Organic light emitting device and method of producing

Detailed description of the invention

The present invention relates to an organic light emitting device and a method for manufacturing the same.

[background] Organic semiconductors are used in the manufacture of simple electronic components (eg resistors, diodes, field effect transistors) and are also optoelectronic components such as organic light emitting devices (eg OLEDs (organic light emitting diodes) and many others). It is also used in the manufacture of diodes. The industrial and economic importance of organic semiconductors and devices using them is reflected in the increasing variety of devices that use active layers of organic semiconductors and the growing number of industries that mainly handle them.

Organic semiconductors can be small molecules such as monomers or oligomers, polymers, copolymers, copolymers of conjugated and non-conjugated moieties, fully or partially crosslinked layers, aggregated structures, or brushed structures. It is formed by layers such as a layer of an organic semiconductor mainly containing a possible conjugated organic compound. Devices formed with different types of compounds in different types of layers, or mixed layers (eg, layers mixed with polymers and small molecules) are also referred to as polymer-small molecule composite devices. Since the deposition technology for processing small molecule OLEDs enables the processing of multi-layer structures, OLEDs that are formed from small molecules are preferentially produced.

Since 1987, research groups and industrial organizations have spent a great deal of effort around the world to improve the performance of OLEDs, especially small molecule OLDEs. One of the first pursuits was to find suitable organic semiconductor materials formed from small molecules that could form uniform layers. Recently, charge transport materials for industrial use are morphologically stable up to temperatures of at least 85 ° C, and typical materials have a glass transition temperature of over 100 ° C. At the same time, the material must meet a set of other requirements, such as high transparency in the visible spectrum and good charge transport capacity.

Many of the good-performing electron-transporting materials or hole-transporting materials are relatively high-cost materials due to their complicated synthetic pathways, and there are problems to be solved there.

Another problem to be solved is the increased efficiency of out-coupling of OLEDs used for lighting. A typical organic light emitting diode has a drawback that only about 25% of the generated light can be emitted from the device. Approximately 50% of the light remains as an internal mode in the array of organic layers located between the reflective and translucent electrodes. An additional 20% is lost due to total internal reflection on the substrate. The cause for this is that the light in the OLED is generated in an optical medium having a refractive index of about 1.6 to about 1.8. At that time, if this light hits a light medium having a low refractive index (for example, another layer in the stack of OLEDs, a substrate on which the OLED is formed, or one of the above electrodes), the angle of incidence thereof. When is above a certain value, total reflection occurs. Several different techniques are used to improve outcoupling, for example, the arrangement of microlenses described in US Patent Application Publication No. 2010/0224313. However, the above technology requires further development because the light extraction efficiency is still far from 100%.

Therefore, the use of OLEDs in the field of lighting and displays requires the use of suitable out-coupling methods that can be further incorporated into the processing process at low cost. For lighting applications, 1 cm to be economically valid for that application²An area of OLED should cost only a few cents. However, this means that only particularly inexpensive methods will be considered to increase the outcoupling of light. So-called small molecule (SM) based OLEDs have recently been processed, for example, with the assistance of thermal deposition in vacuum. Typically, OLEDs consist of 2 to 20 layers, all of which are thermally deposited separately. At that time, if the above out-coupling is improved by just one more thermally deposited layer, the situation at the cost of the out-coupling method will in any case meet the condition. .. The same applies to SM-polymer composite OLEDs.

For the use of OLEDs as components of lighting, it is further necessary to form elements with large areas. For example, OLED is 1000 cd / m²When working with the brightness of, an area within a few square meters is needed to illuminate the office space.

[Outline of Invention] An object of the present invention is to provide an organic light emitting device having improved efficiency of emitting light generated in a light emitting region to the outside (efficiency of outcoupling).

The above problems are solved by the elements according to independent claims 1 and 12, respectively, of the present application. Further, a method for manufacturing an organic light emitting device according to independent claim 13 of the present application is also provided. The dependent claims correspond to the preferred embodiments.

On one side, an organic light emitting device that includes a layered structure is provided. The layered structure includes a substrate, a bottom electrode, a top electrode and an electrically active region, where the bottom electrode is closer to the substrate than the top electrode. The electrically active region comprises one or more organic layers, is provided between the bottom electrode and the top electrode, and is provided in electrical contact with the bottom and top electrodes. A light emitting region is provided in an electrically active region. In the electrically active region, there is a roughened layer provided as an unclosed layer. The above description of "not closed" means, in the present specification, a layer formed from a roughened structure protruding from an underlying layer and separated from each other by a space in which the roughened structure does not exist. It is used as a thing to do. In a space where the roughened structure does not exist, a flat and very thin surface boundary layer having the same chemical composition as the roughened structure and having a layer thickness of less than 5 nm may exist. The surface boundary layer can be, for example, a single layer of one or more molecules deposited in the process of forming the roughened layer.

The roughened layer roughens the top electrode on at least one inner surface facing the electrically active region and on the outer surface of the top electrode facing outward with respect to the electrically active region. This causes the top electrode to have irregularities on the electrode.

The unevenness of the top electrode may include a roughened inner surface structure on the inner surface of the top electrode facing the electrically active region. The unevenness of the top electrode may include a roughened outer surface structure on the outside of the top electrode. Seen from above in the electrode, the roughened inner surface structure and the roughened outer surface structure may essentially overlap.

In another aspect, an organic light emitting device that includes a layered structure is provided. The layered structure includes a substrate, a bottom electrode, a top electrode and an electrically active region, where the bottom electrode is closer to the substrate than the top electrode. The electrically active region comprises one or more organic layers, is provided between the bottom electrode and the top electrode, and is provided in electrical contact with the bottom and top electrodes. A light emitting region is provided in the electrically active region. Between the substrate and the bottom electrode, there is a roughened layer that is not closed and is provided as an electrically inert layer. The roughened layer roughens the bottom electrode on at least one inner surface facing the electrically active region and on the outer surface of the bottom electrode facing outward with respect to the electrically active region. , At least causes the bottom electrode to have irregularities on the electrode. For the bottom electrode, the outer electrode surface faces the substrate. For this device, the roughened layer also forms a top electrode on at least one inner surface facing the electrically active region and on the outer surface of the top electrode facing outward with respect to the electrically active region. It may cause unevenness of the electrode. In addition to the roughened layer below the bottom electrode, there may be additional roughened layers provided within the electrically active region. The additional roughened layer may be provided by one or more embodiments described for the roughened layer, which causes the unevenness of the electrodes at the top electrode.

Due to the unclosed structure of the roughened layer, the layer may not completely cover the underlying layer. The island-like or particulate structure may be provided containing islands / material particles of material separated by regions not covered by the roughened structure described above. The region may not contain the material of the roughened layer. The region in which the material of the roughened layer does not exist can be provided by the pores existing in the roughened layer.

The organic light emitting device may be provided with two or more roughened layers. There may be two or more roughened layers provided in the electrically active region. The plurality of roughened layers may be provided above and / or below the light emitting region.

The unevenness of the electrode caused by the roughened layer may be provided with a light-reflecting surface structure that reflects light, for example, diffusivity. The structure of the roughened layer itself can reflect the light generated by the element. As another structure, the structure of the roughened layer itself may be essentially non-reflective of active light.

