|Publication number||US3621321 A|
|Publication date||Nov 16, 1971|
|Filing date||Oct 28, 1969|
|Priority date||Oct 28, 1969|
|Publication number||US 3621321 A, US 3621321A, US-A-3621321, US3621321 A, US3621321A|
|Inventors||Schadt Martin, Williams Digby F|
|Original Assignee||Canadian Patents Dev|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (6), Non-Patent Citations (1), Referenced by (68), Classifications (11)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Uniteri States Patent  Inventors Dlgby F. Williams 2,938,136 5/1960 Fischer 313/108 Ottawa; 3,172,862 3/1965 Gurnee et a1. 313/108 UX Martin Schadt, Vanier City, Ontario, both 3,382,394 5/1968 Mehl 313/108 of Canada 3,391,068 7/1968 McKay 313/108 X  PP 871,347 3,530,325 9/1970 Mehl et al 313/108 Filed Oct-28,1969 OTHER REFERENCES 22:5 gzngg gzi and Development H lnokuchi et al., The Photovoltaic Behaviors of Aro- Limued matlc Hydrocarbons, Electrical Conductivity in Orgamc Ottawa Ontario, Canada Solids, pp. 69- 75, 1961.
Primary Examiner-Roy Lake Assistant Examiner-Palmer C Demeo ELECTROLUMINESCENT DEVICE WITH LIGHT Attorney-Stevens, Davis, Miller & Mosher EMITTING AROMATllC, HYDROCARBON MATERIAL 6 Claims, 1 Drawing Fig.
ABSTRACT: A thin body of actlve material In the form of  U.S.Cl 313/108 A, anthracene or naphthalene generaes li ht when a curl-em i 317/235 AF passed through it by the injection of electrons from an elec-  Int. Cl. ..H05b33/02, "ode containing negative ions f a Similar materia] 33/26 anthracene, naphthalene or tetracene) to a base electrode to  Field of Search 3 l 5/ 108 R, which an external positive potential rdative to the electromin. 108 358; 317/235 jecting electrode is applied. The base electrode may be solid and trans arent for transmission of light generated in the ac-  Referencw Cited tive matei'ial or at its interface with the base electrode. This UNITED STATES PATENTS device also acts as a rectifier, since virtually no current will 2,834,903 5/ 1958 Roberts 313/108 flow if the externally applied potential is reversed.
A/E4A 7/ v5 fA/C'A P5 04 A 77A/6' WA X//4 4 5: 72005 /2 l \\\\\\\\%&\\\\\\Y 6 RETAIN/N4 n (Yo/V006 n/vg 61/1 55 1 ACTIVE MA nae/ 4 z 1/ 64 7mm dfA/E) ELECTROLUMINESCENT DEVICE WITH LIGHT EMITTING AROMATIC, HYDROCARBON MATERIAL This invention relates to electroluminescent devices. Electroluminescence over a considerable wavelength region is possible using inorganic semiconductor systems. However, at least as versatile in this respect are system using organic materials as the active elements. Such organic materials are normally highly electrically nonconducting, however, so that before electroluminescence can be achieved it is necessary to find the correct conditions for injecting electric charges (electrons or holes) into the materials.
While, as indicated below, the present invention is not restricted in its broad scope to the injection of charges into any one or two particular materials, it will be convenient to take as typical materials anthracene and naphthalene, whether in the form of single crystals or as powder or in a matrix.
lnjection of electric charge carriers into such materials has been achieved using liquid electrodes. See for example H. Kallman et al., J. Chem. Phys, 32,300 1960); M. Pope et al., J. Chem. Phys, Vol. 36, No. 9, May 1, I962, pages 2486 et seq.; and W. Helfrich et al. U.S. Pat. No. 3,457,153 issued July 22, 1969. Only in the latter reference were sufficient currents reported to generate any observable luminescence. Emission from an anthracene crystal occurred primarily in the blue spectral region, and is believed to have been generated by the direct recombination in the body of the crystal of electrons and holes injected from the opposite faces of the crystal by the respective liquid electrodes.
These liquid electrodes are, however, opaque and it has been necessary to remove the light from the system through the edges of the active crystals. This is inconvenient and relatively inefficient, especially since for best performance the crystal will normally be made as a very thin wafer, the liquid electrodes obscuring most or all of the flat faces. Also only relatively short term stability was available due to dissolving the active material in the electrode solutions.
The principal objects of the present invention are to provide a method of injecting carriers into such materials by means of electrodes at least one of which is a transparent solid through which the light generated in the active material can readily emerge, and to give long-term stability to the system.
