FR2897745A1 - Electroluminescent device e.g. organic LED, for forming e.g. lighting window in building, has electrodes placed on surface of substrate, where one of electrodes has diffusing electroconductive layer deposited on tin and oxygen based layer - Google Patents

Abstract

The device has a transparent substrate, and electrodes placed on a same surface of the substrate. An electroluminescent layer is intercalated between the electrodes. One of the electrodes has a diffusing electroconductive layer deposited on a tin and oxygen based layer, where the electroconductive layer presents blur of about 5-20 percentage. A barrier layer comprising thickness of about 20 to 150 nanometers and made of dielectric material is intercalated between the substrate and the electrode close to the substrate.

Description

ELECTROLUMINESCENT DEVICE AND USE OF A LAYER

  The invention relates to an electroluminescent device and to the use of a transparent electroconductive layer in such a device.

  In a known manner, the electroluminescent devices comprise: a transparent substrate; a first electrode and a second electrode on one and the same face of the substrate, the at least one first electrode being transparent; and an electroluminescent layer interposed between the first and second electrodes. In order to maximize the light emitted by an organic electroluminescent device (or OLED), the document EP1406474 proposes to provide the electroluminescent device with a diffusing layer in the form of a polymeric matrix comprising diffusing particles, this layer being placed under or on the transparent electrode. The invention aims a light emitting device maximizing the alternative emitted light, especially simpler design and / or less expensive, and / or a simpler manufacture and / or faster than known devices. The invention firstly relates to an electroluminescent device comprising: - a particularly transparent substrate, - a first electrode and a second electrode on the same face of the substrate, the first electrode at least being transparent, - a light emitting layer interposed between the first and second electrodes, the first electrode comprising a diffusing electroconductive layer. Unexpectedly, a diffusing transparent electrode makes it possible to improve the extraction efficiency of the electroluminescent device while retaining satisfactory electroconductive properties. The electroluminescent device according to the invention is simple to implement because it is not necessary to use a polymeric diffusing layer.

  For the purposes of the invention, the term "layer" (in the absence of any precision) means either a monolayer or a multilayer or a continuous layer, or a discontinuous layer, having in particular conventional patterns including periodic and / or geometric, size millimetric or centimeter (patterns obtained either by etching a continuous layer, or by depositing the discontinuous layer directly to the desired pattern, for example by a mask system). This applies to all layers in this application. Thus, the diffusing electroconductive layer may be divided into several scattering zones, for example of the same level of diffusion. The first electrode may be the upper electrode, that is to say the electrode farthest from the substrate or the lower electrode, that is to say the electrode closest to the substrate. The first electrode may comprise one or more electroconductive layers, diffusing or not, below or above the diffusing electroconductive layer. If both electrodes are transparent, the second electrode may also include an identical or similar diffusing electroconductive layer to improve the extraction efficiency. For applications where a high transparency is desired, for example for illumination through a substrate of high transparency, the electroconductive layer may have a TL light transmission greater than or equal to 50%, especially 70%, or even 80%.

  For applications where transparency is less necessary, the electroconductive layer may have a TL less than or equal to 50%. In preferred embodiments of the invention, one or more of the following provisions may also be used: the diffusing layer comprises a blur greater than or equal to 2%, even more preferentially understood; between 5 and 20%, to further increase the extraction without significantly reducing the transparency if the latter is necessary for the intended application, the first electrode has a product factor fuzzy (H) by the light transmission (TL) expressed in a graph H (TL) which is above a line defined by the following bi-points (15; 82); (10; 84); (6; 85), - the first electrode has a light absorption product by the electrical surface resistance of less than 0.6 S2 / square, - the first electrode has a square resistance (R squared) less than or equal to 15 S2 / square , in particular less than or equal to 12 S2 / square, preferably less than or equal to 10 or 12 S2 / square. The diffusion of the electroconductive layer can be obtained preferably with a diffusing surface, that is to say by a suitable structural surface. For example, this structure is defined by a random or quasi-random roughness.

  The roughness defined above can be achieved in a commercially feasible way by several alternative or cumulative means. The diffusing electroconductive layer may advantageously be a layer having a diffusing surface directly after deposition.

  By thus directly depositing the layer in a rough manner, which is more advantageous on the industrial level, this avoids an additional, discontinuous processing step in the middle of a succession of deposition steps of the various constituent layers of the device.

  The diffusing electroconductive layer can be deposited by various techniques. It can be deposited, for example by a pyrolysis technique, especially in the gas phase (a technique often referred to by the abbreviation of C.V.D, for Chemical Vapor Deposition).

