TWI487696B - Phosphorescent emitters - Google Patents

Description

Phosphorescent emitter

The present invention is directed to novel heterooleptic complexes. In particular, the semi-symmetrical compounds contain phenylpyridine and phenyl benzimidazole. These compounds are useful in organic light-emitting devices (OLEDs).

The present application claims priority to U.S. Provisional Application Serial No. 61/113,257, filed on Nov. 11, 2008, the entire disclosure of which is expressly incorporated by reference.

The claimed invention is carried out by a representative and/or in conjunction with one or more of the following members in a joint university corporation research agreement: directors of the University of Michigan, Princeton University, the University of Southern California, and Universal Display Corporation . This Agreement is effective at the time when the claimed invention is carried out and before, and the claimed invention is carried out as a result of the activities taken within the scope of the agreement.

The demand for optoelectronic devices using organic materials is increasing for a number of reasons. The various materials used to make such devices are relatively inexpensive, so organic optoelectronic devices have the potential to exceed the cost advantages of inorganic devices. In addition, the inherent properties of the organic material, such as its flexibility, can be such that it is well suited for a particular application, such as fabrication on a flexible substrate. Examples of organic optoelectronic devices include organic light-emitting devices (OLEDs), organic optoelectronic crystals, organic photovoltaic cells, and organic photodetectors. For OLEDs, such organic materials can have performance advantages over conventional materials. For example, it is generally convenient to adjust the wavelength of the organic emission layer to emit light with a suitable dopant.

The OLED utilizes an organic thin film that emits light when a voltage is applied to the device. For applications such as flat panel displays, lighting, and backlights, OLEDs are becoming an increasingly interesting technology. Several OLED materials and configurations are described in U.S. Patent Nos. 5,844,363, 6, 303,238, and 5,707,745, each incorporated herein by reference.

One of the phosphorescent emission molecules is a full color display. The industry standard for this display requires pixels that are suitable for emitting a particular color (referred to as a "saturated" color). In particular, these standards require saturated red, green, and blue pixels. Color can be measured using the CIE coordinates of the art.

An example of a green-emitting molecule is tris(2-phenylpyridine)indole, denoted Ir(ppy) ₃ , which has the structure of formula I:

In this figure and in the following figures, we have drawn the valence bond from nitrogen to metal (here Ir) as a straight line.

As used herein, the term "organic" encompasses polymeric materials and small molecular organic materials that can be used in the manufacture of organic optoelectronic devices. "Small molecule" means any non-polymeric organic material, and "small molecules" can actually be very large. In some cases small molecules may contain repeating units. For example, the use of a long chain alkyl group as a substituent does not remove one molecule from the "small molecule" class. Small molecules can also be incorporated into the polymer, for example as pendant groups on the polymer backbone or as part of the backbone. The small molecule can also serve as a core portion of a dendrimer composed of a series of chemical shells built on the core portion. The core portion of the dendrimer can be a fluorescent or phosphorescent small molecule emitter. Dendrimers can be a "small molecule" and it is believed that all dendrimers used today in the field of OLEDs are small molecules.

As used herein, "top" means the farthest from the substrate, and "bottom" means the closest to the substrate. When the first layer is described as being "set on" the second layer "on", the first layer is set to be further away from the substrate. Unless the first layer is "contacted" with the second layer, other layers may be present between the first and second layers. For example, although there are various organic layers in between, the cathode can be described as being "mounted" on the anode.

As used herein, "solution processable" means dissolved, dispersed, or transported in a liquid medium in the form of a solution or suspension and/or deposited from a liquid medium.

When it is believed that a ligand directly contributes to the photoactive nature of an emissive material, the ligand may be referred to as "photoactive". When it is believed that a ligand does not contribute to the photoactive nature of an emissive material, the ligand may be referred to as "auxiliary," although the co-ligand may alter the nature of a photoactive ligand. More than one type of "photoactive" ligand may be present in the complex. Each of the different photoactive ligands can contribute to such properties of the emissive material.

As used herein, and as is generally understood by those skilled in the art, if a first energy level is closer to the vacuum level, then the first "highest occupied molecular orbital" (HOMO) or "lowest unoccupied molecular orbital" ( LUMO) The energy level is "greater than" or "higher" than a second HOMO or LUMO energy level. Since the free potential (IP) is measured as a negative energy relative to a vacuum level, the higher HOMO energy level corresponds to an IP with a smaller absolute value (ie, a lower negative IP). Likewise, a higher LUMO energy level corresponds to an electron affinity (EA) with a smaller absolute value (ie, an EA with a lower negative value). In a conventional energy level diagram, the vacuum energy system is at the top, and the LUMO energy level of a material is higher than the HOMO energy level of the same material. A "higher" HOMO or LUMO energy level appears closer to the top of the figure than a "lower" HOMO or LUMO energy level.