Another object is to obtain more light than has previously been possible with devices of this type of comparable size and under comparable operating conditions.
Yet another object is to produce a device that will act as a rectifier as well as to produce light.
The present invention consists of an electroluminescent device comprising:
a. a thin body of light-generating, aromatic, electrically nonconducting, hydrocarbon material,
b. a first electrode having an electrically conducting surface contacting a first surface of said light-generating material, and
c. a second electrode contacting a second surface of said light-generating material, said second electrode containing negative ions of an aromatic hydrocarbon material capable of injecting electrons into said second surface upon the application of a negative potential to said second electrode relative to a potential applied to said electrically conducting surface of the first electrode;
d. at least one of the said electrodes being in solid phase and transparent for the transmission therethrough of iight generated in said light-generating material by recombination of said injected electrons with holes.
The single figure of the accompanying drawing shows diagrammatically and by way of example a cross section of one device constructed in accordance with the present invention.
This device comprises a base of conducting glass; then a layer 11 of the active material; then a layer of negative electrode material 12 held within a glass-retaining ring 13, if necessary; and finally a body of encapsulating wax l4. Leads 15 and 16 connect to external terminals to which either relative positive or negative direct voltage is applied as illustrated.
That is the glass 10 will always be positive relatively to the electrode 12, the potential of these parts relative to ground being unimportant.
The base 10 is of glass, at least the upper surface of which has been made conducting by one of the known surface treatment methods, to form a first electrode. Alternatively, this conducting glass surface electrode can be replaced by silver or gold paste. However, since these materials are opaque, they would have to be constructed with windows to permit the light emission.
The light-generating active material ill should be kept as thin as possible, since the light generated is proportional to the current, and the current is proportional to the square of the voltage and inversely as the cube of the thickness of the material. A thickness of the order of l to 200 microns is preferred. This active material may take the form of a crystal or may be in powder or other form. For example, the following materials have been used satisfactorily as the active material:
a. Anthracene sublimation flakes.
b. Anthracene melt grown single crystals.
c. Anthracene powder.
d. Anthracene powder in a matrix of methyl methoxylate plastic.
e. Naphthalene sublimation flakes.
The chemical form should be of high purity for maximum emission intensity, and, although anthrancene and naphthalene have been taken as the most convenient and readily available substances, the active material can theoretically be any aromatic hydrocarbon in a relatively pure chemical form. In practice, however, only those materials having a high quantum efficiency of fluorescence can be used with advantage.
The electrode material 12 will preferably consist of solid material made by evaporation from a solution containing negative ions of a hydrocarbon similar to that used as the active material. For example, if the active material lll is anthracene, the electrode material 12 can be the evaporation product of anthracene dissolved in a solvent such as will produce stable negative anthracene ions, e.g. tetrahydrofuran, dimethoxyethane, dimethyl sulfoxide or dimethyl formamide. The material can be prepared by interacting the solution with metallic sodium or other alkali metal, care being taken to keep the material under an inert atmosphere such as nitrogen during production. Direct production of this electrode material 12 by reduction of the active material 11 at its surface is also possible by sublimation of the reductant, e.g. sodium metal.
If the active material 11 is naphthalene, the electrode material i2 can likewise be a similar evaporated product of a negative ion producing solution of naphthalene. While it is convenient to use the same hydrocarbon for both materials this is not essential. For example, the electrode material 12 can be naphthalene or tetracene while the active material lll is anthracene.
The retaining ring 113 is solely physical in function and will be unnecessary if the electrode material 12 is deposited upon the light-emitting material surface by other techniques, e.g. sublimation. The wax M can be replaced by any other inert substance or means for preventing access of air.
Upon application of the relative voltages shown, light is emitted downwardly either through the: glass base or upwardly through the electrode material 12 and wax 14, if these are sufficiently transparent, or in both directions. There will also be emission from the edges of the active material lll unless this is deliberately discouraged by some opaque material. The wavelength of the emitted light may be varied by the choice of hydrocarbon for the active material. Naphthalene will emit in the ultraviolet range mainly from approximately 3500 to 4000A, and anthracene in the blue range mainly from approximately 4100 to 4500A. Wavelength changes can be achieved by doping. For example, anthracene doped with one part per million of tetracene gives a green-blue emission at approximately 48005000A. lt has also been found that color variations can be obtained by varying the voltage or the dopant concentration.