In the electrically active region, one or more layers deposited directly on the roughened layer may be provided as a closed layer. As another structure, the layer can be an unclosed layer in which the particles forming the roughened layer can give an iceberg-shaped structure. The structure of the roughened layer extends to one or more layers deposited directly on the roughened layer.

The concave-convex structure of the electrode can be as thick as the layer of the electrode. Each electrode may only be roughened where the particles of the roughened layer are present at the bottom, and the other parts may be flat. The surface roughness can be measured using, for example, an image of a cross section of a side meter (eg, Dektak) or an electron microscope of the device.

The thickness of the uneven electrode provided by the roughened layer can be given a layer thickness much larger than the nominal layer thickness of the roughened layer.

The roughened layer may be provided with a plurality of separated particles (islands) randomly distributed in the underlying layer on which the roughened layer is deposited. The roughened layer is also referred to as a "particle layer". The plurality of separated particles may be randomly provided in orientation, distance from each other (space between the particles), and / or particle size. The separated particles distributed on the underlying layer provide an island-like structure for the roughened layer. The size of the particles can be in the wavelength range of visible light, preferably the light emitted by the organic light emitting element, where the wavelength is the wavelength in the organic medium around the particles or the wavelength in the material of the particles. Can be.

The particles in the roughened layer may have a size of about 50 to about 500 nm in the lateral direction and / or about 3 to about 50 nm, preferably about 3 to about 15 nm in the height direction. The density of the above particles inside the organic light emitting device is 1 μm.²Between 5-50 particles per, preferably 1 μm²It can be between 10 and 30 particles per. The particles can be up to 1000 nm in size. These magnitudes may provide Mie scattering, which occurs preferentially in objects having a diameter comparable to the wavelength of visible light (between 450 and 700 nm) and is divided by the refractive index of the surrounding organic material. ..

The top electrode may be provided on the top layer of the electrically active region that is roughened by the roughening layer provided below the top layer. The top electrode may be in direct contact with the top layer. In other embodiments, there may be one or more layers provided between the top electrode and the top layer in the electrically active region. The top electrode can be formed from a single layer or multiple electrode layers.

The top electrode can be provided directly on the roughened layer.

The top layer can be a combination of a light emitting layer and an electron transporting layer. The top layer, provided as a single layer or multiple sublayers, may be a closed layer. Alternatively, the top layer may be an unclosed layer in which the particles forming the roughened layer provide an iceberg-like structure. The iceberg-shaped structure will provide direct contact between the top electrode and the iceberg-shaped region.

The roughened layer may be provided between the light emitting region and the top electrode.

The roughened layer may be provided between the light emitting region and the bottom electrode. When two or more roughened layers are present, one roughened layer may be provided at the top of the light emitting region and another roughened layer may be provided at the bottom of the light emitting region.

The roughened layer can be given a nominal layer thickness of about 3 nm to about 50 nm, preferably about 3 nm to about 15 nm. The thickness of the roughened layer is a nominal thickness, which is usually calculated from the mass deposited in a particular region, using knowledge of the density of the material. For example, using thermal vacuum deposition (VTE), the nominal thickness is the value displayed by the thickness observer. The particles in the roughened layer can grow on the surface of the lower layer, where the particles are separated from each other and do not fuse to form a closed layer.

The nominal thickness of the roughened layer can be calculated from AFM measurements.

The roughened layer can be provided on an electrically doped charge transport layer and can be covered by an electrically doped charge transport layer. The roughened layer may be sandwiched between two electrically doped charge transport layers, the two electrically doped layers being a hole transport layer and / or an electron transport layer. The top layer may be an electrically doped single layer or a plurality of electrically doped sublayers. The roughened layer may be provided on the light emitting layer.

The roughened layer can be provided either between the electron transport layer and the cathode or between the hole transport layer and the anode, and can be provided on either the electron transport layer and the cathode or the hole transport layer and the anode. It can be provided in direct contact. The transport layer can be electrically doped. The roughened layer does not have to be doped.

The roughened layer can be formed from a self-crystallizing material. The roughened layer formed from the self-crystallizing material may be arranged adjacent to the hole transport layer. The layer may be provided in direct contact with the hole transport layer. As a result, light out-coupling is increased. As an alternative method, the roughened layer formed from the self-crystallizing material can be arranged on the electron transport side of the device, particularly adjacent to the electron transport layer.

In order to maximize out-coupling from the OLED, it is necessary to minimize internal absorption and allow light emission in waveguide and surface plasmon modes. With respect to corresponding to these optical modes, the roughened layer provides a modification of the conventional flat organic light emitting device structure. In a conventional flat organic light emitting device, two flat electrodes sandwich a flat organic layer between them and are deposited on a flat substrate. In this configuration, the waveguide mode, i.e. the organic layer, and potentially the light propagation mode in the translucent electrode (eg, ITO) is the surface plasmon mode (the light propagation mode in the surface plasmon of a normal metal electrode). Similarly, it can be easily connected to the emitter in the organic light emitting diode. As a result, the movement of light in these modes can no longer be easily emitted during the air mode, which significantly limits the light conversion efficiency of the organic light emitting device.

The structure of the organic light emitting device proposed herein allows for a simple structure of at least one of a top electrode layer and a bottom electrode layer. The concavo-convex structure minimizes plasmon loss and increases outcoupling in waveguide mode. Through this method, electrode irregularities that can act as scatter centers or scatter structures are achieved for both surface plasmon mode and similarly waveguide mode.

As a result of using the roughened layer, not only the out-coupling of light can be increased, but also the angle dependence of light emission can be improved. The spectrum of white light contains light components of several colors (however, typically at least blue, green and red light components). Since the above emission characteristics are different at various wavelengths, different colors can be seen at various viewing angles in the conventional OLED. This property can be dramatically mitigated by the scattering properties of the device proposed herein.

The roughened layer can increase the out-coupling of the internal mode. The roughened layer can also increase outcoupling in substrate mode. The roughened layer can be used because the electrical properties of the OLED are not impaired. Furthermore, it was found that additional power gains that cannot be achieved with conventional out-coupling solutions (conventional scattering layers) can be achieved with out-coupling films. In contrast, in a conventional OLED with a simple conventional scattering layer, no power gain is generated even if another additional out-coupling film is used.

A simple structure is provided for manufacturing a highly efficient organic light emitting device without using an expensive method (for example, a method of making a substrate surface on an electrode side or a substrate surface on a semiconductor side a fine structure). Flat (non-finely structured) bottom electrodes can also be used. The fine structure described above is understood to mean a structure having a magnitude within the wavelength range of light in order to affect light.

All organic layers in the electrically active region may be produced by vacuum deposition (VTE (thermal vacuum deposition)). Alternatively, all organic layers in the stacked arrangement may be prepared by the OVPD method. In a preferred embodiment, all organic layers and both electrodes are deposited by vacuum coating (eg VTE) or sputtering.

The roughened layer can be formed as a thin-film deposition layer derived from an organic material that can be vaporized by a thermal vapor deposition method under vacuum. For this purpose, the material has a vaporization (or sublimation) temperature under vacuum that is lower than the decomposition temperature under vacuum. As an alternative, or additional method, the organic crude layer described above can be produced by OVPD. The roughened layer can be formed, for example, through dewetting of films made through spin coating and subsequent thermal treatment (eg, a 5% solution of (spiro-TTB) in anisole). Moreover, dewetting of organic films on the nanoscale may be achieved through agglutination of the solvent from the vapor.

