Electroluminescent devices

Abstract: An electroluminescent device comprised of a metal thioxinoid of the formula wherein M represents a metal; each n is a number of from 1 to 3; N is nitrogen, S is sulfur, and Z represents an aromatic moiety.

Description: The present invention relates to novel metal thioxinoid compounds which may be used as electroluminescent materials in electroluminescent (EL) devices. The present invention further relates to EL devices which contain such metal thioxinoid compounds. Electrooptical devices, such as cathode ray tubes (CRT's), are known. However, these devices are bulky and consume substantial amounts of energy. Furthermore, it is also difficult to manufacture a cost-effective distortion-free or low-distortion display based on CRT technology. Accordingly, there has been increased interest in developing compact flat-panel display devices which minimize space usage, and which can operate at low voltages of, for example, below 20 volts. From the energy and space usage perspectives, particular attention has been devoted to developing energy-efficient flat-panel displays which are capable of providing a clear display without restrictive viewing angles. Currently, the majority of flat-panel display devices are liquid crystal based, however, these devices are encumbered with the problems of slow response and restrictive viewing angles. The EL display concept appears to offer a solution to these difficulties. Many of the current EL devices are based on inorganic materials, and they generally require high driving voltages. Organic EL devices, in contrast provide the advantage of lower driving voltages, however, they suffer from certain performance shortfalls, such as relatively short serviceable life and low electroluminescent efficiency. The organic EL devices of the present invention avoid or minimize these disadvantages by providing relatively long device life and high electroluminescent efficiency characteristics. A simple organic EL device is generally comprised of a layer of organic luminescent material conductively sandwiched between an anode, typically comprised of a transparent conductor such as indium-tin oxide, and a cathode, typically a low work-function metal, such as magnesium, calcium, aluminum, or its alloy, with other metals. Under an applied electric field, positive charge carriers (holes) and negative charge carriers (electrons) are respectively injected from the anode and cathode into the luminescent layer where some of these oppositely charged carriers are recombined to form excitonic states which subsequently emit light. In one configuration, an organic EL device is comprised of a host organic polymer layer that supports hole injection from the anode and electron injection from the cathode, and is capable of emitting light in response to subsequent electron-hole recombination. The specific host organic polymer layer can further include a compound that facilitates hole injection and transport, a compound that facilitates electron injection and transport, and optionally, a fluorescent material capable of emitting light in response to recombination of holes and electrons. In another configuration, an organic EL device may be comprised of certain dual organic layers in which one layer is adjacent to the anode supporting hole injection and transport, and another layer adjacent to the cathode supporting electron injection and transport. The recombination of charge carriers and subsequent emission of light occurs in one of these layers near the interface between the two layers. Optionally, a fluorescent dye can be added to one of the layers leading to the recombination of charge carriers and subsequent emission of light occurring in that compound. In a further configuration, an EL device can be comprised of three separate layers, a certain hole transport layer, an emission layer, and a certain electron transport layer. These layers are laminated in sequence and are sandwiched as a whole between an anode and a cathode. While the incorporation of a hole injecting and transporting component may lead to improved hole injection performance, there is a need for the design of electron injecting and transporting components which enhance electron injection. Electron injection has been more difficult than hole injection primarily because of the relatively large energy barrier between the n-contact and organic interface. In addition, while there are a number of known hole injecting and transporting materials which have been utilized in organic EL devices, organic electron injecting and