EP0891686B1 - Electroluminescent device - Google Patents

Electroluminescent device Download PDF

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EP0891686B1
EP0891686B1 EP97908105A EP97908105A EP0891686B1 EP 0891686 B1 EP0891686 B1 EP 0891686B1 EP 97908105 A EP97908105 A EP 97908105A EP 97908105 A EP97908105 A EP 97908105A EP 0891686 B1 EP0891686 B1 EP 0891686B1
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layer
electroluminescent
gallium nitride
electrode
nitride
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German (de)
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EP0891686A1 (en
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Marc Ilegems
Michel SCHÄR
Libero Zuppiroli
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Ecole Polytechnique Federale de Lausanne EPFL
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Ecole Polytechnique Federale de Lausanne EPFL
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
    • H05B33/26—Light sources with substantially two-dimensional radiating surfaces characterised by the composition or arrangement of the conductive material used as an electrode
    • H05B33/28—Light sources with substantially two-dimensional radiating surfaces characterised by the composition or arrangement of the conductive material used as an electrode of translucent electrodes

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  • the present invention relates to a device electroluminescent comprising a layer of organic matter light emitting semiconductor disposed between a first electrode, constituted by a material having the property of injecting electrons into said layer of electroluminescent material, and a second electrode constituted by a material having the property of injecting holes in this layer.
  • the semiconductor organic matter consists of either a monomeric organic substance, made up of molecules fluorescent, such as anthracene, perylene and coronene, or molecules of an organic dye, either in a conjugated organic polymer such as poly (p-phenylene-vinylene).
  • the electron-emitting electrode is, for example, constituted by a layer of a metal chosen from aluminum, magnesium and calcium, or by a layer of metallic alloy, such as an alloy of magnesium and silver, and the hole-emitting electrode is constituted, for example, by a layer of a metal such as gold or by a layer of tin oxide (SnO 2 ) or mixed oxide d 'indium and tin (ITO).
  • Such electroluminescent devices can in particular be used as light emitting diodes in display elements, as well as for the manufacture of screens dishes for laptop or television.
  • the hole injector electrode was produced in the form of a transparent layer, constituted, by example, mixed oxide of indium and tin, the electrode being an electron injector, it is opaque or reflective. Devices of this type cannot emit light than on one side. According to one of the variants of the device described in application WO 90/13148, it is however mentioned that at least one of the charge injecting contact layers, when these layers are gold or aluminum and do not exceed not a certain thickness, is transparent or semi-transparent. It is however not specified which of these layers is transparent or semi-transparent.
  • the devices currently known have the disadvantage of having too short a lifespan for the industrial applications envisaged. More specifically, the best known devices of this kind, in which the layer of organic matter electroluminescent consists of an organic substance monomer, only allow a maximum duration of use of around a thousand hours, in continuous operation, while the best known devices, in which the layer of electroluminescent organic matter consists of a conjugated polymer, do not generally last continuous use greater than one hundred hours.
  • the invention aims to provide a device of the kind mentioned above which is capable of emitting light on its two faces, i.e. an electroluminescent device in which the two electrodes placed on either side of the layer of electroluminescent material are transparent or translucent.
  • Another object of the invention is to make it possible to improve the life of the device.
  • the device according to the invention is characterized in that said first electrode is in the form a transparent or translucent layer of a material n-type semiconductor chosen from nitrides and mineral oxides.
  • the material constituting the electron-emitting electrode is chosen from gallium nitride GaN, binary alloys of gallium nitride and indium nitride, of general formula Ga x In ( 1-x ) N, the alloys ternaries of gallium nitride, indium nitride and aluminum nitride, of general formula Ga x Al y In ( 1-xy ) N and mixtures of at least two of these compounds and alloys, where x and y each represent a number between 0 and 1, the sum x + y being at most equal to 1, the conductivity character n of said material possibly resulting from a stoichiometry gap or from doping with at least one element chosen from groups 4a and 6a of the periodic table.
  • doping element one can, in particular use one of the following: Si, Sn, S, Se and Te.
  • n-type semiconductor material in particular gallium nitride and its alloys, can be used in any suitable form, in particular in the form monocrystalline, polycrystalline, nanocrystalline or amorphous, or as a superposition of layers of this type having compositions, so values of x or y, or doping, different.
  • the electron injecting nature of such materials can possibly result from the existence of gaps in stoichiometry or doping with at least one element such as, for example H, Li, Ca, Al, Cs.
  • titanium oxides can be used in any suitable form, in particular in the form monocrystalline, polycrystalline, nanocrystalline or amorphous.
  • electroluminescent semiconductor organic matter constituting the electroluminescent layer we can use any appropriate material, especially those made up of substances already used for this purpose in accordance with the prior art, in particular, polymers conjugates, such as poly (p-phenylene-vinylene), commonly designated by the abbreviation PPV or poly p-phenylene, PPP, or still the polythiophene, PT, those in which the nucleus phenyl or thiophene carry one or more substituents such as an alkyl group, an alkoxy group, a halogen or a nitro group, as well as conjugated polymers such as poly (4,4'-diphenylene-diphenylvinylene), commonly known by the abbreviation PDPV; poly (1,4-phenylene-1-phenylinyene); poly (1,4-phenylene-diphenyvinylene); polymers of the poly (3-alkylthiofen) or poly (3-alkylpyrrole) type, polymers of
  • conjugated polymers derived from known polymers such as those which have been mentioned above, by grafting at the ends of the polymer chains group with the property of strengthening the membership of the electroluminescent conjugated polymer layer on the surface electrodes, in particular the electron-emitting electrode and more particularly on a layer of gallium nitride or titanium oxide is particularly advantageous.
  • polymers derived from poly (phenylene) whose chain ends have one of the following formulas:
  • organic matter electroluminescent constituting the layer electroluminescent a monomeric substance, a dye or organic pigment, this substance or this dye or pigment can in particular be chosen from those who suitable for use in devices prior art light emitting lamps. These dyes can also be functionalized so as to adhere better to the electrode of the invention.
  • the same materials as those used in light-emitting devices according to the prior art can be used, in particular gold, tin oxide SnO 2 or else mixed oxide of indium and tin (in particular the commercial product known by the designation ITO), in the form of a transparent layer.
  • a such material can be, for example, made of a compound of the diphenyl-dimethylphenylamine type, known as TPD designation.
  • any suitable method can be used, in in particular the techniques used for the manufacture of prior art devices.
  • the compound layer is first formed n-type semiconductor mineral constituting the electrode electron emitter, on the surface of the substrate serving support for the electroluminescent device, this substrate being advantageously constituted by a transparent insulating material such as a sapphire or quartz plate.
  • titanium oxide layer as defined above, the methods known per se can be used of titanium oxidation, sol-gel polymerization methods from organic precursors, methods of plasma spraying or bombardment ionic. These latter methods seem particularly indicated.
  • the layer of semiconductor organic matter light-emitting we can also use any appropriate technique, including evaporation processes thermal, soaking in a solution (so-called “dip-coating"), the deposition of a layer of substance, such than a solution of the electroluminescent material, or agents precursors thereof, in a suitable solvent, on the surface of the electron emitting electrode (or, if applicable of the hole emitting electrode), making rotate the substrate (the process known as “spinning” or “spin-coating” so as to obtain a thickness perfectly uniform layer, possibly followed by treatment thermal or chemical to form the film of electroluminescent material proper.
  • the layer of material of the hole-emitting electrode such as gold, tin oxide and mixed oxide of indium and tin
  • a material is used as substrate transparent or translucent and the thicknesses of the layers of material constituting the two electrodes, and those of any auxiliary layers (layers of transport or stop negative or positive charges), so that these layers are all transparent or translucent.
  • auxiliary layers such as reflective layers, forming a mirror, or semi-transparent and / or dielectric layers, in order to direct or reinforce the light emitted by the device certain components, in particular by training microcavities.
  • a second type of multicolored display can be made using elements formed by juxtaposition of a plurality, for example three, of devices according to the invention, these devices comprising layers of material different electroluminescent organic having different light emission wavelengths, operating by mixing colors controlled by variation of voltages applied to the various component devices every element.
  • a third type of multicolored display can be made using elements formed by juxtaposition of a plurality, for example three, of devices according to the invention, these devices comprising layers additional auxiliaries favoring the selection of a narrow wavelength range within the spectrum light emission emitted by the organic layer (s) electroluminescent, working by mixing colors controlled by variation of voltages applied to the different devices making up each element.
  • a thin transparent layer 2 of gallium nitride GaN having a thickness of 10 micrometers is formed on the wafer 1, serving as a substrate, by chemical reaction in the vapor phase between gallium chloride GaCl and ammonia NH 3 at the temperature of 1050 ° C., in the presence helium used as carrier gas, the substrate being maintained at the reaction temperature by means of a susceptor heated by high frequency induction.
  • a carrier gas other than helium, for example nitrogen.
  • gallium chloride instead of gallium chloride, we could also use an organometallic compound of gallium, such as trimethylgallium or triethylgallium.
  • Layer 2 of gallium nitride adheres strongly on the surface of substrate 1. It has a n-type semiconductor character, resulting from vacancies in stoichiometry, in the absence of any doping element.
  • the Layer 2 surface impedance value is approximately 10 ohms.
  • a film 3 of poly [2,5-bis (cholestanoxy) -1,4-phenylenevinylene] (polymer designated by the initials BCHA-PPV) having a thickness of 0.2 micrometer.
  • layer 4 of gold is deposited by vacuum evaporation in a manner known per se, using a classic thermal evaporation device.
  • layer 2 By applying a difference in electrical potential of a few volts between layers 2 and 4 which thus constitute, the negative electrode and the positive electrode respectively device, layer 2 emits electrons which are injected in the polymer film 3 and the layer 4 emits positive charges, generally designated by the term "holes" which are injected, in the opposite direction into film 3.
  • the charges of opposite sign thus injected into the film 3 combine with each other and later decompose into producing an emission of light, in a manner known per se.
  • Current-voltage and current characteristic curves luminous-voltage of the electroluminescent device of FIG. 1 are shown in Figures 4 and 5 respectively.
  • FIG. 2 A second embodiment of the device according to the invention is illustrated in FIG. 2
  • a layer is interposed transparent 6 of material favoring the transport of electrons (this material consisting of 8-hydroxyquinoline aluminum, compound, commonly referred to by the name Alq3) and a transparent layer 7 of material constituting a positive charge barrier layer (this material consisting in 2- (4 biphenyl-5- (tertbutyl-phenyl) 1,3,5-oxadiazole, commonly composed, designated by the name "butyl-PBD”) and, on the other hand, that the hole emitting electrode is consisting of a transparent layer 4a of indium oxide and tin (commercial product designated by ITO name) having a thickness of 0.15 micrometer.
  • Layers 6 and 7 are each 0.02 thick micrometer.
  • a thin and transparent layer 32 of amorphous titanium oxide TiO 2 strongly doped with aluminum is formed on a square glass plate 1 with a side of 1 cm having a thickness of 1 mm.
  • a layer of aluminum 10 nm thick is first evaporated, then a layer of TiO 2 10 nm thick is sprayed with a magnetron, then a new layer of aluminum. 1 nm thick and so on until the total thickness of layer 2 is 50 nm.