The roughened layer may be formed by one of vapor agglomeration, electrodeposition, vacuum spray coating, photolithography, and baking (eg, microcontact printing of nanoparticle arrays) of metal nitride nanoparticles. Good.

The organic roughened layer is preferably formed from a material having a Tg of less than about 40 ° C. Preferably, a material having no Tg is used. In the conventional VTE method, the substrate temperature is usually between 20 ° C and 60 ° C, so that the above organic matter can be deposited on the substrate without using a further tempering step. The material can crystallize itself.

Tg is determined using DSC measurements. The DSC measurement is performed using a material cooled to room temperature by an impact cooling method after fusion. The material is then heated at a rate of 10 K / min during the measurement. No Tg was observed in the preferred material used for the organic roughened layer above.

The roughened layer is preferably crystallized during vapor deposition. Alternatively, a tempering step can occur after the layer is completed and before the next layer is deposited.

Hereinafter, further aspects of the present invention will be described in detail.

The roughened layer may be coated by a charge transport layer such that charges flow around these roughened particles, while the roughened particles are directly coated by a metal electrode. You may. The structure is a p-type and n-type doped transport layer, as the doping of the charge transport layer allows the potential charge traps that can be formed on the surface of the roughened particles to be saturated. Can be achieved through the use of.

The separated structure (particle, island-like structure) of the roughened layer preferably exhibits minimal absorption in the visible region in order to avoid loss of absorbable light. The refractive index of the particles is such that the waveguide mode scattering in the particles is minimal (ie, the refractive index of the roughened particles will match the refractive index of the organic layer of the organic light emitting element) or maximum (ie, organic emission). In contrast to the organic layer of the device, the index of refraction can be approached to either (which needs to be maximized). In the former case, the waveguide mode is not scattered by the roughened particles, but rather only through the irregularities of the metal electrode, and in the latter case, the scattering in the waveguide mode is directly by the roughened particles. Can be triggered.

The particles deposited in the roughened layer may have a round shape in the absence of prominent protrusions or grooves that cause the formation of shortcuts or the undesired cross-section of the electrodes. The roughened particles are either wide or oblate, or microcrystals with well-defined grooves (eg, needles, tetrahedrons, star anise, etc.). The above shape can be achieved, for example, by dewetting due to surface tension. The same is true for the rehashing process under the exact set of parameters, the selection of the appropriate material (for crystallizing them).

The out-coupling methods described can be combined with other methods known to those of skill in the art, such as microlens array films or scattering substrates.

The particles in the roughened layer can grow wider than they are tall (eg, the width: height ratio is 5: 1 to 1: 1). If the particles are taller than the width, the width: height ratio of the particles should be 1: 1 to 1: 5 to avoid crushing or puncturing the top electrodes. Should be.

Organic light emitting devices may be endowed with at least one of the following characteristics: -There is a glass dislocation temperature of at least 300K below the melting temperature. Preferably, the material has no glass transition temperature that can be measured at temperatures above room temperature and either changes directly from the glass state to the crystalline state, or the glass state is completely unknown. -There is high transparency, which is also defined as having a low attenuation coefficient (less than 0.1) for all visible light. -There is no apparent color. -At least 3 eV HOMO-LUMO gap. -The above material is transparent in the visible region (light gap> 3eV). -There are LUMOs less than 2.0 eV (absolute value) that are not typical for ETMs used for OLEDs, or HOMOs greater than 5.5 eV (absolute value) that are not typical for ETMs used for OLEDs. -The molecular weight of the organic material used for electrical doping in the transport layer is greater than 200 g / mol and less than 400 g / mol (<200 g / mol is too volatile). If it is> 400 g / mol, it will be a molecule that does not crystallize sufficiently).

When the dewetting mechanism is used to form the particles of the roughened layer, the material of the particles is higher than Tg (eg, above 85 ° C) so that it is stable under the operation of conventional devices. ) Can have. An example of the dewetting method is a layer of 2,2', 7,7'-tetrakis (N, N-di-p-methylphenyl-amino) -9,9'-spirobifluorene derived from anisole solution. is there.

In one embodiment, the top electrode is the anode and the material of the roughened layer is an electron transport material (ie, the material of the scattering layer has a very high barrier to hole injection into the HOMO, said The material of the roughened layer does not contribute to the transport of holes in the device). Particularly surprisingly, this embodiment works anyway and shows that the scattering layer does not need to have any electronic function in the device.

In another embodiment, the top electrode is the cathode and the material of the coarsening layer is a hole transport material (ie, the material of the scattering layer has a very high barrier to electron injection into the LUMO. The material of the roughened layer does not contribute to the transport of electrons in the device, which is surprising, as explained above.

With respect to the use of scattering or roughening compounds in the electrically active region of the organic light emitting device, for the roughened layer, the nominal layer thickness is preferably less than 50 nm, more preferably less than 10 nm. preferable. When the layer containing the roughened compound serves as a template, the roughened layer is installed between the first electron transporting layer and the second electron transporting layer, and the roughening layer is installed. It has been found that the device obtains the best function when the nominal layer thickness of the chemical layer is 3 nm or more and 30 nm or less, preferably between 5 nm and 15 nm.

The size of the particles can be as described above to achieve a structure on the electrode of a size that is within the range of visible light in the surrounding organic medium to affect the light. Priority, the width in appearance (width parallel to the substrate plane) is within visible light in the surrounding organic medium. Its height is smaller than its width, for example, one-half or one-third times smaller. The particles and their respective properties on the above layers, such as the top electrodes, are randomly distributed. In principle, the index of refraction of organic media is typically between 1.7 and 2, with 1.7 being a good approximation in most cases.

The wavelength can also be the wavelength in the material of the particles, especially in the absence of a layer between the roughened layer and the top electrode. Preferentially, the particles have a size between at least 100 nm and 450 nm.

The roughened structure may have a size to affect the plasmons at the top electrode. Its height is smaller than its width, for example one-half or one-third smaller. The particles and their respective properties on the above layers, such as the top electrodes, are randomly distributed.

In general, organic light emitting devices (OLEDs) are based on the principle of electroluminescence, in which electron-hole pairs, so-called excitons, recombine under emission. To this end, the organic light emitting element is configured in the form of a sandwich structure in which at least one organic film is placed between the two electrodes as an active material, with positive and negative charges injected into the organic material. Charge transport occurs from holes or electrons to the recombination region (light emitting layer) inside the organic layer, where charge recombination for singlet and / or triplet excitons occurs under emission. Subsequent radioactive recombination of excitons causes light emission. At least one of the electrodes needs to be transparent to allow the light to leave the component. Typically, the transparent electrode consists of a conductive oxide named TCO (Transparent Conductive Oxide), or a very thin metal electrode, but other materials may also be used. The starting point for the manufacture of organic light emitting devices is the substrate on which each layer of OLED is deposited. If the electrode closest to the substrate is transparent, the component is named "bottom-emitting OLED", and if the other electrode is transparent, the component is named "top-emitting OLED". The bottom electrode is closer to the substrate than the top electrode. The bottom electrode is formed (deposited) before the top electrode is formed (deposited).

