organic light-emitting diode comprising a PEDOT anode layer

Abstract

The present invention relates to an organic light-emitting diode (well known as "Organic Light Emitting Diode" or OLED) comprising a layer of doped PEDOT, monophasic or obtained by dry oxidative process, which acts both as anode and hole injection layer, its manufacturing method, an optoelectronic device comprising one or more of said organic light-emitting diodes, as well as the use of such a layer of doped PEDOT, monophasic or obtained by dry oxidative process, as an anode layer in an organic light-emitting diode and the use of said organic light-emitting diode or said optoelectronic device, as an authentication or decoration means. Figure for abstract: Fig. 1

Description

Description Title of the invention: organic light-emitting diode comprising a PEDOT anode layer The present invention relates to an organic light-emitting diode (well known by the Anglicism "Organic Light Emitting Diode" or OLED) comprising a layer of doped PEDOT, monophasic or obtained by dry oxidative process, which acts both as anode and hole injection layer, its manufacturing method, an optoelectronic device comprising one or more of said organic light-emitting diodes, as well as the use of such a layer of doped PEDOT, monophasic or obtained by dry oxidative process, as an anode layer in an organic light-emitting diode and the use of said organic light-emitting diode or said optoelectronic device, as a means of authentication or decoration. An organic light-emitting diode is a device based on the phenomenon of electroluminescence that allows the transformation of electric current into light. The OLED may comprise a substrate, two electrodes, one of the electrodes, called the lower one, generally the anode, being associated with the substrate and the other, called the upper one, generally the cathode, and an organic electroluminescent system interposed between said electrodes, said organic electroluminescent system being formed by an organic electroluminescent material (monolayer OLED) or a stack of organic electroluminescent materials (multilayer OLED). The OLED emits light by electroluminescence using the recombination energy of holes injected from the anode and electrons injected from the cathode.In the monolayer device, a single organic material is used to perform the following functions: charge injection, transport, recombination, and light emission. A monolayer OLED is generally made of a luminescent organic semiconductor film about 100 nm thick, inserted between two electrodes of different chemical natures. The anode injects holes and the cathode injects electrons. One of these two electrodes is transparent to allow the emitted light to pass through. Very often, an indium tin oxide (ITO) anode is used, which is a conductive, semi-transparent material with a work function compatible with the role of hole injector. As for the cathode, it is generally made of metals or alloys (Ca, Mg, Mg / Ag, Al / Li or LiF / Al) with a low work function favoring the injection of electrons into the organic semiconductor.The electroluminescent materials used belong to one of two main families: conjugated polymers and low molar mass molecules. In order to enhance charge recombination in the emitting layer and to reduce injection barriers, layers with specific functions can be introduced into the diode structure such as layers for hole and electron injection (HIL for "Hole Injection Layer" and EIL for "Electron Injection Layer" respectively) and / or layers for hole and electron transport (HTL for "Hole Transfert Layer" and ETL for "Electron Transfert Layer" respectively). For example, patent application FR2897983A1 describes an organic light-emitting diode comprising: - a lower electrode and an upper electrode, one serving as an anode, the other as a cathode, and an organic electroluminescent layer interposed between these electrodes, - an electron injection and transport layer made of n-doped organic semiconductor material, which is in contact with the electrode serving as cathode and which is intercalated between this electrode and said organic electroluminescent layer, and - a hole injection and transport layer made of conductive polymer material, which is in contact with the electrode serving as anode and which is interposed between this electrode and said organic electroluminescent layer. An electrode consisting of a 150 nm ITO layer is used as an anode and PEDOT:PSS is implemented as a hole injection and transport layer. PEDOT:PSS is widely used as an HIL / ATL layer in organic optoelectronic devices because it is a good hole conductor and can be easily deposited by liquid means, including spin coating or dip coating. In particular, the PEDOT:PSS complex is in the form of an aqueous suspension comprising a mixture of two polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) and sodium poly(styrene sulfonate) (PSS). PSS, by its hydrophilic nature, stabilizes the aqueous suspension and acts as a dopant to enhance the electrical conductivity of the mixture. However, the liquid deposition route of PEDOT:PSS has drawbacks, such as moderate electrical conductivity (at most 400 S / cm), the presence of water and solvents that may not be compatible with the substrates to be coated and / or the operations carried out subsequently as in the case of OLEDSs, poor control of the deposited thickness, and / or non-conformity of the deposits, in particular on complex substrates (i.e. substrates with submicron patterns). Furthermore, the hygroscopic properties of PEDOT:PSS are a source of premature degradation of OLEDs. Indeed, it has been shown that the presence of water residues at the ITO / organic interface, causes the diffusion of indium into the organic layers of organic devices. In addition, the acidic nature of certain formulations used to deposit PEDOT:PSS leads to the degradation of the ITO / PEDOT:PSS interface. These degradation problems related to PEDOT:PSS have led to the development of alternatives. For example, one of them is based on the use of inorganic materials. Considered more stable than PEDOT:PSS, metal oxide layers, such as molybdenum oxide (MoO;), tungsten oxide (WO4) or vanadium oxides (V,0;) have been integrated into OLEDs as HIL / HTL layers. However, the major drawback of these metal oxide layers lies in the danger and toxicity of these metal oxides. The conductive transparent electrode material also plays an important role in the performance of an OLED (intrinsic properties of the electrode such as optical transmittance, electrical conductivity, surface condition such as roughness). ITO is a reference material in the transparent electrode sector due to its excellent optoelectronic properties and robustness. It has very good conductivity (up to 10* S / em) with a surface resistance of around 10 ©2 / square and excellent optical transmittance in the visible range (between 85 and 95%, particularly in the 380 nm and 800 nm range). However, several problems arise, particularly economic and practical. Indeed, the ITO electrode contains indium, the market for which exploded at the same time as that of liquid crystal displays (LCDs).Its main resources are located mainly in China, maintaining a high level of the price of the raw material, and the global reserve continues to decrease. In addition, its deposition process is heavy and expensive, in addition to being mainly carried out on glass substrates. Indeed, ITO is fragile and brittle on flexible substrates, and therefore not very flexible. This is why the search for alternative materials has been launched for several years. Other transparent conductive oxides such as fluorine-doped tin oxide (FTO) or aluminum-doped zinc oxide have also been proposed. However, they generally have a lower electrical conductivity-to-transparency ratio and higher surface roughness. In addition, they are generally more unstable to humidity when the layers are less than 100 nm thick. Furthermore, the most common method for producing transparent conductive oxide films is sputtering. This technology operates under a secondary vacuum, which makes the fabrication of thin films of transparent conductive oxides often costly in terms of materials and energy. Carbon-based nanomaterials have also been proposed, such as carbon nanotubes or graphene. Despite their excellent electrical, optical and mechanical properties, carbon nanotubes are still struggling to be present in marketable applications due to the impurities present during their manufacture as well as the wide distribution of their dimensions. The electrical conductivity of the layers is ensured by the percolation threshold of carbon nanotubes. For applications in OLEDs, a critical point of these films is the surface roughness which remains higher than that of ITO films. Concerning graphene, its production on an industrial scale has been active for several years. However, the lack of reproducibility of the optoelectronic properties of the films does not yet allow its inclusion in commercial processes. Metallic nanostructures such as