Description

La présente invention concerne un dispositif électroluminescent comprenant une couche de matière organique semiconductrice électroluminescente disposée entre une première électrode, constituée par un matériau ayant la propriété d'injecter des électrons dans ladite couche de matière électroluminescente, et une deuxième électrode constituée par un matériau ayant la propriété d'injecter des trous dans cette couche.The present invention relates to a device electroluminescent comprising a layer of organic matter light emitting semiconductor disposed between a first electrode, constituted by a material having the property of injecting electrons into said layer of electroluminescent material, and a second electrode constituted by a material having the property of injecting holes in this layer.

On connaít déjà des dispositifs de ce genre, dans lesquels la matière organique semiconductrice consiste soit en une substance organique monomère, constituée de molécules fluorescentes, telle que l'anthracène, le pérylène et le coronène, ou de molécules d'un colorant organique, soit en un polymère organique conjugué tel que le poly(p-phénylène-vinylène).We already know devices of this kind, in which the semiconductor organic matter consists of either a monomeric organic substance, made up of molecules fluorescent, such as anthracene, perylene and coronene, or molecules of an organic dye, either in a conjugated organic polymer such as poly (p-phenylene-vinylene).

Dans ces dispositifs, l'électrode émettrice d'électrons est, par exemple, constituée par une couche d'un métal choisi parmi l'aluminium, le magnésium et le calcium, ou par une couche d'alliage métallique, tel qu'un alliage de magnésium et d'argent, et l'électrode émettrice de trous est constituée, par exemple, par une couche d'un métal tel que l'or ou par une couche d'oxyde d'étain (SnO2) ou oxyde mixte d'indium et d'étain (ITO).In these devices, the electron-emitting electrode is, for example, constituted by a layer of a metal chosen from aluminum, magnesium and calcium, or by a layer of metallic alloy, such as an alloy of magnesium and silver, and the hole-emitting electrode is constituted, for example, by a layer of a metal such as gold or by a layer of tin oxide (SnO 2 ) or mixed oxide d 'indium and tin (ITO).