The most reliable and most efficient OLEDs contain a doped layer. Charge density in organic solids by electrical doping of the hole transport layer (p-doping) using the appropriate acceptor material or electrical doping of the electron transport layer using the donor material (n-doping), respectively. (And therefore conductivity) is substantially increased. In addition, similar to the use of inorganic semiconductors, the application can be expected to be precisely based on the use of p-type and n-type doped layers in the components, or other applications. You can't imagine it. The use of a doped charge transport layer in an organic light emitting diode (p-doping of a hole transport layer with a mixture of acceptor-type molecules, n-doping of an electron transport layer with a mixture of donor-type molecules) is a US patent application. It is described in Publication No. 2008/203406 and US Pat. No. 5,093,698.

The material used in the layer construction is a conventional material used for OLEDs in which the material or a mixture thereof satisfies the functions of layers such as an injection layer, a transport layer, a light emitting layer, a connecting portion, and the like. For example, such layers and materials are referred to in U.S. Patent Application Publication No. 2009/045728, U.S. Patent Application Publication No. 2009/0009072, European Patent No. 1336208 and their references. To.

The light emitting region is a region formed from one or more layers in which excitons associated with light emission are formed and / or excitons are associated with issuance. Possible light emitting layers are described, for example, in European Patent No. 1508176, US Patent Application No. 2008/203406, European Patent No. 1705727 and US Pat. No. 6,693,296. Different possible configurations of light emitting layers in OLEDs are described, for example, in European Patent No. 1804308 and European Patent No. 1804309. As a special case, charge injection and charge transport are well balanced and the OLED can be made with a single layer (European Patent No. 1713136), in which case the light emitting layer is sharp. The light emitting layer is a region that does not require an interface and contains excitons related to light emission.

For organic light emitting devices, the hole transport layer (HTL) is a semiconductor with a large gap that can cause transport of holes from the anode or holes from the connecting portion (CU) to the light emitting layer (LEL or EML). It is a layer containing. The HTL is contained between the anode and the LEL, or between the hole-producing side of the CU and the LEL. The HTL can be mixed with another material (for example, when the HTL is said to be p-type doped). The HTL can include several layers and can have a variety of compositions. P-doping on the HTL lowers its resistance and, conversely, avoids each power loss due to the high resistance of the undoped semiconductor. The doped HTL is also used as an optical spacer because it forms very thick up to 1000 nm or more in the absence of a significant increase in resistance.

With respect to organic light emitting devices, an electron transport layer (ETL) is a layer containing a semiconductor having a large gap capable of generating transport of electrons derived from a cathode or electrons derived from a connecting portion to a light emitting layer. The ETL is included between the anode and the LEL, or between the electron-generating side of the junction and the LEL. The ETL can be mixed with another material (when the ETL is said to be n-type doped, eg n-dopant). The ETL can include several layers and can have a variety of compositions. N-doping on the ETL lowers its resistance and, conversely, avoids each power loss due to the high resistance of the undoped semiconductor. The doped ETL is also used as an optical spacer because it forms very thick up to 1000 nm or more without a significant increase in resistance.

Other layers typically used in the manufacture of OLEDs, such as hole and electron barrier layers, injection layers, exciton barrier layers, can be used as well.

The most reliable and at the same time efficient device is an organic light emitting device that contains an electrically doped layer. Charge density in organic solids by electrical doping of the hole transport layer (p-doping) using the appropriate acceptor material or electrical doping of the electron transport layer using the donor material (n-doping), respectively. (And therefore conductivity) is substantially increased. In addition, similar to the use of inorganic semiconductors, some applications can be expected to be precisely based on the use of p-type and n-type doped layers in the components, or You can't imagine other uses. The use of a doped charge transport layer in an organic light emitting diode (p-doping of a hole transport layer with a mixture of acceptor-type molecules, n-doping of an electron transport layer with a mixture of donor-type molecules) is a US patent application. It is described in Publication No. 2008/203406 and US Pat. No. 5,093,698.

Electrical doping is also referred to as redox-doping or charge transport doping. Doping is known to increase the charge density of semiconductors relative to the charge density of undoped matrices.

US Patent Application Publication No. 2008/227979 details the doping of organic transport materials with inorganic and organic dopants. Basically, efficient electron transport occurs from the dopant to the material, increasing the Fermi level of the matrix. For efficient electron transport in the p-dopant, the LUMO energy level of the dopant will be more negative than the HOMO energy level of the matrix, or at least the HOMO energy level of the matrix. On the other hand, it is preferable that the value is slightly positive (0.5 eV or less). For n-doping, the HOMO energy level of the dopant is either more positive than the LUMO energy level of the matrix, or at least slightly negative with respect to the LUMO energy level of the matrix. It is preferably (0.5 eV or more). Due to the energy transfer from the dopant to the matrix, the energy difference described above is preferably less than + 0.3 eV.

A typical example of a doped hole transport material is shown below: doped with tetrafluoro-tetracyanoquinone dimethane (F4TCNQ), which has a LUMO level of about -5.2 eV. , HOMO level is about -5.2eV, copper phthalocyanine (CuPc); zinc phthalocyanine (ZnPc) doped with F4TCNQ (HOMO = -5.2eV); a-NPD doped with F4TCNQ ( N, N'-bis (naphthalen-1-yl) -N, N'-bis (phenyl) -benzidine); 2,2'-(perfluoronaphthalene-2,6-diylidene) doped with dimalononitrile (PD1) A-NPD; 2,2', 2''-(cyclopropane-1,2,3-triylidene) tris (2- (p-cyanotetrafluorophenyl) acetonitrile) (PD2) was doped with a-NPD. All p-doping in the above device examples is performed with 5 mol% PD2. N4, N4, N4'', N4''-Tetra ([1,1'-biphenyl] -4-yl)-[1,1': 4', 1''-terphenyl] -4,4'' -Other useful hole transport materials, such as diamine (HT1), are disclosed in WO 2011/134458. Another hole transport material is 2,2', 7,7'-tetrakis (N, N-di-p-methylphenylamino) -9,9'-spirobifluorene (HT2). Further hole transport materials are published in US Patent Application Publication No. 2012/223296, N4, N4''-di (naphthalene-1-yl) -N4, N4''-diphenyl- [1 , 1': 4', 1''-terphenyl] -4,4''-diamine (HT3).

Typical examples of doped electron transport materials are: C60 fullerenes doped with acridine orange base (AOB); phenylene doped with leuco crystal violet- 3,4,9,10-Tetracarboxylic-3,4,9,10-Dianhydride (PTCDA); Tetrakis (1,3,4,6,7,8-Hexahydro-2H-pyrimid [1,2] -a] Pyrimidine)-Ditungsten (II) (W)₂(hpp)₄, ND1) doped with 2,9-di (phenanthrene-9-yl) -4,7-diphenyl-1,10-phenanthroline; 3,6-bis- (dimethylamino) -doped with acridines Naphthalene tetracarboxylic dianhydride (NTCDA); NTCDA doped with bis (ethylene-dithio) tetrathiafulvalene (BEDT-TTF). 4,4', 5,5'-Tetracyclohexyl-1,1', 2,2', 3,3'-Hexamethyl-2,2', 3,3'-Tetrahydro-1H, 1'H-2, Useful, air-stable precursors for n-dopants, such as 2'-biimidazole (ND2), are disclosed in European Patent No. 1837926. Another material is commercially available 2,4,7,9-1,10-phenanthroline (ET5).