As used herein, and as is generally understood by those skilled in the art, if a first work function has a higher absolute value, then the first work function is "greater than" or "above" a second work function. . Since the work function is generally measured as a negative relative to the vacuum level, this means that a "higher" work function has a larger negative value. In a conventional energy level diagram, the vacuum energy system is at the top, and a "higher" work function is depicted as being further away from the vacuum energy level in the downward direction. Therefore, the definition of HOMO and LUMO energy levels follows a convention different from the work function.

Further details of the OLEDs and the above definitions can be found in U.S. Patent No. 7,279,704, which is incorporated herein in its entirety by reference.

The present invention provides a semi-symmetric compound Ir(L1) _n (L2) _3-n . The semi-symmetrical compounds have the following structural formula:

For L2. R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ may represent a mono-, di-, tri-, or tetra-substituted group, and R ₁ , R ₂ , R ₃ , R ₄ , and R _{5 are} each independently selected from hydrogen, A group of alkyl, heteroalkyl, aryl, substituted aryl, heteroaryl, and substituted heteroaryl groups. Preferably, n is one. In one aspect, R ₁ is selected from the group consisting of aryl, heteroalkyl, substituted aryl, and substituted heteroaryl, wherein R ₁ does not form a conjugated system with L1. Preferably, R ₁ is Wherein X ₁ and X ₂ are independently selected from C and N. Y _{1 is} not hydrogen. Y ₁ may be bonded to other substituents on the aryl ring. The semi-symmetrical compound may have a narrower half-height width (FWHM) and/or lower sublimation temperature than the corresponding homoleptic compound.

The present invention provides specific examples of semi-symmetrical compounds having specific L1 and L2 ligands. Preferably, the semi-symmetrical compounds are selected from the group consisting of:

In another aspect, the semi-symmetrical compound is preferably selected from the group consisting of:

The invention also provides an organic light emitting device. The device has an anode, a cathode, and an organic layer disposed between the anode and the cathode. The organic layer further comprises a semi-symmetric compound Ir(L1) _n (L2) _3-n as described above. Preferably, the organic layer is an emissive layer having a body and an emissive dopant, and the semi-symmetrical compound is the emissive dopant.

The invention also provides a consumer product. The product comprises a device having an anode, a cathode, and an emissive layer disposed between the anode and the cathode, wherein the organic layer further comprises a semi-symmetric compound Ir(L1) _n (L2) ₃ as described above _-n .

In general, an OLED includes at least one organic layer disposed between an anode and a cathode and electrically connected to the anode and cathode. When a current is applied, the anode injects electrons into the (or other) organic layer from the hole and the cathode. The injected holes and electrons each migrate toward the oppositely charged electrode. When an electron and a hole are positioned on the same molecule, an "exciton" is formed, that is, a pair of positioned electron-hole pairs having an excited energy state. Light is emitted when the excitons relax through the illuminating mechanism. In some cases, the excitons can be localized on an excimer or an exciplex. Non-radiative mechanisms, such as thermal relaxation, may also occur, but are generally considered undesirable.

The initial OLEDs use emissive molecules that emit light from their singlet states ("fluorescent"), as disclosed in, for example, U.S. Patent No. 4,769,292, the disclosure of which is incorporated herein in its entirety. Fluorescence emission typically occurs in less than 10 nanoseconds.

More recently, OLEDs having emissive materials derived from triplet emission ("phosphorescence") have been shown. Baldo et al., "Highly Efficient Phosphorescent Emission from Organic Electroluminescent Devices", Nature, Vol. 395, 151-154, 1998; ("Baldo-I") and Baldo "Very high-efficiency green organic light-emitting devices based on electrophosphorescence", Appl. Phys. Lett., vol. 75, No. 3, 4-6 (1999) ("Baldo-II"), which is incorporated herein by reference in its entirety. Phosphorescence is described in more detail in U.S. Patent No. 7,279,704, the disclosure of which is incorporated herein by reference.