  This technique is interesting for the invention because appropriate settings of the deposition parameters make it possible to obtain a certain roughness. The diffusing electroconductive layer may be advantageously chosen from metal oxides, in particular the following materials: doped tin oxide, in particular fluorine SnO 2: F or antimony SnO 2: Sb (the precursors that can be used in the case of CVD deposition may be organometallic compounds or tin halides associated with a hydrofluoric acid or trifluoroacetic acid fluorine precursor), doped zinc oxide, especially with aluminum ZnO: Al (the precursors which can be used, in the case of CVD deposition, may be organo-metallic or zinc and aluminum halides) or gallium ZnO: Ga, or else doped indium oxide, in particular with tin ITO (the precursors that can be used in the case of deposition by CVD may be organometallic or halide tin and indium), or zinc doped indium oxide (IZO). It is also possible to deposit the diffusing electroconductive layer by a vacuum deposition technique, in particular by evaporation or magnetic field assisted sputtering. Spraying can be reactive (starting from metal targets or under-oxidized, in an oxidizing atmosphere) or non-reactive (starting from ceramic targets, in an inert atmosphere). Here again, changes in the deposition parameters may make it possible to obtain a certain porosity and / or roughness. It is thus possible to adjust the pressure in the deposition chamber appropriately: a relatively high pressure generally makes it possible to obtain relatively porous and rough surface layers. One possibility is to modulate this parameter during deposition, so that the electroconductive layer is optionally relatively dense to a certain thickness, then more porous / rough surface. It is also possible to vary other parameters such as the temperature of the process and the mixing of the gases used during the process. An elevated temperature, generally greater than 500 C, of deposition of a layer often makes it possible to obtain at least partially crystallized layers, capable of generating and / or increasing the roughness of the surface, and capable of rendering the surface diffusing or increase the diffusion of light. The surface of the diffusing electroconductive layer may be of RMS roughness> 3 nm and pattern size> 50 nm.

  R.M.S roughness stands for Root Mean Square roughness. This is a measure of measuring the value of the mean square deviation of roughness. This roughness R.M.S, concretely, thus quantifies on average the height of the peaks and troughs of roughness, with respect to the average height. Thus, an R.M.S roughness of 3 nm means a double peak amplitude. It can be measured in various ways: for example, by atomic force microscopy, by a mechanical point system (using for example the measuring instruments marketed by VEECO under the name DEKTAK), by optical interferometry. The measurement is generally made on a square micrometer by atomic force microscopy, and on a larger surface, of the order of 50 micrometers to 2 millimeters for mechanical systems with a peak. RMS roughness of at least 3 or 5 nm corresponds to relatively high values. Preferably, this roughness is random, in that it does not have patterns of a precise geometry. In addition, it is dispersed, depending on the size of the measured surface. Alternatively or cumulatively, the roughness of this diffusing electroconductive layer may also be chosen so that the average size of the patterns of this roughness is at least 50 nm, measured in the dimension parallel to the surface of the substrate. Advantageously, it is chosen to be at least 100 nm, and preferably at most 500 nm. An average pattern size of between 200 and 400 nm is preferred. This average size can be evaluated, in particular, by scanning electron microscopy. When the roughness of the layer is in the form of peaks (of irregular shape), which is the case of the crystallized layers having a columnar growth, this average size corresponds to the size (the largest dimension) of the base of these peaks. To be diffusive, the diffusing electroconductive layer may also have one and / or the other of the characteristics described below. Firstly, the diffusing electroconductive layer may be a textured layer after deposition to form a diffusing or more diffusing surface. This texturing may be carried out chemically, in particular by acid etching, by plasma etching, in particular by means of an appropriate mask, for example a random mask, or by mechanical means, in particular sandblasting type abrasion. In this case, it is possible to use any type of transparent electroconductive layer, for example so-called 'TCO' layers (for Transparent Conductive Oxide in English), for example with a thickness between 2 and 100 nm. It is also possible to use metal thin films known as 'TCC' (for Transparent Conductive Coating in English), for example in Ag, Al, Pd, Cu, Au and typically of thickness between 2 and 50 nm. Then, the diffusing electroconductive layer may be composed of a doped metal oxide and predominantly, preferably substantially crystalline. The crystalline character confers a natural roughness after deposition. By way of example, mention may be made of SnO 2: F deposited by CVD. Finally, the very structure of the diffusing surface of the electrode layer is optionally generated or amplified by an undercoat or under layers, electroconductive or otherwise, and / or by the substrate.

  The electroconductive layer being preferably inorganic, the inorganic sublayer (s) is preferably chosen, preferably obtained by the same deposition technique (for example PVD, by CVD, in particular by evaporation or by magnetron cathode sputtering or by pyrolysis). Thus, the diffusing electroconductive layer may also be roughness induced at least in part by the substrate which is textured. The layer is deposited directly or not on this textured substrate. The texturing of the glass substrate is described in document FR283706. In particular, textured glass coated with a SnO 2: F layer described in Example 3 of this document is referred to. The diffusing electroconductive layer may also be roughness induced by the second underlying electrode comprising an electroconductive layer (transparent or otherwise) roughened naturally or roughened. The diffusing electroconductive layer may also be deposited, directly or indirectly, on a rough inorganic layer directly after deposition, this layer being preferably an undercoat based on tin and oxygen and possibly other element (s). (s) like silicon, carbon or nitrogen. A SiySnxO-based layer is for example deposited by CVD and the roughness is favored by the presence of tin. In a particularly advantageous embodiment, because simple and fast to achieve, the diffusing electroconductive layer is a multilayer which comprises a first electroconductive layer composed of an undoped mineral oxide, said first layer being coated by a second electroconductive layer composed of the same inorganic oxide, said mineral oxide being however doped.

  The thickness of the first undoped mineral oxide layer may be between 150 and 900 nm. Preferably, the doped and / or undoped mineral oxide is (are) deposited at high temperature, especially at a temperature above 600 ° C., in particular by pyrolysis, for example by CVD, to form (partially) crystalline oxides. . In the latter mode, the first layer may be based on tin oxide (SnO2) and the second layer is based on fluorine-doped tin oxide (SnO2: F) deposited in particular by CVD.