The organic light emitting device may include an external out-coupling layer outside the electrically active region (region between the electrodes). This external out-coupling layer is separate from the scattering layer, as described. For top luminescent OLEDs, this external outcoupling can be a layer compatible with the index of refraction of the laminate to improve outcoupling from the transparent top electrode into the air. Top emitting OLEDs are described, for example, in WO 2005/106987 and European Patent No. 1739765. In one preferred embodiment, the scattering layer is in direct contact with the top electrode. The external out-coupling layer may also contain microparticles on the bottom of the substrate from the bottom luminescent OLED.

The organic light emitting device can be formed as a non-inverted structure or an inverse structure. In the case of the non-inverted structure, the bottom electrode is the anode and the top electrode is the cathode. In the case of the reverse structure, the bottom electrode is the cathode and the top electrode is the anode.

The roughened layer can be uniformly formed from a material having a single molecular structure.

The organic light emitting device can be a lighting device having a large area in which the roughened layer is patterned with a pattern that can be analyzed by the human eye. For example, the above pattern has a size that can be analyzed by the human eye when a human observer observes the instrument at a distance of one to several meters. The pattern has the advantage that the pattern is observed as a faint sign in the off state, for example due to the various specular / diffusive surfaces of the reflective layer. In addition, the above signs can also be observed in the on state, between areas of strong outcoupling and areas of weak outcoupling when the device is set to a moderate brightness level. The control can be perceived by a human observer.

The usual value understood from the resolution of the human eye is 1 degree = 1/60 degrees. Considering the visible distance of 1 m from the light emitting layer, this corresponds to 0.29 mm. Assuming a viewing distance of 30 cm, a resolution of 35 results in about 100 μm. Then, for the lateral distance and / or width of the strip-type light emitting layer, a value of about 100 μm can be considered as a convenient lower limit for the lateral distance of the light emitting layer, which can still be analyzed by the human eye. ..

The formation process for the roughened layer is adjusted to obtain the preferred growth mode (deposition rate, substrate temperature during deposition, latency after film deposition (tempering)). A low vaporization rate results in a low density of the particles. On the other hand, if the vaporization rate is too high, the particles can be fused together, or the layer can be just amorphous. In the process of forming the roughened layer, the vaporization rate of the material can be in the range of about 1 to about 10 Å / s.

The LUMO of the roughened layer differs significantly by more than 0.5 eV from the LUMO of at least one adjacent layer. The roughened layer is preferably formed without being doped. When the material of the organic roughened layer is HTL (used as HTL), it is then preferable that the HOMO differs from the HOMO of the adjacent layer by more than 0.5 eV. The roughened layer is preferably formed without being doped.

The material of the roughened layer can be an insulator, depending on the practical purpose of the device.

Therefore, a preferred variant has the following layered structure: -Undoped roughened layer / n-type doped ETL / cathode -Undoped roughened layer / p-type doped HTL / anode.

The roughened layer is preferably formed from molecules having a linear chemical structure and no branches. An example is a fused ring system with less than seven rings such as anthracene, phenanthrene, pentacene and BP fen. Materials having a chemical structure capable of at least one axial rotation along the spindle can also be used.

When the organic roughened layer also forms an electron transport layer (ETL) (between the cathode and the organic light emitting layer), the type of crosslinked bisoxazole (and higher homologues), especially 1, It is possible to use a material derived from 4-di (benzo [d] oxazole-2-yl) benzene.

The following materials, which have other properties, can be excluded when used as electron-transporting materials or in electron-transporting regions / electron-transporting layers: cross-linked bisoxazole types (and higher homologues). , Especially materials derived from 1,4-di (benzo [d] oxazol-2-yl) benzene.

Benzanelate oxatin, which has other properties, can be excluded as a hole-transporting material or in the hole-transporting region / hole-transporting layer. In one embodiment, the following compounds may be excluded as hole-transporting materials or in the hole-transporting region / hole-transporting layer, although they also have other properties:

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Here, X and Y are different from each other, but are independently selected from oxygen, sulfur, selenium and tellurium; n is 1, 2, 3, 4, 5 or 6; R_1-9Independently hydrogen, alkyl, aryl, heteroaryl, condensed carbon ring, condensed heterocycle, OR', SR'and NR₂Selected from', where R'is independently selected from alkyl, aryl, heteroaryl, condensed carbon rings and condensed heterocycles.

The layer below the roughened layer may be free of 2,7,9-triphenyl-4- (p-tolyl) pyrido [3,2-h] quinazoline.

[Explanation of Further Embodiments] The present invention will be described in detail in the text below by further embodiments with reference to the images in the drawings. The above image is shown below: Figure 1: Schematic (cross section) of the layered structure of an organic light emitting device, Figure 2: Schematic (cross-section) of a layered structure with a roughened layer on top of the underlying layer, Figure 3: Schematic (cross section) of a layered structure with a roughened layer on top of the underlying layer, Figure 4: Substrate with a roughened layer and a schematic (cross-sectional) schematic of the roughened layer deposited on top of the roughened layer. Figure 5: Schematic (cross section) of the layered structure of an organic light emitting device, Figure 6: Cross-sectional measurements made using AFM ("Atomic Force Microscope") for the layer structure of the sample. Figure 7: Layered structure for organic light emitting devices, Figure 8: Experimental results obtained by SEM (scanning electron microscope) for organic light emitting devices. Figure 9: Experimental results obtained by SEM for organic light emitting devices, Figure 10: Experimental results obtained by SEM for organic light emitting devices, Figure 11: Experimental results obtained by SEM for organic light emitting devices, Figure 12: Experimental results obtained by SEM for organic light emitting devices, Figure 13: Layered structure for organic light emitting devices, Fig. 14: Experimental results of an organic light emitting device prepared by using the layer structure in Fig. 13 obtained by SEM. Fig. 15: Experimental results of an organic light emitting device prepared by using the layer structure in Fig. 13 obtained by SEM. Figure 16: Experimental results obtained by AFM for layered structure, Figure 17: Layered structure for organic light emitting devices, Figure 18: Layered structure for organic light emitting devices, and Figure 19: Experimental results obtained by SEM for organic light emitting devices.

FIG. 1 shows a schematic (cross section) of the layered structure of an organic light emitting device. Organic light emitting devices can provide organic light emitting diodes (OLEDs). The layered structure includes a substrate 1, a bottom electrode 2, an electrically active region 10, a roughened layer 6, and a top electrode 8 coated with an encapsulation 9. A transport layer 7 exists between the top electrode 8 and the roughened layer 6. In another embodiment, the transport layer 7 may not be present. The layered structure in FIG. 1 also includes a light emitting layer 5 and a transport layer 4. In another embodiment, the transport layer 4 may not be present. In addition, there is an additional light emitting layer 3 that can be formed from one or more layers and may not be present in another embodiment. Unlike the schematic diagram in FIG. 1, there may be an additional transport layer between the light emitting layer 5 and the roughened layer 6.