transporting materials are not readily available. Primarily in view of the complexities and difficulties associated with the fabrication of layered organic EL devices, substantial efforts have been devoted to developing new charge injecting and transporting materials which improve EL device performance. Specifically, thus there is provided with the organic EL devices of the present invention in embodiments thereof a number of advantages, such as improved charge injection, low operation voltages, and enhanced electroluminescent efficiency, and which devices can be fabricated with an electron injecting and transporting component selected from a novel class of metal thioxinoid compounds. JP-A-07-133,481 discloses an organic EL device containing a metal complex of 8-mercaptoquinoline. US-A-5,456,988 discloses an EL device comprising a metal (8-quinolinethiolato) complex. It is an object of the present invention to provide novel metal thioxinoid compounds which may be used as electroluminescent materials in EL devices. It is a further object of the present invention to provide organic EL devices which can be operated at low operating voltages of, for example, below 20 volts, such as from 5 to 19.5 volts, and high energy conversion efficiency, and enhanced thermal stability and operational stability. The present invention provides novel metal thioxinoid compounds as specified in claim 23. The present invention further provides EL devices as specified in claims 1 and 16. Preferred embodiments of the present invention are set forth in the claims. In embodiments, the present invention relates to organic EL devices comprised of an electron injecting and electron transporting layer or zone, or layer comprised of a metal thioxinoid compound, a hole injecting and transporting layer or zone, or layer comprised of for example aromatic tertiary amine molecules, and polynuclear aromatic tertiary amine. In a preferred aspect the polynuclear aromatic tertiary amine compounds are of Formula (II) which possess excellent thermal stability, and can be readily vacuum deposited as thin films for use as hole transport components in organic EL devices wherein R 1 , R 2 , R 3 , R 4 , and R 5 are aryl groups such as phenyl, tolyl, xylyl, or naphthyl, and A 1 and A 2 are biaryl groups such as biphenyl, or bitolyl, or wherein aryl can include from 6 to 24 carbon atoms, and biaryl can include from 12 to 48 carbon atoms. The organic EL devices of the present invention, with polynuclear aromatic tertiary amines, exhibit improved thermal and operational stability, and excellent device durability at temperatures around and above 35°C. In embodiments, the electron injecting layer may inject electrons, transport electrons, or a combination thereof, and the hole injecting layer may inject holes, transport holes, or a combination thereof. In embodiments, the present invention relates to organic EL devices comprised in the following order of an anode, an organic hole injecting and transporting zone or layer, an electron injecting and transporting zone or layer, and a cathode, wherein the electron injecting and transporting zone or layer is comprised of a metal thioxinoid compound as illustrated by Formula (I) herein. In embodiments, the present invention relates to an organic EL device comprised of a single luminescent layer comprised of an aromatic tertiary amine hole transport component, a metal thioxinoid electron injection component as described by Formula (I), and an optional fluorescent component, sandwiched between an anode and a cathode. wherein M represents a metal; each n is an integer of from 1 to 3; S is sulfur, N is nitrogen, and Z is benzo{f}quinoline, substituted benzo{f}quinoline, benzo{h}quinoline, substituted benzo{h}quinoline, quinoxaline, 2-phenylbenzoxazole, or 2-phenylbenzothiazole. The metals are known and can be monovalent, divalent, or trivalent. Specific examples of metals include those which are known to form chelated compounds with thioxines, and preferably such metals are zinc, cadmium, gallium, or indium. The embodiments of the present invention will be described in more detail with reference to the schematic diagrams of EL devices as depicted in Figures 1 and 2. Figure 1 illustrates an EL device which comprises an organic light emitting diode comprised of a supporting substrate 2 of, for example, glass, an anode 3, a vacuum deposited organic hole injecting and transporting zone 4, a vacuum deposited electron injecting and transporting zone 5 comprised of at least one metal thioxinoid compound illustrated herein and of Formula (I), and in contact therewith a low work function metal as a cathode 6. In this EL device, a luminescent zone in which the electron-hole recombination takes place with subsequent light emission, encompasses the hole transport zone and/or the electron transport zone. Preferably, a fluorescent material, which is capable of emitting light subsequent to electron-hole recombination, may be added to the luminescent zone wherein the charge transport component functions as the host material. More specifically, the device may include two zones, that is in place of 4, 4a and 4b, and in place of 5, 5a and 5b, wherein 4a is the hole injecting layer, 4b is the hole transport layer, 5a is electron transporting and 5b is electron injecting; 4a and 4b together with 5 alone, or 5a and 5b together with 4 alone. Figure 2 illustrates another device configuration of the present invention comprising a single vacuum deposited luminescent zone 7, sandwiched between a cathode 6 and an anode 3 resting on a substrate 2. In embodiments of the present invention, the luminescent zone 7 is comprised of a hole injecting and transporting component, an electron injecting and transport component comprised of one metal thioxinoid compound of Formula (I), and a light emitting component. Illustrative examples of supporting substrates include polymeric components, glass, polyesters like MYLAR®, polycarbonates, polyacrylates, polymethacrylates, polysulfones, and quartz. Other substrates can be selected provided, for example, they are essentially nonfunctional and can support the other layers. The thickness of the substrate can be, for example, from 25 to over 1,000 µm, preferably from 50 to 1,000 µm, depending, for example, on the structural demands of the device. The anode contiguous to the substrate in the organic EL devices of the present invention can be comprised of a metal, an alloy, an electroconducting compound or mixtures thereof, preferably with a work function equal to, or greater than 4 electron volts (eV), for example from 4 to 7 eV. Specific examples of an anode, includes positive charge injecting electrodes such as indium tin oxide, tin oxide, zinc oxide, gold, platinum, or other materials including electrically conductive carbon and conjugated polymers such as polyaniline, and polypyrrole. The thickness of the anode can range from 10 nm to 1 µm with the preferred range being dictated by the optical constants of the anode material. One preferred range of thickness is from 10 to 200 nm. The hole injecting and transporting zone 4 in the EL device of the present invention may be of a number of convenient forms. For example, the substrate may be comprised of one layer comprising one, two or more of hole transport components. In another preferred form, it may be laminately formed of a layer in contact with the anode containing a hole injecting component and a layer containing a hole transporting component interposed between the hole injecting layer and the electron injecting and transporting zone. The thickness of the hole injecting and transporting zone can be from 5 nm to 500 nm, and preferably from 10 nm to 100 nm. Any conventional materials which can inject and transport holes into the luminescent zone at a low electric field may be employed for forming the hole injecting and transporting zone. Preferred hole injecting and transporting materials include porphyrin derivatives and aromatic tertiary amines disclosed in US-A-4,720,432. Representative examples of phorphyrine derivatives are porphyrine; 1,10,15,20-tetraphenyl-21H,23H-porphyrin copper (II); copper phthalocyanine; copper tetramethyl phthalocyanine; zinc phthalocyanine; titanium phthalocyanine oxide; and magnesium phthalocyanine. Illustrative examples of aromatic tertiary amines are bis(4-dimethylamino-2-methylphenyl)phenylmethane, N,N,N-tri(p-tolyl)amine, 1,1-bis(4-di-p-tolylaminophenyl)-cyclohexane, 1,1-bis(4-di-p-tolylaminophenyl)-4-phenylcyclohexane, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine, N, N'-diphenyl-N,N'-bis(4-methoxyphenyl)-1,1'-biphenyl-4,4'-diamine, N,N,N',N'-tetra-p-tolyl-1,1'-biphenyl-4,4'-diamine, and N,N'-di-1-naphthyl-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine. Particularly preferred aromatic tertiary amines for the hole transporting layer or zone, and which amines may also inject holes, can be selected from those of polynuclear aromatic amines of Formula (II) illustrated herein. Specific examples include