Un tel dispositif est décrit dans la demande internationale de brevet publiée sous le numéro WO 90/13148.Such a device is described in the application international patent published under number WO 90/13148.

De tels dispositifs électroluminescents peuvent notamment être utilisés comme diodes électroluminescentes dans des éléments d'affichage, ainsi que pour la fabrication d'écrans plats pour ordinateur portable ou appareil de télévision.Such electroluminescent devices can in particular be used as light emitting diodes in display elements, as well as for the manufacture of screens dishes for laptop or television.

Ces dispositifs présentent l'avantage de permettre aisément la réalisation de grandes surfaces d'affichage ainsi que de se prêter à un ajustement de la longueur d'onde de la lumière émise donc de la couleur d'émission, en choisissant de manière appropriée la matière organique semiconductrice qui constitue la couche électroluminescente parmi le grand nombre de matières connues, qui conviennent à cette fin, ainsi que les multiples combinaisons ou modifications de ces matières à la disposition des spécialistes.These devices have the advantage of allowing easily creating large display areas as well than to lend itself to an adjustment of the wavelength of the therefore emitted light of the emission color, choosing to appropriately the semiconductor organic matter which constitutes the electroluminescent layer among the great number of known materials which are suitable for this purpose, as well as the multiple combinations or modifications of these materials to available to specialists.

D'autre part, ces dispositifs ont, en général, un rendement d'émission lumineuse déjà tout à fait acceptable, dans l'état actuel de la technique, et qui semble susceptible d'améliorations futures à la portée des hommes de métier.On the other hand, these devices have, in general, a light emission efficiency already quite acceptable, in the current state of the art, and which seems likely future improvements within the reach of those skilled in the art.

Selon l'état antérieur de la technique relative aux dispositifs de ce genre, l'électrode injectrice de trous a été réalisée sous forme d'une couche transparente, constituée, par exemple, d'oxyde mixte d'indium et d'étain, l'électrode injectrice d'électrons étant, elle, opaque ou réfléchissante. Des dispositifs de ce type ne peuvent émettre de la lumière que sur une face. Selon l'une des variantes du dispositif décrit dans la demande WO 90/13148, il est cependant mentionné qu'au moins une des couches de contact injectrices de charges, lorsque ces couches sont en or ou en aluminium et n'excédent pas une certaine épaisseur, est transparente ou semi-transparente. Il n'est toutefois pas précisé laquelle de ces couches est transparente ou semi-transparente.According to the prior art relating to devices like this, the hole injector electrode was produced in the form of a transparent layer, constituted, by example, mixed oxide of indium and tin, the electrode being an electron injector, it is opaque or reflective. Devices of this type cannot emit light than on one side. According to one of the variants of the device described in application WO 90/13148, it is however mentioned that at least one of the charge injecting contact layers, when these layers are gold or aluminum and do not exceed not a certain thickness, is transparent or semi-transparent. It is however not specified which of these layers is transparent or semi-transparent.

D'autre part, les dispositifs actuellement connus présentent l'inconvénient d'avoir une durée de vie trop courte pour les applications, industrielles envisagées. Plus précisément, les meilleurs dispositifs connus de ce genre, dans lesquels la couche de matière organique électroluminescente est constituée par une substance organique monomère, ne permettent qu'une durée d'utilisation maximale de l'ordre d'un millier d'heures, en fonctionnement continu, alors que les meilleurs dispositifs connus, dans lesquels la couche de matière organique électroluminescente consiste en un polymère conjugué, ne résistent généralement pas à une durée d'utilisation continue supérieure à une centaine d'heures. On the other hand, the devices currently known have the disadvantage of having too short a lifespan for the industrial applications envisaged. More specifically, the best known devices of this kind, in which the layer of organic matter electroluminescent consists of an organic substance monomer, only allow a maximum duration of use of around a thousand hours, in continuous operation, while the best known devices, in which the layer of electroluminescent organic matter consists of a conjugated polymer, do not generally last continuous use greater than one hundred hours.

L'invention a pour but de fournir un dispositif du genre susmentionné qui soit capable d'émettre de la lumière sur ses deux faces, c'est-à-dire un dispositif électroluminescent dans lequel les deux électrodes placées de part et d'autre de la couche de matière électroluminescente sont transparentes ou translucides.The invention aims to provide a device of the kind mentioned above which is capable of emitting light on its two faces, i.e. an electroluminescent device in which the two electrodes placed on either side of the layer of electroluminescent material are transparent or translucent.

Un autre but de l'invention est de permettre d'améliorer la durée de vie du dispositif.Another object of the invention is to make it possible to improve the life of the device.

A cet effet, le dispositif selon l'invention est caractérisé en ce que ladite première électrode est sous forme d'une couche transparente ou translucide en un matériau semiconducteur de type n choisi parmi les nitrures et les oxydes minéraux.To this end, the device according to the invention is characterized in that said first electrode is in the form a transparent or translucent layer of a material n-type semiconductor chosen from nitrides and mineral oxides.

Avantageusement, le matériau constitutif de l'électrode émettrice d'électrons est choisi parmi le nitrure de gallium GaN, les alliages binaires de nitrure de gallium et nitrure d'indium, de formule générale GaxIn(1-x)N, les alliages ternaires de nitrure de gallium, nitrure d'indium et nitrure d'aluminium, de formule générale GaxAlyIn(1-x-y)N et les mélanges d'au moins deux de ces composés et alliages, où x et y représentent chacun un nombre compris entre 0 et 1, la somme x + y étant au plus égale à 1, le caractère de conductivité n dudit matériau résultant éventuellement d'une lacune de stoechiométrie ou d'un dopage par au moins un élément choisi dans les groupes 4a et 6a de la classification périodique.Advantageously, the material constituting the electron-emitting electrode is chosen from gallium nitride GaN, binary alloys of gallium nitride and indium nitride, of general formula Ga x In ( 1-x ) N, the alloys ternaries of gallium nitride, indium nitride and aluminum nitride, of general formula Ga x Al y In ( 1-xy ) N and mixtures of at least two of these compounds and alloys, where x and y each represent a number between 0 and 1, the sum x + y being at most equal to 1, the conductivity character n of said material possibly resulting from a stoichiometry gap or from doping with at least one element chosen from groups 4a and 6a of the periodic table.