FIG. 2 shows a (cross-sectional) schematic of a layered structure with a roughened layer 22 on top of a base layer 21. The roughened layer 22 is provided with an unclosed layer. The particles 23 in the roughened layer 22 are separated from each other to provide an island-like or granular structure. The particle 23 has a height of 24. There is a vacant space or vacant area 25 located between adjacent particles. In the vacant space 25, the material of the roughened layer 22 does not cover the base layer 21. The above layer design can be generated, for example, by growing the roughened layer 22 on the underlying layer 21 using the Warimel Weber (VW) mode.

FIG. 3 shows a (cross-sectional) schematic of a roughened structure, i.e., a layered structure with a roughened layer 32 to which particles 33 are imparted, on the underlying layer 31. In the region between the particles 33, which are formed from the same material as the particles 33 and have a thickness of 5 nm or less and give the roughened structure, there is a surface boundary layer 34 covering the underlayer 31. Both the particles 33 and the surface boundary layer 34 provide an iceberg-shaped structure for the roughened layer. The layer structure can be generated, for example, by growing the roughened layer 22 on the underlying layer 21 using the Stranski-Kranow (SK) mode.

FIG. 4 shows a schematic (cross-sectional) view of the underlying layer 40 with the roughened layer 41 and the roughened layer 42 deposited on the roughened layer 41. The roughened layer 42 is provided with irregularities including the concave-convex structure 43 on the outer surface 44 and the inner surface 45. In another embodiment (not shown), the roughened layer 42 imparts surface roughness only on the inner surface 45, while the outer surface 44 is flat.

Layer 42 can be an optionally doped transport layer, or electrode.

FIG. 4 also shows a region 46 with no roughened structure (no particles present), which can be created, for example, by using a shadow mask during vaporization. In region 46, the thickness of layer 42 can be measured directly, for example using a side gauge. It should be noted that the figure is merely an outline and does not necessarily correspond to a certain scale.

FIG. 5 shows a schematic (cross section) of the layered structure of the organic light emitting device. There is a substrate 50, a bottom electrode 51 (eg, the anode of an ITO), organic layers 52, 53 and 54. The organic-organic interface is marked by a dashed line (eg 56). The organic layer 54 also contains roughened particles (not explicitly shown), resulting in, for example, the unevenness 57 of the top electrode 55, which is the Al cathode.

Figure 6 shows a compound at 2,7,9-triphenyl-4- (p-tolyl) pyrido [3,2-h] quinazoline / 10 nm at quartz / 30 nm (1a-see below) / 2,7 at 30 nm. A cross-sectional measurement made using AFM in a sample of Ag, 9-triphenyl-4- (p-tolyl) pyrido [3,2-h] quinazoline / 100 nm is shown. The 30 nm 2,7,9-triphenyl-4- (p-tolyl) pyrido [3,2-h] quinazoline layer on quartz was a flat layer with irregularities smaller than 3 nm. The layer of compound (1a) did not form a closed layer (exclusively particles only). This measurement is shown from the top of the Ag electrode, as this freezes the morphology of the layer of compound (1a) (shortest wait time).

The organic layered structure is the one containing at least one light emitting layer. Typical layered structures for organic light emitting diodes are described, for example, in European Patent No. 1705727 and European Patent No. 1804309. The OLED may also have, for example, the pin layered structure described in US Pat. No. 7,074,500 and US Patent Application Publication No. 2006/250076. The n- and p-lactones used in pin OLEDs are, for example, US Pat. No. 6,908,783, US Patent Application Publication No. 2008/265216, International Publication No. 07/107306, European Patent No. 1672714. It is described in the specification.

The following compounds can be used to produce the roughened layer in organic light emitting devices:

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Compounds (1a)-(1f) and their synthesis are known in their own right. One or more of the above compounds are used as optical brighteners.

Compounds used in electron transport layers (4- (dibenzo [c, h] acridine-7-yl) phenyl) diphenylphosphine oxide (ET3) and 7- (4'-(1-phenyl-1H-benzo [d]] The synthesis of imidazol-2-yl)-[1,1'-biphenyl] -4-yl) dibenzo [c, h] acridine (ET4) was carried out as follows. THF means tetrahydrofuran, MTBE means methyl-t-butyl ether, DCM means dichloromethane, Et₂O means diethyl ether, MeOH means methanol, BuLi means butyllithium, HPLC means high performance liquid chromatography, and NMR means nuclear magnetic resonance.

First step: Synthesis of (E) -2- (4-bromobenzylidene) -3,4-dihydronaphthalene-1 (2H) -one (c). All operations were performed in air without further purification of commercially available solvents / chemicals.

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A 250 mL flask was filled with tetralone (3.22 g, 22 mmol) and 4-bromobenzaldehyde (5.3 g, 28.6 mmol). It was dissolved in warm tetrahydrofuran (12 mL) and 4 wt% methanol solution of KOH (100 mL) was slowly added to this yellow solution. The reaction was stirred at room temperature for 4 days. The mixture was concentrated and reduced by about 10% by volume. The residue was filtered, washed with MTBE (3 times x 50 ml) and dried to give a pale yellow powder (6.61 g, 96%).

Second step: Synthesis of 7- (4-bromophenyl) -5,6,8,9-tetrahydrodibenzo [c, h] acridine (d). Both reactions were carried out under argon.

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c (6.54 g, 20.9 mmol) and tetralon (2.93 g, 20.0 mmol) are BF₃ Et₂It was introduced into the flask with O (3 mL, 23.7 mmol). The mixture is stirred at 100 ° C. for 4 hours and cooled to room temperature. Et₂O (25 mL) is added and the mixture is stirred for an additional hour. The precipitate is filtered and Et₂Washed with O (20 mL). The dried powder (3.8 g) was then introduced into the flask with an ethanol solution of ammonia at 0 ° C. The mixture was allowed to stir at room temperature for 5 hours and the precipitate was filtered and washed several times with ethanol.

2.98 g (34% yield) of white powder was obtained.

Third step: Synthesis of 7- (4-bromophenyl) dibenzo [c, h] acridine (7). The oxidative dehydrogenation is carried out under argon.

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d (2.98 g, 6.80 mmol) was dissolved in 190 mL dioxane and 2,3-dichloro-5,6-dicyanobenzoquinone (10.9 g, 48 mmol). The mixture was refluxed under argon for 2 days. The reaction mixture was then cooled to room temperature, poured into 600 mL saturated aqueous sodium carbonate solution and stirred at 65 ° C. for 30 minutes. The mixture was then cooled to room temperature. The precipitate was filtered and washed with water and dichloromethane.

Yield: 2g (68%).¹HNMR (500MHz, CD₂Cl₂) δ (ppm): 9.80 (d, J = 8.0, 2H), 8.00 to 7.68 (m, 10H), 7.53 (d, J = 9.2, 2H), 7.45 to 7.34 (m, 2H).

Step 4: Synthesis of (4- (dibenzo [c, h] acridine-7-yl) phenyl) diphenylphosphine oxide (23). The reaction of butyllithium with diphenylphosphine chloride was carried out under argon in a dry solvent.