N,N-bis-[4'-(N-phenyl-N-m-tolylamino)-4-biphenylyl]aniline; N,N-bis-[4'-(N-phenyl-N-m-tolylamino)-4-biphenylyl]-m-toluidine; N,N-bis-[4'-(N-phenyl-N-m-tolylamino)-4-biphenylyl]-p-toluidine; N,N-bis-[4'-(N-phenyl-N-p-tolylamino)-4-biphenylyl]aniline; N,N-bis-[4'-(N-phenyl-N-p-tolylamino)-4-biphenylyl]-m-toluidine; N,N-bis-[4'-(N-phenyl-N-p-tolylamino)-4-biphenylyl]-p-toluidine; N,N-bis-[4'-(N-phenyl-N-p-chlorophenylamino)-4-biphenylyl]-m-toluidine; N,N-bis-[4'-(N-phenyl-N-m-chlorophenylamino)-4-biphenylyl]-m-toluidine; N,N-bis-[4'-(N-phenyl-N-m-chlorophenylamino)-4-biphenylyl]-p-toluidine; N,N-bis-[4'-(N-phenyl-N-m-tolylamino)-4-biphenylyl]-p-chloroaniline; N,N-bis-[4'-(N-phenyl-N-p-tolylamino)-4-biphenylyl]-m-chloroaniline; and N,N-bis-[4'-(N-phenyl-N-m-tolylamino)-4-biphenylyl]-1-aminonaphthalene. The electron injecting zone or layer, and which layer may also transport electrons, for the organic EL device of the present invention is comprised of a novel class of electron injecting and transporting components comprised of metal thioxinoid compounds as illustrated by Formula (I) wherein M represents a metal; each n is an integer of from 1 to 3; S is sulfur, N is nitrogen, and Z is benzo{f}quinoline, substituted benzo{f}quinoline, benzo{h}quinoline, substituted benzo{h}quinoline, quinoxaline, 2-phenylbenzoxazole, or 2-phenylbenzothiazole. The metals therein can be monovalent, divalent, or trivalent. Specific examples of metals include those which are known to form chelated compounds with thioxines, and preferably these metals include zinc, cadmium, gallium, or indium. Illustrative examples of metal thioxinoide compounds include (1) bis[benzo{f}-8-quinolinethiolato]zinc, (2) bis[3-methylbenzo{f}-8-quinolinethiolato]zinc, (3) bis[3,7-dimethylbenzo{f}-8-quinolinethiolato]zinc, (4) bis(4-quinoxaline thiolato)zinc, (5) bis[2-(2-mercaptophenyl)benzothiazolate]zinc, and (6) bis[2-(2-mercaptophenyl) benzoxazolate]zinc. The metal thioxinoid compounds can be prepared, for example, by the reaction of 8-quinolinethiol derivatives with the corresponding metal salts, followed by purification. In a typical reaction, thioxine and metal salt (1/2 equivalent amount of divalent metal salt or 1/3 equivalent amount of trivalent metal salt is used) are suspended in an aliphatic alcoholic solvent such as methanol or ethanol. With stirring, the suspension is treated with one equivalent amount of base, such as sodium hydroxide, potassium hydroxide, or sodium ethoxide, at room temperature under an inert atmosphere. The precipitated solid is collected by filtration and further purified by sublimation. The structure and composition of the metal chelated compounds are confirmed by known analytical techniques such as ultraviolet-visible and infrared spectra, and elemental analysis. The electron injecting and transporting layer or zone may be a number of convenient forms. For example, it may be comprised of one layer comprising at least one metal thioxinoid compound and mixtures thereof with other known electron transport materials, and which mixture contains effective amounts of each component, for example from 5 to 95 percent of the metal thioxinoid complex, and from 95 to 5 weight percent of a known electron transporting material. Also, the electron injecting and transporting zone may be comprised of a layer in contact with the cathode containing an electron injecting metal thioxinoid compound, and a layer containing a known electron transporting compound interposed between the electron injecting layer and the hole injecting and transporting zone. Examples of known electron transport materials other than the metal thioxinoid chelate compounds include fused ring luminescent materials, such as anthracene, phenathrecene, pyrene, perylene, as illustrated by US-A-3,172,862; butadienes such as 1,4-diphenylbutadiene and tetraphenylbutadiene, and stilbenes, as illustrated in US-A-4,356,429 and US-A-5,516,577; optical brightness such as those disclosed by US-A-4,539,507. Preferred electron transport materials are metal chelates of 8-hydroxyquinoline disclosed in US-A-4,539,507; US-A-5,151,629 and US-A-5,150,006. Illustrative examples of the metal chelated compounds include tris(8-hydroxyquinolinate)aluminum (AIQ3), bis(8-hydroxyquinolinate)magnesium, tris(7-propyl-8-quinolinolato)aluminum, bis(2-methylquinolinolato)aluminum(III)-µ-oxo-bis(2-methyl-8-quinolinolato) aluminum(III), bis(2-methyl-8-quinolinolato)(phenolato)aluminum, bis(2-methyl-8-quinolinolato)(para-phenylphenolato)aluminum, and bis(2-methyl-8-quinolinolato)(2-naphthalolato)aluminum. Various effective layer thicknesses can be selected for the EL devices as indicated herein, for example, and more specifically, the hole injecting