Comme élément dopant, on peut, notamment utiliser l'un des élément suivants: Si, Sn, S, Se et Te.As doping element, one can, in particular use one of the following: Si, Sn, S, Se and Te.

Le matériau semiconducteur de type n susmentionné, notamment le nitrure de gallium et ses alliages, peut être utilisé sous toute forme appropriée, en particulier sous forme monocristalline, polycristalline, nanocristaline ou amorphe, ou encore sous forme d'une superposition de couches de ce type ayant des compositions, donc des valeurs de x ou y, ou des dopages, différents.The aforementioned n-type semiconductor material, in particular gallium nitride and its alloys, can be used in any suitable form, in particular in the form monocrystalline, polycrystalline, nanocrystalline or amorphous, or as a superposition of layers of this type having compositions, so values of x or y, or doping, different.

On peut aussi utiliser comme matériau constitutif de l'électrode émettrice d'électrons un matériau choisi parmi les oxydes de titane TiOx, quelle que soit leur stoechiométrie en oxygène et notamment les phases anatase et rutile sous-stoechiométriques TiO2-y, ainsi que les mélanges d'au moins un oxyde de titane avec au moins un autre oxyde minéral, notamment les matériaux multiphasés tels que les phases de Maneli ou les mélanges multiphasés de plusieurs oxydes accompagnant l'oxyde de titane.One can also use as material constituting the electron-emitting electrode a material chosen from titanium oxides TiO x , whatever their oxygen stoichiometry and in particular the substoichiometric anatase and rutile phases TiO 2-y , as well as mixtures of at least one titanium oxide with at least one other mineral oxide, in particular multiphase materials such as the Maneli phases or multiphase mixtures of several oxides accompanying titanium oxide.

Le caractère injecteur d'électrons de tels matériaux peut éventuellement résulter de l'existence de lacunes de stoechiométrie ou d'un dopage par au moins un élément tel que, par exemple H, Li, Ca, Al, Cs.The electron injecting nature of such materials can possibly result from the existence of gaps in stoichiometry or doping with at least one element such as, for example H, Li, Ca, Al, Cs.

Les oxydes de titane susmentionnés peuvent être utilisés sous toute forme appropriée en particulier sous forme monocristalline, polycristalline, nanocristalline ou amorphe.The above titanium oxides can be used in any suitable form, in particular in the form monocrystalline, polycrystalline, nanocrystalline or amorphous.

Comme matière organique semiconductrice électroluminescente constitutive de la couche électroluminescente, on peut utiliser toute matière appropriée, notamment celles constituées par les substances déjà utilisées à cette fin conformément à l'art antérieur, en particulier, des polymères conjugués, tel que le poly(p-phénylène-vinylène), couramment désigné par l'abréviation PPV ou le poly p-phénylene, PPP, ou encore le polythiophène, PT, ceux dans lesquels le noyau phényl ou thiophène portent un ou plusieurs substituants tels qu'un groupe alkyle, un groupe alkoxy, un halogène ou un groupe nitro, ainsi que des polymères conjugués tels que le poly(4,4'-diphénylène-diphénylvinylène), couramment désigné par l'abréviation PDPV; le poly (1,4-phénylène-1-phényliny-ène); le poly(1,4- phénylène-diphényvinylène); des polymères du type poly (3-alkylthiofène) ou poly(3-alkylpyrrole), des polymères du type poly (2,5-dialkoxy-p-phénylènevinylène), ou encore des copolymères ou des mélanges de tels polymères conjugués.As an electroluminescent semiconductor organic matter constituting the electroluminescent layer, we can use any appropriate material, especially those made up of substances already used for this purpose in accordance with the prior art, in particular, polymers conjugates, such as poly (p-phenylene-vinylene), commonly designated by the abbreviation PPV or poly p-phenylene, PPP, or still the polythiophene, PT, those in which the nucleus phenyl or thiophene carry one or more substituents such as an alkyl group, an alkoxy group, a halogen or a nitro group, as well as conjugated polymers such as poly (4,4'-diphenylene-diphenylvinylene), commonly known by the abbreviation PDPV; poly (1,4-phenylene-1-phenylinyene); poly (1,4-phenylene-diphenyvinylene); polymers of the poly (3-alkylthiofen) or poly (3-alkylpyrrole) type, polymers of the poly (2,5-dialkoxy-p-phenylenevinylene) type, or further copolymers or blends of such polymers conjugates.

L'utilisation de polymères conjugués dérivés des polymères connus, tels que ceux qui ont été mentionnés ci-dessus, par greffage aux extrémités des chaínes de polymères de groupement ayant la propriété de renforcer l'adhésion de la couche de polymère conjugué électroluminescent sur la surface des électrodes, notamment l'électrode émettrice d'électrons et plus particulièrement sur une couche de nitrure de gallium ou d'oxyde de titane est particulièrement avantageuse.The use of conjugated polymers derived from known polymers, such as those which have been mentioned above, by grafting at the ends of the polymer chains group with the property of strengthening the membership of the electroluminescent conjugated polymer layer on the surface electrodes, in particular the electron-emitting electrode and more particularly on a layer of gallium nitride or titanium oxide is particularly advantageous.

Par exemple, on peut utiliser des polymères dérivés de poly(phénylène) dont les extrémités de chaíne ont l'une des formules suivantes:

Figure 00060001
Figure 00060002
Figure 00060003
Figure 00060004
For example, one can use polymers derived from poly (phenylene) whose chain ends have one of the following formulas:
Figure 00060001
Figure 00060002
Figure 00060003
Figure 00060004

On peut également, utiliser, comme matière organique électroluminescente constitutive de la couche électroluminescente, une substance monomère, un colorant ou pigment organique, cette substance ou ce colorant ou pigment pouvant notamment être choisi parmi celles ou ceux qui conviennent à l'utilisation dans les dispositifs électroluminescents de l'art antérieur. Ces colorants peuvent être aussi fonctionnalisés de façon à adhérer mieux à l'électrode de l'invention.It is also possible to use, as organic matter electroluminescent constituting the layer electroluminescent, a monomeric substance, a dye or organic pigment, this substance or this dye or pigment can in particular be chosen from those who suitable for use in devices prior art light emitting lamps. These dyes can also be functionalized so as to adhere better to the electrode of the invention.

