RU2528128C1 - Method of manufacturing organic light-emitting diode - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: light-emitting diode contains a transparent or a partly transparent substrate with an applied on it layered structure, which contains at least one organic electroluminescent layer and transport sublayers from organic substances of n- and p-types of conductivity, located on the borders of an electroluminescent layer-contact layer. An organic layered structure is placed between the lower cathode, on the surface of which a system of microspikes is formed, and the upper anode, made of the ITO film also with the formed system of microspikes.

EFFECT: providing a possibility of increasing a level and evenness of injection of carriers, realisation of the product, meeting the requirements as to brightness of luminescence and operation characteristics, without complication of technology, and provision of a possibility to apply easily available metals.

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Description

The invention relates to the technology of manufacturing organic light emitting diodes (OLED) and can be used to create alternative light sources and OLED displays.

Known organic electroluminescent device [1], which includes a package of organic layers for generating light, a partially transparent upper electrode and a base material with a conductive metal sublayer deposited on it as the lower electrode. A feature of the device in question is that its large radiation area is provided by a set of a large number of fragments of a small area. This leads to a uniform distribution of brightness over the entire area of the radiating surface, which provides stable characteristics during the service life.

Also known is a method of manufacturing an organic light emitting diode [2] (the closest analogue), comprising a carrier base made in the form of a glass or plastic substrate with a transparent layer of anode placed on it. A layer of organic matter with hole conductivity (hole transport layer) is located on the anode, followed by an organic emitting (emission) layer, an organic layer with electron conductivity (electron transport layer). The function of the electron transport layer can be simultaneously performed by the emission layer. Above the organic layers is a cathode layer. The cathode is made of a composite material containing ytterbium doped with thulium or europium in an amount of at least 10%. The use of such a cathode material allows to obtain high performance unit: turn-on voltage of 4.3-4.6 V, the operating voltage at brightness of 150 cd / m ^2, which corresponds to the brightness running monitor, 4.5-5.5 V, the luminescence efficiency - 2.21-3.41 lm / W.

A significant disadvantage of this method is that the cathode is made of exotic and expensive metals, which will undoubtedly increase the cost of the final product and the complexity of the technology of its formation.

The problem to which the claimed invention is directed is to implement a product that meets modern requirements for brightness and performance, while not complicating the technology of its manufacture.

The problem is solved by using as a cathode for an organic LED a composition: aluminum plus a material with a low work function (for example, Ва, Cs, Mg or LiF) with a system of micropoints on the surface facing the organic material. The anode is made on the basis of ITO film also with a system of micropoints formed by the lithography method facing the layer of organic material.

The invention is illustrated in the drawing. The drawing shows a General view of the claimed device.

The device comprises a substrate 1, on which the following layers are successively applied: cathode 2 with a system of micropoints on the surface; organic transport and electroluminescent layers 3; an upper electrode 4 made of an In ₂ O ₃ oxide that is optically transparent to the generated light radiation 5.

The operation of the device is as follows. When the current is transmitted in the forward direction in the organic electroluminescent layer 3, electrons and holes recombine, injecting from layers 2 and 4, respectively, which is accompanied by emission of light quanta 5. The brightness of the diode is determined by the magnitude of the flux of injected electrons from the cathode and holes from the anode. Since the injection mechanism is due to Schottky emission (over-barrier emission) and thermoelectronic emission, to increase the level and uniformity of injection, it is necessary to have a small height of the barrier at the electrode – organic phosphor interface and the presence of a strong electric field. In this regard, a system of micropoints with a certain geometry is created on one or both electrodes.

The proposed method of manufacturing an organic light emitting diode can be carried out as follows. A thin-film system of layers of an organic LED is applied in a vacuum to a metal or dielectric substrate (copper, glass, sapphire) having a processing class of 13-14. Before applying thin-film elements, the substrate is thoroughly cleaned by sequential washing in an ultrasonic bath, in a washing chromium mixture and in purified water. In a vacuum of 10 ^-5 mm Hg at a substrate temperature of + 300 ° C, a layer of aluminum with a thickness of 1500-2000 A is applied by thermal evaporation, then a layer of metal with a low work function (Ba, Cs, Mg). Then, an ordered system of micropoints is formed on the surface of the deposited cathode using electron beam lithography. The distance between the tips of 500 nm, the density of their placement on the surface of 10 ⁷ -10 ⁸ pieces / cm ² . Films of organic layers are applied by centrifugation, which consists in the accumulation of a solution of organic matter on a rotating substrate, resulting in a uniform film of a given thickness, covering the entire substrate. The last step is the deposition of a transparent electrically conductive layer of indium oxide doped with tin (ITO) 2500 A thick by the method of magnetron sputtering of the target.

List of sources used

1. Young E.V.A., Berner H.F. Organic electroluminescent device. RF patent No. 2414018 for the invention according to the application No. 2008129758/28 of 08/08/2006. Publ. in BI No. 7 of 03/10/2011.

2. Bochkarev M.N., Katkova M.A., Ilyichev V.A. Organic light emitting diode. RF patent No. 2352028 for the invention according to application No. 2007143118/28 of 11.23.2007. Publ. in BI No. 10 of 04/10/2009.

Claims (1)

An organic light-emitting diode containing a carrier base made in the form of a metal or dielectric substrate coated with a metal cathode, transport and electroluminescent organic layers and a transparent anode, characterized in that, in order to increase the level and uniformity of injection of charge carriers from the electrodes into transport and organic layers, on the surfaces of the electrodes facing the organic material, ordered electron micrographs are formed using electron beam lithography points, the distance between the points 500 nm, the density of their placement on the surface of 10 ⁷ -10 ⁸ pcs / cm ² .