KR20090024230A - Organic light emitting devices - Google Patents

Abstract

A white organic light emitting device is provided to secure improved efficiency and stability by using blue, green, red, and yellow fluorescence emitters in comparison with a white fluorescence device using only fluorescence emitter. A white organic light emitting device comprises: a substrate(100); an positive electrode(110) adjacent to the substrate; a hole transport region(120) adjacent to the positive electrode; an electron transport region(130); a negative electrode(140) adjacent to the electron transport region; and a light emitting region(125) having one or more electron and hole transport material. Red, green, and blue emitter molecules are doped within a host material. Selectively, the blue and yellow emitter molecules are doped within the host material.

Description

Organic light emitting devices

1 illustrates an exemplary embodiment of an organic light emitting device according to the invention;

2 illustrates another exemplary embodiment of an organic light emitting device according to the invention; And

3 illustrates another exemplary embodiment of an organic light emitting device according to the present invention.

The present invention relates to photovoltaic devices, and more particularly to organic light emitting devices (organic electroluminescent (EL) devices). More specifically, the present invention relates to efficient white organic EL devices.

The organic electroluminescent (EL) device or OLED may consist of a layer of organic light emitting material sandwiched between an anode and a cathode, the anode consisting of a typically transparent conductor, such as indium tin oxide, the cathode It is typically composed of a metal having a low work function, such as magnesium, calcium, aluminum, or other metals and their alloys. The EL element operates in accordance with the main law under which the positive charges (holes) and negative charges (electrons) are injected into the luminescent material from the anode and the cathode, respectively, and recombine to form excitation states that emit light later. Numerous organic EL devices have been fabricated from laminates of electrodes of opposite polarity with organic light emitting materials, such devices as described, for example, in US Pat. No. 3,530,325, the disclosure of which is fully incorporated herein by reference. Luminescent materials include single crystal materials, such as single crystal anthracene. Devices of this type are thought to require excitation voltages of 100 volts or more.

The organic EL device having a multilayer structure may include one organic layer adjacent to the anode supporting hole transfer, and another organic layer adjacent to the cathode supporting electron transfer and serving as an organic light emitting region of the device. Examples of these devices are described in US Pat. No. 4,356,429, the disclosures of which are hereby fully incorporated by reference; 4,539,507; 4,720,432, and 4,769,292. In US Pat. No. 4,769,292, the disclosure of which is fully incorporated herein by reference, the organic EL device comprises three separate layers, a hole transporting layer, a light emitting layer, and an electron transporting layer, which layers are sequentially laminated so as to sandwich the anode and cathode. Sandwiched therein, where a fluorescent dopant material is added to the light emitting region or light emitting layer, so that the combination of charges results in excitation of the fluorescent material. For example, in some of these multilayer structures, such organic light emitting devices as described in US Pat. No. 4,720,432, the disclosures of which are hereby fully incorporated by reference, the organic light emitting device is interposed between the hole transport layer and the anode. It further comprises a buffer layer. The combination of the hole transport layer and the buffer layer forms a double layer hole transport region, including these references to S. A. Van Slyke et al., "Organic Electroluminescent Devices with Improved Stability," Appl. Phys. Lett. 69, pp. 2160-2162, 1996.

Attempts have been made to obtain electroluminescence from organic light emitting devices comprising mixed layers, eg, layers in which a hole transport material and an emission electron transport material are mixed together in one layer, such as Kido et al. Organic Electroluminescent Devices Based On Molecularly Doped Polymers, "Appl. Phys. Lett. 61, pp. 761-763, 1992; S. Naka et al., "Organic Electroluminescent Devices Using a Mixed Single Layer," Jpn. J. Appl. Phys. 33, pp. L1772-L1774, 1994; W. Wen et al., Appl. Phys. Lett. 71, 1302 (1997); And C. Wu et al., "Efficient Organic Electroluminescent Devices Using Single-Layer Doped Polymer Thin Films with Bipolar Carrier Transport Abilities", IEEE Transactions on Electron Devices 44, pp. 1269-1281, 1997. In many of these devices, the electron transporting material and the electron emitting material may be the same or the mixed layer may further include the emitting material as a dopant. Other examples of organic light emitting devices formed from a single organic layer comprising a hole transport material and an electron transport material include, for example, US Pat. No. 5,853,905, the disclosures of which are hereby incorporated by reference in their entirety; 5,925,980; 6,114,055 and 6,130,001.

Recent advances in organic EL research have increased the potential for the development of organic EL devices for a wide range of applications, while the driving stability of currently available devices has been less than expected in some examples. Many known organic light emitting devices have relatively short drive lifetimes before their brightness drops to some percentage of their initial value. See, eg, S. A. Van Slyke, "Organic Electroluminescent Devices with Improved Stability," Appl. Phys. Lett. 69, pp. Providing interfacial layers as described in 2160-2162, 1996, and, for example, in Y. Hamada et al., "Influence of the Emission Site on the Running Durability of Organic Electroluminescent Devices", Jpn. J. Appl. Phys. 34, pp. Doping as described in L824-L826, 1995 may possibly increase the drive life of organic light emitting devices for room temperature operation, but the efficiency of these organic light emitting devices is degraded for high temperature device driving.