Comme matériau constitutif de l'électrode émettrice de trous, on peut utiliser les mêmes matériaux que ceux qui sont utilisés dans les dispositifs électroluminescents conformes à la technique antérieure, en particulier de l'or, de l'oxyde d'étain SnO2 ou encore de l'oxyde mixte d'indium et d'étain (en particulier le produit commercial connu sous la désignation de ITO), sous forme d'une couche transparente.As the constituent material of the hole-emitting electrode, the same materials as those used in light-emitting devices according to the prior art can be used, in particular gold, tin oxide SnO 2 or else mixed oxide of indium and tin (in particular the commercial product known by the designation ITO), in the form of a transparent layer.

On peut éventuellement intercaler, entre l'électrode émettrice d'électrons et la couche organique semiconductrice électroluminescente, une ou plusieurs couches de matière facilitant le transport des charges négatives, cette matière consistant, par exemple, dans le composé 8-hydroxyquinoline aluminium (désigné habituellement par le terme Alq3), ainsi qu'une ou plusieurs couches de matière ayant la propriété de bloquer le passage de charges positives (couche d'arrêt de trous), une telle matière étant, par exemple, constituée du composé 2-(4-biphényl-5-tertbutyl-phényl)-1,3,5-oxadiazole (composé connu sous la dénomination "Butyl-PBD").It is possible to interpose, between the electrode electron emitter and the organic semiconductor layer electroluminescent, one or more layers of material facilitating the transport of negative charges, this material consisting, for example, in the compound 8-hydroxyquinoline aluminum (usually referred to as Alq3), as well that one or more layers of material having the property of block the passage of positive charges (barrier layer of holes), such material being, for example, made of compound 2- (4-biphenyl-5-tertbutyl-phenyl) -1,3,5-oxadiazole (compound known under the name "Butyl-PBD").

D'autre part, on peut aussi, éventuellement, intercaler, entre l'électrode émettrice de trous et la couche organique semiconductrice électroluminescente, une ou plusieurs couches de matière facilitant le transport des charges positives. Une telle matière peut être, par exemple, constituée d'un composé du type diphényl-diméthylphénylamine, connus sous la désignation TPD. On the other hand, we can also, if necessary, interpose, between the hole emitting electrode and the organic layer electroluminescent semiconductor, one or more layers of material facilitating the transport of positive charges. A such material can be, for example, made of a compound of the diphenyl-dimethylphenylamine type, known as TPD designation.

Pour la fabrication du dispositif électroluminescent selon l'invention, on peut utiliser tout procédé approprié, en particulier les techniques employées pour la fabrication des dispositifs de l'art antérieur.For the manufacture of the electroluminescent device according to the invention, any suitable method can be used, in in particular the techniques used for the manufacture of prior art devices.

Ainsi, pour former la couche de nitrure telle que définie ci-dessus, notamment le nitrure de gallium, constituant l'électrode émettrice d'électrons, on peut employer les méthodes, connues en soi, de dépôt par pulvérisation thermique, en particulier au moyen d'une torche à plasma, ou encore les techniques de dépôt à partir de la phase liquide ainsi que les procédés de dépôt par réaction chimique en phase vapeur. Ces derniers procédés semblent donner les meilleurs résultats.So, to form the nitride layer as defined above, in particular gallium nitride, constituting the electron emitting electrode, we can use the methods, known per se, of spray deposition thermal, in particular by means of a plasma torch, or still the deposition techniques from the liquid phase as well as chemical phase reaction deposition processes steam. These latter processes seem to give the best results.

Plus particulièrement, on peut avantageusement mettre en oeuvre pour former une couche mince de nitrure de gallium, un procédé de dépôt par réaction chimique en phase vapeur dans des conditions opératoires identiques ou similaires à celles qui ont été décrites dans la publication de M. Ilegems, Journal of Crystal Growth, 13/14, p. 360 (1972).More particularly, it is advantageously possible to works to form a thin layer of gallium nitride, a chemical vapor deposition process in operating conditions identical or similar to those which were described in the publication by M. Ilegems, Journal of Crystal Growth, 13/14, p. 360 (1972).

De préférence, on forme d'abord la couche de composé minéral semiconducteur de type n constitutive de l'électrode émettrice d'électrons, sur la surface du substrat servant de support au dispositif électroluminescent, ce substrat étant avantageusement constitué par un matériau isolant transparent tel qu'une plaquette de saphir ou de quartz.Preferably, the compound layer is first formed n-type semiconductor mineral constituting the electrode electron emitter, on the surface of the substrate serving support for the electroluminescent device, this substrate being advantageously constituted by a transparent insulating material such as a sapphire or quartz plate.

Toutefois, il est également possible de former d'abord sur le substrat la couche de matériau constitutif de l'électrode émettrice de trous.However, it is also possible to train first on the substrate the layer of material constituting the hole emitting electrode.

Pour former la couche d'oxyde de titane telle que définie ci-dessus, on peut utiliser les méthodes connues en soi d'oxydation du titane, des méthodes de polymérisation sol-gel à partir de précurseurs organiques, des méthodes de pulvérisation à l'aide d'un plasma ou d'un bombardement ionique. Ces dernières méthodes semblent particulièrement indiquées.To form the titanium oxide layer as defined above, the methods known per se can be used of titanium oxidation, sol-gel polymerization methods from organic precursors, methods of plasma spraying or bombardment ionic. These latter methods seem particularly indicated.

Pour former la couche de matière organique semiconductrice électroluminescente, on peut également utiliser toute technique appropriée, notamment les procédés d'évaporation thermique, le trempage dans une solution (procédés dits de "dip-coating"), le dépôt d'une couche de substance, telle qu'une solution de la matière électroluminescente, ou d'agents précurseurs de celle-ci, dans un solvant approprié, sur la surface de l'électrode émettrice d'électrons (ou, le cas échéant, de l'électrode émettrice de trous), en faisant tourner le substrat (procédé dit de la "tournette" ou "spin-coating" de façon à obtenir une épaisseur parfaitement uniforme de cette couche, suivi éventuellement d'un traitement thermique ou chimique permettant de former la pellicule de matière électroluminescente proprement dite.To form the layer of semiconductor organic matter light-emitting, we can also use any appropriate technique, including evaporation processes thermal, soaking in a solution (so-called "dip-coating"), the deposition of a layer of substance, such than a solution of the electroluminescent material, or agents precursors thereof, in a suitable solvent, on the surface of the electron emitting electrode (or, if applicable of the hole emitting electrode), making rotate the substrate (the process known as "spinning" or "spin-coating" so as to obtain a thickness perfectly uniform layer, possibly followed by treatment thermal or chemical to form the film of electroluminescent material proper.