metallic nanoparticles and nanowires have also been described. However, due to their size and spherical shape, metal nanoparticles are rarely used as transparent electrodes since they must be assembled in a certain way or combined with other compounds to demonstrate interesting electrical and optical performance. Nanowires can be based on copper or silver. Due to their optoelectronic properties, which allow a good compromise between electrical conductivity and transmittance, electrodes based on silver nanowires are already marketed by Cambrios in the form of transparent conductive films integrated into touch screens. However, these films present a significant disadvantage for display applications. Indeed, the geometry of the nanowires leads to a milky appearance of the screens.This visual aspect thus limits applications in OLEDs. Furthermore, just like carbon nanotubes, the main limitation to the use of nanowire arrays as electrodes is roughness. Indeed, upright nanowires can cause short circuits or leakage currents in multilayer devices. On the other hand, the stability of nanowire electrodes also remains problematic since during prolonged exposure to high temperature and humidity conditions, or after being supplied with a direct electric current, the conductivity of the electrode degrades. Conductive polymers have also been proposed, such as polythiophenes. The most widely used conductive polymer as a transparent electrode in the field of organic electronics is PEDOT:PSS, as described above as a HIL / TIL layer. However, several problems arise, including the conductivity, which remains below other alternatives with equal transparency, and also the hygroscopy and acidity of this material. The PSS group is negatively charged and therefore makes the medium very acidic, which, coupled with hygroscopy, leaves PEDOT:PSS films relatively unstable for prolonged use in OLEDs. However, stability can be improved using additives. Furthermore, it is also possible to form composite layers with this polymer and carbon- or metal-based nanomaterials. Chemical modification of the nanomaterials to be combined with PEDOT:PSS has also been studied, always with the aim of increasing the conductivity and robustness of the electrode. The aim of the present invention is therefore to overcome the drawbacks of the prior art, and in particular to provide a more economical and ecological organic light-emitting diode (OLED), while guaranteeing good performance in terms of luminance, transmittance, electrical conductivity, stability, and / or roughness. The first subject of the invention is an organic light-emitting diode, characterized in that it comprises, successively, in the following order: - a transparent non-conductive substrate, - a conductive transparent anode layer comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process, - an organic electroluminescent system, and - a cathode layer. The diode according to the first subject of the invention uses a layer comprising doped PEDOT obtained by dry oxidative process or monophasic doped PEDOT as an anode layer. This makes it possible, on the one hand, to avoid the use of PEDOT-based complexes having the aforementioned disadvantages such as PEDOT:PSS or the use of ITO; and on the other hand to reduce the costs and the environmental and energy footprint of OLEDs, to better meet the needs of the current market (aeronautics, automotive, urban lighting, etc.), while guaranteeing good performance in terms of luminance, transmittance, electrical conductivity, stability, and / or roughness. Transparent non-conductive substrate The non-conductive transparent substrate (or support) is transparent. In the present invention, the term "transparent substrate" means a substrate transmitting at least a portion of the incident light (or incident light ray) with very little or no dispersion. Preferably, the substrate is transparent in the visible wavelength range. The transparent substrate has a light transmission (transmittance) of at least about 70%, and particularly preferably of at least about 80%. Light transmission is the quantity of light that the transparent substrate lets pass from an incident light ray. Visible light transmission is the quantity of visible light, corresponding to electromagnetic waves whose wavelength corresponds to the visible spectrum, i.e. between the wavelengths of about 380 and 800 nm (inclusive), that the substrate lets pass from an incident light ray. Light transmission or transmittance can be determined using a Perkin Elmer Lambda 35 UV / Vis spectrometer. It is preferably measured at around 550 nm. The transparent substrate is non-conductive. In the present invention, the term "non-conductive substrate" means a substrate having a resistivity or surface resistance of at least approximately 10* chm / square, and particularly preferably of at least approximately 106 ohm / square. Resistivity can be determined with a four-pin meter or by the Van der Pauw method. In the present invention, the term "non-conductive substrate" means a substrate having an electrical conductivity of at most approximately 106 S / cm, and particularly preferably of at most approximately 10* S / cm. Electrical conductivity can be determined with a four-point measuring device or by the Van der Pauw method combined with thickness measurement by profilometry or Atomic Force Microscopy. The non-conductive transparent substrate may comprise (or be made of) a material selected from silicon oxide-based inorganic materials, alumina-based inorganic materials such as alumina-based ceramic materials, polymeric materials, cellulosic materials, and textile materials. Polymeric materials include polyacrylates such as polymethyl methacrylate, polyesters such as polyethylene terephthalate or polylactic acid, parylenes such as parylene type C (parylene-C), and polyimides. Among the inorganic materials based on silicon oxide, we can cite glass or quartz. Among the alumina-based ceramic materials, we can cite polycrystalline alumina (AI,O4), sapphire, aluminum nitride (ALN), aluminum oxynitride (ALON), or spinel (MgA1,O,). Cellulosic materials include paper, cardboard, paperboard, and cellulose-based materials. Textile materials include natural or synthetic fibers, such as linen, cotton, or polymer fibers. Preferably, the non-conductive transparent substrate comprises (or is made of) glass, quartz, polymethyl methacrylate, polyethylene terephthalate, paper, textile material, polylactic acid, parylene-C, or polycrystalline alumina. The non-conductive transparent substrate may be a treated non-conductive transparent substrate, i.e. having undergone one or more surface treatments, in particular in order to prevent its contamination with oxygen and / or water. In this embodiment, the treated non-conductive transparent substrate comprises one or more barrier layers (to contamination). The barrier layer(s) may be chosen from a SiO layer, a layer of Al,O,, a layer of parylene-C, a layer of silicon nitride (SiN,), and a mixture thereof, Each of the barrier layers can have a thickness ranging from approximately 100 nm to 1000 nm. The Al:O layer is preferably deposited by atomic layer deposition or ALD (well known by the Anglicism “atomic layer deposition”) or by cathode sputtering. The parylene-C layer is preferably deposited by chemical vapor deposition or CVD (well known by the Anglicism “chemical vapor deposition”). The SiO or SiN layer is preferably deposited by cathodic sputtering or ALD. The layers of Al,O3, SiO, or SIN can each have a thickness ranging from approximately 15 nm to 50 nm. The parylene-C layer can have a thickness ranging from about 100 nm to 1000 nm. The transparent non-conductive substrate (including the barrier layer(s) if they exist) can have a thickness ranging from approximately 0.1 to 10 mm. The transparent non-conductive substrate may be porous or non-porous, and preferably non-porous. The non-conductive transparent substrate preferably does not comprise conductive carbon materials such as graphene, carbon nanotubes or fibers, or conductive metallic materials such as silver particles, nanoparticles or nanowires. The transparent non-conductive substrate can be rigid or flexible, flat or curved. Organic electroluminescent system In the invention, the term "electroluminescent system" means that the system emits light in response to an electric current passing through it, or to a strong electric field. The system preferably emits light in the wavelength range of about 380 to 800 nm. The organic electroluminescent system characterizes the OLED, it is notably intercalated between the electrodes, i.e. between the anode layer and the cathode layer. The electroluminescent system is organic. In other words, it comprises at least carbon atoms covalently bonded to hydrogen atoms. In other words, the organic electroluminescent system essentially comprises organic compounds and / or organometallic compounds. The electroluminescent system preferably does not comprise any inorganic compound(s), i.e. any compound(s) free of carbon atoms covalently bonded