  The first electrode may furthermore comprise at least one conductive metal oxide-based overcoat, in particular tin-zinc-doped or undoped zinc-doped indium oxide, this overcoat being deposited on the second layer. based on fluorine doped tin oxide (SnO2: F) In the latter mode, the first layer can also be based on zinc oxide (ZnO) and the second layer is based on doped zinc oxide with aluminum (ZnO: Al). For example, ZnO: Al is deposited by magnetron sputtering and textured, for example etched with acid, or it is the ZnO layer which is textured. Furthermore, the device may preferably be provided with at least one barrier layer, in particular with respect to the alkalis, inserted between said selected glass substrate and the electrode closest to the substrate. This layer having alkaline barrier properties may be based on dielectric material, chosen from at least one of the following compounds: silicon nitride or oxynitride, aluminum nitride or oxynitride, silicon oxide or oxycarbide, according to a thickness between 20 and 150 nm, the barrier layer may comprise alternating layers of high refractive index, between 1.9 and 2.3, and low refractive index layers, between 1.4 and 1, 7, especially according to the sequences Si3N4 / S102 or S13N4 / S102 / S13N4. It can be deposited by the same type of technique as the electroconductive layers, for example by pyrolysis (CVD) or sputtering, in a known manner. It can also be deposited so that it also has a certain roughness and / or is diffusing. In addition, this barrier layer may be above or below a naturally roughened inorganic layer after deposition, for example from a silicon, tin and oxygen underlayer.

  The second electrode layer may be opaque, reflecting metal in particular comprising a layer of Al, Ag, Cu, Pt, Cr, obtained by spraying or evaporation. The electroluminescent layer may be inorganic or organic.

  With an inorganic electroluminescent layer, we speak of TFEL (Thin Film Electroluminescent in English). This system generally comprises a so-called phosphor layer between two dielectric layers. The dielectric layers non-exhaustively include the following materials: Si3N4, SiO2, Al2O3, AlN, BaTiO3, SrTiO3, HfO, TiO2. The phosphor layer can be composed for example by the following materials: ZnS: Mn, ZnS: TbOF, ZnS: Tb, SrS: Cu, Ag, SrS: Ce. Examples of inorganic electroluminescent stacks are for example described in US6358632.

  With an organic electroluminescent layer, it is called OLED (Organic Light Emitting Diodes). OLEDs are generally dissociated into two major families depending on the organic material used. If the organic electroluminescent layers are polymers we speak of PLED (Polymer Light Emitting Diodes in English). If the electroluminescent layers are small molecules, they are called SMOLED (Small Mollecule Organic Light Emitting Diodes). An example of PLED consists of a following stack: a 50nm poly (styrenesulphonate) doped poly (2,4-ethilene dioxythiophene) layer (PEDOT: PSS), a phenyl poly (p-phenylenevynilene) layer; PPV of 50nm. The upper electrode may be a layer of Ca. In general, the structure of an SM-OLED consists of a hole injection layer stack, a hole transport layer, an emissive layer, a layer of An example of a hole injection layer is copper phthalocyanine (CuPC), the hole transport layer may be, for example, N, N'-Bis (naphthalen-1-yl) -N, N'- bis (phenyl) benzidine (alpha-NPB), The emitting layer may be for example by a layer of 4,4t, 4h1-tri (N-carbazolyl) triphenylamine (TCTA) doped with tris (2-phenylpyridine) iridium [Ir (ppy) 3]. The electron transport layer may be composed of tris- (8-hydroxyquinoline) aluminum (Alg3) or bathophenanthroline (BPhen). The upper electrode may be a layer of Mg / Al or LiF / Al. Examples of organic electroluminescent stacks are for example described in US6645645. In a particular embodiment, the electroluminescent layer is inorganic and the first electrode is based on doped and / or undoped mineral oxide (s) deposited at high temperature, preferably by pyrolysis, in particular in the gas phase on the electroluminescent layer and the second electrode is metallic, for example based on silver or aluminum.

  In this configuration, the inorganic layer also acts as an alkali barrier. Moreover, the substrate may be a flat, rigid or flexible substrate, such as plastic or metal, may further form or be part of one of the electrodes. The substrate preferably may be a glass, especially extraclair. In particular, a silicosodocalcic glass with less than 0.05% of Fe III or Fe 2 O 3 is chosen, in particular Saint-Gobain's Diamant glass and Albarino glass from Saint-Gobain. This substrate may be large, for example with a surface greater than 0.5 or 1 m2. The device can be part of a multiple glazing, including a vacuum glazing or with an air knife or other gas or laminated glazing. The device can also be monolithic, include a monolithic glazing, to gain compactness and / or lightness. The device (notament a panel and / or a glazing) can form (alternative or cumulative choice) an illuminating, decorative, architectural, signaling system, a billboard-for example of the type drawing, logo, alphanumeric signaling also arranged both outdoors and indoors - The device, including glazing, may be intended for the building, thus forming an illuminating facade, an illuminating window, a glazing for a transport vehicle, such as a rear window, a window car roof, or any other land, water or air vehicle, a glazing for street furniture such as a bus shelter, a display, a jewelery display, a showcase, an element of shelf, at an aquarium, at a greenhouse, may be intended for interior furnishing, a mirror, a piece of furniture, an electrically controllable glazing. The device can furthermore integrate any functionalization (s) known in the field of glazing, preferably on the non-illuminating face. Among the functionalizations, mention may be made of: hydrophobic / oleophobic, hydrophilic / oleophilic layer, photocatalytic anti-fouling, thermal radiation (solar control) or infra-red (low-emissive) reflective stack, anti-reflective stack. The invention also relates to the use of a diffusing electroconductive layer as electrode of a light-emitting device, in particular having a blur greater than or equal to 2%. This diffusing electroconductive layer may be as described above. The present invention will be better understood on reading the following detailed description of nonlimiting exemplary embodiments and the following figures - FIGS. 1 and 2 which illustrate points of comparison between a single-layer stacking structure and bi-layers of SnO2: F on the one hand and SnO2 / SnO2: F on the other hand forming diffusing transparent electrodes according to the invention for electroluminescent devices.

