FR3032065A1 - METHOD FOR PRODUCING A SPRAY CONTACT - Google Patents

Abstract

The present invention relates to a method for producing an organic electroluminescent diode comprising a step of forming a stack of layers on a substrate (100); said stack comprising, successively and in order, a first electrode (200), an organic layer (300), a second electrode (400). The method comprises, successively, a step of forming a barrier layer (500), configured so that the barrier layer (500) overlies the stack of layers, and a step of implanting at least a first portion (510) of the barrier layer (500) and at least a second portion (520) of the barrier layer (500); the metallization step being shaped to render at least partially conductive the first portion (510) and the second portion (520) of the barrier layer (500).

Description

FIELD OF THE INVENTION The present invention relates to the field of lighting and in particular the use of organic light-emitting diodes which, when powered by an electric current, emit their own light. The present invention receives for advantageous application a method of producing such an organic light-emitting diode. BACKGROUND ART The light-emitting diode, better known by the acronym LED in English for "Light Emitting Diode", is a semiconductor with physical properties such that the light-emitting diode has the ability to directly convert electricity into light, while being unparalleled in terms of energy efficiency. Light-emitting diode illumination allows a homogeneous distribution of the light beam; this lighting is particularly close to the light of day. It is these advantageous characteristics that have attracted designers to take an increasing interest in light-emitting diodes for automotive applications, for example, or in the field of lighting. These light sources also represent excellent opportunities for "designers". For example, it is possible to combine several diodes in order to create different shapes, luminance sets (the organic-type light-emitting diodes having, for example, a lower luminous radiation than that of the other diodes) and thus to obtain original visual effects. .

Nevertheless, current technologies have limitations. Organic light-emitting diodes in particular have a constraining manufacturing process because of the high sensitivity to water and air of the organic layer, thereby requiring protection by encapsulation of this layer. On the other hand, arrangements must be made to avoid short circuits; the production of light sources of organic electroluminescent diode type in large size requires for example a separation of two electrodes.

Currently, the organic layers are thermally deposited through a common stencil and serve in other words to separate the anode and the cathode. However, one of the disadvantages is that the organic layer is not fully protected by the cathode and is, therefore, particularly sensitive to degradation as well as oxidation. In terms of manufacturing method, the positioning of the various layers forming the diode requires a particular machining of the stencils used during masking steps.

One solution to protect the organic layers in particular is to deposit a barrier layer so as to encapsulate the stack of layers (anode, organic layer, cathode) forming the organic light-emitting diode. To do this, it has been demonstrated that the technique of deposition of atomic monolayers (ALD in English for "Atomic Layer 15 Deposition") makes it possible to produce a barrier layer, preferably formed of a material chosen from aluminum oxide. (A1203), silicon dioxide (SiO2) or titanium dioxide (TiO2), of excellent quality, typically between 10 and 100 nm thick. Nevertheless, one of the disadvantages of the ALD deposition technique is the difficulty in performing a masking step 20 to save the electrical contacts (typically electrode contact pickups: anode and cathode) of the organic light-emitting diodes. In fact, the contacts are not illuminated and are used for the external electrical connection to the organic light emitting diode; they should therefore not be covered by a barrier layer; said barrier layer being electrically insulating. It is however possible to selectively remove the barrier layer for example by chemical etching, mechanical or laser ablation. However, these shrinkage techniques are said to be relatively aggressive with respect to underlying layers considered sensitive to water and air (eg, organic layers) and are, therefore, poorly compatible with the process. embodiment of organic light emitting diodes.

Given the constraints related to the manufacturing process of light-emitting diodes, the present invention proposes a simplified and less expensive method, allowing the realization of an organic light-emitting diode having a better encapsulation of the organic layer, while promoting a better luminous homogeneity of said organic electroluminescent diode. SUMMARY OF THE INVENTION The present invention relates to a method of producing an organic electroluminescent diode comprising a step of forming a stack of layers on a substrate; said stack comprising, successively and in order, a first electrode deposited on the substrate, one or more organic layers deposited in contact with at least a part of the first electrode, a second electrode deposited in contact with at least one part of the organic layer; the first electrode comprising an overflowing portion not covered either by the organic layer or by the second electrode, and a step of forming a barrier layer made of an electrically insulating material, said step being configured so that the barrier layer covers the stack of layers. The method also comprises a step of implanting electrically conductive atoms in the entire thickness of a first portion of the barrier layer and a second portion of the barrier layer, so as to establish electrical continuity between a first face and a second face of each of the first and second portions of the barrier layer, said first and second faces being opposed; said first face of the first portion being positioned to be in direct contact with the protruding portion of the first electrode and said first face of the second portion being positioned to be in direct contact with the second electrode.