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(7) (2.84 g, 5.11 mmol) was dissolved in 40 mL of THF. The solution is cooled to -78 ° C, n-BuLi is added in a dropwise manner within 20 minutes (2.5 mol / L, 3.5 mL, 8.68 mmol), then stirred at the same temperature for 1 hour. It was. The temperature was then raised to -50 ° C, diphenylphosphine chloride (1.13 g, 5.11 mmol) was added and the mixture was stirred at room temperature overnight. The reaction was then quenched with methanol (25 mL) and the solvent was evaporated. The residue is dissolved in 40 mL of dichloromethane, followed by 8 mL of H₂O₂Aqueous solution was added (30% aqueous solution, w / w) and stirred overnight. The reaction mixture is then washed several times with 50 mL of saline, after which the organic phase is dried and evaporated. The crude product is column chromatography (SiO)₂, Dichloromethane, followed by DCM / methanol = 97: 3). The foamy product obtained by vacuum deposition was then washed with 200 mL MTBE.

The yield is 1.6 g (43%). HPLC purity greater than 97%.

NMR:³¹PNMR (CDCl₃, 121.5MHz): δ (ppm): 29 (m).¹HNMR (500MHz, CD₂Cl₂): δ (ppm): 9.79 (d, 8.06Hz, 2H), 7.86 (m, 10Hz), 7.75 (m, 2Hz), 7.69 (d, 9.20Hz, 2H), 7.58 (m, 8Hz), 7.44 ( d, 9.18Hz, 2H).

Step 4: 7-(4'-(1-phenyl-1H-benzo [d] imidazol-2-yl)-[1,1'-biphenyl] -4-yl) dibenzo [c, h] acridine (26) ) Synthesis. The Pd-catalytic condensation is carried out under argon.

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(7) (2.1 g, 4.8 mmol), 1-Phenyl-2- (4- (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) phenyl) -1H-benzo [d] Imidazole (3.8 g, 9.6 mmol), palladium tetrakistriphenylphosphine (830 mg) and 17 mL of 1M aqueous potassium carbonate solution were introduced into the flask with 35 mL of degassed toluene. The mixture was stirred at 80 ° C. for 36 hours, cooled to room temperature and filtered. The resulting solid was then dissolved in 600 mL of DCM and filtered over a pad of Celite. Volatiles were removed by rotary evaporation, after which the solid residue was dried overnight in a vacuum furnace.

The yield is 1.2 g (40%). HPLC purity greater than 98%.¹HNMR (500MHz, CD₂Cl₂) δ (ppm): 9.82 (d, 8.16Hz, 2H), 7.85 (d, 7.60Hz, 2H), 7.88 (m, 5H), 7.79 (m, 2H), 7.76 (s, 4H), 7.74 (s) , 1H), 7.63 (d, 9.2Hz, 2H), 7.59 (m, 3H), 7.56 (m, 1H), 7.43 (dd, 3.13Hz, 5.32Hz, 2H), 7.36 (m, 1H), 7.29 ( dt, 3.01Hz, 3.01Hz, 7.35Hz, 2H).

2,7,9-Triphenyl-4- (p-tolyl) pyrido [3,2-h] quinazoline (ET1) and 4- (naphthalene-1-yl) -2,7,9-triphenylpyrid The synthesis of de- [3,2-h] quinazoline (ET2) is described in European Patent No. 1970371.

The following layer order is an example of how to make the desired form. The order of the layers was included inside the organic light emitting diode. In each layer set, the layer formed by the first material is provided with an underlayer (ETL or n-ETL) and the subsequent layers formed by the second material are roughened layers. provide. The above structure in the stacking of devices is as follows: EML / Underlayer / Roughened Layer.

Best results were achieved by inserting the order of the layers in the OLED stack using electrically doped layers. All depositions were performed at room temperature. The materials used in the light emitting layer are commercially available from Sun Chemicals and are represented by trade codes such as ABH036, NRD129 and NUBD369.

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Contrary to many techniques for increasing light outcoupling, where various additional methods do not further affect the function of the OLED, it is possible that the function of the OLED can be further improved in the present invention. It was a surprising discovery.

By adding an external out-coupling foil containing a microlens array to increase light extraction, the efficiency of the best OLED is almost doubled by almost double the factor, and the power efficiency is greater than 60lm / W. Was able to be obtained.

The organic light emitting device was manufactured as shown in FIG. The following layered structures were prepared: 7.1: Glass substrate 7.2: ITO 7.3: HT1: PD2 (97: 3) (layer thickness: 30 nm) 7.4: HT1: PD2 (99: 1) (145nm) 7.5: HT1 (10nm) 7.6: ABH036: NRD129 (99: 1) (5nm) 7.7: ABH036: NUBD369 (95: 5) (25nm) 7.8: ET2 (10nm) 7.9: Compound (1d)-(1f) 7.10: ET2: ND2 (90:10) (30nm) 7.11: Ag (100nm) For reference, the organic light emitting device was prepared without layer 7.9.

For the above devices containing layer 7.9, the following materials were used: compound (1d), compound (1e) and compound (1f).

The following references are made for FIGS. 8-12.

Organic light emitting devices prepared using the layered structure as shown in FIG. 7 were prepared and investigated in detail. Figures 8 to 12 are the experimental results obtained by SEM (scanning electron microscope), and the cuts were made for various devices using a focused ion beam (FIB).

8 to 12, the upper drawing shows a cross section of the device, while the lower drawing shows a plan view of the top electrode of the device. For the image of the above cross section, the following parameters are used: magnification: 100,000 times, EHT (electron high voltage): 1 kV, working distance (WD): 5.1 mm to 5.2 mm, aperture size: 30 μm and detector: In-lens, or SESI (composite secondary electron secondary ion) (Figure 12a only). For the plan view of the electrode surface, the following parameters are used: Magnification: 50000x, EHT (Electronic High Voltage): 3kV, Working Distance (WD): 4.9mm-5.1mm, Aperture Size: 30μm and Detection Vessel: SESI, or SE2 (Figure 15b only).

In FIG. 8, layer 7.9 has a layer thickness of 6.7 nm (deposition rate 3 Å / s) and was prepared from material (A). In FIG. 9, layer 7.9 has a layer thickness of 6.1 nm (deposition rate 3 Å / s) and was prepared from material (B). In FIG. 10, layer 7.9 has a nominal layer thickness of 10.1 nm (deposition rate 1 Å / s) and was prepared from material (A). In FIG. 11, layer 7.9 has a nominal layer thickness of 10.1 nm (deposition rate 1 Å / s) and was prepared from material (B). In FIG. 12, layer 7.9 has a layer thickness of 5.6 nm (deposition rate 3 Å / s) and was prepared from material (C).

The experimental results for the devices shown in FIGS. 8 to 12 are summarized below.

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The area is the area of the active region of the OLED. CIE X and CIE Y are chromaticities according to the definition of the International Commission on Illumination (CIE) in 1931. Peff indicates power efficiency (or luminance efficiency) (measured at lm / W). EQE is external quantum efficiency. The increase in EQE is the ratio between the EQE of the laminate with the roughened layer and the EQE of the laminate without the roughened layer. The values were obtained from measurements on the integrating sphere at the currents specified in the table above.