to hydrogen atoms. The organic electroluminescent system preferably comprises at least one hole-transporting material (eg p-type material) and at least one electron-transporting material (eg n-type material). The hole-transporting material is well known to those skilled in the art and is generally defined as a material that conducts positive charges (holes) more easily than negative charges (electrons). In particular, it is capable of transporting holes to an emission region. The electron-transporting material is well known to those skilled in the art and is generally defined as a material that conducts negative charges (electrons) more easily than positive charges (holes). In particular, it is capable of transporting electrons to an emission zone. The organic electroluminescent system preferably has a thickness ranging from about 100 to 250 nm. The organic electroluminescent system can be in the form of a single layer or several layers stacked on top of each other. This is referred to as a monolayer or multilayer system respectively. The organic electroluminescent system is preferably at least partly in direct physical contact with the cathode layer. In other words, in this preferred embodiment, at least a portion of the surface of the organic electroluminescent system is in direct physical contact with the surface of the cathode layer. This means that the cathode layer is deposited directly on at least a portion, and preferably the entire surface of said organic electroluminescent system. As such, the organic light-emitting diode of the invention does not comprise any additional layer(s) interposed between the cathode layer and the organic electroluminescent system. The conductive transparent anode layer comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process is preferably at least partly in direct physical contact with the organic electroluminescent system. In other words, in this preferred embodiment, at least a portion of the surface of the conductive transparent anode layer comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process is in direct physical contact with the surface of the organic electroluminescent system. This means that the organic electroluminescent system is deposited directly on at least a portion, and preferably the entire surface of said conductive transparent anode layer comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process. As such, the organic light-emitting diode of the invention does not comprise any additional layer(s) interposed between the organic electroluminescent system and the conductive transparent anode layer comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process. The organic electroluminescent system is preferably multilayer, particularly preferably bilayer or trilayer, and more particularly preferably bilayer. In the case of a monolayer organic electroluminescent system, the hole-transporting material and the electron-transporting material can be one and the same material. The multilayer organic electroluminescent system preferably comprises: - at least one hole transport layer, preferably at least partly in direct physical contact with the conductive transparent anode layer comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative route; and - at least one electron transport layer, preferably at least partly in direct physical contact with the cathode layer. The hole transport layer preferably has a thickness of about 35 to 60 nm. The hole transport layer may comprise (or consist of) at least one organic or organometallic compound, as a hole transport material, selected from N,N"-Di(1-naphthyl)-N,N-diphenyl-(1,1"-biphenyl)-4,4"-diamine (NPD or NPB), 4,4,4"-tris|phenyl(m-tolyl)amino|triphenylamine (m-MTDATA), 3,3"-Di(9H -carbazol-9-yl)-1,1"-biphenyl (MCBP), tris(4-carbazoyl-9-ylphenyl)amine (TCTA), 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), and copper(I) phthalocyanine (CuPc). The electron transport layer preferably has a thickness ranging from about 20 to 80 nm. The electron transport layer may comprise (or consist of) at least one organic or organometallic compound, as electron transport material, selected from tris-(8-hydroxyquinoline)aluminum (AIQ;), bathocuproine (BCP), bathophenanthroline (Bphen), 2,2',2"-(1,3,5-benzinetriyl)-tris(1-phenyl-1H - benzimidazole) (TPBi), bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum (Balg), and 3-(biphenyl-4-y1)-5-(4-tertbutylphenyl)-4-phenyl-4H-1,2,4-triazole (TAZ). The organic electroluminescent system generally includes an emission region either in the hole transport layer, in the electron transport layer, or at the interface between the two layers. The multilayer organic electroluminescent system may further comprise a emission layer (well known as “Emission Layer” or EML), interposed between the hole transport and electron transport layers, in particular to optimize emission (color, light output, etc.). The cathode layer The cathode layer may comprise (or consist of) a metal selected from barium, magnesium, silver, calcium, aluminum, and aluminum combined with a layer of lithium fluoride. Calcium is preferred, particularly because of its low work function (-2.9 eV). The cathode layer can have a thickness ranging from about 80 to 130 nm. The cathode layer in particular generates negative charges. The cathode layer preferably has a work function of less than about -4 eV. In the diode of the invention, the cathode layer is electrically connected to the anode layer. The anode layer comprising PEDOT The organic light-emitting diode of the invention comprises a conductive transparent anode layer comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process. The anode layer is transparent. In the present invention, the term "transparent anode layer" means a layer transmitting at least a portion of the incident light (or incident light ray) with very little or no dispersion. Preferably, the transparent anode layer is transparent in the UV-visible wavelength range. The transparent layer has a light transmission (transmittance) of at least approximately 80%, and particularly preferably of at least approximately 90%. The light transmission is the quantity of light that the transparent layer lets pass from an incident light ray. The UV-visible light transmission is the quantity of UV-visible light, corresponding to electromagnetic waves whose wavelength corresponds to the UV-visible spectrum, i.e. between the wavelengths of approximately 100 and 800 nm (inclusive), that the transparent layer lets pass from an incident light ray. Light transmission or transmittance can be determined using a Perkin FElmer Lambda 35 UV / Vis spectrometer. Flle is preferably measured at about 550 nm. The anode layer is conductive. The anode layer is notably a generator of positive charges. In the present invention, the term "conductive anode layer" means a layer having a surface resistivity or resistance of at most approximately 500 ohm / square, and particularly preferably at most approximately 20 ohm / square. Resistivity can be determined with a four-pin meter or by the Van der Pauw method. In the present invention, the term "conductive anode layer" means a layer having an electrical conductivity of at least approximately 500 S / cm, and particularly preferably of at least approximately 800 S / cm. Electrical conductivity can be determined with a four-point measuring device or by the Van der Pauw method combined with thickness measurement by profilometry or Atomic Force Microscopy. The anode layer of the invention preferably has a work function greater than approximately -4.8 eV. This thus makes it possible to promote the transfer of positive charges to the energy level for transporting positive charges in organic materials of the organic electroluminescent system, called "HOMO" (well known by the Anglicism "Highest Occupied Molecular Orbital"). The anode layer of the diode of the invention has the function of generating and injecting positive charges (holes) into the organic electroluminescent system. It plays the role of both anode and hole injection layer. The conductive transparent anode layer comprises monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process. The anode layer of the invention is preferably a flexible layer. PEDOT is poly(3,4-ethylenedioxythiophene). It is preferentially doped with anions chosen from halides such as chlorides, bromides, iodides or fluorides. The anions acting as dopants in PEDOT are preferably non-polymeric, i.e. they do not comprise a polymer chain. Halides such as chlorides are particularly preferred. The anode layer may have a thickness ranging from about 8 to 80 nm, and preferably from 30 to 50 nm. The anode layer preferably has a roughness Rq or root mean square deviation of at most approximately 10 nm in root mean square (well known according to the Anglicism "Roots Mean Square" or RMS), and particularly preferably of at most approximately 5 nm in RMS. If the roughness is too high, conduction paths may appear between the two electrodes, creating short circuits that prevent the OLED from functioning