and transporting layer, and electron injecting layer each are of a thickness of from 5 to 200 nm, and preferably from 40 to 100 nm. Other specific thicknesses may be selected and which thickness depends on a number of factors, such as the thicknesses of the other layers, and the components for each layer. It may be desirable to incorporate in the EL device charge transport layers a fluorescent dye to improve the device performance, reference the dyes of US-A-4,769,292. Examples of fluorescent materials which can be employed in the EL devices of the present invention include those capable of being blended with the host material to form a common phase. Although any convenient techniques for dispersing the fluorescent agents in the host materials can be undertaken, the preferred technique is by vacuum vapor deposition wherein both the fluorescent agent and the host material can be simultaneously deposited. One preferred class of fluorescent materials is fluorescent dyes. Illustrative examples of fluorescent dyes are disclosed in US-A-4,769,292 and include known compounds, such as coumarin dyes like 7-diethylamino-4-methylcoumarin, 4,6-dimethyl-7-ethylaminocoumarin, 4-methylumbelliferone, fluorescent 4-dicyanomethylene-4H-pyrans such as 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran. Also, another preferred class of fluorescent materials are fused ring fluorescent dyes. The light emitting fluorescent material is present in an amount of, for example, from 0.01 to 10 weight percent, and preferably from 1 to 5 weight percent of the host transport layer. The cathode 6 is formed by deposition thereof on the surface electron injecting layer 5. The cathode 6 can be comprised of any metal including any low work function metal useful for this purpose. The cathode can also be formed from a combination of a low work function metal and at least one other metal. A low work function metal is a metal having a work function equal to, or less than 4.0 eV, for example from 1 to 4 eV. The lower the work function of the metal, the lower the voltage required for electron injection into layer 5 or 7. The thickness of the cathode 6 is, for example, from 1 to 500 nm. Suitable low work function metals include alkaline metals, Group 2A, or alkaline earth metals, and Group III metals including rare earth metals and the actinide group metals. Lithium, magnesium and calcium are particularly preferred. Low work function metals exhibiting, for example, work functions in the range of from 2.8 to 4.0 eV are usually more stable than metals exhibiting lower, or higher work functions and are, therefore, preferred. The cathode 6 may include a second metal for the purpose of increasing stability both during storage and operation. The second metal can be selected from any metal other than an alkaline metal. The second metal itself can be a low work function metal and suitable examples of the second metal include the examples of metals for the first metal having a work function of less than 4 eV. As an alternative, the second metal can be selected from various metals having a work function of greater than, for example, from 4.0 to 5.5 eV. The second metal includes elements more resistant to oxidation and therefore more commonly fabricated as metallic elements. The second metal contributes to the stability of cathode 6. Suitable metals with a work function of 4 eV or greater include aluminum, indium, the Group IB metals, metals in Groups IV, V and VI and the Group VIII transition metals, particularly noble metals. Aluminum, indium, copper, silver, gold, tin, led, bismuth, tellurium and antimony are particularly preferred high work function second metals for incorporation into cathode 6. A primary function of the second metal is to stabilize the first, low work function metal. A second function is to reduce sheet resistance of the cathode 6 as a function of the thickness of the cathode. This results in a very stable cathode 6 of acceptably low resistance and high electron injection efficiency. A third function of the second metal is to facilitate vacuum vapor deposition of the first metal. Suitable proportions of the low work function metal to the second metal, preferably a metal having a work function greater than 4.0 eV, may range from less than 1 percent to 99 percent by weight. The thickness of the cathode 6 is of, for example, from 1 to 500 nm. The Mg:Ag cathodes of US-A-4,885,211 constitute one preferred cathode construction. Another preferred cathode construction may be as illustrated in US-A-5,429,884 in which the cathodes are formed of lithium