The present invention also relates to an organic electroluminescent diode comprising a stack of layers on a substrate; said stack comprising, successively and in order, a first electrode deposited on the substrate, one or more organic layers deposited in contact with at least a part of the first electrode, a second electrode deposited in contact with at least a part of the organic layer; the first electrode comprising an overflowing portion not covered either by the second electrode or by the organic layer, and comprising a barrier layer made of an electrically insulating material, said layer being shaped to cover the stack of layers. The diode is characterized in that said barrier layer comprises a first portion and a second portion; said portions comprising electrically conductive atoms throughout their entire thickness so as to provide electrical continuity between a first face and a second face of each of the first and second portions of the barrier layer; said first and second faces being opposed; said first face of the first portion being positioned to be in direct contact with the protruding portion of the first electrode and said first face of the second portion being positioned to be in direct contact with the second electrode. Thus, the technical effect of the present invention is to provide a thin-film encapsulation solution of the organic light-emitting diode, a guarantee of reliability regarding the electrical conductivity from the diode electrodes, as well as luminous homogeneity. said diode, while avoiding the use of a step of removing the barrier layer; said removal being able to cause degradations of the sensitive layers such as the organic layer. In this way, the layers present in the organic light-emitting device, known to be particularly sensitive to water and oxygen, are protected by the means used.

BRIEF INTRODUCTION OF THE FIGURES Other features, objects and advantages of the present invention will become apparent upon reading the following detailed description, with reference to the accompanying drawings, given by way of nonlimiting example, and in which: - Figure 1 illustrates a schematic longitudinal sectional view of a stack on a substrate of different layers, forming an organic light emitting diode according to the prior art. FIG. 2 illustrates a schematic view in longitudinal section of a stack on a substrate of different layers, forming an organic light-emitting diode; said stack being covered with a barrier layer. - Figure 3 illustrates a schematic longitudinal sectional view of said stack; metal contacts being made at each of the 10 electrodes forming the diode. For the sake of clarity, the elements in the figures are not represented to scale. DETAILED DESCRIPTION It is pointed out that in the context of the present invention, the term "on" does not necessarily mean "in contact with". Thus, for example, the deposition of a layer on another layer does not necessarily mean that the two layers are directly in contact with each other but that means that one of the layers at least partially covers the other being either directly in contact with it, or being separated from it by a film, yet another layer or another element. It is also specified that a layer may comprise a plurality of layers. On the other hand, the term "layer" does not necessarily mean a full plate distribution on the substrate.

Before going into detail of preferred embodiments of the invention with reference to the drawings in particular, other optional features of the invention, which can be implemented in combination in any combination or alternatively, are shown below: The implantation step comprises implantation of metal atoms in the first portion of the barrier layer and in the second portion of the barrier layer; the implantation is advantageously carried out by cathodic sputtering so as to make the metal atoms migrate in the entirety of the thickness of the first and second portions of the barrier layer. The implantation step is performed by sputtering. In another embodiment, the implantation step is performed by ion deposition. The implantation step comprises the formation of at least a first metal layer in direct contact with the second face of the first portion of the barrier layer and the formation of at least one second metal layer in direct contact with the second face the second portion of the barrier layer; so that the first metal layer and the second metal layer are in electrical continuity respectively with the first portion and the second portion of the barrier layer. Prior to the implantation step, a step is performed to mask the barrier layer so as to expose only the second face of the first portion and the second face of the second portion of the barrier layer. The step of forming the barrier layer is carried out by depositing atomic layers.

The step of forming the stack is performed so that the second electrode comprises an overflowing portion covering neither the first electrode nor the organic layer. The implantation step is performed so that the first face of the second portion of the barrier layer is positioned to be in direct contact with the protruding portion of the second electrode. At least one of the first portion and the second portion of the barrier layer comprises metal atoms. The second electrode comprises a protruding portion covering neither the first electrode nor the organic layer. The first face of the second portion of the barrier layer is positioned to be in direct contact with the protruding portion of the second electrode.