Pour former la couche de matériau constitutif de l'électrode émettrice de trous, tel que l'or, l'oxyde d'étain et l'oxyde mixte d'indium et d'étain, on peut également procéder de manière connue en soi, par exemple, évaporation sous pression réduite ou par pulvérisation thermique, évaporation sous vide par bombardement au moyen d'un faisceau d'électrons, d'ions, etc.To form the layer of material of the hole-emitting electrode, such as gold, tin oxide and mixed oxide of indium and tin, we can also proceed in a manner known per se, for example, evaporation under reduced pressure or by thermal spraying, vacuum evaporation by bombardment by means of a beam electrons, ions, etc.

Avantageusement, on utilise comme substrat une matière transparente ou translucide et on règle les épaisseurs des couches de matière constitutrices des deux électrodes, et celles des couches auxiliaires éventuelles (couches de transport ou d'arrêt des charges négatives ou positives), de façon que ces couches soient toutes transparentes ou translucides.Advantageously, a material is used as substrate transparent or translucent and the thicknesses of the layers of material constituting the two electrodes, and those of any auxiliary layers (layers of transport or stop negative or positive charges), so that these layers are all transparent or translucent.

De cette façon, on peut réaliser un dispositif électroluminescent émettant de la lumière sur ses deux faces. In this way, we can make a device electroluminescent emitting light on both sides.

On peut également de manière connue en soi éventuellement former, sur les faces externes du dispositif selon l'invention, une ou plusieurs couches auxiliaires supplémentaires telles que des couches réfléchissantes, formant miroir, ou des couches semi-transparentes et/ou diélectriques, afin de diriger la lumière émise par le dispositif ou d'en renforcer certaines composantes, notamment par formation de microcavités.It is also possible in a manner known per se forming, on the external faces of the device according to the invention, one or more additional auxiliary layers such as reflective layers, forming a mirror, or semi-transparent and / or dielectric layers, in order to direct or reinforce the light emitted by the device certain components, in particular by training microcavities.

On peut, en outre, en superposant une pluralité, par exemple trois, de dispositifs selon l'invention, émettant chacun de la lumière sur ses deux faces, ces dispositifs comportant des couches de matières organiques électroluminescentes différentes ayant des longueurs d'ondes d'émission lumineuse différentes, fabriquer un dispositif d'affichage multicolore, fonctionnant par mélanges de couleurs commandés par variation des tensions appliquées aux différentes couches de ce dispositif.It is also possible, by superimposing a plurality, by example three, of devices according to the invention, emitting each light on both sides, these devices with layers of organic material different light emitting ones having wavelengths different light emission, make a device multicolor display, working by mixing colors controlled by varying the voltages applied to different layers of this device.

Un deuxième type d'affichage multicolore peut être réalisé à l'aide d'éléments formés par juxtaposition d'une pluralité, par exemple trois, de dispositifs selon l'invention, ces dispositifs comportant des couches de matière organiques électroluminescentes différentes ayant des longueurs d'onde d'émission lumineuse différentes, fonctionnant par mélanges de couleurs commandés par variation de tensions appliqués aux différents dispositifs composant chaque élément.A second type of multicolored display can be made using elements formed by juxtaposition of a plurality, for example three, of devices according to the invention, these devices comprising layers of material different electroluminescent organic having different light emission wavelengths, operating by mixing colors controlled by variation of voltages applied to the various component devices every element.

Un troisième type d'affichage multicolore peut être réalisé à l'aide d'éléments formés par juxtaposition d'une pluralité, par exemple trois, de dispositifs selon l'invention, ces dispositifs comportant des couches auxiliaires supplémentaires favorisant la sélection d'un domaine de longueurs d'ondes étroit à l'intérieur du spectre d'émission lumineux émis par la ou les couches organiques électroluminescentes, fonctionnant par mélanges de couleurs commandés par variation de tensions appliqués aux différents dispositifs composant chaque élément.A third type of multicolored display can be made using elements formed by juxtaposition of a plurality, for example three, of devices according to the invention, these devices comprising layers additional auxiliaries favoring the selection of a narrow wavelength range within the spectrum light emission emitted by the organic layer (s) electroluminescent, working by mixing colors controlled by variation of voltages applied to the different devices making up each element.

L'invention sera encore mieux comprise grâce à la description détaillée, qui va suivre, d'exemples non limitatifs de la réalisation de formes d'exécution du dispositif selon l'invention, en se référant au dessin annexé, dans lequel:

  • La figure 1 est une vue schématique, en coupe, d'une première forme d'exécution du dispositif à base de GaN;
  • La figure 2 est une vue schématique, en coupe, similaire à celle de la Figure 1, d'une deuxième forme d'exécution du dispositif à base de GaN;
  • La figure 3 est une vue schématique, en coupe, d'une forme d'exécution du dispositif à base de TiO2.
  • Les figures 4 et 5 sont des diagrammes montrant, respectivement, la courbe caractéristique courant-tension et la courbe caractéristique intensité lumineuse-tension du dispositif électroluminescent illustré à la figure 1.
  • Les figures 6 et 7 sont des diagrammes montrant respectivement la courbe caractéristique courant-tension et la courbe caractéristique intensité lumineuse-tension du dispositif illustré à la figure 3.
    • The invention will be better understood thanks to the detailed description which follows of nonlimiting examples of the embodiment of embodiments of the device according to the invention, with reference to the appended drawing, in which:
  • Figure 1 is a schematic sectional view of a first embodiment of the GaN-based device;
  • Figure 2 is a schematic sectional view, similar to that of Figure 1, of a second embodiment of the device based on GaN;
  • FIG. 3 is a schematic view, in section, of an embodiment of the device based on TiO 2 .
  • FIGS. 4 and 5 are diagrams showing, respectively, the current-voltage characteristic curve and the light intensity-voltage characteristic curve of the electroluminescent device illustrated in FIG. 1.
  • FIGS. 6 and 7 are diagrams respectively showing the current-voltage characteristic curve and the light intensity-voltage characteristic curve of the device illustrated in FIG. 3.

