Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
  • H10K71/60—Forming conductive regions or layers, e.g. electrodes
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K50/00—Organic light-emitting devices
  • H10K50/80—Constructional details
  • H10K50/805—Electrodes
  • H10K50/81—Anodes
  • H10K50/813—Anodes characterised by their shape
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K50/00—Organic light-emitting devices
  • H10K50/80—Constructional details
  • H10K50/805—Electrodes
  • H10K50/81—Anodes
  • H10K50/814—Anodes combined with auxiliary electrodes, e.g. ITO layer combined with metal lines
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K2102/00—Constructional details relating to the organic devices covered by this subclass
  • H10K2102/10—Transparent electrodes, e.g. using graphene
  • H10K2102/101—Transparent electrodes, e.g. using graphene comprising transparent conductive oxides [TCO]
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K2102/00—Constructional details relating to the organic devices covered by this subclass
  • H10K2102/301—Details of OLEDs
  • H10K2102/351—Thickness

Definitions

• the present invention relates to a method of manufacturing a gate-shaped electrode supported for OLED using a silver dewetting step. It also relates to the electrode obtained by this method.
• TCO transparent conductive oxides
• Such metal networks can be manufactured by complex photolithography processes comprising several steps of masking, etching, exposure to radiation, washing, deposition etc.
• the object of the present invention is to provide a considerably simpler method of forming an OLED transparent electrode comprising, on a mineral glass substrate, a transparent conductive layer and a continuous metal network in contact with the transparent conductive layer.
• the method of the present invention unlike the photolithographic methods usually used for forming metal grids, does not require any masking, printing, ablating or selective etching step.
• the key steps of the method of the present invention are likely to be implemented on a magnetron sputtering line, which greatly facilitates the industrialization of this method of producing supported electrodes for OLED.
• the physical phenomenon underlying the present invention is the dewetting of thin films of solid silver. It is known that certain solid metal films, when heated to a much lower temperature than their melting temperature, do not remain in the form of continuous films but dewax to form metallic "droplets" having a smaller contact area. with the substrate.
• the present invention takes advantage of the relatively slow dynamics of this dewetting phenomenon to freeze the film being dewaxed before the individualization of the metal droplets. A metallic network is thus spontaneously formed which, when sufficiently continuous, allows the passage of an electric current.
• the Applicant has discovered that the conductivity and the transparency in the visible light of such a "dewaxed" metal network could easily be adjusted by modifying the initial film thickness, the temperature and the heating time.
• the geometry of the formed metal network may further be adjusted by performing the dewetting of the silver not on a perfectly smooth substrate, but on a substrate comprising a relief.
• This transparent conductive material can act as anode, output work adaptation layer or hole transport layer of the OLED organic stack. In all cases it will serve as a protective layer against oxidation of the silver grid during a possible storage and / or transport.
• the subject of the present invention is therefore a method for manufacturing an electrode for OLED, comprising the following successive steps:
• the present invention also relates to an electrode that can be obtained by such a method and which successively comprises a transparent substrate, a silver grid or random silver alloy obtained by dewetting a metal film, and a continuous layer of transparent conductive material covering said silver or silver alloy grid.
• any transparent heat-resistant substrate of step (b) can be used in principle. It is of course preferably inorganic glass substrates, especially thin or ultrathin glasses having a thickness of less than 1 mm, but one could also consider the use of polymer substrates.
• the substrate may be perfectly smooth, that is to say have a roughness of less than a few nanometers.
• the dewetting of the metal film will then be governed primarily by the surface and interfacial tensions of the metal.
• the substrate is not smooth but has a roughness or a sufficiently deep relief to guide or guide the dewetting.
• Such relief must be formed of juxtaposed individualized patterns of regular or irregular shape, formed for example by etching or embossing.
• the metal When a silver metallic film is deposited on such a relief formed of juxtaposed individualized patterns (pyramids, mounds, islets), the metal will fill, after dewaxing, preferentially the valleys. If the valleys form a continuous network, the metal network obtained should have good electrical conductivity while having an opening rate ensuring good transparency to the electrode.
• the silver or silver alloy film may be deposited by any known method for controlling its thickness. Examples of such methods include vacuum evaporation deposition, magnetron sputter deposition and chemical silver plating (reduction of silver salt). It is particularly interesting to deposit the silver film by magnetron sputtering because this technique also allows the deposition of a transparent conductive oxide, the process thus being able to be implemented on the same magnetron cathode sputtering line.