  We first describe the structure of electroluminescent devices.

  Organic electroluminescent devices

  A first organic electroluminescent device, for example of the OLED type, comprises a transparent substrate, preferably an extraclear and possibly textured glass, one side of which is coated in this order: optionally with an alkali barrier layer, for example a nitride or oxynitride; silicon, an aluminum nitride or oxynitride, a silicon oxide or oxycarbide or an alternation of high refractive index layers, between 1.9 and 2.3, and low refractive index layers, between 1 , 4 and 1.7, in particular according to the Si 3 N 4 / SiO 2 or Si 3 N 4 / SiO 2 / Si 3 N 4 - sequences of a first transparent electrode (monolayer or multilayer) comprising a diffusing electroconductive layer (monolayer or multilayer) - of an organic electroluminescent system, (OLED) typically formed of: - an alpha-NPD layer, - a TCTA + Ir (ppy) 3 layer, - a BPhen layer, - a LiF layer, - a second reflected electrode health, especially metal, preferably in the form of an electroconductive layer including silver or aluminum base.

  The first transparent electrode may or may not comprise other electroconductive layers above or below the diffusing layer, for example ITO or a thin Ag layer, for example with a thickness of less than or equal to 50 nm. The second electrode may also be a transparent and possibly diffusing electrode, for example identical to the first electrode. In this case, it is possible to relate a reflector on another surface, for example a metal layer with a thickness of 150 nm. This diffusing electroconductive layer (monolayer or multilayer) preferably having a blur greater than or equal to 2% may be chosen: a doped crystalline oxide monolayer, deposited in a hot state, in particular a SnO2: F layer, as described later in more detail; - a textured TCO layer after deposition, for example etched with acid or etched by plasma, for example ITO with a thickness between 60 and 500 nm or ZnO: Al. a multilayer of the same undoped and doped crystalline inorganic oxide, as described later in more detail. As a first variant, this diffusing electroconductive layer (monolayer or multilayer) may be of roughness induced by a textured or naturally rough inorganic sub-layer after deposition. For example, 50 nm of SnO 2 is deposited by CVD followed by 20 nm of SiO 2. We finish with 700 nm of SnO2: F. For example, a layer of ZnO of 100 nm is deposited by magnetron sputtering. The ZnO layer was etched with acid and deposited on top of a 60 nm ITO or IZO layer. Another example is to deposit a SiSnOX layer by CVD with a thickness of 100 nm followed by a thin layer of Ag with a thickness of between 5 and 20 nm. In the second variant, this diffusing electroconductive layer (monolayer or multilayer) may be of roughness induced by the barrier sub-layer which is textured and / or by the glass which is textured. For example, a layer of SiO 2 is deposited by CVD. The SiO2 layer is etched by plasma to obtain a rough surface. A TCO layer such as SnO2: F, ZnO: Al, ITO, IZO, or a thin metal layer is then deposited.

  A second electroluminescent device comprises a preferably mineral and optionally transparent and / or rough substrate, one side of which is coated in this order: - optionally of the alkali barrier layer, - a reflecting electrode in the form of an electroconductive layer in particular metal, preferably based on silver or aluminum, palladium, gold or molybdenum, - the organic electroluminescent system OLED, - a transparent electrode (monolayer or multilayer) comprising a diffusing electroconductive layer.

  This diffusing electroconductive layer (monolayer or multilayer) preferably having a blur greater than or equal to 2% can be either: a layer deposited by cathodic sputtering or evaporation and textured after deposition, for example etched with acid or by chemical etching , for example ITO or ZnO: Al or IZO, or a metal thin layer, a roughness layer induced by the metal electrode previously structured for example by photolithography and / or by the substrate which is textured, a layer deposited by cathodic sputtering, for example of ITO, directly onto a textured sub-layer, also deposited by cathodic sputtering, for example acid-etched ZnO, or by evaporation as a textured aluminum layer; a multilayer of the same undoped and doped crystalline inorganic oxide deposited by cathodic sputtering, of which one of the layers is textured, for example ZnO and ZnO: Al. 15 Electroluminescent inorganic devices (TFEL)

  A third electroluminescent device comprises a transparent substrate 5, preferably an extraclear and optionally textured glass, one side of which is coated in this order: optionally an alkali barrier layer, for example a silicon nitride or oxynitride, a nitride or aluminum oxynitride, a silicon oxide or oxycarbide or alternation of high refractive index layers, between 1.9 and 2.3, and low refractive index layers, between 1.4 and 1 , 7, in particular according to the Si 3 N 4 / SiO 2 or Si 3 N 4 / SiO 2 / Si 3 N 4 - sequences of a transparent electrode (monolayer or multilayer) 15 comprising a diffusing electroconductive layer (monolayer or multilayer) - of an inorganic electroluminescent system (TFEL) typically formed of: - a layer of Si3N4, - a layer of ZnS: Mn, - a layer of Si3N4 - a reflecting electrode in the form of an electroconductive layer, in particular metal lique, preferably based on silver or aluminum. The first transparent electrode may or may not include other electroconductive layers above or below the diffusing layer, for example of the ITO of ZnO: Al, IZO. The second electrode may also be a transparent and possibly diffusing electrode, for example identical to the first electrode. In this case, it is possible to relate a reflector such as a metal layer with a thickness greater than 150 nm and preferably formed of Ag, Al, or Au.