If the externally applied potential is reserved, virtually no current flows, so that the device acts as a rectifier. The forward and reverse current ratio is of the order of Under the condition of flow of injected electrons from the second electrode 12 to the first electrode 10 the latter must be able to supply sufficient holes to recombine with a sufficient number of electrons to produce the required intensity of electroluminescence. Many electrode materials satisfy this criteria, for example conducting glass, silver paste and gold paste. If there is substituted a solid substance capable of injecting holes into the lower surface of the active material 11, for example anthracene positive ions or naphthalene positive ions, a current will flow, light will be generated, and also a rectifying action will be observed. The positive ion electrodes, however, are opaque and only permit light emitted from the sides of the device to be observed.
I. An electroluminescent device comprising:
a. a thin body of light-generating, aromatic, electrically nonconducting, hydrocarbon material,
b. a first solid phase electrode having an electrically con ducting surface contacting a first surface of said light generating material,
c. a second solid phase electrode contacting a second surface of said light-generating material, said second electrode containing negative ions of an aromatic hydrocarbon material capable of injecting electrons into said second surface upon the application of a negative potential to said second electrode relative to a potential applied to said electrically conducting surface of the first electrode, and
d. at least one of said electrodes being transparent for the transmission therethrough of light generated in said lightgenerating material by recombination of said injected electrons with holes.
2. A device according to claim I, wherein said light-generating material is anthracene and said second electrode includes negative anthracene ions.
3. A device according to claim 1, wherein said light-generating material naphthalene and said second electrode includes negative naphthalene ions.
4. A device according to claim 1, wherein said light-generating material is anthracene and said second electrode includes negative naphthalene ions.
5. A device according to claim 1, wherein said light-generating material is anthracene and said second electrode includes tetracene ions.
6. A device according to claim 1, wherein said first electrode is formed of electrically conducting glass.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US2834903 *||Oct 30, 1952||May 13, 1958||Gen Electric||Electroluminescent lighting device|
|US2938136 *||Aug 26, 1958||May 24, 1960||Gen Electric||Electroluminescent lamp|
|US3172862 *||Sep 29, 1960||Mar 9, 1965||Dow Chemical Co||Organic electroluminescent phosphors|
|US3382394 *||Mar 24, 1965||May 7, 1968||American Cyanamid Co||Electroluminescent process including injection of negative carriers into a crystal of an organic compound|
|US3391068 *||Jul 13, 1964||Jul 2, 1968||American Cyanamid Co||Chemiluminescence|
|US3530325 *||Aug 21, 1967||Sep 22, 1970||American Cyanamid Co||Conversion of electrical energy into light|
|1||*||H. Inokuchi et al., The Photovoltaic Behaviors of Aromatic Hydrocarbons, Electrical Conductivity in Organic Solids, pp. 69 75, 1961.|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US3995299 *||Oct 7, 1975||Nov 30, 1976||The Secretary Of State For Industry In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland||Radiation sources|
|US4356429 *||Jul 17, 1980||Oct 26, 1982||Eastman Kodak Company||Organic electroluminescent cell|
|US4539507 *||Mar 25, 1983||Sep 3, 1985||Eastman Kodak Company||Organic electroluminescent devices having improved power conversion efficiencies|
|US4725513 *||Mar 3, 1987||Feb 16, 1988||Canon Kabushiki Kaisha||Electroluminescent device|
|US4734338 *||Feb 27, 1987||Mar 29, 1988||Canon Kabushiki Kaisha||Electroluminescent device|
|US4741976 *||Feb 27, 1987||May 3, 1988||Canon Kabushiki Kaisha||Electroluminescent device|
|US4769292 *||Oct 14, 1987||Sep 6, 1988||Eastman Kodak Company||Electroluminescent device with modified thin film luminescent zone|