FIG. 1 shows an organic light emitting device 100. These figures are not necessarily drawn to scale. The device 100 can include a substrate 110, an anode 115, a hole injection layer 120, a hole transport layer 125, an electron blocking layer 130, an emissive layer 135, a hole blocking layer 140, and an electron transport layer 145. An electron injection layer 150, a protective layer 155, and a cathode 160. The cathode 160 is a compound cathode having a first conductive layer 162 and a second conductive layer 164. Device 100 can be fabricated by sequentially depositing the layers. The nature and function of the various layers, and example materials, are described in more detail in U.S. Patent No. 7,279,704, the disclosure of which is incorporated herein by reference.

More examples of each of these layers can be obtained. A flexible and transparent substrate-anode combination is disclosed, for example, in U.S. Patent No. 5,844,363, the disclosure of which is incorporated herein by reference. An example of a p-type doped hole transport layer is doped with m-MTDATA of F ₄ -TCNQ at a molar ratio of 50:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980. The manner of reference is incorporated herein. Examples of emissive and host materials are disclosed in U.S. Patent No. 6,303,238, the entire disclosure of which is incorporated herein by reference. An example of an n-type doped electron transport layer is BPhen doped with Li at a molar ratio of 1:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated herein in its entirety by reference. in. Examples of cathodes comprising a compound cathode having a thin layer of metal such as Mg:Ag and an overlying transparent, electrically conductive, sputter-deposited ITO layer are disclosed in U.S. Patent Nos. 5,703,436 and 5,707,745, each incorporated by reference. The theory and use of the barrier layer is described in more detail in U.S. Patent No. 6,097,147, and U.S. Patent Application Serial No. 2003/0230, the entire disclosure of each of which is incorporated herein by reference. Examples of injection layers are provided in U.S. Patent Application Publication No. 2004/0174116, which is incorporated herein in its entirety by reference. A description of the protective layer can be found in U.S. Patent Application Publication No. 2004/0174116, which is incorporated herein in its entirety by reference.

FIG. 2 shows an inverted OLED 200. The device comprises a substrate 210, a cathode 215, an emissive layer 220, a hole transport layer 225, and an anode 230. Device 200 can be fabricated by sequentially depositing the layers. Since the most common OLED configuration has a cathode disposed above the anode and the cathode 215 of device 200 is disposed below anode 230, device 200 can be referred to as an "inverted" OLED. Materials similar to those described with reference device 100 can be used in corresponding layers of device 200. FIG. 2 provides an example of how certain layers may be omitted from the structure of device 100.

The simple layered structure shown in Figures 1 and 2 is provided as a non-limiting example, and it should be understood that embodiments of the invention can be used in conjunction with a variety of other structures. The specific materials and structures are exemplary and other materials and structures may be used. Functional OLEDs may be obtained by combining the various layers in different ways, or may be omitted entirely based on design, performance, and cost factors. Other layers not specifically described may also be included. Materials other than those specifically described may be used. While many of the examples provided herein describe a plurality of layers including a single material, it will be appreciated that combinations of materials that may be used, such as a mixture of host and dopant, or, more generally, a mixture. The layers can also have multiple sublayers. The names given to the various layers herein are not intended to be strictly limited. For example, in device 200, hole transport layer 225 transports holes and injects holes into emissive layer 220, and may be described as a hole transport layer or a hole injection layer. In one embodiment, an OLED can be described as having an "organic layer" disposed between a cathode and an anode. The organic layer may comprise a single layer or may further comprise a plurality of different organic materials as described, for example, with reference to Figures 1 and 2.

OLEDs (PLEDs) comprising a polymeric material, as disclosed in U.S. Patent No. 5,247,190, issued to s. As a further example, an OLED having a single organic layer can be used. </ RTI> </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; The OLED structure can deviate from the simple layered structure shown in Figures 1 and 2. For example, the substrate can include an angled reflective surface to improve out-coupling, such as the mesa structure described in U.S. Patent No. 6,091,195 to Forrest et al., and/or U.S. Pat. The pit structure described in U.S. Patent No. 5,834,893, the entire disclosure of which is incorporated herein by reference.