  A fourth electroluminescent device comprises an optionally transparent and / or rough substrate, one face of which is coated in this order: - optionally of the alkaline barrier layer, - of a reflecting electrode in the form of a metallic electroconductive layer, preferably silver or aluminum base - the inorganic electroluminescent system (TFEL), - a transparent electrode (monolayer or multilayer) comprising a diffusing electroconductive layer (monolayer or multilayer).

  The transparent electrode may or may not include other electroconductive layers above or below the diffusing layer, for example, ITO, ZnO 2 AlZO 2 or a thin metal layer.

  For these third and fourth devices, the diffusing electroconductive layer (monolayer or multilayer) may be any of the layers described for the first and second devices. It is not necessary to use an alkali barrier layer because the inorganic electroluminescent dielectric may serve as a barrier. For these four devices, the other side of the selected glass substrate may comprise one or more layers providing other functionalities, as described later.

  The following are examples of the production of diffusing electroconductive layers in the form of tin oxide monolayer or undoped and doped tin oxide (or zinc) multilayer. 17 Manufacture of diffusing electroconductive layers

  A two-layer based on SnO2 / SnO2: F is produced, after having carried out a temperature rise of a transparent substrate at a temperature greater than 600 ° C., a mixture of (CnH 2n + 1) 4 Sn vapor is decomposed with n = 1-4, (CH3) 2SnH2, (C4H9) 3SnH, (C4H9) 2Sn (000CH3) 2, SnCl4, (CH3) 2SnCl2 or tin monobutyl trichloride (MBTC1), and water vapor, of oxygen and nitrogen.

  The partially coated substrate is then heated again and brought into contact with a fluorinated tin compound or a tin compound and a fluorinated compound to obtain the second SnO 2: F layer. To deposit the SnO 2: F layer, all of the above tin compounds can be used provided that the fluorine donor is supplemented with CF 3 COOH, HF, CH 3 CH 2 F 2, CHClF 2, CH 3 CClF 2, CHF 3, CF 2 Cl 2, CF 3 Cl, CF 3 Br. To bring these tin compounds into contact with heated transparent substrates and to cause oxidation and thermal decomposition, the chemical vapor deposition method (CVD method) by which a vapor of tin compounds is used is used. and an oxidizing gas in contact with a high temperature transparent substrate, or the spraying method by which a solution of the tin compound is sprayed onto the transparent substrate at high temperature using a sprayer.

  The CVD method is preferably used by which a vapor mixture of tin compounds, oxidizing gas, etc. is contacted with the transparent substrate heated to a temperature of 400 to 700.degree. C., preferably in the vicinity of the temperature range between 600 and 680 C. Thus, a transparent electroconductive film with two layers is deposited, that is to say, a SnO2 layer and another layer SnO2: F, coated. According to the present invention, the thickness of the two-layer film SnO 2 / SnO 2: F is preferably 0.6 to 1.5 micron.

  To produce a ZnO / ZnO: Al bilayer, at least one dielectric layer is deposited on the substrate by cathode sputtering, in particular assisted by a magnetic field and preferably reactive in the presence of oxygen and / or nitrogen, in an enclosure. sputtering The ZnO layer is obtained from a cathode of a doped metal, ie containing a minor element: by way of illustration, it is common to use zinc cathodes containing a minor proportion of another metal such as aluminum or gallium. The setting parameters are as follows: P [kW] = 4.0; I [A] = 40; U [V] = 360; Gas [sccm] = 350 (Ar). However, in order to create blur in the ZnO / ZnO: Al bilayer, it is necessary to texturize the first ZnO layer by acid etching.

  We detail below the properties of diffusing electroconductive layers in the form of monolayer tin oxide or zinc oxide or tin oxide multilayer or undoped and doped zinc.

  Examples of Diffuse Electroconductive Layers A glass substrate of the Albarino and / or Diamond type is produced, with Diamant and Albarino being registered trademarks by the applicant company of the present patent application for glass substrates respectively of extra-clear type and of type possessing surface reliefs a series of deposits as follows. The first series of deposits comprises a single layer of SnO2: F, deposited at high temperature (at least greater than 600 C) by CVD, by decomposition of precursors based on those mentioned above + air + H2O + a fluorinated compound.