alloys with other high work function metals such as aluminum and indium. Both anode 3 and cathode 6 of the organic EL devices of the present invention can be of any convenient forms. A thin, for example from 20 to 50 nm, conductive layer can be coated onto a light transmissive substrate, for example a transparent or substantially transparent glass plate or plastic film. The EL device can include a light transmissive anode 3 formed of tin oxide or indium tin oxide coated on a glass plate. Also, very thin, for example from 10 to 40 nm, light-transparent metallic anodes can be used, such as gold, or palladium. In addition, transparent or semitransparent thin layers of conductive carbon or conjugated polymers such as polyaniline, polypyrrole can be used as anodes. Any light transmissive polymeric film can be employed as the substrate. Further suitable forms of the anode 3 and cathode 6 are illustrated by US-A-5,429,884. Additionally, in embodiments, the present invention is directed to organic layered EL devices comprised of a supporting substrate as illustrated herein, such as glass, a semitransparent layer of, for example, indium or tin oxide, an active single layer comprised of a polynuclear arylamine as illustrated herein, an emitter compound, the thioxinoid metal complex electron transport compound and a low work function electrode as the top layer; an EL device wherein the hole injecting and transporting layer is comprised of a mixture of an organic host material comprised of hole transport components, and a fluorescent dye having a band gap no greater than that of the host material and a reduction potential less negative than that of the host material, or wherein the electron transport layer is comprised of a blend of an organic host material comprised of electron transport, and a fluorescent dye having a band gap no greater than that of the host material and a reduction potential less negative than that of the host; an EL device wherein the fluorescent dye is selected from the group consisting of coumarin, dicyanomethylenepyrans, polymethine, oxabenzanthrane, xanthene, pyrylium, carbostyl, perylene, quinacridone, and fused aromatic ring fluorescent dyes; and an EL device wherein the supporting substrate is of a thickness of from 25 to 1,000 µm, the anode is of a thickness of from 10 to 500 nm, the luminescent layer is of a thickness of from 5 to 5,000 nm, and the cathode is of a thickness of from 5 nm to 5 µm.

Claims: An electroluminescent device comprising an anode, a cathode, and a metal thioxinoid of the formula: wherein M represents a metal; each n is a number of from 1 to 3; N is nitrogen, S is sulfur, and Z is benzo{f}quinoline, substituted benzo{f}quinoline, benzo{h}quinoline, substituted benzo{h}quinoline, quinoxaline, 2-phenylbenzoxazole, or 2-phenylbenzothiazole. The electroluminescent device of claim 1, wherein the metal thioxinoid is selected from the group consisting of bis[benzo{f}-8-quinolinethiolato]zinc, bis[3-methylbenzo{f}-8-quinolinethiolato]zinc, bis[3,7-dimethylbenzo{f}-8-quinolinethiolato]zinc, bis(4-quinoxalinethiolato)zinc, bis[2-(2-mercaptophenyl)benzothiazolate]zinc, and bis[2-(2-mercaptophenyl) benzoxazolate]zinc. The electroluminescent device of claim 1, comprising in sequence a supporting substrate, an anode, an organic hole injecting and hole transporting layer or zone, an organic electron injecting and electron transporting layer or zone, and a cathode, wherein said organic electron injecting and transporting zone or layer comprises said metal thioxinoid. The electroluminescent device of claim 3, wherein the hole injecting and transporting zone comprises polynuclear arylamines as represented by the following formula: wherein R 1 , R 2 , R 3 , R 4 , and R 5 are aryl, and A 1 and A 2 are biaryl. The electroluminescent device of claim 3, wherein the hole injecting and transporting zone comprises aromatic tertiary amines as represented by the following formula: wherein P is a phenylene group; n is an integer of from 1 to 4; and R 6 , R 7 , R 8 , and R 9 are aryl groups independently selected from the group consisting of phenyl groups, and naphthyl groups. The electroluminescent device of claim 3, wherein said hole injecting and transporting layer comprises a mixture of an organic host material comprising hole transport components, and a fluorescent dye with a band gap no greater than that of said host material and a reduction potential less negative than that of said host material. The electroluminescent device of claim 6, wherein said fluorescent dye is selected from the group consisting