properly. The roughness of the anode layer can be measured using a contact or non-contact device, such as a probe profilometer, an optical cutting device, or an atomic force microscope. Roughness is preferably measured using an atomic force device such as an atomic force microscope (AFM). The root mean square deviation of roughness Rq is defined in the international standard NF EN ISO 4287. According to one embodiment of the invention, the anode layer comprises at least 90% by mass of monophasic doped PEDOT or obtained by dry oxidative route, particularly preferably at least 95% by mass of monophasic doped PEDOT or obtained by dry oxidative route, relative to the total mass of the anode layer, and more particularly preferably consists of monophasic doped PEDOT or obtained by dry oxidative route. According to a particularly preferred embodiment of the invention, the non-conductive transparent substrate is at least partly in direct physical contact with the conductive transparent anode layer. In other words, in this particularly preferred embodiment, the conductive transparent anode layer is deposited directly on at least a portion, and preferably the entire surface of said non-conductive transparent substrate. As such, the organic light-emitting diode of the invention does not comprise any additional layer(s) interposed between the conductive transparent anode layer and the non-conductive transparent substrate (treated or untreated). This also means that the organic light-emitting diode does not comprise any conductive transparent anode layer(s) other than that of the invention comprising monophasic doped PEDOT or obtained by dry oxidative process. Preferably, the organic light-emitting diode does not comprise hole injection layer(s) other than the conductive transparent anode layer comprising monophasic doped PEDOT or obtained by dry oxidative process. The dry oxidative process or the monophasic nature of doped PEDOT makes it possible to replace some of the current constituent materials of light-emitting diodes (PEDOT complexes such as PEDOT:PSS, ITO, other metal oxide anodes, graphene, etc.) which are harmful to the environment, inefficient, and / or too expensive; and to provide a water-free, solvent-free anode layer of controlled, uniform thickness on any type of rigid or flexible substrate, and in particular on complex substrates (i.e. substrates with submicron patterns). Furthermore, this avoids the use of rigid anodes such as ITO and opens the way to the manufacture of OLEDs on flexible and lightweight substrates (plastic, paper, fabric, etc.), promising new applications (luminescent bandages for phototherapy, papers with tamper-evident markers, illuminating fabrics, etc.). The dry oxidative route means that the doped PEDOT is obtained or prepared in a dry medium, i.e. free of liquid. In other words, the dry route is not limited to the "proper" polymerization of the 3,4-ethylenedioxythiophene (EDOT) monomer to form PEDOT, but concerns both the (dry) polymerization of the EDOT monomer; and the (dry) state of the reagents used in the preparation of doped PEDOT. The dry route must, for example, be distinguished from vapor phase polymerization, also known as "vapor phase polymerization" or VPP, which involves a centrifugal coating step of a liquid solution of an oxidizing agent followed by its exposure to a continuous flow of EDOT vapors. As explained above, so-called "wet" or liquid methods are perfectly suited to mass production, but one of the critical points remains the elimination of solvents during the development of the layers. Indeed, the presence of solvent residues in the layers is responsible for the formation of defects (such as pinholes). These are caused by dewetting zones in the layer. These defects lead to premature degradation of OLEDs. The dry oxidative process in particular makes it possible to avoid the formation of this type of defect. The dry process is called “oxidative” in that it uses at least one oxidizing agent. The dry oxidative route can be chosen from oxidative chemical vapor deposition (oCVD) and oxidative molecular layer deposition (oMLD). In a preferred embodiment, the doped PEDOT of the conductive transparent anode layer is obtained from the EDOT monomer and at least one oxidizing agent, said EDOT monomer and oxidizing agent being gaseous species (I.e. in gaseous form). The oxidizing agent can be chosen from CuCl, FeCI;, FeBrs, IL, POBr;, GeCL, ShIz, Br, SbFs, H,SO4, SbCIs, TIC, POCIs, SOzCI,, CrO:Cl2, S2CI, O(CH3):SbCle, VCL, MoCl,, VOCI,, BF+, (CH,(CHz)):O.BF;, (C,H;)4O(BF;,), and BF,.0(C,H5)>. FeCl;, SbCls, and VOCI; are preferred. In particular, FeCls exhibits low toxicity and modest cost. oCVD and oMLD are single-step, purely gas-phase processes, and therefore do not generate any substrate-solvent compatibility issues or liquid contamination of a deposit. In these processes, the oxidizing agent serves both as a promoter of the polymerization of the EDOT monomer and as a doping agent to form the conductive polymer. oCVD and oMLD differ in that oCVD involves simultaneously feeding the aforementioned gaseous species into a reactor and oMLD involves sequentially feeding the aforementioned gaseous species into a reactor. In both In this case, a thin layer of doped PEDOT is formed on the substrate(s), in particular placed in a reactor. In a preferred embodiment, the doped PEDOT obtained by dry oxidative process is a monophasic doped PEDOT. In the invention, the term "monophasic doped PEDOT" means that the doped PEDOT (i.e. associated with the dopant) forms a single phase. In other words, it is not in the form of several phases such as PEDOT-based complexes of the PEDOT:PSS or PEDOT:PTS type. The monophasic or multiphasic character can be easily determined by vibrational spectroscopy (Raman or FTIR). In a preferred embodiment, the monophasic doped PEDOT is obtained by dry oxidative route. The dry oxidative route is as defined in the invention. The process for obtaining the doped PEDOT layer by dry oxidative means is explained in detail in the third subject of the invention. The second subject of the invention is an optoelectronic device, characterized in that it comprises a plurality of organic light-emitting diodes, at least one of the organic light-emitting diodes of said plurality being in accordance with the first subject of the invention. Preferably, the plurality of light-emitting diodes successively comprises, in the following order: - a transparent non-conductive substrate, - one or more conductive transparent anode layer(s) comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process, - an organic electroluminescent system, and - several cathode layers. The non-conductive transparent substrate, the conductive transparent anode layer(s) comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process, the organic electroluminescent system, and the cathode layers are as defined in the first subject of the invention. In a particular embodiment, the optoelectronic device comprises a plurality of organic light-emitting diodes, each of the organic light-emitting diodes of said plurality being in accordance with the first subject of the invention. The optoelectronic device can be a lighting or image display panel. The cathode layers are preferably on the same plane, which is parallel to the plane formed by the organic electroluminescent system. The organic electroluminescent system is preferably at least partly in direct physical contact with the cathode layers. In other words, in this preferred embodiment, at least a portion of the surface of the organic electroluminescent system is in direct physical contact with the surface of the cathode layers. This means that the cathode layers are deposited directly on at least a portion, and preferably the entire surface of the organic electroluminescent system. As such, the organic electroluminescent diode of the invention does not comprise any additional layer(s) interposed between the cathode layers and the organic electroluminescent system. The conductive transparent anode layers comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process (when there are several) are preferably on the same plane, which is parallel to the plane formed by the organic electroluminescent system. The conductive transparent anode layer(s) comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process are preferably at least partly in direct physical contact with the organic electroluminescent system. In other words, in this preferred embodiment, at least a portion of the surface of the conductive transparent anode layers comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process is in direct physical contact with the surface of the organic electroluminescent system. This means that the organic electroluminescent system is deposited directly on at least a portion, and preferably the entire surface of the conductive transparent anode layers comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process. As such, the organic light-emitting diode of the invention does not comprise any