At least one first metal layer is positioned in direct contact with the second face of the first portion of the barrier layer and at least one second metal layer is positioned in direct contact with the second face of the second portion of the barrier layer. so that the first metal layer and the second metal layer are in electrical continuity respectively with the first portion and the second portion of the barrier layer. The first metal layer and the second metal layer comprise a material selected from aluminum, silver, magnesium, chromium, copper, titanium or an alloy of several of these materials. The barrier layer comprises a thickness of less than 100 nanometers. The barrier layer comprises a material selected from aluminum oxide, silicon oxide, titanium oxide. As indicated above, the following process aims to provide at least one organic light-emitting diode comprising a barrier layer; said barrier layer serving as a layer for encapsulating and protecting sensitive layers such as the organic layer. In a first step, illustrated in FIG. 1, a stack of layers 200 is formed on a substrate 100. Advantageously, the substrate 100 is a flat plate made of a transparent material. Optionally, the substrate 100 is made of glass. A first electrode 200 is preferably deposited on the substrate 100. An organic layer 300 is advantageously deposited so as to cover part of the first electrode 200. Preferably, the first electrode 200 protrudes laterally from the organic layer 300.

Advantageously, the first electrode 200 has an overflowing portion 250 not covered by the organic layer 300. A second electrode 400 is deposited so as to at least partially cover the organic layer 300. According to a preferred embodiment, the second electrode 400 3032065 8 extends beyond the organic layer 300 as illustrated in FIG. 1. The second electrode 400 protrudes laterally from the stack of layers 200. The protruding portion 250 of the first electrode 200 and the protruding portion 450 of the second electrode 400 are neither superimposed nor in contact. They can be located on opposite edges of the stack of layers. Preferably, the first electrode 200 constitutes the anode. The first electrode 200 is typically made of a metallic material. According to an embodiment where the emission of light is in the opposite direction to the substrate 100, the first electrode 200 is selected as a reflective (or even semi-reflective) material. The first electrode 200 may be, for example, aluminum. According to a preferred embodiment where the emission of light is through the substrate 100, then the first electrode 200 is selected from a transparent material. Preferably, the first electrode 200 is composed of tin-doped indium oxide (Indium Tin Oxide, ITO). Optionally, the first electrode 200 is at least 85% transparent to allow the transmission of light. According to a preferred embodiment, the organic layer 300 is advantageously arranged so as to be inserted between the first electrode 200 and the second electrode 400. The organic layer 300 is advantageously composed of one or more sublayers. These sub-layers preferably comprise specific materials, making it possible to improve the injection of electrons and holes, and consequently to improve the efficiency of the light emission device. For example, the organic layer 300 may include a hole injection layer, a hole transport layer, a light emitting layer produced by the recombination of the holes and electrons, a layer of electron transport and an electron injection layer. The second electrode 400 generally constitutes the cathode.

Advantageously, the second electrode 400 is transparent. Optionally, it is semi-transparent. The second electrode 400 is typically made of a metallic material. The second electrode 400 may, for example, be of a material such as aluminum or silver 3032065 or a magnesium / silver alloy. It is preferably deposited by thermal evaporation. The thicknesses of the first electrode 200, the organic layer 300 and the second electrode 400 are advantageously between 10 nm and 200 nm. According to a preferred embodiment, the deposition conditions of the different layers are under a controlled atmosphere. The presence, in fact, of impurities depends on the atmosphere in which the structures are manufactured.

As illustrated in FIG. 2, after the step of forming a stack of layers, a step of forming a barrier layer 500 above said stack of layers follows. The barrier layer 500 is preferably arranged so as to cover the entire stack of layers.