Any of the various embodiments may be deposited by any suitable method, unless otherwise specified. Preferred methods for such organic layers include thermal evaporation, ink jet methods (as described in U.S. Patent Nos. 6,013,982 and 6,087,196, the entire contents of each of each of each of (OVPD) (as described in U.S. Patent No. 6,337,102 to the entire disclosure of U.S. Pat. As described in U.S. Patent No. 10/233,470, the entire disclosure of which is incorporated herein by reference. Other suitable deposition methods include spin coating and other solution based methods. The solution based process is preferably carried out in a nitrogen or inert gas environment. For other layers, the preferred method comprises thermal evaporation. A preferred method of patterning includes cold-melting as described in U.S. Patent Nos. 6,294,398 and 6,468,819, the disclosures of each of which are incorporated herein by reference inco Patterning of the method and the deposition method of OVJD. Other methods can also be used. The material to be deposited can be modified to be compatible with a particular deposition process. For example, a substituent such as a branched or unbranched group, and preferably an alkyl group having at least 3 carbons and an aryl group may be used in the small molecule to enhance its ability to undergo solution treatment. A substituent having 20 or more carbons and a preferred range of 3 to 20 carbon systems may be used. Materials with asymmetric structures can have better solution processability than materials with symmetric structures because asymmetric materials can have a lower tendency to recrystallize. Dendrimers can be substituted for the ability to undergo solution processing based on enhanced small molecules.

Devices made in accordance with embodiments of the present invention can be incorporated into a variety of consumer products, including flat panel displays, computer monitors, televisions, advertising panels, indoor or outdoor lighting and/or signaling fixtures, heads-up displays, fully transparent displays , flexible displays, laser printers, telephones, mobile phones, personal digital assistants (PDAs), laptops, digital cameras, camcorders, viewfinders, microdisplays, vehicles, large-area walls, theaters or Stadium screen, or logo. A variety of control mechanisms can be used to control a device made in accordance with the present invention, including a passive matrix and an active matrix. Many of these devices are designed for use in a suitable temperature range for humans, such as 18 degrees Celsius to 30 degrees Celsius, and more preferably at room temperature (20-25 degrees Celsius).

The materials and structures described herein can be used in devices other than OLEDs. For example, other optoelectronic devices such as organic solar cells and organic photodetectors can utilize such materials and structures. More generally, organic devices, such as organic transistors, may utilize such materials and structures.

The terms halo, halo, alkyl, cycloalkyl, alkenyl, alkynyl, aralkyl, heterocyclyl, aryl, aromatic, and heteroaryl are known in the art and are defined in U.S. Patent No. No. 7,279,704, in columns 31-32, which is incorporated herein by reference.

The present invention provides a material comprising 2-phenylbenzimidazole (referred to herein as "phenylbenzimidazole") and phenylpyridine which can be used to produce high efficiency, high stability, long operating life, and improved color. In a phosphorescent organic light-emitting device. These materials can be used as phosphorescent emissive dopants in green light devices.

The present invention provides a semi-symmetrical compound containing phenylpyridine and phenyl benzimidazole. Semi-symmetrical compounds provide highly tunable phosphorescent emissive materials, and thus such compounds are required to achieve a wide range of colors and highly saturated colors. The emission of the metal complex can be adjusted by careful selection of different ligands, depending on the triplet energy of the different ligands and the HOMO/LUMO energy level. Although phenylbenzimidazole provides good lifetime performance of the device, it generally has a higher sublimation temperature and can have an electronic vibrational emission spectrum (see Figure 3). A semi-symmetric complex containing both a phenylbenzimidazole ligand and a phenylpyridine ligand provides a lower sublimation temperature while still retaining the beneficial properties of the phenylbenzimidazole (ie, long life and high stability) .

The sublimation temperature generally accepted by a complex can be determined from the molecular structure of the complex. High molecular weight typically results in higher sublimation temperatures. Therefore, it is expected that a half symmetrical compound has a sublimation temperature between the sublimation temperatures of the corresponding fully symmetric compounds because the molecular weight of the semi-symmetric compound is between the molecular weights of the respective fully symmetric compounds. However, some semi-symmetric compounds containing phenylpyridine and phenylbenzimidazole as disclosed herein have lower specificity than the two corresponding fully symmetric compounds (ie, phenylpyridine fully symmetric compounds and phenylbenzimidazole asymmetric compounds). Sublimation temperature. The reduction in sublimation temperature of the semi-symmetrical complex provides improved device fabrication.

In addition, the semi-symmetrical compounds can also provide a narrower emission spectrum. Without wishing to be bound by theory, it is pointed out that the two ligands (i.e., phenylpyridine and phenylbenzimidazole) are green emitters of similar energy levels, so both ligands can directly contribute to the emission of the compound. The observed emission spectra of the semi-symmetrical compounds disclosed herein are unexpectedly narrow (see Figure 3). The emission spectrum of this compound is expected to be similar to that of phenylbenzimidazole because the electrochemical gap of benzimidazole is smaller than that of phenylpyridine (i.e., benzimidazole has a shallower HOMO and a deeper LUMO than phenylpyridine). However, the observed emission of the semi-symmetrical compound is closer to the emission profile of the phenylpyridine than the benzimidazole (eg, no electronically vibrating structure). It is believed that the observed emission spectra of such compounds can be the result of unforeseen interactions between the phenylpyridine and the phenyl benzimidazole ligand when both ligands are included in the same complex. Therefore, a complex containing a phenylpyridine and a phenyl benzimidazole ligand can be advantageously used as an emissive material in a PHOLED having long life, high stability, and improved manufacturing and improved color.