additional layer(s) interposed between the organic electroluminescent system and the conductive transparent anode layers comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process. According to a particularly preferred embodiment of the invention, the non-conductive transparent substrate is at least partly in direct physical contact with the conductive transparent anode layer(s) comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process. In other words, in this preferred embodiment, this means that the conductive transparent anode layers are deposited directly on at least a portion, and preferably the entire surface of said non-conductive transparent substrate. As such, the organic light-emitting diode of the invention does not comprise any additional layer(s) interposed between the conductive transparent anode layers and the non-conductive transparent substrate (treated or untreated). This also means that the organic light-emitting diode does not comprise any conductive transparent anode layer(s) other than those of the invention comprising monophasic doped PEDOT or obtained by dry oxidative route. Preferably, the organic light-emitting diode does not comprise hole injection layer(s) other than the conductive transparent anode layers comprising monophasic doped PEDOT or obtained by dry oxidative process. Method of manufacturing a light-emitting diode The third subject of the invention is a method for manufacturing a light-emitting diode in accordance with the first subject of the invention, characterized in that it comprises at least one step i) of depositing a conductive transparent anode layer comprising doped PEDOT on a non-conductive transparent substrate, said step i) being carried out by dry oxidative means. The non-conductive transparent substrate and the conductive transparent anode layer are as defined in the first subject of the invention. The method of the invention is simple, easy to implement and makes it possible to produce doped PEDOT layers with a thickness controllable to within a few nanometers, uniform over several tens of cm°, conformable on complex substrates, with electrical conductivity that can reach at least 500 S / cm, or even 1000 S / cm, and with an optical transmittance that can reach at least 90% at 550 nm, or even 95% at 550 nm. Step i) Since step i) is carried out by the dry method, it is implemented without solvent. In step 1), a conductive transparent anode layer comprising doped PEDOT is deposited on a non-conductive transparent substrate, by dry oxidative means. The dry oxidative route can be chosen from oxidative chemical vapor deposition (oCVD) and oxidative molecular layer deposition (oMLD). In a preferred embodiment, step 1) is carried out from the EDOT monomer and at least one oxidizing agent, said EDOT monomer and oxidizing agent being in the form of gas. The oxidizing agent can be chosen from CuCl, FeCI;, FeBrs, IL, POBr;, GeCL, ShIz, Br, SbFs, SbCIs, TiCL, POCIs, SO:CI,, CrO,Cl,, S,CI, O(CHz)3SbCle, VCL,, MoCIs, VOCI,, BF,, (CH,(CH:)):O.BF,, (C,H,)40(BF;,), and BF,.0(C,Hs),. FeCl, SbCls, and VOCI; are preferred. In particular, FeCls exhibits low toxicity and modest cost. In step 1), the oxidizing agent promotes the polymerization of the EDOT monomer and subsequently allows the neutral PEDOT polymer to be oxidized to form the doped PEDOT polymer. According to one embodiment of the invention, step 1) is carried out in a reactor, in particular equipped with a substrate holder. The reactor can be a cold wall reactor or a hot wall reactor, and preferably a hot wall reactor. This allows for uniform deposition on larger substrates and allows for the processing of non-thermally conductive substrates such as polymeric materials and cellulosic materials such as paper. The substrate holder may be made of a material selected from ceramic materials, silicon oxide-based materials such as glass or quartz, and metals such as steel or aluminum. In the method of the invention, the substrate holder preferably carries the non-conductive transparent substrate. Step 1) can be carried out at a temperature ranging from approximately 15°C to approximately 190°C, and preferably from approximately 130°C to 180°C. A temperature lower than or equal to 190°C makes it possible to coat heat-sensitive substrates (paper, fabric, plastic, etc.). Step 1) may be carried out under reduced pressure, in particular at a gas pressure ranging from approximately 1.10* mbar to 1.5 mbar, and preferably ranging from approximately 10! mbar to 1 mbar. According to the process in accordance with the second subject of the invention, step 1) can be carried out in the presence of a quantity in moles N of said oxidizing agent, and a quantity in moles N of said EDOT monomer. According to a preferred embodiment, N, is strictly less than N>. According to a particularly preferred embodiment, the molar ratio N, / N; ranges from approximately 0.01 to 0.8, and more particularly preferably from approximately 0.05 to 0.1. Step i) may last from about 1 min to 1 hour, and preferably from about 2 min to 30 min. Step 1) is preferably carried out at a speed ranging from approximately 0.2 to 30 nm.min*. Step 1) may include the following sub-steps: - a sub-step i-1) during which one or more non-conductive transparent substrate(s) are heated (previously deposited on the substrate holder), - a sub-step i-2) of supplying the reactor with gaseous EDOT, and - a sub-step i-3) of supplying the reactor with gaseous oxidizing agent. As soon as sub-steps i-2) and i-3) are initiated, the EDOT polymerizes into PEDOT Between sub-steps i-1) and i-2) or sub-steps i-1) and i-3), the reactor is preferably purged, in particular by placing it under vacuum. In sub-step i-2), the EDOT is preferably transported to the reactor in the presence of an inert gas such as nitrogen. This allows the EDOT to be diluted. In sub-step i-3), the oxidizing agent is preferably transported to the reactor in the presence of an inert gas such as nitrogen. This thus makes it possible to dilute the oxidizing agent. When step 1) is carried out by oCVD, the EDOT reagents and oxidizing agent are introduced in the gas phase at the same time or simultaneously into the reactor. Substeps i-2) and i-3) are therefore concomitant. When step 1) is carried out by oMLD, the EDOT and oxidizing agent reactants are introduced in the gas phase sequentially or alternately into the reactor. In other words, several sub-steps i-2) and i-3) are carried out one after the other. Preferably, a nitrogen purge sub-step is carried out between sub-steps i-2) and i-3) or sub-steps i-3) and i-2). This purge sub-step makes it possible to eliminate excess EDOT and oxidizing agent, and any secondary volatile product of the polymerization. The gas flow of EDOT can range from approximately 1 to 10 cm° / min (under standard temperature and pressure conditions), and preferably from approximately 2 to 6 cm” / min (under standard temperature and pressure conditions). The gas flow of oxidizing agent can range from approximately 0.2 to 3 cm* / min (under standard temperature and pressure conditions), and preferably from approximately 0.5 to 1 cm* / min (under standard temperature and pressure conditions). Sub-steps i-1) and i-2) [respectively sub-steps i-1) and i-3)] are preferably concomitant. Sub-step i-1) is preferably carried out at a temperature ranging from approximately 15°C to approximately 190°C, and preferably ranging from approximately 130°C to approximately 180°C. Step ii) The method may further comprise a step ii) of acid treatment after step i). Step ii) may make it possible to eliminate any residues of oxidizing agent and / or to increase the doping level of the PEDOT to improve its electrical conductivity. Step ii) may comprise contacting the non-conductive transparent substrate coated with the conductive transparent anode layer comprising doped PEDOT formed in step i), with a solution comprising a protic polar organic solvent and at least one strong acid. The strong acid can be chosen from hydrochloric acid, hydrobromic acid and sulfuric acid. The protic polar organic solvent can be a C;-C3 alcohol, such as methanol. Contacting is preferably carried out by immersing the non-conductive transparent substrate coated with the conductive transparent anode layer comprising doped PEDOT formed in step 1) in said solution, for example for 15 to 60 min. Step ii) may further comprise, after contacting with the solution, drying the non-conductive transparent substrate coated with the conductive transparent anode layer comprising doped PEDOT in air or argon. Step a) The process further comprises, before step i), a step a) during which the EDOT monomer and said oxidizing agent in gaseous form are prepared. The preparation of gaseous EDOT can be carried out by subjecting the EDOT to a temperature of at least 70°C. The preparation of the gaseous oxidizing agent may be carried out by subjecting the oxidizing agent to a temperature of at least 50°C, Step b) The method further comprises, before step i), a step b) during which the non-conductive transparent substrate