  TL and blur measurements (H) were made with a hazemeter. The following set of samples is obtained: Sample Rcarred, TL, (%) Soft or H, (%) e (SnO2: F) (S2 / square) (nm) 1 6.1 79.4 14.7 1340 2 9.5 82.7 1.9 580 3 7.8 81.1 3.2 685 4 6.3 79.1 9.6 1050 8.0 80.9 2.6 660 Then, on a glass substrate of the albarino and / or diamond type, under the same operating conditions as above, a series of layer deposits of the SnO2 / SnO2 double-layer type are produced: F 5 (respective thicknesses ranging from 25% / 75% to 75% / 25% for total thicknesses of 750 to 1000 nm), the following samples are obtained: Sample Rcarré, (S2 / carré) TL, (%) Blur or H, (%) 6 9.7 83.1 14.8 7 10.0 81.0 17.0 8 7.7 82.0 14.3 9 10.5 82.0 19.2 11.2 81.6 18.2 11 7.8 81. 7 12.0 12 9.2 82.7 12.0 sample Thickness (SnO2) Thickness (nm) (Sn02: F) (nm) ) 6 180 530 7 610 240 8 170 530 9 600 340 10 640 360 11 180 600 12 250 510 The measurements show that for all the samples, we have particularly good performances (blur and TL higher concomitantly) with bilayers. This situation is illustrated by the graph of FIG. 1. For the second samples, the following spectrophotometer-measured values of mobility and density of the carriers, blur and TL are obtained, showing that the performances are very satisfactory concomitantly (mobility). high, moderate density, high TL, high blur): sample Carrier Density Mobility, TL, (%) Blur, (%) carrier, cm2 / V / sec 10E20 cm-3 6 37.6 2.25 85.4 15.6 7 40.6 1.75 84.0 18.7 8 39.9 2.8 84.1 16.1 9 38.9 1.7 84.4 20.0 10 36.8 1.8 84.3 18.4 11 36.6 2.7 83.6 15.1 12 33.9 2.2 85.0 13.1 For the samples of the second deposit series (samples 6 to 12), it is proposed to define a second criterion expressing the relationship between H or blur and the light transmission. As it appears in FIG. 2, all the samples are above the curve defined by the bi-points (15; 82); (10; 84); (6; 85) (non-hatched area). Other comparative examples are given below showing the influence of the doping on the value of the blur obtained and the influence of the production temperature on the blur (the optical measurements being carried out using a hazemeter). Thus, the first example below shows the difference between a monolayer of SnO 2: F deposited at high temperature Ti (greater than 600 ° C.) and the same layer produced at a temperature T2 greater than at least 30 ° C. at T1. Dope rate 8kg / h Haze temperature SnO2: F T1> at 600 C 0.94 SnO2: F T2> T1 + 30 C 1.8 The blur value is almost doubled from Ti to T2. The second example shows the relationship between dopant flow and blur for a thick layer deposited at high temperature (above 600 ° C). Doping rate (kg / h) Haze (%) TL (%) 0 20.8 78.5 1.6 13.3 77.1 2 12.7 76.8 3 8.45 75.8 4 7.63 75.6 6 6.05 74.6 10 It can be observed that doping decreases TL. The more the layer is doped, the more the absorption by the charge carriers is important. In the double-layer strategy, therefore, the SnO2 sublayer is used to create the optimal conditions for blur. At the same time, the SnO2 underlayer promotes high light transmittance. The SnO2: F overlay also makes it possible to adjust the square resistance of the TCO. Alternatively, a ZnO overcoat layer may be deposited by a magnetron sputtering route on the SnO2 / SnO2: F overlay, this overlayer being a protective layer against hydrogenated plasma attacks and having a thickness of between 10 and 10. and 50 nm and preferably close to 20 nm.

  It follows that according to the present invention, it is possible to obtain transparent electroconductive films of low electrical resistance and allowing a large light transmission as well as a large blur or haze value.

  Additional functions As already said, it may be wise to functionalize the other side of the substrate (opposite side of the electroluminescent system). Thin layers are thus deposited on the surface to give them a particular property, for example that which consists in allowing the substrate to remain as clean as possible, whatever the environmental aggressions, that is to say aimed at permanence of the surface and appearance properties over time, and in particular making it possible to space the cleanings, by succeeding in gradually eliminating the soils gradually deposited on the surface of the substrate, in particular soils of organic origin such as fingerprints or volatile organic products present in the atmosphere, or even soot-type soiling, dust pollution. However, it is known that there are certain semiconductor materials, based on metal oxide, which are capable, under the effect of radiation of adequate wavelength, initiating radical reactions causing the oxidation of organic products: we generally speak of photocatalytic or photo-reactive materials. It is known in the field of substrates with a glazing function, the use of photocatalytic coatings on substrate, which have a marked anti-fouling effect and that can be manufactured industrially. These photo-catalytic coatings generally comprise at least partially crystallized titanium oxide, incorporated in said coating in the form of particles, in particular of size ranging from a few nanometers (3 or 4) to 100 nm, preferably around 50 nm for the essential crystallized form anatase or anatase / rutile. Titanium oxide is in fact part of the semiconductors which, under the action of light in the visible range or ultraviolet, degrade organic products which are deposited on their surface. Thus, according to a first exemplary embodiment, the photo-catalytically-active coating results from a solution based on TiO 2 nanoparticles and a mesoporous silica (SiO 2) binder.

  According to a second exemplary embodiment, the photo-catalytically active coating results from a solution based on TiO 2 nanoparticles and an unstructured silica (SiO 2) binder. Whatever the embodiment of the photo-catalytic coating, at the level of the titanium oxide particles, the choice was furthermore made on titanium oxide which is at least partially crystallized because it has been shown to be much more efficient in terms of photo-catalytic property than amorphous titanium oxide. Preferably, it is crystallized in anatase form, in rutile form or in the form of a mixture of anatase and rutile.