• the deposition of the metal film (step (a)) and the deposition of the transparent conductive oxide (step (c)) are both implemented by physical deposition in vapor phase (PVD), preferably by magnetron sputtering, on the same magnetron sputtering line.
• PVD physical deposition in vapor phase
• the step (b) of heating the substrate carrying the silver film is preferably carried out very shortly after the end of step (a) in order to avoid the oxidation of silver.
• the heating of the silver-coated substrate is carried out under vacuum, on the magnetron sputtering line, between step (a) and step (c).
• the heating temperatures indicated above are understood as the temperatures of the substrate carrying the metal film.
• the temperature of the heating elements is of course considerably higher than the temperature of the substrate, typically greater than 200 ° C to 300 ° C at the temperature at which it is desired to heat the substrate.
• the random metal grid formed after dewetting has a greater thickness than the initially deposited silver film. This thickness is however generally less than about 150 nm.
• the transparent electroconductive material deposited in step (c) may be a transparent conductive oxide (TCO). When it is deposited in a sufficient quantity, for example at a rate of 1 to 3 g / m 2 , it plays both the role of a planarization layer of the metal grid obtained by dewetting and the role of anode in the OLED final. The amount of transparent conductive oxide deposited must be sufficient to completely cover the grid.
• Deposition of the TCO is preferably by magnetron sputtering using a ceramic target. Reactive cathode sputtering from a metal target should be avoided as oxygen may oxidize the silver gate.
• the transparent conductive material may also be formed of an organic polymer, such as a PEDOTPSS polymer which has the same function as a TCO.
• an organic polymer such as a PEDOTPSS polymer which has the same function as a TCO.
• Such an organic polymer has the advantage of being liquid deposited and planarize perfectly the metal grid.
• the transparent conductive material may be the first layer, that is to say the hole transport layer (HTL) of the organic stack of the OLED.
• HTL hole transport layer
• the process of the present invention preferably comprises, after step (c), a second annealing step (d) at a temperature between 150 and 350 ° C for a period of 5 and 60 minutes.
• This second annealing essentially has the function of increasing the crystallinity and the conductivity of the partially amorphous TCO after deposition.
• the TCO layer deposited on the relief created by the metal grid generally has a large surface roughness, incompatible with the deposition of the stack of organic layers which requires a perfectly flat surface, otherwise leakage currents due to short circuits in the final OLED.
• the TCO layer is subjected, before or after annealing, to a step of polishing the transparent conductive oxide layer.
• Influence of the thickness of the silver film on the properties of the grid formed after dewetting Magnetron sputtering films of different thicknesses are deposited on a mineral glass substrate.
• the substrates carrying the films are immediately annealed in a radiation oven.
• the temperature at the substrate is 300 ° C and the heating time 30 and 45 minutes.
• the table below shows the resistances per square (Ra) and transmissions of silver films of different thicknesses, dewaxed by heating at a temperature of 300 ° C for 30 and 45 minutes.
• Dewetting a film 40 nm thick leads to an electroconductive network after 45 minutes of annealing.
• the lack of conductivity of the sample obtained after 30 minutes annealing is probably due to a lack of reproducibility.
• the optimum film thickness is 50 nm.
• the two samples obtained after 30 and 45 minutes of annealing have a resistance per square less than 3 ⁇ / ⁇ and have a transmission of between 29 and 41%. As the thickness of the silver film increases further, a decrease in square resistance accompanied by a decrease in transmission is observed.
• Figure 1 shows two electron microscopy snapshots of a silver grid obtained by dewetting (30 minutes at 300 ° C) of a silver film having a thickness of 40 nm.

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• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Electroluminescent Light Sources (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)
• Physical Vapour Deposition (AREA)

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• 2013
  • 2013-08-01 FR FR1357665A patent/FR3009436B1/fr not_active Expired - Fee Related
• 2014
  • 2014-07-29 US US14/908,427 patent/US20160163984A1/en not_active Abandoned
  • 2014-07-29 KR KR1020167002359A patent/KR20160037918A/ko not_active Application Discontinuation
  • 2014-07-29 EP EP14750596.0A patent/EP3028321A1/de not_active Withdrawn
  • 2014-07-29 JP JP2016530585A patent/JP2016527688A/ja active Pending
  • 2014-07-29 WO PCT/FR2014/051962 patent/WO2015015113A1/fr active Application Filing
  • 2014-07-29 CN CN201480043463.4A patent/CN105409029A/zh active Pending
  • 2014-07-30 TW TW103126007A patent/TW201521263A/zh unknown

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