In particular, in order to realize full-color displays, there is a need for the development of OLEDs emitting in the red, green and blue regions of the visible spectrum. Recent developments have led to the development of green and red light emitting OLEDs with improved performance in commercial applications, but the driving stability of blue light emitting OLEDs is still particularly unsatisfactory.

White OLEDs using one or more colors of light emitting materials experience the same disadvantages with regard to efficiency and stability as color light emitting OLEDs.

The present invention provides organic light emitting devices (OLEDs) with improved performance, including increased efficiencies and stability.

Exemplary embodiments of the white organic light emitting device include an anode; A cathode, and a light emitting area, wherein the light emitting area comprises one or more phosphors emitting red light, one or more phosphors emitting green light, and one or more phosphors emitting blue light. In an alternative embodiment, the emissive region comprises one or more phosphors emitting yellow and one or more phosphors emitting blue.

Exemplary embodiments of light emitting devices according to the present invention include an anode, a cathode, and a light emitting zone between the anode and the cathode. The light emitting zone can include a wide range of other organic light emitting materials.

In order to avoid confusion in understanding the scope of the invention, the following guidelines may be used:

The term "layer" generally refers to a single coating having a composition different from that of the adjacent layer;

The term “region” refers to a plurality of layers, such as a single layer, two, three or more layers;

As used in the context of a light emitting zone, the term "zone" refers to a single layer, multiple layers, a single functional area in a layer, or multiple functional regions in a layer, or one or more regions. say (regions);

In general, all regions and layers of the display element which are between two electrodes or participate in the charge conduction processes necessary to drive the display element are considered as part of either the cathode, the light emitting region, or the anode. .

In general, a layer (eg, a substrate) that may appear to be outside of the two electrodes without participating in the charge conduction processes of the display element will not be considered part of the electrodes. However, such a layer (eg a substrate) may still be considered part of the display element;

"Light emission zone", "light emitting zone", and "luminescent zone" are used interchangeably.

Light emission from OLEDs is typically via fluorescence, but light emission through phosphorescence has recently emerged. As used herein, the term "phosphorescence" refers to the emission from the triplet excited state of an organic molecule, and the term "fluorescence" refers to the emission from a singlet excited state of an organic molecule. Says release. The term luminescence refers to fluorescent emission or phosphorescent emission.

One advantage of phosphorescence is that by the recombination of holes and electrons, either the singlet or triplet excited state, all formed excitons may participate in luminescence. This is because the lowest singlet excited state of the organic molecule is typically slightly higher in energy than the lowest triplet excited state. For example, in typical phosphorescent organometallic compounds, the lowest singlet excited state may quickly decay to the lowest triplet excited state where phosphorescence is produced. In contrast, only a small portion (about 25%) of excitons in the fluorescent elements can produce fluorescent luminescence resulting from a singlet excited state. In fluorescent devices, the remaining excitons produced in the lowest triplet excited state cannot typically be converted to the higher energy singlet excited states where fluorescence is generated. Therefore, this energy is lost in the decay processes of heating the device rather than emitting visible light.

Typically, phosphorescent emission from organic molecules is less common than fluorescent emission. However, phosphorescence can be observed from organic molecules under a set of appropriate conditions. Organic molecules coordinated with lanthanide elements are often released from excitation states that are localized on the lanthanide metal. Such radioactive emissions do not occur from triplet excited states. Moreover, it has not been shown that such emission can produce efficiencies high enough to be a practical value in expected OLED applications. Europium diketonate complexes illustrate one group of these types of species.

Organic phosphorescence can be observed in molecules containing heteroatoms with pairs of unshared electrons, but typically at very low temperatures. Benzophenone and 2,2'-bipyridine are such molecules. By trapping organic molecules in close proximity to atoms with high atomic numbers, preferably via bonding, phosphorescence can be improved over fluorescence at room temperature. This phenomenon, called the heavy atom effect, is created by a mechanism known as spin-orbit coupling. A related phosphorescent transition is metal-to-ligand transfer (MLCT) observed in molecules such as tris (2-phenylpyridine) iridium (III).

Recently, high-efficiency green and red organic electroluminescent devices have emerged, which yield single and triplet excitons, leading to internal quantum efficiency approaching 100%. Baldo, M. A., O'Brien, D. F., You, Y., Shoustikov, A., Sibley, S., Thompson, M. E., and Forrest, S. R., Nature (London), 395, 151-154 (1998); Baldo, M. A., Lamansky, S., Burrows, P. E., Thompson, M. E., and Forrest, S. R., Appl. Phys. Lett., 75, 4-6 (1999); Adachi, C., Baldo, M. A., and Forrest, S. R., App. Phys. Lett., 77, 904-906, (2000); Adachi, C., Lamansky, S., Baldo, M. A., Kwong, R. C., Thompson, M. E., and Forrest, S. R., App. Phys. Lett., 78, 1622-1624 (2001); and Adachi, C., Baldo, M. A., Thompson, M. E., and Forrest, S. R., Bull. Am. Phys. See Soc., 46, 863 (2001). Wide external quantum efficiencies of (17.6 ± 0.5)%, corresponding to internal quantum efficiencies greater than 85%, using green phosphors, in particular fac tris (2-phenylpyridine) iridium (Ir (ppy) 3) Energy gap host material, for example 3-phenyl-4- (1'-naphthyl) -5-phenyl-1,2,4-triazole (3-phenyl-4- (1'-naphthyl) -5 -phenyl-1,2,4-triazole) (TAZ). Adachi, C., Baldo, M. A., Thompson, M. E., and Forrest, S. R., Bull. Am. Phys. See Soc., 46, 863 (2001). More recently, high efficiency (external) employing bis (2- (2'-benzo [4,5-a] thienyl) pyridinato-N, C3) iridium (acetylacetonate) [Btp2 Ir (acac)] Red field phosphorescence of quantum efficiency = (7.0 ± 0.5)% appeared. Adachi, C., Lamansky, S., Baldo, M. A., Kwong, R. C., Thompson, M. E., and Forrest, S. R., App. Phys. See Lett., 78, 1622-1624 (2001).

