sheet resistance of the ITO thin film 4 was 60 ⁇ /D, and the transparency of the coated substrate was -80% throughout the visible spectrum
• the substrate 2 was ultrasonically cleaned in detergent for two minutes, then rinsed with deiomzed water Next, it was rinsed m 2- propanol , n ⁇ ld at room temperature for two to three minutes, and then ooiled in 2-propanol again for two to three minutes, followed by drying with a blow gun using a stream of filtered dry nitrogen
• An 800 A thick layer 6 of tne nole conducting material, TPD was
• the turn-on voltages (defined as the voltages at which the current due to ohmic and trap limited conduction are equal) of the three curves was almost identical (-6.5V), while the leakage current at low voltages of the flexible device was even less than that of the conventional device, and was not increased after bending. This indicated that the ITO film precoated on the flexible substrate is sufficiently uniform such that current shunt paths between the too and bottom contacts 12 and 4 are not induced after bending, even for very thin film (-1600 A molecular organic structures) .
• the light output power versus current (L-I) characteristics of the flexible device before and after Dending, and of the conventional device are shown m Fig. 3 by graph 22.
• Curve 24 illustrates the L-I output of a standard device having a glass substrate.
• the external quantum efficiency of the flexible device was 0.20%, and that of the conventional device was 0.14%. In both cases, the efficiency was calculated from light emitted only in the forward scattering direction. This considerably underestimates the true quantum efficiency but is useful for comparing between devices. Once again, the quantum efficiency of the flexible device was demonstrated not to be affected by repeated bending.
• Large-area ⁇ -1 cm 2 ) devices were also fabricated by similar methods. As in the case of the smaller devices, the large devices were also be bent over radii of -0.5 cm without apparent degradation. That these larger areas can be achieved indicates that flexible OLED's can be used m large, roll-up, or conformable flat panel displays. This, in conjunction with the fact that the ITO-precoated substrate is available m large spools, indicates that flexible, OLED-based displays can be mass manufactured on a roll-to-roll basis by use of suitable volume growtn technologies such as organic vapor phase deposition.
• vacuum-deposited, van der Waais-bonded, non- polymeric flexible OLED's such as illustrated in Fig. 5, have been fabricated using an ITO-precoated transparent polyester film as the substrate. It has been shown that an ITO thin film, when precoated on a flexible suostrate, provides a flat, highly transparent, conductive, flexible contact suitable for OLED applications.
• This hole- injecting ITO-coated substrate may also oe used with OLED's comprising polymeric nole transporting, electron transporting, and/or emissive layers comprised of polymers
• performance similar to that disclosed herein is expected if non-polymeric devices are vacuum deposited on polymeric, transparent hole- injecting contacts sucn as polvamline, which may be useful if even greater flexibility is required m certain applications

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• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Electroluminescent Light Sources (AREA)
• Physical Vapour Deposition (AREA)
• Heating, Cooling, Or Curing Plastics Or The Like In General (AREA)
• Illuminated Signs And Luminous Advertising (AREA)
• Devices For Indicating Variable Information By Combining Individual Elements (AREA)
• Materials For Medical Uses (AREA)

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• 1997
  • 1997-07-30 DE DE69735425T patent/DE69735425T2/de not_active Expired - Lifetime
  • 1997-07-30 KR KR10-1999-7001235A patent/KR100462723B1/ko not_active Expired - Lifetime
  • 1997-07-30 CN CNB971979022A patent/CN1134039C/zh not_active Expired - Lifetime
  • 1997-07-30 WO PCT/US1997/013451 patent/WO1998007173A1/en not_active Ceased
  • 1997-07-30 AT AT97938075T patent/ATE320085T1/de not_active IP Right Cessation
  • 1997-07-30 BR BRPI9711155-4A patent/BR9711155B1/pt not_active IP Right Cessation
  • 1997-07-30 JP JP10509779A patent/JP2000516761A/ja active Pending
  • 1997-07-30 CA CA002263150A patent/CA2263150C/en not_active Expired - Lifetime
  • 1997-07-30 EP EP97938075A patent/EP0946958B1/en not_active Expired - Lifetime
  • 1997-07-30 AU AU40488/97A patent/AU4048897A/en not_active Abandoned
  • 1997-10-27 US US08/957,909 patent/US6602540B2/en not_active Expired - Lifetime
• 2003
  • 2003-05-14 US US10/437,051 patent/US6888306B2/en not_active Expired - Lifetime
• 2004
  • 2004-10-15 US US10/966,417 patent/US7247073B2/en not_active Expired - Fee Related
• 2007
  • 2007-03-15 JP JP2007067619A patent/JP2007242623A/ja active Pending
• 2008
  • 2008-11-26 JP JP2008301649A patent/JP2009111400A/ja not_active Withdrawn
• 2011
  • 2011-12-16 JP JP2011275676A patent/JP2012104492A/ja not_active Withdrawn
• 2014
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