The present invention provides a semi-symmetric compound Ir(L1) _n (L2) _3-n which can be advantageously used in an OLED having the following formula:

Where n=1 or 2, where L1 and Is L2. R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ each may represent a mono-, di-, tri-, or tetra-substitution. R ₁ , R ₂ , R ₃ , R ₄ , and R _{5 are} each independently selected from the group consisting of hydrogen, alkyl, heteroalkyl, aryl, substituted aryl, heteroaryl, and substituted heteroaryl. Group. Preferably, n is one.

In one aspect, the compound has the formula: Wherein R ₄ is hydrogen or methyl.

In another aspect, R ₁ is selected from the group consisting of alkyl, heteroalkyl, aryl, heteroaryl, substituted aryl, and substituted heteroaryl, and wherein R _{1 is} not associated with L1 Form a conjugated system. The phenylbenzimidazole moiety is important to achieve the advantageous properties of the semi-symmetrical compounds. Thus, to maintain these advantageous characteristics, the R ₁ substituent is a chemical group having a very small conjugation. In addition, the conjugation between the phenyl and benzimidazole moieties of L1 will likely result in reduced LUMO energy levels and loss of saturated green light emission. Thus, the substituents (e.g., R ₁ and R ₂ ) are not fused to form an extended conjugated system.

Preferably, the R ₁ substituent is a branched alkyl group or a coiled aryl group (e.g., isopropyl and isobutyl). As used herein, "curled aryl" refers to a structure having the formula: Wherein X ₁ and X ₂ are independently selected from C and N, Y _{1 is} not hydrogen, and Y ₁ may be bonded to other substituents on the aryl ring. Branched alkyl and fused aryl substituents provide reduced solids filling and lower sublimation temperatures.

More preferably, the R ₁ system Wherein X ₁ and X ₂ are independently selected from C and N. Y _{1 is} not hydrogen. Y ₁ may be bonded to other substituents on the aryl ring. A non-planar configuration is believed to promote the advantageous properties of the compound. For example, a semi-symmetrical compound having this R ₁ substituent can have a better color and a lower sublimation temperature. Furthermore, this R ₁ substituent is less likely to lower the triplet energy of the compound.

In another aspect, each of R ₂ , R ₃ , and R ₅ is hydrogen.

Specific examples of the semi-symmetric compound include a compound containing L1 selected from the group consisting of:

Further specific examples of the semi-symmetric compound include a compound containing L2 selected from the group consisting of:

In one aspect, the semi-symmetrical compound comprises one selected from the group consisting of L1 and L2 provided above.

Further examples of specific semi-symmetrical compounds include compounds containing L1 selected from the group consisting of:

Additional specific examples of the semi-symmetric compound include a compound containing L2 selected from the group consisting of:

In another aspect, the semi-symmetrical compound comprises L1 and L2 from the first two groups.

Preferably, the semi-symmetrical compound is selected from the group consisting of:

More preferably, the semi-symmetrical compound is selected from the group consisting of compounds 1, 3, 5-8.

In another aspect, the semi-symmetrical compound is preferably selected from the group consisting of:

In one aspect, the semi-symmetric compound has a ratio A narrower half-height width (FWHM) emission spectrum. In another aspect, the semi-symmetrical compound can have a ratio Lower sublimation temperature.

Further, the present invention also provides an organic light-emitting device. The device includes an anode, a cathode, and an organic layer disposed between the anode and the cathode. The organic layer further comprises a semi-symmetric compound Ir(L1) _n (L2) _3-n as described above. Preferably, the organic layer contains a semi-symmetrical compound selected from the group consisting of Compound 1 - Compound 8. More preferably, the organic layer contains a semi-symmetrical compound selected from the group consisting of compounds 1, 3, and 5-8.

In addition, the present invention also provides an organic light-emitting device comprising an anode, a cathode, and an organic layer disposed between the anode and the cathode, the organic layer itself further comprising a group selected from the group consisting of Compound 1 - Compound 9. Semi-symmetrical compound.