|US4775820 *||Jul 29, 1985||Oct 4, 1988||Canon Kabushiki Kaisha||Multilayer electroluminescent device|
|US4792500 *||Aug 17, 1987||Dec 20, 1988||Clarion Co., Ltd.||Electroluminescence element|
|US4885211 *||Feb 11, 1987||Dec 5, 1989||Eastman Kodak Company||Electroluminescent device with improved cathode|
|US4950950 *||May 18, 1989||Aug 21, 1990||Eastman Kodak Company||Electroluminescent device with silazane-containing luminescent zone|
|US5047687 *||Jul 26, 1990||Sep 10, 1991||Eastman Kodak Company||Organic electroluminescent device with stabilized cathode|
|US5059861 *||Jul 26, 1990||Oct 22, 1991||Eastman Kodak Company||Organic electroluminescent device with stabilizing cathode capping layer|
|US5059862 *||Jul 26, 1990||Oct 22, 1991||Eastman Kodak Company||Electroluminescent device with improved cathode|
|US5061569 *||Jul 26, 1990||Oct 29, 1991||Eastman Kodak Company||Electroluminescent device with organic electroluminescent medium|
|US5073446 *||Jul 26, 1990||Dec 17, 1991||Eastman Kodak Company||Organic electroluminescent device with stabilizing fused metal particle cathode|
|US5247190 *||Apr 18, 1990||Sep 21, 1993||Cambridge Research And Innovation Limited||Electroluminescent devices|
|US5376456 *||May 13, 1993||Dec 27, 1994||Polaroid Corporation||Electroluminescent devices comprising polymers, and processes for their use|
|US5399502 *||May 5, 1993||Mar 21, 1995||Cambridge Display Technology Limited||Method of manufacturing of electrolumineschent devices|
|US5401827 *||Aug 22, 1991||Mar 28, 1995||Cambridge Display Technology Limited||Semiconductive copolymers for use in luminescent devices|
|US5409783 *||Feb 24, 1994||Apr 25, 1995||Eastman Kodak Company||Red-emitting organic electroluminescent device|
|US5414069 *||Feb 1, 1993||May 9, 1995||Polaroid Corporation||Electroluminescent polymers, processes for their use, and electroluminescent devices containing these polymers|
|US5425125 *||Feb 18, 1994||Jun 13, 1995||Cambridge Display Technology Limited||Optical device incorporating semiconductive conjugated polymer|
|US5512654 *||May 19, 1994||Apr 30, 1996||Cambridge Display Technology Limited||Semiconductive copolymers for use in luminescent devices|
|US5558904 *||Jul 8, 1994||Sep 24, 1996||Xerox Corporation||Electroluminescent devices containing a conjugated polymer obtained via halogen precursor route chemistry|
|US5561304 *||Mar 25, 1992||Oct 1, 1996||The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland||Electroluminescent silicon device|
|US5571626 *||Dec 15, 1994||Nov 5, 1996||Polaroid Corporation||Electroluminescent devices comprising polymers, and processes for their use|
|US5609970 *||Jan 12, 1995||Mar 11, 1997||Polaroid Corporation||Electroluminescent device with polymeric charge injection layer|
|US5670792 *||Oct 12, 1994||Sep 23, 1997||Nec Corporation||Current-controlled luminous element array and method for producing the same|
|US5672678 *||Sep 18, 1995||Sep 30, 1997||Cambridge Display Technology Limited||Semiconductive copolymers for use in luminescent devices|
|US5856434 *||Sep 1, 1994||Jan 5, 1999||Hoechst Aktiengesellschaft||Use of polymers containing isolated chromophores as electroluminescence materials|
|US5965241 *||Aug 25, 1993||Oct 12, 1999||Polaroid Corp||Electroluminescent devices and processes using polythiophenes|
|US6137223 *||Jul 28, 1998||Oct 24, 2000||Eastman Kodak Company||Electron-injecting layer formed from a dopant layer for organic light-emitting structure|
|US6140763 *||Jul 28, 1998||Oct 31, 2000||Eastman Kodak Company||Interfacial electron-injecting layer formed from a doped cathode for organic light-emitting structure|
|US6172459||Jul 28, 1998||Jan 9, 2001||Eastman Kodak Company||Electron-injecting layer providing a modified interface between an organic light-emitting structure and a cathode buffer layer|
|US6759147 *||Jun 28, 2002||Jul 6, 2004||Koninklijke Philips Electronics N.V.||Electroluminescent device|
|US6867539||Jul 12, 2000||Mar 15, 2005||3M Innovative Properties Company||Encapsulated organic electronic devices and method for making same|
|US7001639||Apr 30, 2002||Feb 21, 2006||Lumimove, Inc.||Electroluminescent devices fabricated with encapsulated light emitting polymer particles|
|US7029763||Jul 29, 2002||Apr 18, 2006||Lumimove, Inc.||Light-emitting phosphor particles and electroluminescent devices employing same|