In each of these latter cases, high efficiency is achieved through energy transfer from the host singlet and triplet states to phosphorus triplet, or through direct trapping of charge on the phosphorescent material. This is a significant improvement over what can be expected using fluorescence in either low molecular or polymer light emitting devices (OLEDs). Baldo, M. A., O'Brien, D. F., Thompson, M. E., and Forrest, S. R., Phys. Rev., B 60, 14422-14428 (1999); Friend, RH, Gymer, RW, Holmes, AB, Burroughes, JH, Marks, RN, Taliani, C., Bradley, DDC, Dos Santos, DA, Bredas, JL, Logdlund, M., Salaneck, WR, Nature (London ), 397, 121-128 (1999); and Cao, Y, Parker, I. D., Yu, G., Zhang, C., and Heeger, A. J., Nature (London), 397, 414-417 (1999).

The quality of the white illumination sources can be fully explained by a simple set of variables. The color of the light source is given by its Commission Internationale de 'Eclairage (CIE) chromaticity coordinates x and y. CIE color coordinates are typically displayed on a two-dimensional plot. Monochromatic colors correspond to the periphery of a horseshoe-shaped curve starting from blue at the bottom left and past the colors of the spectrum clockwise to red at the bottom right. The CIE coordinates of a light source of a given energy and spectral shape will be in the region of the curve. The uniform sum of light at all wavelengths is the white or midpoint point, found in the middle of the plot (CIE x, y-coordinates, 0.33, 0.33). Mixing light from two or more sources provides light whose color is represented by the intensity weighted average of the CIE coordinates of the independent sources. Thus, mixing light from two or more sources can be used to generate white light. Although bicomponent or tricomponent white light sources look the same to the viewer (CIE, x, y-coordinates, 0.32, 0.32), they will not be equivalent illumination sources. When considering the use of such illumination white light sources, the CIE color rendering index (CRI) needs to be considered in addition to the CIE coordinates of the source. The CRI provides an indication of how the light source looks good with the colors of the objects it illuminates. The perfect combination of standard light source and provided light source provides 100 CRI. Although a CRI value of at least 70 may be justified in some applications, a preferred white light source will have a CRI of about 80 or more.

As such, OLEDs are particularly suitable as sources of white light sources. The structure of luminescent fluorescent or phosphorescent additives can be tailored to emit any desired color, including white. Mixing light from two or more light sources provides light whose color is determined by a weighted average of CIE coordinates. Substantially any shade of white or temperature of white light can be generated in OLEDs. White light can be produced by mixing two or more different dyes or polymers that emit different colors in one or more layers. Other ways of generating white light include using horizontally stacked narrow bands or pixels to emit basic colors, using monomer-excimer complexes, and efficient blue emitter and down-conversion phosphors. It includes using.

The light emitting zone for generating white light may include, for example, two or more layers in which at least one layer produces blue light emission and at least one layer produces yellow, green, orange or red light emission. One or more layers that produce blue luminescence include, for example, one or more blue electroluminescent materials described herein, and at least one or more layers that produce green, yellow, orange or red luminescence, As described herein, it is possible to include any electroluminescent material that can emit in the desired color range by adding luminescent dopants into a suitable electroluminescent material. Optionally, the white light emitting region or region generating white light may comprise a single layer of blue electroluminescent material further comprising a green, yellow, orange, or red light emitting dopant, wherein the red light emitting dopant is blue. Allows partial retention of blue light emission from the electroluminescent material and when combined with green, yellow, orange, or red emission components from the dopant, it provides white light emission. If the dopant is a fluorescent material, the concentration may be, for example, from 0.01% to 5% by volume, and in particular, the concentration may be, for example, from 0.2% to 2% by volume. If the dopant is a phosphorescent material, the concentration may be, for example, from 0.01 vol% to 25 vol%, in particular the concentration may be, for example, from 3 vol% to 15 vol%.

1 illustrates an exemplary embodiment of an organic light emitting element (OLEDs) 1 according to the invention. The organic light emitting diode 1 may include a substrate 100, an anode 110 adjacent to the substrate 100, a hole transport region 120 adjacent to the anode 110, an electron transport region 130, and the electron transport region ( A cathode 140 adjacent to 130 and a light emitting region 125 comprising one or more electron and hole transport materials. The emission area 125 may be one or more layers that emit red, green, and blue. In one embodiment, red, green, and blue emitter molecules are doped into the host material. Optionally, blue and yellow emitter molecules are doped into the host material.