The organic layer of the device may comprise a semi-symmetrical compound, wherein R ₁ is selected from the group consisting of alkyl, heteroalkyl, aryl, heteroaryl, substituted aryl, and substituted heteroaryl, and wherein R ₁ does not form a conjugated system with L1.

Preferably, the R ₁ system Wherein X ₁ and X ₂ are independently selected from C and N. Y _{1 is} not hydrogen. Y ₁ may be bonded to other substituents on the aryl ring.

In one aspect, the emissive layer further includes a body. Preferably, the body has the following formula:

Wherein R ₁ and R ₂ independently represent a mono-, di-, tri- or tetra-substituted group selected from alkyl, alkoxy, amino, alkenyl, alkynyl, aralkyl, aryl and heteroaryl groups, or none a substituent; and wherein at least one of R ₁ and R ₂ comprises a co-triphenyl group.

In another aspect, the subject has the following formula:

Wherein R ₁ , R ₂ , and R _{3 are} each independently hydrogen, a non-fused aryl group, or a non-fused heteroaryl group having one or more meta substituents, wherein R ₁ , R ₂ , and R ₃ At least one of them is not hydrogen. Each meta-substituent is optionally a non-fused aryl or heteroaryl group substituted with a further substituent selected from the group consisting of a non-fused aryl group, a non-fused heteroaryl group, and an alkyl group.

Materials described herein for a particular layer in an organic light-emitting device can be used in combination with a variety of other materials present in the device. For example, the emissive dopants disclosed herein can be used in conjunction with a variety of host, transport, barrier, injection, electrode, and other layers that may be present. The materials described or referenced below are non-limiting examples of materials that can be used in combination with the compounds disclosed herein, and those skilled in the art can readily reference the literature to identify other materials that may be used in the combination.

The invention also provides a consumer product comprising a device, wherein the device further comprises an anode, a cathode and an organic layer. The organic layer further comprises a complex comprising phenylpyridine and phenylbenzimidazole as described.

In particular, the present invention provides a consumer product comprising a device wherein the organic layer of the device comprises a semi-symmetrical compound selected from the group consisting of compounds 1-9.

In addition to the materials disclosed herein and/or in combination with the materials disclosed herein, many hole injection materials, hole transport materials, host materials, dopant materials, exciton/hole barrier materials, electron transport and electronics Injection materials are used in OLEDs. Non-limiting examples of materials that can be used in OLEDs in conjunction with the materials disclosed herein are listed in Table 1 below. Table 1 lists non-limiting classes of materials, non-limiting examples of various classes of compounds, and references that disclose such materials.

experiment Compound instance Synthesis of Compound 1

Synthesis of Compound 1. In a three-necked flask in the presence of nitrogen, intermediate 1 (1.4 g, 1.96 mmol) and 1-neopentyl-2-phenyl-1H-benzo[d]imidazole (1.6 g, 5.9 mmol) with 30 mL of ethanol mixing. The mixture was heated to reflux for 24 hours. After cooling to room temperature, the precipitate was collected by filtration. The product was purified via column chromatography using 1:2 dichloromethane and hexanes as eluent. After purification, 0.3 g of the desired product was obtained.

Synthesis of 1,2-diphenyl-1H-benzo[d]imidazole. In a three-necked flask, N ¹ -phenylbenzene-1,2-diamine (4.15 g, 22 mmol) and benzaldehyde (2.1 g, 20 mmol) were mixed with methoxyethanol (60 ml). The mixture was heated to reflux for 48 hours. After cooling to room temperature, the solvent was evaporated. The residue was purified by column chromatography using dichloromethane eluting with 5% ethyl acetate as eluent. 2 g of the desired product were obtained.

Synthesis of Compound 2. Intermediate 1 (1.32 g, 1.86 mmol) and 1,2-diphenyl-1H-benzo[d]imidazole (1.5 g, 5.5 mmol) were mixed with 40 mL of ethanol in a three-necked flask in the presence of nitrogen. The mixture was heated to reflux for 24 hours. After cooling to room temperature, the precipitate was collected by filtration. The product was purified via column chromatography using 1:2 dichloromethane and hexanes as eluent. After purification, 0.3 g of the desired product was obtained.

Synthesis of 2-isopropyl-N-(2-nitrophenyl)aniline. 2-isopropyl aniline (27 g, 200 mmol), 2-fluoronitrobenzene (14 g, 100 mmol), and potassium fluoride (8.6 g, 150 mmol) were mixed in a one-neck flask. The mixture was heated to 180 ° C for 48 hours in the presence of nitrogen. After cooling to room temperature, water (200 mL) was added. The mixture was then extracted three times with dichloromethane (200 mL). The solvent was evaporated and the residue was purified by column chromatography using 20% dichloromethane in hexanes. 22.5 g of the desired product were obtained.