  The coating is manufactured in such a way that the crystalline titanium oxide it contains is in the form of crystallites, that is to say single crystals, having an average size of between 0.5 and 100 nm. preferably 3 to 60 nm. It is indeed in this size range that the titanium oxide appears to have an optimal photo-catalytic effect, probably because the crystallites of this size develop a large active surface. The photocatalytically active coating may also comprise, in addition to titanium oxide, at least one other type of mineral material, especially in the form of an amorphous or partially crystalline oxide, for example silicon oxide (or a mixture of oxides), titanium, tin, zirconium or aluminum. This mineral material can also participate in the photo-catalytic effect of crystallized titanium oxide, itself having a certain photo-catalytic effect, even small compared to that of crystallized TiO 2, which is the case of the amorphous or partially crystalline titanium oxide. It is also possible to increase the number of charge carriers by doping the crystalline lattice of titanium oxide by inserting at least one of the following metallic elements: niobium, tantalum, iron, bismuth, cobalt, nickel, copper, ruthenium, cerium molybdenum. This doping can also be done by surface doping only of the titanium oxide or of the whole coating, surface doping carried out by covering at least a portion of the coating with a layer of oxides or metal salts, the metal being selected from iron, copper, ruthenium, cerium, molybdenum, vanadium and bismuth. Finally, the photo-catalytic phenomenon can be amplified by increasing the yield and / or kinetics of the photo-catalytic reactions by covering the titanium oxide or at least a part of the coating which incorporates it with a noble metal in the form of a thin layer. platinum, rhodium, silver. The coating with photocatalytic property also has an outer surface of hydrophilic and / or oleophilic pronounced, especially in the case where the binder is inorganic, which brings two significant advantages: a hydrophilic character allows a perfect wetting of water which can be deposited on the coating, thus facilitating cleaning. Together with a hydrophilic character, it can also have an oleophilic character, allowing the wetting of organic soils which, as for water, then tend to deposit on the coating in the form of a continuous film less visible than spots well localized . An organic antifouling effect is thus obtained which operates in two stages: as soon as it is deposited on the coating, the soil is already not very visible. Then, gradually, it disappears by radical degradation initiated by photo-catalysis. The thickness of the coating is variable, it is between a few nanometers and a few microns, typically between 50 nm and 10 m.

  In fact, the choice of the thickness may depend on various parameters, in particular the envisaged application of the substrate, or on the size of the TiO 2 crystallites in the coating. The coating may also be chosen with a more or less smooth surface: a low surface roughness may indeed be advantageous if it makes it possible to develop a larger active photo-catalytic surface. However, too pronounced, it can be penalizing by favoring the encrustation, the accumulation of soiling. According to another variant, the functionality that is reported on the other side of the substrate may be constituted by an anti-reflection coating thus maximizing the energy conversion efficiency. The following are the preferred ranges of the geometric thicknesses and indices of the four layers of the antireflection stack according to the invention, this stack being called A: n1 and / or n3 are between 2.00 and 2.30, in particular between 2.15 and 2.25, and preferably close to 2.20. n2 and / or n4 are between 1.35 and 1.65. and is between 5 and 50 nm, especially between 10 and 30 nm, or between 15 and 25 nm. e2 is between 5 and 50 nm, especially less than or equal to 35 nm or 30 nm, in particular between 10 and 35 nm. e3 is between 40 and 180 nm and preferably between 45 and 150 nm. e4 is between 45 and 110 nm and preferably between 70 and 105 nm. The most suitable materials for forming the first and / or third layer of the stack A, which is of anti-reflective type, those with a high index, are based on mixed nitride of silicon and zirconium or a mixture of these nitrides. mixed. In a variant, these high-index layers are based on mixed nitrides of silicon and tantalum or a mixture of these. All these materials may be optionally doped to improve their chemical and / or mechanical and / or electrical resistance properties.

  The most suitable materials for constituting the second and / or fourth layer of the stack A, those with low index, are based on silicon oxide, oxynitride and / or silicon oxycarbide or based on a mixed oxide of silicon and aluminum. Such a mixed oxide tends to have a better durability, especially chemical, than pure SiO 2 (an example is given in patent EP-791 562). The respective proportion of the two oxides can be adjusted to achieve the expected improvement in durability without greatly increasing the refractive index of the layer.

  A preferred embodiment of this antireflection stack is of the substrate / Si3N4 / SiO2 / Si3N4 / SiO2 form, it being understood that the choice of the different thicknesses and in particular at the level of the thicknesses of the third and fourth layers is optimized so that the light transmission is located in most of the spectrum (ie in the visible and in the infrared).

  It goes without saying that the invention applies in the same way to the use of other electroluminescent systems than those described in the examples.

Claims (29)