is cleaned. The purpose of cleaning the non-conductive transparent substrate is to remove organic residues from its manufacture. Step b) promotes the proper functioning of the OLED (reduce contamination, eliminate any roughness on the surface, etc.) Step b) may comprise immersing said non-conductive transparent substrate in one or more solvents, in the presence of ultrasound. The solvent may be ethanol, water (preferably deionized), isopropanol, and / or acetone When the transparent non-conductive substrate is made of glass, it can, for example, be immersed successively in several ultrasonic baths: namely in a deionized water bath (e.g. for 5 minutes), in an acetone bath (e.g. for 5 minutes), then in an isopropanol bath (e.g. for 5 minutes). When the transparent non-conductive substrate is made of plastic, it can, for example, be immersed successively in several ultrasonic baths: namely in a deionized water bath (e.g. for 5 minutes), in an ethanol bath (e.g. for 5 minutes), then in an isopropanol bath (e.g. for 5 minutes). Step b) may further comprise, after immersion, a UV-Ozone treatment, for example for 10 min, preferably followed by drying of the non-conductive transparent substrate under an inert atmosphere, in particular under inert argon or nitrogen gas. Step iii) The method may further comprise, after step 1) or ii), a step iii) of depositing the organic electroluminescent system. Step iii) is preferably carried out under an inert atmosphere, and in particular under a nitrogen atmosphere. Step iii) can be carried out by thermal evaporation. Step iii) is preferably carried out under vacuum, in particular at a pressure of less than approximately 105 mbar. Step iii) is preferably carried out at a speed of approximately 0.1 to 0.2 nm.s! A mask may be used during step iii) to obtain one or more organic electroluminescent layers having the desired shape and / or surface. When the organic electroluminescent system is multilayer, the method comprises several steps iii-1), iii-2), etc… depending on the number of organic electroluminescent layers to be deposited, each of steps iii-1), iii-2) etc… being similar to step iii) as defined in the invention. In a preferred embodiment, the method comprises, after step 1) or ii, a step iii-1) of depositing a hole transport layer, followed by a step iii-2) of depositing an electron transport layer. Step iv) The method may further comprise, after step iii), a step iv) of depositing the cathode layer. Step iv) is preferably carried out under an inert atmosphere, and in particular under a nitrogen atmosphere. Step iv) can be carried out by thermal evaporation. Step iv) is preferably carried out under vacuum, in particular at a pressure of less than approximately 105 mbar. Step iv) is preferably carried out at a speed ranging from approximately 0.05 to 0.1 nm.s*. A mask may be used during step iv) to obtain a cathode layer having the desired shape and / or surface. The fourth subject of the invention is the use of a layer comprising monophasic doped PEDOT or obtained by dry oxidative process, as an electrode, and in particular as an anode (transparent conductive), in an organic light-emitting diode. The fifth object of the invention is the use of an organic light-emitting diode conforming to the first object or of an optoelectronic device conforming to the second object, as a means of authentication (eg. particular signature, obvious marking or non-obvious marking), or of decoration. As a means of authentication, it can be used: - to mark packaging in the food industry, particularly when the transparent non-conductive substrate is made of plastic, or - to solve problems of falsification and counterfeiting of payment documents and official documents, for example by marking security papers. As a means of decoration, the organic light-emitting diode or device Optoelectronics can be used in the luxury sector, particularly to decorate fabrics. The organic light-emitting diode or optoelectronic device can be used in the health field, for example to produce a luminescent bandage activating photosensitive molecules for medical treatments. Brief description of the drawings The accompanying drawings illustrate the invention. [Fig.1] [Fig.1] represents the different layers of an organic light-emitting diode and an optoelectronic device according to the invention. [Fig.2] [Fig.2] represents the reactor implemented according to the method of the invention. [Fig.3] [Fig.3] represents the luminance properties of an organic light-emitting diode according to the invention. [Fig.4] [Fig.4] represents the luminance properties of an organic light-emitting diode according to the invention and of an organic light-emitting diode not according to the invention. [Fig.5] [Fig.5] represents the luminance properties of an organic light-emitting diode according to the invention and of an organic light-emitting diode not according to the invention. Other characteristics and advantages of the present invention will appear in light of the description of non-limiting examples of the organic light-emitting diode according to the invention, as well as its manufacturing method. Examples [Fig. 1] represents several diagrams of the stacking of an OLED according to the invention, with downward light emission. In particular, [Fig. 1] represents an organic light-emitting diode according to the first subject of the invention comprising successively, in the following order: - a transparent non-conductive substrate 2, such as a glass or plastic substrate (e.g. 1-2 mm thick), - a conductive transparent anode layer 3 comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process (for example 34 nm thick), - an organic electroluminescent system (4, 5), and - a cathode layer 6 such as a calcium layer (for example 80 nm thick). The organic electroluminescent system comprises in particular a hole transport layer 4 such as an NPD layer (for example 55 nm thick), and an electron transport layer 5 such as an AlQ layer; (for example 85 nm thick). [Fig.1] b represents the conductive transparent anode layer 3 comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process, which was deposited on the non-conductive transparent substrate 2. [Fig. 1] c represents an optoelectronic device 1 composed of five organic light-emitting diodes according to the invention. The device comprises in particular, successively, in the following order: - a transparent non-conductive substrate 2, such as a glass or plastic substrate (e.g. 1-2 mm thick), - a conductive transparent anode layer 3 comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative process (for example 34 nm thick), - an organic electroluminescent system (4, 5), and - five cathode layers 6 such as calcium layers (for example 80 nm thick) on the same plane, which is parallel to the plane formed by the organic electroluminescent system (4, 5). The organic electroluminescent system comprises in particular a hole transport layer 4 such as an NPD layer (for example 55 nm thick), and an electron transport layer 5 such as an AIQ layer (for example 85 nm thick). The non-conductive transparent substrate 2, the conductive transparent anode layer 3 comprising monophasic doped PEDOT or doped PEDOT obtained by dry oxidative method, and the organic electroluminescent system (4, 5) are common to the five diodes, and each of the organic electroluminescent diodes has its own cathode layer 6. The size of the transparent non-conductive substrate 2 (made of glass or plastic) can be 24 x 36 cm?, In the device 1, the transparent non-conductive substrate 2 can accommodate up to five OLEDS, i.e. five cathode layers 6. The emissive surface of each OLED is 0.20 cm? Example 1: Method for manufacturing an OLED in accordance with the invention and according to a method in accordance with the invention Preparation of the doped PEDOT layer obtained by dry oxidative process [Fig. 2] is a schematic representation of the oCVD reactor 10 for depositing the doped PEDOT layer used in the method of the invention. The reactor 10 comprises a borosilicate glass tube 4.9 cm in diameter and 32 cm long (30 cm useful length), surrounded by a heating mantle 11 and connected at its two ends to steel flanges of reference “KF50” which make it possible to connect gas inlet 12 and outlet 13 tubes. Each flange is heated by a heating tape. This is therefore a hot wall reactor. A thermocouple is placed on the outer wall of the reactor, 15 cm from the inlet of the glass tube and connected to a PID (proportional, integral, derivative) controller to control the temperature of the heating mantle. On the reactor inlet 12 side, the two ambient liquid reactants, the oxidant (SbCIs) and the monomer (EDOT), are each placed in a glass tank (14, 15) respectively, connected to a micrometric valve and a quarter-turn valve by means of stainless steel tubes. The tank + stainless steel tubes + micrometric valves assembly is placed in a thermostatically controlled furnace 16 to best control the vaporization of the two reactants and the flow of steam sent to the reactor. The stainless steel