Another organic light emitting device was prepared as shown in FIG. The following layered structure was prepared: 13.1: Glass substrate 13.2: ITO 13.3: HT1: PD2 (97: 3) (layer thickness: 30 nm) 13.4: HT1: PD2 (99: 1) (145nm) 13.5: HT1 (10nm) 13.6: ABH036: NRD129 (99: 1) (5nm) 13.7: ABH036: NUBD369 (95: 5) (25nm) 13.8: ET2 (10nm) 13.9: Compound (1d)-(1f) 13.10: ET2: ND1 (30nm) 13.11: Ag For reference, the organic light emitting device was prepared without layer 13.9.

14 and 15 show the experimental results for the organic light emitting device prepared by using the layer structure in FIG. 13 obtained by using SEM. In this case as well, the upper drawings in FIGS. 14 and 15 show the cross section of the device, while the lower drawings show the plan view of the device.

With respect to FIGS. 14 and 15, layer 13.9 was formed from compound (1a). A deposition rate of 0.8 Å / s was used in FIG. 14 and for the example in FIG. 15 was a deposition rate of 6 Å / s. It should be noted that the areas of the active regions are different and therefore the increase in efficiency due to the effect of substrate thickness is incomparable in these two cases. In the above stack, there are also some differences that do not affect the increase in morphology and efficiency: Figure 14-ET2: ND1 (15%), 100 nm cathode, and Figure 15-ET2: ND1 (8%). ), 250 nm cathode.

The experimental results for the devices shown in FIGS. 14 and 15 are summarized below.

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FIGS. 16a to 16d show the experimental results obtained by using AFM for the layered structure in which compound (1a) was deposited on the organic layer formed by ET2.

Figures 16a and 16c show results for a layered structure without a metal top electrode and with a metal top electrode formed of a 100 nm Ag layer. FIGS. 16b and 16d show the results for the layer structure on which the transport layer formed by ET2 and having a thickness of 30 nm was deposited on the roughened layer. Again, FIGS. 16b and 16d show the results for those with a metal top electrode made of Ag and those without a metal top electrode made of Ag.

The organic light emitting device was prepared as shown in FIG. The following layered structure was prepared: 17.1: Glass substrate 17.2: ITO (layer thickness: 90nm) 17.3: HT2: PD1 (98.5: 1.5) (50nm) 17.4: a-NPD (20nm) 17.5: Compound (1d) (10nm) 17.6: a-NPD: RE076 (95: 5) (20nm) 17.7: ET5 (10nm) 17.8: ET2 (10nm) 17.9: ET2: ND1 (92: 8) (40nm) 17.10: Ag The material of the electron shielding layer (EBL) 17.4 can be HT1, HT2 and HT3 instead. The scattering layer 17.5 can also be formed from the materials shown as compounds (1e) and (1f). In other embodiments, the device can be formed without the scattering layer 17.5. The abbreviation RE076 refers to a commercially available material for iridium (III) bis (2-methyldibenzo- [f, h] quinoxaline) (acetylacetone).

Another organic light emitting device was prepared as shown in FIG. The self-crystallizing compound (1d) is placed on the hole side of the laminate. This is an example of a layer in which the roughened layer is not allowed to be arranged on the electron transporting layer side. The following layered structure was prepared (pii-laminated): 18.1: Glass substrate 18.2: ITO (layer thickness: 90nm) 18.3: HT2: PD1 (98.5: 1.5) (50nm) 18.4: a-NPD (20nm) 18.5: Compound (1d) (10nm) 18.6: a-NPD: RE076 (95: 5) (20nm) 18.7: ET5 (60nm) 18.8: LiQ (2nm) 18.9: Al The material of the electron shielding layer (EBL) 18.4 can be HT1, HT2 and HT3 instead. The scattering layer 18.5 can also be formed from the materials shown as compounds (1e) and (1f).

The table below shows the external quantum efficiency (EQE) for various EBL materials with and without compound (1d) and compound (1f). External quantum efficiency is 3mA / cm²It was measured in an integrating sphere at a constant current density of. The increase in efficiency is 35% -40%.

<tables num="4"><img id="000012" he="47" wi="158" file="JP6139552B2_D0001.tif" img-format="tif" img-content="drawing" /></tables>

FIG. 19 shows a cross section of an organic light emitting device formed from one of compounds (1d) to (1f) and having a layer (3 nm) arranged adjacent to HT1. HT1 functions as an electron shielding layer (EBL). The interface between the terminal organic layer and the cathode is wavy. The image was obtained using SEM. From FIG. 19, the mechanism of out-coupling is similar to the case where the layer formed from one of the compounds (1d) to (1f) is arranged on the electron transport side of the device. It can be concluded.

The features of the invention disclosed in the above detailed description, claims and drawings may be important both individually and in any combination for the practice of the invention in its various embodiments.

<figref num="1">Schematic (cross section) of the layered structure of an organic light emitting device.</figref><figref num="2">Schematic (cross section) of a layered structure with a roughened layer on top of the underlying layer.</figref><figref num="3">Schematic (cross section) of a layered structure with a roughened layer on top of the underlying layer.</figref><figref num="4">FIG. 6 is a schematic (cross-sectional) view of a base layer with a roughened layer and a roughened layer deposited on top of the roughened layer.</figref><figref num="5">Schematic (cross section) of the layered structure of an organic light emitting device.</figref><figref num="6">Cross-sectional measurement made using AFM ("Atomic Force Microscope") for the layer structure of the sample.</figref><figref num="7">Layered structure for organic light emitting devices.</figref><figref num="8a">Experimental results obtained by SEM (scanning electron microscope) for organic light emitting devices.</figref><figref num="8b">Experimental results obtained by SEM (scanning electron microscope) for organic light emitting devices.</figref><figref num="9a">Experimental results obtained by SEM for organic light emitting devices.</figref><figref num="9b">Experimental results obtained by SEM for organic light emitting devices.</figref><figref num="10a">Experimental results obtained by SEM for organic light emitting devices.</figref><figref num="10b">Experimental results obtained by SEM for organic light emitting devices.</figref><figref num="11a">Experimental results obtained by SEM for organic light emitting devices.</figref><figref num="11b">Experimental results obtained by SEM for organic light emitting devices.</figref><figref num="12a">Experimental results obtained by SEM for organic light emitting devices.</figref><figref num="12b">Experimental results obtained by SEM for organic light emitting devices.</figref><figref num="13">Layered structure for organic light emitting devices.</figref><figref num="14a">Experimental results for an organic light emitting device prepared by using the layer structure shown in FIG. 13 obtained by SEM.</figref><figref num="14b">Experimental results for an organic light emitting device prepared by using the layer structure shown in FIG. 13 obtained by SEM.</figref><figref num="15a">Experimental results for an organic light emitting device prepared by using the layer structure shown in FIG. 13 obtained by SEM.</figref><figref num="15b">Experimental results for an organic light emitting device prepared by using the layer structure shown in FIG. 13 obtained by SEM.</figref><figref num="16a">Experimental results obtained by AFM for layered structure.</figref><figref num="16b">Experimental results obtained by AFM for layered structure.</figref><figref num="16c">Experimental results obtained by AFM for layered structure.</figref><figref num="16d">Experimental results obtained by AFM for layered structure.</figref><figref num="17">Layered structure for organic light emitting devices.</figref><figref num="18">Layered structure for organic light emitting devices.</figref><figref num="19">Experimental results obtained by SEM for organic light emitting devices.</figref>