The barrier layer 500 has the advantage of being deposited by atomic layer deposition (ALD in English for "Atomic Layer Deposition"). Preferably, the barrier layer 500 is formed so as to have a water vapor transmission rate (WVTR) for the order of 10-4 g / m 2 / d. The barrier layer 500 is advantageously formed of an insulating material. It comprises, preferably, an inorganic material chosen, for example, from Alumina (Al 2 O 3), Aluminum Oxide (AlOx), Silicon Dioxide (SiO 2), Titanium Oxide (TiO 2) or nitrate from Silicon (SiN), zirconium oxide (ZrO 2), Hafnium oxide (HfO 2), tantalum oxide (Ta 2 O 5), or even Nobium oxide (Nb 2 O 5), the oxide of Yttrium (Y203), magnesium oxide (MgO), cerium oxide (CeO2), Lanthanum oxide (La203), Strontium titanate (SrTiO3), Barium titanate (BaTiO3), sulfide of Zinc (ZnS), Selenium sulphide (ZnSe), Telluride zinc (ZnTe), Indium oxide (In203), Tin dioxide (5nO2), Gallium oxide (Ga203), nickel oxide (NiO). Particularly advantageously, the barrier layer 500 has a thickness to form a uniform and homogeneous coating on the stack of layers. According to a preferred embodiment, the barrier layer 500 has a thickness advantageously less than 100 nanometers and preferably of the order of 50 nanometers. The barrier layer 500 has the advantage of being formed in such a way as to perfectly follow the surface roughness of the stack of layers. The barrier layer 500 also has the particularity of forming a coating on the stack of layers, and thereby isolating it electrically. On the other hand, the barrier layer 500, thus arranged, acts particularly advantageously as a sealed protective barrier for the sensitive layers such as the first electrode 200, the organic layer 300 and the second electrode 400. encapsulation (in particular of the organic layer 300) obtained is thus perfectly achieved. FIG. 3 illustrates the step of implantation of a first portion 510 of the barrier layer 500 and of a second portion 520 of the barrier layer 500. The first and second portions 510, 520 each comprise a first face and a second face; said first and second faces being opposite. Advantageously, said first face of the first portion 510 is positioned so as to be in direct contact with the projecting portion 250 of the first electrode 200. Said first face of the second portion 520 is advantageously positioned so as to be in position. direct contact with the second electrode 400. According to a particularly advantageous but nonlimiting embodiment of the invention, the first face of the second portion 520 is positioned so as to be in direct contact with the protruding portion 450 of the second electrode 400. In particular, the implantation step is shaped to make the first portion 510 and the second portion 520 of the barrier layer 500 conductive. Advantageously, the implantation step comprises an implantation (or a bombardment). neutral, preferably metallic, atoms in the entire thickness of the first portion 51 0 and the second portion 520 of the barrier layer 500. The bombardment or implantation is advantageously by cathodic sputtering so as to migrate the metal atoms in (and especially through the thickness of the substrate 100) the first and second portions 510, 520 of the barrier layer 500. According to a preferred but non-limiting embodiment of the invention, the deposition rate is of the order of 5Â / s. In a particularly advantageous manner, the implantation step is carried out by sputtering or ion plating. The implantation step advantageously makes the first and second portions 510, 520 of the barrier layer 500 conductive. Only the portions of the barrier layer 500 exposed during the implantation step are made conductive; the remainder of the barrier layer 500 remaining insulating. Conductive layer is understood to mean a layer comprising a conductivity threshold greater than 10 S / cm. According to a preferred embodiment, prior to the implantation step, a step is performed to mask the barrier layer 500 so as to expose only the second faces of the first and second portions 510, 520 of the barrier layer. 500; the remainder of the barrier layer 500 being covered with a protective layer during the implantation step. The masking step thus makes it possible to spare the active zone (ie the stack formed of the first electrode 200, the organic layer 300 and the second electrode 400) of the organic light-emitting diode.

The implantation step advantageously comprises the formation of a first metal layer 610 in direct contact with the second face of the first portion 510 of the barrier layer 500 and the formation of a second metal layer 620 in contact with the second face of the second portion 520 of the barrier layer 500; so that the first metal layer 610 and the second metal layer 620 are in electrical continuity, respectively, with the first portion 510 and the second portion 520 of the barrier layer 500. Preferably, at least one of the first layer metal 610 and the second metal layer 620 comprises a material selected from aluminum, titanium, copper, chromium, silver, zinc, nickel, gold, platinum, magnesium.

The first and second metal layers 610, 620 are advantageously formed during the implantation step; the implantation step being advantageously carried out by sputtering. Vacuum deposition advantageously makes it possible to obtain first and second metal layers 610, 620 with thicknesses between a few nanometers and a few microns (for example, between 50 nanometers and 5 microns). Particularly advantageously, the process according to the invention makes it possible to form metal layers 610, 620 acting as contact recovery for the first and second electrodes 200, 400, ie the anode and the cathode, without resorting to steps The metal layers 610, 620 are advantageously in electrical continuity with each of the electrodes 200, 400 of the diode. Particularly advantageously, the barrier layer 500 makes it possible to serve as encapsulation layers for sensitive layers such as the organic layer 300; said barrier layer 500 remaining in place and not requiring openings in this layer 500 to access the electrodes 200, 400 to establish electrical continuity.

The present invention thus provides a particularly simple and inexpensive method for obtaining an organic light emitting device having increased reliability and luminous homogeneity; the sensitive layers of the diode being protected from any damage that may occur during a conventional method of producing organic light-emitting diodes. On the other hand, the encapsulated device is advantageously compatible with industrial requirements, also for large areas. The invention is not limited to the embodiments previously described, but extends to all embodiments within its spirit.