  An electroluminescent device comprising: a substrate, in particular a transparent substrate, a first electrode and a second electrode on the same face of the substrate, the at least one first electrode being transparent, a light-emitting layer interposed between the first and second electrodes, characterized in the first electrode comprises a diffusing electroconductive layer.   2. Electroluminescent device according to claim 1, characterized in that the diffusing electroconductive layer has a blur greater than or equal to 2%, preferably between 5 and 20%.   3. Electroluminescent device according to one of the preceding claims, characterized in that the first electrode has a fuzzy product factor (H) by the light transmission (TL) expressed in a graph H (TL) is above a defined line by the following bi-points (15; 82); (10; 84); (6; 85).   4. Electroluminescent device according to one of the preceding claims, characterized in that the first electrode has a light absorption product by the electrical surface resistance of less than 0.6 S2 / square. 25   5. Electroluminescent device according to one of the preceding claims, characterized in that the first electrode has a resistance per square (R squared) less than or equal to 15 S2 / square, in particular less than or equal to 12 S2 / square, preferably lower. or equal to 10 or 12 S2 / square. 30   6. Electroluminescent device according to one of the preceding claims, characterized in that the diffusing electroconductive layer is a layer having a diffusing surface directly after deposition.   Electroluminescent device according to one of the preceding claims, characterized in that the surface of the diffusing electroconductive layer has a roughness RMS> 3 nm and a pattern size> 50 nm.   8. Electroluminescent device according to one of the preceding claims, characterized in that the diffusing electroconductive layer is composed of a doped metal oxide and predominantly crystalline.   9. Electroluminescent device according to one of the preceding claims, characterized in that the diffusing electroconductive layer is a textured layer after deposition.   10. Electroluminescent device according to one of the preceding claims, characterized in that the diffusing electroconductive layer is roughness induced at least in part by the substrate which is textured and / or by the second underlying electrode comprising a rough electroconductive layer.   11. Electroluminescent device according to one of the preceding claims, characterized in that the diffusing electroconductive layer is deposited on a rough inorganic layer directly after deposition and which is preferably a layer based on tin and oxygen.   12. Electroluminescent device according to one of the preceding claims, characterized in that the diffusing electroconductive layer is a multilayer which comprises a first electroconductive layer composed of an undoped mineral oxide, said first layer being coated with a second electroconductive layer composed of same inorganic oxide, said mineral oxide being however doped.   13. Electroluminescent device according to claim 12, characterized in that the thickness of the first undoped mineral oxide layer is between 150 and 900 nm.   14. electroluminescent device according to one of claims 12 or 13, characterized in that the doped and / or undoped mineral oxide is (are) deposited (s) at high temperature especially at a temperature above 600 C.   15. Electroluminescent device according to one of claims 12 to 14, characterized in that the first layer is based on tin oxide (SnO2) and the second layer is based on fluorine-doped tin oxide (SnO2). F).   16. Electroluminescent device according to one of claims 12 to 15, characterized in that the first electrode further comprises at least one overcoating based on conductive metal oxide, in particular indium oxide doped tin zinc molybdenum or doped, zinc oxide, this overcoat being deposited on the second fluorine-doped tin oxide layer (SnO2: F).   Electroluminescent device according to one of Claims 12 or 13, characterized in that the first layer is based on zinc oxide (ZnO) and the second layer is based on zinc oxide doped with aluminum (ZnO). Al).   18. Electroluminescent device according to one of the preceding claims, characterized in that it is provided with at least one barrier layer, particularly vis-à-vis the alkaline, inserted between said selected glass substrate and the most electrode close to the glass substrate.   19. Electroluminescent device according to claim 18, characterized in that the barrier layer is rough and / or diffusing.   20. Electroluminescent device according to one of claims 18 to 19, characterized in that the barrier layer is based on a dielectric material, chosen from at least one of the following compounds: silicon nitride or oxynitride, nitride or oxynitride. aluminum, silicon oxide or oxycarbide and preferably the barrier layer has a thickness of between 20 nm and 150 nm.   Electroluminescent device according to claim 18 to 20, characterized in that the barrier layer is part of a multilayer optical coating consisting of at least two layers of dielectric materials of different refractive indices and preferably the barrier layer comprises an alternation of high refractive index layers, between 1.9 and 2.3, and low refractive index layers, between 1.4 and 1.7, in particular according to the S13N4 / SiO2 sequences OR Si3N4 / SiO2 / Si3N4.   22. Electroluminescent device according to one of the preceding claims according to, characterized in that the electroluminescent layer is inorganic or organic.   23. Electroluminescent device according to one of claims 11 to 15, characterized in that the electroluminescent layer is inorganic and the first electrode is based on doped and / or undoped mineral oxide deposited by pyrolysis, in particular by gas phase, on the electroluminescent layer, and the second electrode is metallic.   Electroluminescent device according to one of the preceding claims, characterized in that the substrate is a preferably extra-clear glass.   25. An electroluminescent device according to any one of the preceding claims, characterized in that one of the faces of the substrate is coated with a stack providing a function of the anti-reflective or hydrophobic or photocatalytic type or solar control or low emissivity.   26. An electroluminescent device according to any one of the preceding claims, characterized in that it forms an illuminating, decorative, architectural, signaling system, a display panel, is intended for the building, thus forming an illuminating facade, a illuminating window, or is intended for a transport vehicle, such as a rear window, a side window or an automobile roof, or any other land vehicle, whether aquatic or aerial, is intended for street furniture such as a bus shelter , at a display stand, at a jewelery showcase, at a showcase, a shelf element, at an aquarium, at a greenhouse, is intended for interior furnishings, a mirror, a piece of furniture, an electrically controllable glazing unit .   27. Use of a diffusing electroconductive layer as an electrode layer of an electroluminescent device. 30   28. Use of a diffusing electroconductive layer according to the preceding claim characterized in that it has a blur greater than or equal to 2%.   29. Use of a diffusing electroconductive layer according to one of claims 27 to 28 characterized in that the diffusing electroconductive layer is a multilayer which comprises a first transparent electroconductive layer composed of an undoped mineral oxide, said first layer being coated with a second transparent electroconductive layer composed of the same inorganic oxide, said mineral oxide being however doped, and preferably the first layer is based on tin oxide (SnO2) and the second layer is based on fluorine-doped tin (SnO2: F) or the first layer is based on zinc oxide (ZnO) and the second layer is based on zinc oxide doped with aluminum (ZnO: Al).