The substrate 100 is shown in FIG. 1 as adjacent to the anode 110, but may also be located adjacent to the cathode 140.

As shown in another exemplary embodiment shown in FIG. 2, the light emitting region 125 is formed by one or more layers 126 emitting red and green light and one or more layers 127 emitting blue light. Optionally, the layer 126 emits yellow light.

As shown in another embodiment shown in FIG. 3, the emissive region 125 includes one or more layers 128 emitting red light, one or more layers 129 emitting green light, and one or more layers 127 emitting blue light. Is formed.

In general, as discussed in more detail below, the present invention utilizes fluorescent emitters for blue light emission and phosphorescent emitters for green, red, and yellow light emission.

In an exemplary embodiment, the fluorescent emitters and phosphorescent emitters are dopants in a suitable matrix or host material that support emitting colors. In this way, the OLED according to the invention combines the advantages of long-lived blue fluorescent emitters with the advantages of high efficiency and long lifetime of green, red and yellow phosphorescent emitters. Moreover, relative to white devices using only fluorescent emitters, the relatively short lifespan of blue phosphorescent emitters can be avoided while increasing the overall efficiency of the OLED. Examples of common luminescent, hole transporting and injecting materials, and electron transporting and injecting materials, as well as fluorescent and phosphorescent emitters, are described in more detail below.

In general, the hole transport region 120, the electron transport region 130, and the light emitting region 125 are collectively referred to as a light emitting region. During operation, the applied electric field causes positive charges (holes) and negative charges (electrons) to be injected and recombined from the anode 110 and the cathode 140 into the light emitting zone, respectively, thereby emitting light in the light emitting zone.

The light emitting zone comprises an organic light emitting material. Examples of suitable organic light emitting materials include, for example, metal oxinoid compounds, stilbene compounds, anthracine compounds, oxadiazole metal chelate compounds, Polyfluorenes, polyphenylenevinylenes and derivatives and mixtures thereof. Other suitable organic light emitting materials are described below.

The hole transport region 120 may comprise suitable hole transport materials and suitable electron transport materials, the suitable hole transport materials being, for example, polyphenylenevinylenes, polythiophenes, 3 Secondary aromatic amines, and indolocarbazole compounds and other materials, and suitable electron transport materials include, for example, metal oxynoids, triazines, oxadiazole metal chelates, stilbenes, polyflu Orens and other materials.

Various light emitting materials, hole transporting materials and electron transporting materials are known in the art to have their combined choice for achieving the desired color emission. In addition, the selection of such materials to provide the desired color emission can be readily performed by one of ordinary skill in the art using routine experimentation.

Embodiments of organic light emitting devices can be operated under alternating current (AC) and / or direct current (DC) driving conditions. AC drive conditions may provide increased operating life.

Other parts of the organic light emitting elements according to the invention will now be described in more detail.

Substrate 100 may comprise any suitable material. For example, the substrate 100 may include polymer components, glass, quartz, or the like. Suitable polymeric components include, but are not limited to, polyesters such as MYLAR ^® , polycarbonates, polyacrylates, polymethacrylates, polysulfones and the like. Mixtures of these various materials can also be used. Other suitable materials may also be provided if they can effectively support other layers and do not interfere with the functional performance of the device. The substrate 100 may be formed of a light transmitting material.

The thickness of the substrate 100 is, for example. There is no particular limitation, except by the structural requirements of the organic light emitting device and its intended use. Typically, the substrate 100 may have a thickness, for example, from about 25 μm to at least 1,000 μm or more.

The anode 110 formed over the substrate 100 may comprise any suitable, known or later developed material. For example, positive charge injection electrodes such as indium tin oxide (ITO), tin oxide, gold and platinum may be used. Other suitable materials for the anode are, but are not limited to, polyaniline, polypyrrole, having an electrically conductive carbon and a work function, for example, at least about 4 eV, and preferably in the range of about 4 eV to about 6 eV. Π-conjugated polymers and the like.

The anode 110 may have any suitable structure. A thin conductive layer can be coated over the light transmissive substrate, such as, for example, a transparent or substantially transparent glass plate or plastic film. Embodiments of the organic light emitting devices according to the present invention may include a light transmissive anode formed from tin oxide or indium tin oxide (ITO) coated on a glass plate. Also, for example, very thin translucent metal anodes having a thickness of less than about 200 mm 3, preferably from about 75 mm 3 to about 150 mm 3 can be used. These thin anodes can include metals such as gold, palladium, and the like. In addition, transparent or semi-transparent thin layers of conductive carbon or the above-mentioned conjugated polymers having a thickness of, for example, about 50 kPa to about 175 kPa can be used as the anodes. Additional suitable forms of anode 110 (and cathode 140 as described in detail below) are described in US Pat. No. 4,885,211, which is incorporated herein by reference in its entirety.

The thickness of anode 110 may range from about 1 nm to about 500 nm, with an exemplary thickness range depending on the optical constants of the anode material. One exemplary thickness range of the anode depends on the optical constants of the anode material. In one embodiment, the thickness of the anode ranges from about 30 nm to about 300 nm. Of course, thicknesses outside this range may also be used.