Claims (16)

REVENDICATIONS1. A method of producing an organic electroluminescent diode comprising: - a step of forming a stack of layers on a substrate (100); said stack comprising, successively and in order, a first electrode (200) deposited on the substrate (100), an organic layer (300) deposited in contact with at least a portion of the first electrode (200), a second electrode (400) deposited in contact with at least a portion of the organic layer (300); the first electrode (200) comprising an overflowing portion (250) not covered either by the organic layer (300) or by the second electrode (400), - a step of forming a barrier layer (500) made of a material electrically insulating, said step being configured so that the barrier layer (500) covers the stack of layers, characterized in that it comprises: - a step of implantation of electrically conductive atoms in the entirety of the thickness of a first portion (510) of the barrier layer (500) and a second portion (520) of the barrier layer (500), so as to establish electrical continuity between a first face and a second face of each of the first and second portions (510, 520) of the barrier layer (500), said first and second faces being opposed; said first face of the first portion (510) being positioned to be in direct contact with the protruding portion (250) of the first electrode (200) and said first face of the second portion (520) being positioned so as to be in direct contact with the second electrode (400). 2. Method according to the preceding claim wherein the implantation step comprises an implantation of metal atoms. 3032065 14 3. Method according to the preceding claim wherein the implantation step is carried out by sputtering or ionic deposition. 5 The method of any one of the preceding claims wherein the step of implanting comprises forming a first metal layer (610) in direct contact with the second face of the first portion (510) of the barrier layer ( 500) and forming a second metal layer (620) in direct contact with the second face of the second portion (520) of the barrier layer (500); so that the first metal layer (610) and the second metal layer (620) are in electrical continuity respectively with the first portion (510) and the second portion (520) of the barrier layer (500). 15 5. Method according to one of the preceding claims wherein prior to the implantation step, a step is performed to mask the barrier layer (500) so as to expose only the second face of the first portion (510). ) and the second face of the second portion (520) of the barrier layer (500). 20 6. Method according to the preceding claim wherein the step of forming the barrier layer (500) is performed by atomic layer deposition. 25 7. Method according to any one of the preceding claims wherein the step of forming the stack of layers is carried out so that the second electrode (400) comprises an overflowing portion (450) not overlapping by the first electrode (200), or the organic layer (300). 30 8. Method according to the preceding claim wherein the implantation step is carried out so that the first face of the second portion (520) of the barrier layer (500) is positioned so as to be in direct contact. with the protruding portion (450) of the second electrode (400). An organic electroluminescent diode comprising: a stack of layers on a substrate (100); said stack comprising, successively and in order, a first electrode (200) deposited on the substrate (100), an organic layer (300) deposited in contact with at least a portion of the first electrode (200), a second electrode (400) deposited in contact with at least a portion of the organic layer (300); the first electrode (200) comprising a protruding portion (250) not covered either by the second electrode (400), or by the organic layer (300), a barrier layer (500) made of an electrically insulating material, said layer (500 ) being shaped to cover the stack of layers, characterized in that said barrier layer (500) comprises a first portion (510) and a second portion (520); said portions (510, 520) comprising electrically conductive atoms throughout their thickness so as to provide electrical continuity between a first face and a second face of each of the first and second portions (510, 520) of the barrier layer (500); said first and second faces being opposed; said first face of the first portion (510) being positioned to be in direct contact with the protruding portion (250) of the first electrode (200) and said first face of the second portion (520) being positioned so as to be in direct contact with the second electrode (400). 10. Diode according to the preceding claim wherein at least one of the first portion (510) and the second portion (520) of the barrier layer (500) comprises metal atoms. 30 11. Diode according to any one of the two preceding claims wherein the second electrode (400) comprises a protruding portion 3032065 (450) not covering either the first electrode (200) or the organic layer (300). 12. Diode according to the preceding claim wherein the first face of the second portion (520) of the barrier layer (500) is positioned so as to be in direct contact with the protruding portion (450) of the second electrode (400). . 13. Diode according to any of the four preceding claims comprising a first metal layer (610) in direct contact with the second face of the first portion (510) of the barrier layer (500) and a second metal layer (620). in direct contact with the second face of the second portion (520) of the barrier layer (500) so that the first metal layer (610) and the second metal layer (620) are in electrical continuity respectively with the first portion (510) and the second portion (520) of the barrier layer (500). 14. Diode according to the preceding claim wherein at least one of the first metal layer (610) and the second metal layer (620) comprise a material selected from aluminum, copper, titanium, chromium silver, zinc, nickel, gold, platinum, magnesium. The diode of any one of the six preceding claims wherein the barrier layer (500) comprises a thickness of less than 100 nanometers. The diode of any one of the preceding claims wherein the barrier layer (500) comprises a material selected from aluminum oxide, silicon oxide, titanium oxide. 30