Synthesis of N ¹ -(2-isopropylphenyl)benzene-1,2-diamine. Mixing 2-isopropyl-N-(2-nitrophenyl)aniline (22.7 g, 89 mmol) and 10% palladium/carbon (0.6 g) in 150 mL ethanol in a plastic coated hydrogenation vessel in the presence of nitrogen . The mixture was placed on a par hydrogenator and reacted under 40 psi of hydrogen until no pressure drop occurred. The catalyst was filtered through a bed of Celite. The solvent was evaporated. This product was used in the next step without further purification. 20 g of the desired product were obtained.

Synthesis of 1-(2-isopropylphenyl)-2-phenyl-1H-benzo[d]imidazole. N ¹ -(2-isopropylphenyl)benzene-1,2-diamine (20 g, 88 mmol) and benzaldehyde (8.5 g, 80 mmol) were reacted in acetonitrile (100 mL) at reflux for 3 hr. The reaction mixture was cooled to room temperature. Iron chloride (0.13 g, 0.8 mmol) was added. The reaction mixture was again heated under reflux overnight. Air is bubbled through the reaction while refluxing. The solvent was evaporated. The residue was dissolved in dichloromethane (200 mL) and passed thru a pad. The crude product was purified by column chromatography using dichloromethane to EtOAc. The product was further purified by recrystallization from ethanol. 8 g of the desired product were obtained.

Synthesis of Compound 3. Intermediate 1 (1.5 g, 2.1 mmol) and 1-(2-isopropylphenyl)-2-phenyl-1H-benzo[d]imidazole (2 g, in a three-necked flask in the presence of nitrogen) 6.4 mmol) was mixed with 30 ml of ethanol. The mixture was heated under reflux for 24 hours. After cooling to room temperature, the precipitate was collected by filtration. The product was purified via column chromatography using 1:2 dichloromethane and hexanes as eluent. After purification, 0.7 g of the desired product was obtained.

Synthesis of Compound 4. Intermediate 2 (7.4 g, 10 mmol) and 1,2-diphenyl-1H-benzo[d]imidazole (8.11 g, 30 mmol) were mixed with 200 ml of ethanol in a three-necked flask in the presence of nitrogen. The mixture was heated to reflux for 24 hours. After cooling to room temperature, the precipitate was collected by filtration. The product was purified via column chromatography using 1:2 dichloromethane and hexanes as eluent. After purification, 1.4 g of the desired product was obtained.

Synthesis of 2,6-diisopropyl-N-(2-nitrophenyl)aniline. 2,6-Diisopropylaniline (25 g, 141 mmol), 2-fluoronitrobenzene (10 g, 70 mmol), and potassium fluoride (6.2 g, 106 mmol) were mixed in a one-neck flask. The mixture was heated to 180 ° C for 48 hours in the presence of nitrogen. After cooling to room temperature, water (200 mL) was added. The mixture was then extracted three times with dichloromethane (200 mL). The solvent was evaporated and the residue was purified by column chromatography using 20% dichloromethane in hexanes. 10 g of the desired product were obtained.

Synthesis of N ¹ -(2,6-diisopropylphenyl)benzene-1,2-diamine. 2,6-Diisopropyl-N-(2-nitrophenyl)aniline (9.5 g, 32 mmol) and 10% palladium/carbon (0.4 g) in a plastic coated hydrogenation vessel in the presence of nitrogen Mix 150 ml of ethanol. The mixture was placed on a Parr hydrogenator and reacted under 40 psi of hydrogen until no pressure drop occurred. The catalyst was filtered through a bed of diatomaceous earth. The solvent was evaporated. This product was used in the next step without further purification. 8.5 g of the desired product were obtained.

Synthesis of 1-(2,6-diisopropylphenyl)-2-phenyl-1H-benzo[d]imidazole. Reaction of N ¹ -(2,6-diisopropylphenyl)benzene-1,2-diamine (8.5 g, 32 mmol) and benzaldehyde (3 g, 28.8 mmol) in acetonitrile (100 ml) under reflux 3 hour. The reaction mixture was allowed to cool to room temperature. Ferric chloride (0.05 g, 0.28 mmol) was added. The reaction mixture was again heated under reflux overnight. Air is bubbled through the reaction while refluxing. The solvent was evaporated. The residue was dissolved in dichloromethane (200 mL) and passed through a pad. The crude product was purified by column chromatography using dichloromethane to EtOAc. 3.4 g of the desired product were obtained.