    • Exemple 1 (Fabrication d'une première forme d'exécution du dispositif selon l'invention, telle qu'illustrée à la Fig. 1) Example 1 (Manufacture of a first embodiment of the device according to the invention, as illustrated in FIG. 1)

    Sur une plaquette 1 de saphir carrée de 1 cm de côté, ayant une épaisseur de 0,5 mm, on forme une couche 2 mince transparente de nitrure de gallium GaN ayant une épaisseur de 10 micromètres. A cet effet, on dépose la couche 2 de nitrure de gallium sur la plaquette 1, servant de substrat, par réaction chimique en phase vapeur entre le chlorure de gallium GaCl et l'ammoniac NH3 à la température de 1050°C, en présence d'hélium utilisé comme gaz porteur, le substrat étant maintenu à la température de réaction au moyen d'un suscepteur chauffé par induction à haute fréquence. On pourrait également effectuer le chauffage par radiation thermique et utiliser un autre gaz porteur que l'hélium, par exemple l'azote.On a square sapphire plate 1 with a side of 1 cm, having a thickness of 0.5 mm, a thin transparent layer 2 of gallium nitride GaN having a thickness of 10 micrometers is formed. To this end, the layer 2 of gallium nitride is deposited on the wafer 1, serving as a substrate, by chemical reaction in the vapor phase between gallium chloride GaCl and ammonia NH 3 at the temperature of 1050 ° C., in the presence helium used as carrier gas, the substrate being maintained at the reaction temperature by means of a susceptor heated by high frequency induction. One could also carry out heating by thermal radiation and use a carrier gas other than helium, for example nitrogen.

    Au lieu de chlorure de gallium, on pourrait également utiliser un composé organométallique du gallium, tel que le triméthylgallium ou le triéthylgallium.Instead of gallium chloride, we could also use an organometallic compound of gallium, such as trimethylgallium or triethylgallium.

    La couche 2 de nitrure de gallium, ainsi obtenue, adhère fortement sur la surface du substrat 1. Elle présente un caractère de semiconducteur de type n, résultant de lacunes de stoechiométrie, en l'absence de tout élément de dopage. La valeur de l'impédance de surface de la couche 2 est d'environ 10 ohms.Layer 2 of gallium nitride, thus obtained, adheres strongly on the surface of substrate 1. It has a n-type semiconductor character, resulting from vacancies in stoichiometry, in the absence of any doping element. The Layer 2 surface impedance value is approximately 10 ohms.

    On forme ensuite, sur la surface libre de la couche de nitrure de gallium 2, une pellicule 3 de poly[2,5-bis(cholestanoxy)-1,4-phénylènevinylène] (polymère désigné par les initiales BCHA-PPV) ayant une épaisseur de 0.2 micromètre. A cet effet, on fait tomber sur la surface de la couche 2 de nitrure de gallium, une goutte de solution de BCHA-PPV dans du xylène (concentration de cette solution 10 g/litre) et l'on répartit la couche de solution sur cette surface de manière à lui conférer une épaisseur uniforme en faisant tourner la plaquette 1 autour d'un axe vertical, en maintenant la surface libre de la couche 2 orientée vers le haut dans un plan horizontal, avec une vitesse de 2000 tours par minute environ (procédé dit de "dépôt à la tournette" également désigné par le terme anglais de "spin-coating"). On chauffe ensuite pendant 1 heure à une température de 100°C la plaquette 1, ainsi revêtue de la couche 2 et de la solution de BCHA-PPV, dans une étuve sous pression réduite de gaz neutre (argon). Ce traitement provoque l'évaporation du xylène et la formation d'une pellicule 3 de BCHA-PPV dure et adhérant bien sur la surface libre de la couche 2 de nitrure de gallium; cette pellicule ayant une épaisseur de 0,2 micromètre.Then, on the free surface of the layer of gallium nitride 2, a film 3 of poly [2,5-bis (cholestanoxy) -1,4-phenylenevinylene] (polymer designated by the initials BCHA-PPV) having a thickness of 0.2 micrometer. For this purpose, we drop onto the surface of layer 2 of gallium nitride, a drop of BCHA-PPV solution in xylene (concentration of this solution 10 g / liter) and distributes the layer of solution on this surface so that give it a uniform thickness by rotating the plate 1 around a vertical axis, maintaining the surface free from layer 2 facing up in a plane horizontal, with a speed of around 2000 rpm (process called "spinning deposit" also designated by the English term for "spin-coating"). We then heat for 1 hour at a temperature of 100 ° C. the wafer 1, thus coated with layer 2 and the BCHA-PPV solution, in an oven under reduced pressure of neutral gas (argon). This treatment causes xylene to evaporate and form of a film 3 of BCHA-PPV hard and adhering well on the free surface of layer 2 of gallium nitride; this 0.2 micrometer thick film.

    Finalement, on recouvre la surface libre de la couche 3 d'une couche mince 4 d'or ayant une épaisseur de 0,3 micromètre. A cet effet, on dépose la couche 4 d'or par évaporation sous vide de manière connue en soi, en utilisant un dispositif classique d'évaporation thermique.Finally, we cover the free surface of layer 3 of a thin layer 4 of gold having a thickness of 0.3 micrometer. For this purpose, layer 4 of gold is deposited by vacuum evaporation in a manner known per se, using a classic thermal evaporation device.

    Pour constituer un dispositif électroluminescent, il suffit de relier les couches 2 et 4 recouvrant la plaquette 1 et disposées comme illustré à la Fig. 1 de part et d'autre de la pellicule de polymère électroluminescent 3, à la borne négative et à la borne positive d'une source de tension électrique 5.To constitute an electroluminescent device, it just connect layers 2 and 4 covering the wafer 1 and arranged as illustrated in FIG. 1 on either side of the electroluminescent polymer film 3, at the terminal negative and to the positive terminal of a voltage source electric 5.

    En appliquant une différence de potentiel électrique de quelques volts entre les couches 2 et 4 qui constituent ainsi, respectivement l'électrode négative et l'électrode positive du dispositif, la couche 2 émet des électrons qui sont injectés dans la pellicule de polymère 3 et la couche 4 émet des charges positives, désignées généralement par le terme "trous" qui sont injectés, en sens inverse dans la pellicule 3. Les charges de signe opposé ainsi injectées dans la pellicule 3 se combinent entre elles et se décomposent ultérieurement en produisant une émission de lumière, de manière connue en soi. Les courbes caractéristiques courant-tension et intensité lumineuse-tension du dispositif électroluminescent de la Fig. 1 sont indiquées respectivement aux Figures 4 et 5.By applying a difference in electrical potential of a few volts between layers 2 and 4 which thus constitute, the negative electrode and the positive electrode respectively device, layer 2 emits electrons which are injected in the polymer film 3 and the layer 4 emits positive charges, generally designated by the term "holes" which are injected, in the opposite direction into film 3. The charges of opposite sign thus injected into the film 3 combine with each other and later decompose into producing an emission of light, in a manner known per se. Current-voltage and current characteristic curves luminous-voltage of the electroluminescent device of FIG. 1 are shown in Figures 4 and 5 respectively.