The light emitting zone comprises one or more materials, any suitable, known or later developed, including an organic light emitting material. Suitable organic light emitting materials that can be used in the light emitting zone are, for example, poly (p-phenylenevinylene) (PPV), poly (2-methoxy-5- (2-ethylhexoxy) 1,4 -Phenylenevinylene) (MEHPPV) and poly (2,5-dialkoxyphenylenevinylene) (PDMeOPV), and other polyphenylenevinyls such as those disclosed in US Pat. No. 5,247,190, which is incorporated herein by reference in its entirety. And lenenes.

Other suitable organic light emitting materials that can be used in the light emitting zone are, for example, poly (p-phenylene) (PPP), ladder-poly-para-phenylene (LPPP), And polyphenylenes such as poly (tetrahydropyrene) (PTHP).

Still other suitable organic light emitting materials that can be used in the light emitting zone are, for example, Bemius et al., "Developmental progress of Electroluminescent Polymeric Materials and Devices," Proceedings of SPIE Conference on Organic Light Emitting, for example. Materials and Devices III, Denver, Colo., July 1999, Volume 3797, p. As described at 129, poly (9,9-di-n-octylfluorene-2,7-diyl), poly (2,8- (6,7,12,12-tetraalkylindenofluorene) and Same polyfluorenes, and also copolymers containing fluorenes, such as fluorene-amine copolymers.

Exemplary classes of organic electroluminescent materials that can be used in the light emitting zone include, but are not limited to, US Pat. No. 4,539,507, each of which is incorporated herein by reference; 5,151,629; 5,150,006; Metal oxinoid compounds as described in 5,141,671 and 5,846,666. Examples include tris (8-hydroxyquinolinate) aluminum (AlQ ₃ ), one example, and bis (8-hydroxyquinolato)-(4-phenylphenorato) aluminum (BAlQ), another example. do. Other examples of this class of materials include tris (8-hydroxyquinolinate) gallium, bis (8-hydroxyquinolinate) magnesium, bis (8-hydroxyquinolinate) zinc, tris (5-methyl- 8-hydroxyquinolinate) aluminum, tris (7-propyl-8-quinolinolato) aluminum, bis [benzo {f} -8-quinolinate] zinc, bis (10-hydroxybenzo [h] Quinolinate) beryllium, etc., and bis (8-quinolinthiorato) zinc, bis (8-quinolinthiorato) caddium, tris (8-quinolinthiorato) gallium, tris (8-quinolinthiorato) indium, Bis (5-methylquinolinethiorato) zinc, tris (5-methylquinolinethiorato) gallium, tris (5-methylquinolinethiorato) indium, bis (5-methylquinolinethiorato) cadmium, bis (3-methylquinoline Thiorato) cadmium, bis (5-methylquinolinethiorato) zinc, bis [benzo {f} -8-quinolinethiorato] zinc, bis [3-methylbenzo {f} -8-quinolinethiora ] Metal thioxynoid compounds disclosed in US Pat. No. 5,846,666, such as zinc, bis [3,7-dimethylbenzo {f} -8-quinolinethiorato] zinc, and similar metal thioxinoid compounds. Include. Exemplary materials include bis (8-quinolinthiorato) zinc, bis (8-quinolinthiorato) cadmium, tris (8-quinolinthiorato) gallium, tris (8-quinolinethiorato) indium and bis [benzo {f} -8-quinolinethiorato] zinc.

Another exemplary class of organic electroluminescent materials that can be used in the light emitting zone include stilbene derivatives such as those disclosed in US Pat. No. 5,516,577, which is incorporated herein by reference in its entirety. An example of a stilbene derivative is 4,4'-bis (2,2-diphenylvinyl) biphenyl.