of coumarin, dicyanomethylenepyrans, polymethine, oxabenzanthrane, xanthene, pyrylium, carbostyl, perylene, quinacridone, and fused aromatic ring fluorescent dyes. The electroluminescent device of claim 6, wherein said fluorescent dye is rubrene. The electroluminescent device of claim 3, wherein the substrate is a polymer or glass. The electroluminescent device of claim 3, wherein the anode is an indium tin oxide. The electroluminescent device of claim 3, wherein the cathode is a layer of a plurality of metals, at least one of said metals having a work function of less than 4 eV. The electroluminescent device of claim 11, wherein said metal having a work function of less than 4 eV comprises at least one alkaline metal, an alkaline earth metal, a rare earth metal, or a Group III metal. The electroluminescent device of claim 3, wherein the supporting substrate has a thickness ranging from 25 to 1,000 µm, the anode has a thickness ranging from 10 to 500 nm, the hole injecting and transporting layer has a thickness ranging from 5 to 500 nm, the electron injecting and transporting layer has a thickness ranging from 5 to 200 nm, and the cathode has a thickness ranging from 5 nm to 5 µm. The electroluminescent device of claim 3, wherein the supporting substrate has a thickness ranging from 25 to 1,000 µm, the anode has a thickness ranging from 10 to 500 nm, and the cathode has a thickness ranging from 5 nm to 5 µm. The electroluminescent device of claim 1, wherein said metal is zinc, cadmium, gallium, or indium. An electroluminescent device comprising a luminescent layer sandwiched between a cathode and an anode resting on a substrate, said luminescent layer comprising a hole injecting and transporting component, an electron injecting and transport component comprising a metal thioxinoid compound of the following formula, and a light emitting component: wherein M represents a metal; each n is a number of from 1 to 3; N is nitrogen, S is sulfur, and Z is benzo{f}quinoline, substituted benzo{f}quinoline, benzo{h}quinoline, substituted benzo{h}quinoline, quinoxaline, 2-phenylbenzoxazole, or 2-phenylbenzothiazole. The electroluminescent device of claim 16, wherein the metal thioxinoid is selected from the group consisting of bis[benzo{f}-8-quinolinethiolato]zinc, bis[3-methylbenzo{f}-8-quinolinethiolato]zinc, bis[3,7-dimethylbenzo{f}-8-quinolinethiolato]zinc, bis(4-quinoxalinethiolato)zinc, bis[2-(2-mercaptophenyl)benzothiazolate]zinc, and bis[2-(2-mercaptophenyl) benzoxazolate]zinc. The electroluminescent device of claim 16, wherein the hole injecting and transporting component comprises polynuclear arylamines as represented by the following formula: wherein R 1 , R 2 , R 3 , R 4 , and R 5 are aryl, and A 1 and A 2 are biaryl. The electroluminescent device of claim 16, wherein the hole injecting and transporting component comprises aromatic tertiary amines as represented by the following formula: wherein P is a phenylene group; n is an integer of from 1 to 4; and R 6 , R 7 , R 8 , and R 9 are aryl groups independently selected from the group consisting of phenyl groups, and naphthyl groups. The electroluminescent device of claim 16, wherein the cathode is a layer of a plurality of metals, at least one of said metals having a work function of less than 4 eV. The electroluminescent device of claim 16, wherein the anode comprises a material selected from the group consisting of electrically conductive carbon, electrically conductive polyaniline and electrically conductive polypyrrole. The electroluminescent device of claim 3, wherein said metal is zinc, cadmium, gallium, or indium. A metal thioxinoid of the formula: wherein M represents a metal; each n is a number of from 1 to 3; N is nitrogen, S is sulfur, and Z is benzo{f}quinoline, substituted benzo{f}quinoline, benzo{h}quinoline, substituted benzo{h}quinoline, quinoxaline, 2-phenylbenzoxazole, or 2-phenylbenzothiazole. The metal thioxinoid of claim 23, wherein said metal thioxinoid is a compound selected from the group consisting of bis[benzo{f}-8-quinolinethiolato]zinc, bis[3-methylbenzo{f}-8-quinolinethiolato]zinc, bis[3,7-dimethylbenzo{f}-8-quinolinethiolato]zinc, bis(4-quinoxalinethiolato)zinc, bis[2-(2-mercaptophenyl)benzothiazolate]zinc, and bis[2-(2-mercaptophenyl) benzoxazolate]zinc.

Inventors: HOR AH-MEE, HU NAN-XING, ONG BENG S, POPOVIC ZORAN D, XIE SHUANG, HOR, AH-MEE, HU, NAN-XING, ONG, BENG S., POPOVIC, ZORAN D., XIE, SHUANG
Applicants: XEROX CORP, XEROX CORPORATION
Application year: 1998
Main classification: H05B33
IPC codes: C07D215, H01L51, H05B33, C09K11