tubes and the quarter-turn valves are thermostatically controlled by heating strips 17 to prevent any re-condensation of the reactant vapors. These heating strips 17 pass through the furnace wall a few centimeters thick, so that there are no cold spots. A dilution nitrogen line 18, thermostatically controlled by a heating strip, is also present at the reactor inlet 12. On the reactor outlet 13 side, the steel tube is also thermostatically controlled by a heating tape, then connected to a butterfly valve controlled by an electronic pressure control system 19 and a pressure sensor 20 (“MKS Baratron capacitance manometer”; 100 mbar). A liquid nitrogen trap is placed before the vacuum pump 21. A total of 7 heating strips and 1 heating jacket are present on the installation. Each is connected to a control electronics and the temperature of the gas lines or flanges is precisely controlled by thermocouples either fixed in situ or floating, which are moved on demand. The temperature profile inside the reactor is measured by a specific procedure, outside of any deposition experiment, using a thermocouple placed in the reactor and moved along the entire length of the borosilicate glass tube. A substrate holder, consisting of a glass plate 30 cm long, 4.2 cm wide and 2 mm thick, allows different substrates to be coated horizontally along the entire length of the reactor. Step i) of the method of the invention is carried out with the conditions listed in Table 1 below. [Tables 1] Temperature of furnace 16 containing the two 90°C tanks Temperature of heating ribbons at the inlet of the 150°C reactor 12 Temperature of N2 line #8 410°C Temperature of heating ribbons at the outlet of the | 165°C reactor 13 Volume of reactant initially placed in each | 2 om tank 44 and 45 Flow rate of EDOT gas 2.9 cm? SbCls gas flow rate These ribbons are made from the | 300 L reactor 13 Volume of reagent initially placed in each | 2 om tank 14 and 45 Flow rate of EDOT gas 2.9 cm* / min (at standard temperature and pressure Flow rate of SbCls gas 0.9 om“ / min (at standard temperature and pressure Flow rate of N2 30 cm' / min (at standard temperature and pressure Deposition time 5-8 min Set temperature of the heating mantle 150 “C Temperature of the transparent non-conductive substrate 145°C Pressure inside the reactor 40 Pa This gives a layer of PEDOT doped with monophasic chloride anions having a controllable and uniform thickness over several tens of cm?. This gives a layer of PEDOT doped with monophasic chloride anions with a controllable and uniform thickness over several tens of cm. Preparation of the other layers The substrate 2 covered with the doped PEDOT layer 3 is then transferred to a glove box (under a nitrogen atmosphere). The hole transport layers 4 and electron transport layers 5 are deposited within a “Boc Edwards Auto 500” evaporator, placed in a glove box, and containing two low-temperature sources (“Edwards”) and quartz sensors (“Inficon, model 103220”) of 6 MHz in gold. The organic compounds used NPD and AlQ; are in powder form and are sublimated (at a temperature < 300°C) using a crucible. The NPD / AIQ; combination allows for emission at 550 nm in the green. A mask with an appropriate shape is placed between the thermal sources and the sample holder. The mask allows defining the surface of the hole transport layer 4 and the electron transport layer 5. The deposition of layers 4 and 5 is carried out under a vacuum lower than 105 mbar at a deposition rate of 0.1-0.2 nm.s!. The thickness of the layers is controlled by quartz sensors. By replacing AlQ; with TPBi under the same deposition conditions, the NPD / TPBi association allows for emission at 435 nm in the blue. A cathode layer composed of calcium 6 is then deposited by thermal evaporation through a mask in the same enclosure. The calcium is evaporated at 575°C with a deposition rate of 0.05-0.1 nm.s-!. The cathode layer 6 is made in the form of a comb in order to have the most homogeneous lighting surface possible. On the same substrate, five OLEDs can be manufactured, in particular by adding cathode layers. The emissive surface of OLEDs is defined by the size of the cathode layers, which is 0.2 cm°. Example 2: performance of an OLED according to the invention Electrical characterizations are carried out using a sourcemeter ("Keithley"), by connecting the positive terminal of the latter to the anode layer and its negative terminal to the cathode layer. Measurements are carried out in a glove box, under a controlled atmosphere (nitrogen) to avoid any degradation linked to ambient oxygen and water. The optical characteristics of OLEDs (luminances and electroluminescence spectra) are measured using a spectroradiometer ("SpecBos"). Light measurements are carried out in a glove box, in the dark so that the spectroradiometer is not disturbed by the surrounding light. [Fig.3] shows the luminance (in cd / m°) as a function of the voltage (in V) of an organic light-emitting diode D, according to the invention as shown in [Fig.1]a with a glass substrate and emitting in the green (NPD / AIQ 3 combination). The OLED of the invention demonstrates a luminous potential, with a maximum luminance of 1200 Cd / m°. [Fig.4] shows the luminance (in cd / m°) as a function of the current (in mA) of the organic light-emitting diode D, in accordance with the invention as represented in [Fig.1] a with a glass substrate [curve a)] and detailed above for [Fig.3]; and for comparison of an organic light-emitting diode D4 not in accordance with the invention in which the 34 nm thick doped PEDOT layer is replaced by a 150 nm thick ITO layer deposited by cathodic sputtering [curve b)]. The OLED of the invention demonstrates a luminous potential, with a maximum luminance of 1200 Cd / m° which approaches that of the comparative ITO-based diode. This demonstrates that the layer comprising monophasic doped PEDOT or obtained by dry oxidative process, can be used as an electrode, and in particular as an anode (transparent conductive), in an organic light-emitting diode, while guaranteeing good performance. [Fig. 5] shows the luminance (in cd / m?) as a function of the current (in mA) of an organic light-emitting diode D» according to the invention as shown in [Fig.1] a with a glass substrate [curve a)] and emitting in the blue (NPD / TPBi association instead of NPD / AIQ?); and for comparison of an organic light-emitting diode D4 not in accordance with the invention and detailed above for [Fig.4] [curve b)]. The OLED of the invention demonstrates a luminous potential, with a maximum luminance of 300 Cd / m° which approaches that of the comparative diode based on ITO. This makes it possible to demonstrate that the layer comprising monophasic doped PEDOT or obtained by dry oxidative process, can be used as an electrode, and in particular as an anode (transparent conductive), in an organic light-emitting diode, while guaranteeing good performances. The performance obtained is of interest, for example, for applications in the field of ambient lighting or decorative display or signaling devices which do not require high luminances (a few hundred Cd / m°). The characteristics of the two fabricated diodes Dy and Dz are listed in Tables 2 and 3 below. [Tables 2] 8700 5 B4 Diode | Current | Voltage | Luminance | Conductivity | Roughness | Transmittance (mA) (V) (Cdimë) (Sim) (in nm, (%) at 550 nm RMS Di 10 21 1200 560 1 84 Da 40 15 1450 8700 5 84 [Tables 3] Biode | Current | Voltage | Luminance | Conductivity | Roughness | Transmittance (mA) (V) (Cdim?) (S / m} (in nm, (20) at 435 nm RMS D, 40 22 300 560 4 88 6700 5 80 [10 12 7th On the contrary, the comparative diode comprising ITO has numerous disadvantages: - OLEDs comprising an ITO anode layer deposited on a plastic substrate are difficult to produce due to the poor mechanical strength of the ITO layer on plastic substrates. A bonding layer is then necessary, which is not the case for the doped PEDOT anode layer of the diode of the invention which can be deposited on any type of substrate. - the deposition protocol (by cathodic sputtering) of ITO must be carried out at low temperature due to the low glass transition temperature of plastic substrates (Tg < 200°C), which results in: * higher surface roughness of the ITO layer, * low flexibility of the ITO layer deposited on a flexible PET (polyethylene terephthalate) type substrate: formation of microcracks on the surface of the ITO layer under mechanical stress, * a loss of its electrical properties (greater surface resistance) compared to an ITO layer deposited on a glass substrate, * reduced luminance properties: for an OLED with an ITO layer deposited on a plastic substrate, a loss of up to 40% of luminance can be observed compared to that obtained with an OLED deposited on a glass substrate (for the same current density and for the same OLED structure). Furthermore, a 34 nm ITO layer (the same thickness as the doped PEDOT layer of the invention) will be very weakly or even non-conductive. The corresponding diode will therefore have an equally low luminance.