Another class of suitable organic luminescent materials for forming the luminescent zone is the oxadiazole metal chelate disclosed in co-pending US patent application Ser. No. 08 / 829,398, filed March 31, 1997, which is hereby incorporated by reference in its entirety. admit. These materials include bis [2- (2-hydroxyphenyl) -5-phenyl-1,3,4-oxadiazolato] zinc; Bis [2- (2-hydroxyphenyl) -5-phenyl-1,3,4-oxadiazolato] beryllium; Bis [2- (2-hydroxyphenyl) -5- (1-naphthyl) -1,3,4-oxadiazolato] zinc; Bis [2- (2-hydroxyphenyl) -5- (1-naphthyl) -1,3,4-oxadiazolato] beryllium; Bis [5-biphenyl-2- (2-hydroxyphenyl) -1,3,4-oxadiazolato] zinc; Bis [5-biphenyl-2- (2-hydroxyphenyl) -1,3,4-oxadiazolato] beryllium; Bis (2-hydroxyphenyl) -5-phenyl-1,3,4-oxadiazolato] lithium; Bis [2- (2-hydroxyphenyl) -5-p-tolyl-1,3,4-oxadiazolato] zinc; Bis [2- (2-hydroxyphenyl) -5-p-tolyl-1,3,4-oxadiazolato] beryllium; Bis [5- (p-tert-butylphenyl) -2- (2-hydroxyphenyl) -1,3,4-oxadiazolato] zinc; Bis [5- (p-tert-butylphenyl) -2- (2-hydroxyphenyl) -1,3,4-oxadiazolato] beryllium; Bis [2- (2-hydroxyphenyl) -5- (3-fluorophenyl) -1,3,4-oxadiazolato] zinc; Bis [2- (2-hydroxyphenyl) -5- (4-fluorophenyl) -1,3,4-oxadiazolato] zinc; Bis [2- (2-hydroxyphenyl) -5- (4-fluorophenyl) -1,3,4-oxadiazolato] beryllium; Bis [5- (4-chlorophenyl) -2- (2-hydroxyphenyl) -1,3,4-oxadiazolato] zinc; Bis [2- (2-hydroxyphenyl) -5- (4-methoxyphenyl) -1,3,4-oxadiazolato] zinc; Bis [2- (2-hydroxy-4-methylphenyl) -5-phenyl-1,3,4-oxadiazole lato] zinc; Bis [2-α- (2-hydroxynaphthyl) -5-phenyl-1,3,4-oxadiazolato] zinc; Bis [2- (2-hydroxyphenyl) -5-p-pyridyl-1,3,4-oxadiazolato] zinc; Bis [2- (2-hydroxyphenyl) -5-p-pyridyl-1,3,4-oxadiazolato] beryllium; Bis [2- (2-hydroxyphenyl) -5- (2-thiophenyl) -1,3,4-oxadiazolato] zinc; Bis [2- (2-hydroxyphenyl) -5-phenyl-1,3,4-thiadiazolato] zinc; Bis [2- (2-hydroxyphenyl) -5-phenyl-1,3,4-thiadiazolato] beryllium; Bis [2- (2-hydroxyphenyl) -5- (1-naphthyl) -1,3,4-thiadiazolato] zinc; And bis [2- (2-hydroxyphenyl) -5- (1-naphthyl) -1,3,4-thiadiazolato] beryllium and the like.

Another class of suitable organic luminescent materials that can be used in the luminescent zone is described in U.S. Patent No. 6,057,048, which is incorporated herein by reference in its entirety, and in U.S. Patent Application Serial No. 09 / 489,144, filed Jan. 21, 2000. As disclosed, triazines.

Another class of suitable organic light emitting materials that can be used in the light emitting zone are anthracenes.

Other examples of organic light emitting materials that can be used in the light emitting zone are, for example, coumarin, dicyanomethylene pyranes, polymethine, oxabenzanthrane, xanthene ( fluorescent materials such as xanthene, pyrilium, carbostyl, and perylene. Another particular exemplary class of fluorescent materials is quinacridone dyes. Examples of quinacridone dyes are described in US Pat. No. 5,227,252, which is hereby incorporated by reference in its entirety; 5,276,381; And as disclosed in 5,593,788, quinacridone, 2-methylquinacridone, 2,9-dimethylquinacridone, 2-chloroquinacridone, 2-fluoroquinacridone, 1,2-benzoquinacridone, N, N'-dimethylquinacridone, N, N'-dimethyl-2-methylquinacridone, N, N'-dimethyl-2,9-dimethylquinacridone, N, N'-dimethyl-2-chloro Quinacridone, N, N'-dimethyl-2-fluoroquinacridone, N, N'-dimethyl-1,2-benzoquinacridone, and the like. Another class of fluorescent materials are conjugated ring fluorescent dyes. Examples of such conjugated ring fluorescent dyes are perylene, rubrene, anthracene, coronene, phenanthrecene, pyrene, as illustrated in US Pat. No. 3,172,862, which is hereby incorporated by reference in its entirety. (pyrene) and the like. Fluorescent materials also include butadienes such as 1,4-diphenylbutadiene and tetraphenylbutadiene, and stilbenes, and the like, as disclosed in US Pat. Nos. 4,356,429 and 5,516 577, each disclosure of which is incorporated herein by reference. do. Other examples of fluorescent materials that can be used are those disclosed in US Pat. No. 5,601,903, which is hereby incorporated by reference in its entirety.

Another exemplary class of organic luminescent materials that can be used in the light emitting zone are the fluorescent dyes disclosed in US Pat. No. 5,935,720, which is incorporated herein by reference in its entirety. Exemplary materials of the fluorescent dyes are, for example, 4- (dicyanomethylene) -2-1-propyl-6- (1,1,7,7-tetramethyljulolidyl-9-enyl ) -4H-pyran (DCJTB). Another exemplary class of organic luminescent materials that can be used in the luminescent zone is described in Kido et al., "White light emitting organic electroluminescent device using lanthanide complexes," Jpn. J. Appl. Phys., Volume 35, pp. As those disclosed in L394-L396 (1996), for example, tris (acetyl acetonato) (phenanthroline) terbium, tris (acetyl acetonato) (phenanthroline) europium, and tris (tenoyl trisfluoro Lanthanide metal chelate complexes such as acetonato) (phenanthroline) europium.