|US7303827||Feb 1, 2006||Dec 4, 2007||Lumimove, Inc.||Light-emitting phosphor particles and electroluminescent devices employing same|
|US7361413||Jan 28, 2003||Apr 22, 2008||Lumimove, Inc.||Electroluminescent device and methods for its production and use|
|US7944410||Sep 29, 2005||May 17, 2011||Cambridge Display Technology Limited||Multi-line addressing methods and apparatus|
|US7953682||Nov 30, 2005||May 31, 2011||Cambridge Display Technology Limited||Method of driving a display using non-negative matrix factorization to determine a pair of matrices for representing features of pixel data in an image data matrix and determining weights of said features such that a product of the matrices approximates the image data matrix|
|US8115704||Sep 29, 2005||Feb 14, 2012||Cambridge Display Technology Limited||Multi-line addressing methods and apparatus|
|US8237635||Aug 7, 2012||Cambridge Display Technology Limited||Multi-line addressing methods and apparatus|
|US8237638||Sep 29, 2005||Aug 7, 2012||Cambridge Display Technology Limited||Multi-line addressing methods and apparatus|
|US8657985||Mar 31, 2011||Feb 25, 2014||3M Innovative Properties Company||Encapsulated organic electronic devices and method for making same|
|US9052102 *||Dec 10, 2012||Jun 9, 2015||Abl Ip Holding, Llc||Electrical interconnect system for thin body structures|
|US20030032361 *||Apr 30, 2002||Feb 13, 2003||Matthew Murasko||Electroluminescent devices fabricated with encapsulated light emitting polymer particles|
|US20040016907 *||Jul 21, 2003||Jan 29, 2004||Eastman Kodak Company||Method of using predoped materials for making an organic light-emitting device|
|US20040018379 *||Jul 29, 2002||Jan 29, 2004||Kinlen Patrick J.||Light-emitting phosphor particles and electroluminescent devices employing same|
|US20050122037 *||Nov 24, 2004||Jun 9, 2005||Tetsuya Utsumi||Electroluminescent element and lighting unit|
|US20050129841 *||Jan 14, 2005||Jun 16, 2005||3M Innovative Properties Company||Encapsulated organic electronic devices and method for making same|
|US20060127670 *||Feb 1, 2006||Jun 15, 2006||Lumimove, Inc., A Missouri Corporation, Dba Crosslink Polymer Research||Light-emitting phosphor particles and electroluminescent devices employing same|
|US20060251798 *||Oct 27, 2005||Nov 9, 2006||Lumimove, Inc. Dba Crosslink Polymer Research||Electroluminescent devices fabricated with encapsulated light emitting polymer particles|
|US20070046603 *||Sep 29, 2005||Mar 1, 2007||Smith Euan C||Multi-line addressing methods and apparatus|
|US20070069992 *||Sep 29, 2005||Mar 29, 2007||Smith Euan C||Multi-line addressing methods and apparatus|
|US20070085779 *||Sep 29, 2005||Apr 19, 2007||Smith Euan C||Multi-line addressing methods and apparatus|
|US20080291122 *||Nov 30, 2005||Nov 27, 2008||Euan Christopher Smith||Digital Signal Processing Methods and Apparatus|
|US20110177637 *||Jul 21, 2011||3M Innovative Properties Company||Encapsulated organic electronic devices and method for making same|
|US20130147398 *||Jun 13, 2013||Abl Ip Holding, Llc||Electrical interconnect system for thin body structures|
|US20130154471 *||Dec 15, 2011||Jun 20, 2013||General Electric Company||Oled devices|
|DE2637099A1 *||Aug 18, 1976||Mar 3, 1977||Ici Ltd||Verfahren zur herstellung von komposit-anordnungen mit duennschichtkomponenten und danach erhaltene bauteile|
|EP0771459A2 *||May 7, 1996||May 7, 1997||Philips Electronics N.V.||Display device|
|WO1990013148A1 *||Apr 18, 1990||Nov 1, 1990||Cambridge Research And Innovation Limited||Electroluminescent devices|
|WO1992003490A1 *||Aug 22, 1991||Mar 5, 1992||Cambridge Research And Innovation Limited||Semiconductive copolymers for use in luminescent devices|
|WO1992003491A1 *||Aug 22, 1991||Mar 5, 1992||Cambridge Research And Innovation Limited||Patterning of semiconductive polymers|
|WO1992019084A1 *||Mar 25, 1992||Oct 29, 1992||The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland||Electroluminescent silicon device|
|U.S. Classification||313/504, 257/100, 257/99, 257/103, 257/632|
|International Classification||H05B33/14, H05B33/26|
|Cooperative Classification||H05B33/145, H05B33/26|
|European Classification||H05B33/14F, H05B33/26|