    Exemple 2Example 2

    Une deuxième forme d'exécution du dispositif selon l'invention est illustrée à la Fig. 2A second embodiment of the device according to the invention is illustrated in FIG. 2

    Cette forme d'exécution est en tout point similaire à celle de la Fig. 1 et en diffère uniquement, d'une part, en ce que, entre la couche 2 de nitrure de gallium et la couche 3 de matière électroluminescente, sont intercalées une couche transparente 6 de matière favorisant le transport des électrons (cette matière consistant en 8-hydroxyquinoline aluminium, composé, couramment désigné par la dénomination Alq3) et une couche transparente 7 de matière constituant une couche d'arrêt de charges positives (cette matière consistant en 2-(4 biphényl-5-(tertbutyl-phényl) 1,3,5-oxadiazole, composé couramment, désigné par la dénomination "butyl-PBD") et, d'autre part, en ce que l'électrode émettrice de trous est constituée par une couche transparente 4a d'oxyde d'indium et d'étain (produit commercial désigné par la dénomination ITO) ayant une épaisseur de 0,15 micromètre.This form of execution is in every respect similar to that of FIG. 1 and differs from it only, on the one hand, in that that between layer 2 of gallium nitride and layer 3 of electroluminescent material, a layer is interposed transparent 6 of material favoring the transport of electrons (this material consisting of 8-hydroxyquinoline aluminum, compound, commonly referred to by the name Alq3) and a transparent layer 7 of material constituting a positive charge barrier layer (this material consisting in 2- (4 biphenyl-5- (tertbutyl-phenyl) 1,3,5-oxadiazole, commonly composed, designated by the name "butyl-PBD") and, on the other hand, that the hole emitting electrode is consisting of a transparent layer 4a of indium oxide and tin (commercial product designated by ITO name) having a thickness of 0.15 micrometer.

    Les couches 6 et 7 ont chacune une épaisseur de 0,02 micromètre.Layers 6 and 7 are each 0.02 thick micrometer.

    Exemple 3 (Fabrication d'une troisième forme d'exécution du dispositif selon l'invention, telle qu'illustrée à la figure 3). Example 3 (Manufacture of a third embodiment of the device according to the invention, as illustrated in Figure 3).

    Sur une plaquette 1 de verre carrée de 1 cm de côté ayant une épaisseur de 1 mm, on forme une couche 32 mince et transparente d'oxyde de titane amorphe TiO2 fortement dopé d'aluminium. A cet effet, on évapore d'abord une couche d'aluminium de 10 nm d'épaisseur, puis on pulvérise à l'aide d'un magnetron une couche de TiO2 de 10 nm d'épaisseur puis une nouvelle couche d'aluminium de 1 nm d'épaisseur et ainsi de suite jusqu'à ce que l'épaisseur totale de la couche 2 soit de 50 nm. Une fois l'opération finie et après un traitement thermique d'homogénéisation à 300°C pendant une heure, sous atmosphère d'oxygène, on constate que l'aluminium s'est allié à l'oxyde de titane de telle sorte que la couche finale de TiO2 allié soit transparente et présente une résistance de l'ordre de 100 ohms, pour un élément de surface carré.On a square glass plate 1 with a side of 1 cm having a thickness of 1 mm, a thin and transparent layer 32 of amorphous titanium oxide TiO 2 strongly doped with aluminum is formed. To this end, a layer of aluminum 10 nm thick is first evaporated, then a layer of TiO 2 10 nm thick is sprayed with a magnetron, then a new layer of aluminum. 1 nm thick and so on until the total thickness of layer 2 is 50 nm. Once the operation is finished and after a homogenization heat treatment at 300 ° C. for one hour, under an oxygen atmosphere, it is found that the aluminum has alloyed with the titanium oxide so that the layer final TiO 2 alloy is transparent and has a resistance of the order of 100 ohms, for a square surface element.

    On forme ensuite à la tournette, tout comme dans l'exemple 1 une couche 3 de polymère électroluminescent BCHA-PPV. We then train on the spinner, just like in Example 1 a layer 3 of BCHA-PPV electroluminescent polymer.

    Finalement, on dispose sur la surface libre de la couche 3 une mince couche 4a d'ITO obtenue de manière connue en soi par pulvérisation d'une cible d'ITO par bombardement ionique.Finally, we have on the free surface of the layer 3 a thin layer 4a of ITO obtained in a manner known per se by spraying an ITO target by ion bombardment.

    L'utilisation de ce dispositif électroluminescent est en tout point similaire à celle du dispositif de l'exemple 1. Les courbes caractéristiques courant-tension et intensité lumineuse-tension du dispositif électroluminescent illustré à la figure 3 sont indiquées, respectivement, aux figures 6 et 7.The use of this electroluminescent device is in any point similar to that of the device of example 1. The current-voltage and current characteristic curves light-voltage of the electroluminescent device illustrated in Figure 3 are shown, respectively, in Figures 6 and 7.

    Claims (3)

    1. An electroluminescent device, comprising a layer of electroluminescent semiconductive organic material, arranged between a first electrode, constituted by a material having the property of injecting electrons into the said layer of electroluminescent material, and a second electrode, constituted by a layer of electrically conductive material having the property of injecting holes into the layer of electroluminescent material, characterised in that the said first electrode is in the form of a transparent or translucent layer of a type n semiconductor material chosen from among mineral nitrides.
    2. A device according to claim 1, characterised in that the said semiconductor material is chosen from among gallium nitride GaN, binary alloys of gallium nitride and indium nitride, of the general formula GaxIn(1-x)N, binary alloys of gallium nitride and aluminium nitride and ternary alloys of gallium nitride, indium nitride, and aluminium nitride, of the general formula GaxAlyIn(1-x-y)N, and mixtures of at least two of these compounds and alloys, where x and y each represent a number between 0 and 1, the total of x + y being at the most equal to 1.
    3. A device according to claim 2, characterised in that gallium nitride is in the sub-stoichiometric state or in the state of being doped by at least one element chosen from among groups 4a and 6a of the periodic classification table.
    EP97908105A 1996-04-03 1997-04-02 Electroluminescent device Expired - Lifetime EP0891686B1 (en)

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    PCT/CH1997/000133 WO1997038558A1 (en) 1996-04-03 1997-04-02 Electroluminescent device

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    US6208074B1 (en) 2001-03-27
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    DE69700602D1 (en) 1999-11-11
    EP0891686A1 (en) 1999-01-20

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