Another exemplary class of organic luminescent materials that can be used in the light emitting zone is that disclosed in Baldo et al., "Highly efficient organic phosphorescent emission from organic electroluminescent devices," Letters to Nature, 395, pp 151-154 (1998). Like compounds, they are phosphorescent materials such as organometallic compounds, for example, which lead to strong spin-orbit bonds and contain heavy metal elements. Examples of such materials are 2,3,7,8,12,13,17,18-octaethyl-21H23H-phorpine platinum (II) (PtOEP) and fac tris (2-phenylpyridine) iridium (Ir (ppy) 3).

Without limiting the usefulness of the organic light emitting materials discussed herein, blue organic light emitting materials can be, for example, polyfluorenes such as 9,10-diphenylanthracene ("DPA"), 9,10-bis [4-2,2-diphenylethenyl) phenyl] anthracene ("ADN"), and tert-butyl substituted 9,10-bis [4- (2,2-diphenylethenyl) phenyl] anthracene ( "TBADN", which is also represented by the abbreviation of "BH2"), anthracene derivatives as described in US Pat. Nos. 6,479,172, 6,562,485, 6,465,115, and 6,565,996, stilbene derivatives such as those described above, US Pat. Triazine derivatives such as those described in 6,229,012, carbazole derivatives including bicarbozole derivatives, or binafs such as those described in US patent application Ser. No. 10 / 774,577, filed February 10, 2004. It may also be a teal derivative. The specifications of the mentioned patents and applications are hereby fully incorporated by reference.

Without limiting the usefulness of the organic light emitting materials discussed herein, red organic light emitting materials can be, for example, polyfluorenes such as those mentioned above, polyphenylene vinylenes such as MeHPPV, or other as described herein. It may be substances. In exemplary embodiments, some red light emitting devices emit green or blue light by themselves, but use an electroluminescent material doped with one or more red light emitting materials.

Without limiting the usefulness of the organic light emitting materials discussed herein, green organic light emitting materials may be selected from polyfluorenes such as those mentioned above, polyphenylene vinylenes such as those described herein, or metal chelates such as AlQ _3. Or other materials described herein. In exemplary embodiments, some green light emitting devices emit blue light by themselves, but use an electroluminescent material doped with one or more green light emitting materials.

The hole transport material that can be used in the present invention can be any suitable, known or later developed material.

Exemplary hole transport materials include polypyrrole, polyaniline, poly (phenylene vinylene), polythiophene, polyarylamine, and derivatives thereof, and known derivatives (disclosed in US Pat. No. 5,728,801, which is incorporated herein by reference in its entirety). Semiconductor organic materials; Porphyrin derivatives such as 1,10,15,20-tetraphenyl-21H, 23H-phosphine copper (II) disclosed in US Pat. No. 4,356,429, which is incorporated herein by reference in its entirety; Copper phthalocyanine; Copper tetramethyl phthalocyanine; Zinc phthalocyanine; Titanium oxide phthalocyanine; Magnesium phthalocyanine and the like.

An exemplary class of hole transporters that can be used are aromatic tertiary amines, such as those disclosed in US Pat. No. 4,539,507, which is hereby incorporated by reference in its entirety. Suitable examples of aromatic tertiary amines are, for example, bis (4-dimethylamino-2-methylphenyl) phenylmethane; N, N, N-tri (p-tolyl) amine; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; 1,1-bis (4-di-p-tolylaminophenyl) -4-phenyl cyclohexane; N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-biphenyl-4,4'-diamine; N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-biphenyl-4,4'-diamine; N, N'-diphenyl-N, N'-bis (4-methoxyphenyl) -1,1'-biphenyl-4,4'-diamine; N, N, N ', N'-tetra-p-tolyl-1,1'-biphenyl-4,4'-diamine; N, N'-di-1-naphthyl-N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine; Mixtures thereof and the like.

Another class of aromatic tertiary amines available are polynuclear aromatic amines. Examples of such polynuclear aromatic amines include, for example, N, N-bis- [4 '-(N-phenyl-N-m-tolylamino) -4-biphenylyl] aniline; N, N-bis- [4 '-(N-phenyl-N-m-tolylamino) -4-biphenylyl] -m-toluidine; N, N-bis- [4 '-(N-phenyl-N-m-tolylamino) -4-biphenylyl] -p-toluidine; N, N-bis- [4 '-(N-phenyl-Np-tolylamino) 4-biphenylyl] aniline: N, N-bis- [4'-(N-phenyl-Np-tolylamino) -4 -Biphenylyl] -m-toluidine; N, N-bis- [4 '-(N-phenyl-N-p-tolylamino) -4-biphenylyl] -p-toluidine; N, N-bis- [4 '-(N-phenyl-N-p-chlorophenylamino) -4-biphenylyl] -m-toluidine; N, N-bis- [4 '-(N-phenyl-N-m-chlorophenylamino) -4-biphenylyl] -m-toluidine; N, N-bis- [4 '-(N-phenyl-N-m-chlorophenylamino) -4-biphenylyl] -p-toluidine; N, N-bis- [4 '-(N-phenyl-N-m-tolylamino) -4-biphenylyl] -p-chloroaniline; N, N-bis- [4 '-(N-phenyl-N-p-tolylamino) -4-biphenylyl] -m-chloroaniline; And N, N-bis- [4 '-(N-phenyl-N-m-tolylamino) -4-biphenylyl] -1-aminonaphthalene, mixtures thereof, and the like.