Claims

Claims

1. Organic light-emitting diode, characterized in that it includes, successively, in the following order: - a non-conductive transparent substrate (2), - a conductive transparent anode layer (3) comprising Monophasic doped PEDOT or dry-process doped PEDOT oxidative, - an organic electroluminescent system (4, 5), and - a cathode layer {6).

2. Diode according to claim 1, characterized in that the PEDOT is doped with anions chosen from halides.

3. Diode according to claim 1 or 2, characterized in that the layer anode (3) has a thickness ranging from 8 to 80 nm.

4. A diode according to any preceding claim, ca- characterized in that the doped PEDOT of the transparent anode layer conductive (3) is obtained from the EDOT monomer and at least an oxidizing agent, said EDOT monomer and oxidizing agent being gaseous species.

5. A diode according to any preceding claim, ca- characterized in that the non-conductive transparent substrate (2) is at less partly in direct physical contact with the anode layer transparent conductive (3).

6. A diode according to any preceding claim, ca- characterized in that the non-conductive transparent substrate (2) comprises a material selected from inorganic materials based on oxide of silicon, alumina-based inorganic materials, materials polymers, cellulosic materials, and textile materials.

7. A diode according to any preceding claim, ca- characterized in that the organic electroluminescent system (4, 5) is multi-layer and includes: - at least one hole transport layer (4); and - at least one electron transport layer (5).

8. A diode according to any preceding claim, ca- characterized in that the cathode layer (6) comprises a selected metal among barium, silver, magnesium, calcium, aluminum, and aluminum combined with a layer of lithium fluoride.

9. Optoelectronic device (1), characterized in that it comprises a plurality of organic light-emitting diodes, at least one of the organic light-emitting diodes of said plurality being such that defined in any one of the preceding claims.

10. A method of manufacturing a light-emitting diode as defined to any one of claims 1 to 8, characterized in that it comprises at least one step 1) of depositing an anode layer transparent conductive (3) comprising PEDOT doped on a non-conductive transparent substrate (2), said step 1) being carried out by dry oxidative route.

11. Method according to claim 10, characterized in that the dry route oxidative is chosen from oxidative chemical vapor deposition and the oxidative deposition of a molecular layer.

12. Method according to claim 10 or 11, characterized in that step i) is carried out in a hot wall reactor (10).

13. Use of a layer comprising monophasic doped PEDOT or obtained by dry oxidative route as defined in any one of the claims | to 4, as an electrode in a light-emitting diode organic growth.

14. Use of an organic light-emitting diode as defined in any one of claims 1 to 8 or an optoelectronic device electronics (1) as defined in claim 9, as means authentication, or decoration.