Another class of hole transport materials available is, for example, 4,4'-bis (9-carbazoryl) -1,1'-biphenyl and 4,4'-bis (3-methyl-9-carba 4,4'-bis (9-carbazoryl) -1,1'-biphenyl compounds such as zyl) -1,1'-biphenyl and the like.

An exemplary class of hole transporting materials available are indolo-carbazoles, such as those disclosed in US Pat. Nos. 5,942,340 and 5,952,115, which are incorporated herein by reference in their entirety.

Another exemplary class of hole transporting materials available consists of N, N, N ', N'-tetraarylbenzidines, where aryl is phenyl, m-tolyl, p-tolyl, m-methoxyphenyl, p-methoxyphenyl, 1-naphthyl, 2-naphthyl and the like. Examples of N, N, N ', N'-tetraarylbenzidine are more exemplary N, N'-di-1-naphthyl-N, N'-diphenyl-1,1'-biphenyl-4,4 '-Diamine; N, N'-bis (3-methylphenyl) -N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine; N, N'-bis (3-methoxyphenyl) -N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine.

Exemplary hole transport materials available are naphtyl-substituted benzidine derivatives.

Examples of available electron transport materials can be selected from metal oxynoid compounds, oxadiazole metal chelate compounds, triazine compounds and stilbene compounds, as described above.

Other examples of available electron transport materials include poly (9,9-di-n-octylfluorene-2,7-diyl), poly (2,8- (6,7,12,12-tetraalkylindenoflu) Polyfluorenes such as orene) and copolymers containing fluorenes, such as fluorene-amine copolymers, see, for example, Bernius et al., "Proceedings of SPIE Conference on Organic Light Emitting Materials and Devices III, See Denver, Colo., July 1999, Volume 3797, p.129.

The light emitting region may be formed using mixtures of any of the suitable exemplary hole transport materials and electron transport materials described herein, including materials used to form the hole transport and electron transport layers. Can be.

One or more layers comprising the light emitting zone can be prepared by forming one of the materials described above into a thin film by any suitable known or later developed method. Suitable methods for this purpose include, for example, vapor deposition and spin coating techniques.

The light emitting zone has a thickness in the range of about 10 nm to about 1000 nm. Preferably, this thickness is about 50 nm to about 250 nm. In embodiments in which the light emitting region consists of one or more adjacent layers, the thickness of the individual layers may be at least about 5 nm.

The cathode 140 may comprise, for example, high work function components having a work function in the range of about 4 eV to about 6 eV, or metals having a work function in the range of about 2.5 eV to about 4 eV, for example. As such, it may include any suitable metal that includes low work function components. The cathode may comprise a combination of a low work function (less than about 4 eV) metal and at least one other metal. Effective fractions of the low work function metal relative to the second or other metal are from about 0.1% to about 99.9% by weight. Examples of low work function metals include, but are not limited to, alkali metals such as lithium or sodium; Group 2A or alkaline earth metals such as beryllium, magnesium, calcium or barium; And Group III metals including rare earth metals and actinide metals such as scandium, yttrium, lanthanum, cerium, europium, terbium or actinium. Lithium, magnesium, and calcium are exemplary low work function metals.

The Mg-Ag alloy cathodes of US Pat. No. 4,885,211 are one exemplary cathode configuration. Another exemplary cathode configuration is described in US Pat. No. 5,429,884, where the cathodes are formed from lithium alloys having other high work function metals such as aluminum and indium. These patents are hereby incorporated by reference in their entirety.

The thickness of the cathode 140 may, for example, range from about 10 nm to about 500 nm. Of course, thicknesses other than this range may also be used.

Examples of fluorescent molecules and metal complexes used as luminescent and electron transporting materials are listed below:

Examples of phosphorescent dopants are listed below:

Examples of fluorescent dopants are listed below:

The following U.S. patent applications generally owned by the assignee of the present invention can be used with the present invention, which is hereby incorporated by reference in its entirety: 10 / 909,691; 10 / 909,689; 10 / 372,547; 10 / 702,857; 10 / 401,238; 11 / 006,000; 10 / 774,577; 11 / 133,977; 11 / 133,978; 11 / 133,975; 11 / 133,752; 11 / 122,290; 11 / 122,288; 11 / 133,753; 11 / 122,290; 11 / 122,288; 11 / 133,753; 11 / 184,775; and 11 / 184,776.

In addition, each of the aforementioned patents, articles, and references cited herein is hereby incorporated by reference in its entirety.

Although the present invention has been described in connection with the specific embodiments described above, it is evident that many alternatives, modifications, and variations will be apparent to those of ordinary skill in the art. Accordingly, the preferred embodiments of the invention claimed above are exemplary and not limiting. Various changes may be made without departing from the spirit and scope of the invention.

The present invention provides organic light emitting devices (OLEDs) with improved performance, including increased efficiencies and stability.

Claims (1)

anode; cathode; And A light emitting region comprising a single layer of one or more phosphorescent materials emitting red light and one or more fluorescent materials emitting blue light doped with one or more phosphorescent materials emitting green light; An organic light emitting device comprising a.

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