Synthesis of Compound 5. Intermediate 1 (2.1 g, 2.9 mmol) and 1-(2,6-diisopropylphenyl)-2-phenyl-1H-benzo[d]imidazole in a three-necked flask in the presence of nitrogen (3.1 g, 8.7 mmol) was mixed with 60 ml of ethanol. The mixture was heated under reflux for 24 hours. After cooling to room temperature, the precipitate was collected by filtration. The product was purified by column chromatography using 1:2 dichloromethane and hexanes as eluent. After purification, 1.1 g of the desired product was obtained.

Synthesis of intermediate 3. 1-(2-isopropylphenyl)-2-phenyl-1H-benzo[d]imidazole (3 g, 9.6 mmol) and ruthenium chloride (1.5 g, in a three-necked flask in the presence of nitrogen. 4.36 mmol) was mixed with 60 mL of 2-ethoxyethanol and 20 ml of water. The mixture was heated under reflux for 24 hours. After cooling to room temperature, the precipitate was collected by filtration. The solid was thoroughly washed with methanol and hexane and then dried under vacuum. 3.5 g of product were obtained.

Synthesis of intermediate 4. Intermediate 3 (3.5 g, 2.06 mmol) and silver triflate (1.06 g, 4.12 mmol) were combined with 300 mL of dichloromethane and 30 mL of methanol. The mixture was stirred at room temperature for 24 hours. The solid was filtered. The filtrate was evaporated to dryness. 4.2 g of product were obtained.

Synthesis of Compound 6. Intermediate 4 (2.0 g, 1.95 mmol) and 2,5-diphenylpyridine (1.4 g, 5.83 mmol) were mixed with 50 mL of ethanol in a three-necked flask in the presence of nitrogen. The mixture was heated under reflux for 24 hours. After cooling to room temperature, the precipitate was collected by filtration. The product was purified by column chromatography using 1:1 dichloromethane and hexanes as eluent. After purification, 0.5 g of the desired product was obtained.

Synthesis of Compound 7 and Compound 8

Synthesis of Compound 7 and Compound 8. Intermediate 4 (2.0 g, 1.95 mmol) and 2-(biphenyl-3-yl)pyridine (1.5 g, 5.8 mmol) were mixed with 60 ml of ethanol in a three-necked flask in the presence of nitrogen. The mixture was heated under reflux for 24 hours. After cooling to room temperature, the precipitate was collected by filtration. The product was purified by column chromatography using 1:1 dichloromethane and hexanes as eluent. 1.4 g of compound 7 and 0.4 g of compound 8 were collected.

Synthesis of N-(2-nitrophenyl)biphenyl-2-amine. 1-Fluoro-2-nitrobenzene (13.06 g, 92.6 mmol), 2-aminobiphenyl (31.3 g, 185.2 mmol), and potassium fluoride (8.1 g, 138.9 mmol) were prepared in a 100 mL round bottom flask. mixture. The flask was evacuated and replaced with nitrogen. The mixture was heated to 200 ° C overnight. The reaction mixture was cooled and ethyl acetate and water were added. The layers were separated and the aqueous layer was extracted with ethyl acetate. The organic layer was dried over magnesium sulfate, filtered and evaporated. The residue was pre-absorbed on diatomaceous earth and purified by column chromatography eluting with 0, 2, and 5% ethyl acetate / hexane. 24.5 g (91%) of product was obtained.

Synthesis of N ¹ -(biphenyl-2-yl)benzene-1,2-diamine. N-(2-Nitrophenyl)biphenyl-2-amine (19.69 g, 67.8 mmol), 10% palladium on carbon (0.29 g, 0.27 mmol), and 150 mL of ethanol were placed in a one-par. The mixture was hydrogenated on a Parr hydrogenator until no more hydrogen was absorbed by the solution. The solution was filtered through celite to remove the catalyst, the celite was washed with dichloromethane, and the filtrate was evaporated to yield 14.8 g (84%) of a brown oil. This product was used in the next step without further purification.

Synthesis of 1-(biphenyl-2-yl)-2-phenyl-1H-benzo[d]imidazole. Add N'-(biphenyl-2-yl)benzene-1,2-diamine (14.8 g, 56.85 mmol), benzaldehyde (5.2 mL, 51.68 mmol), and 200 mL of acetonitrile to a 500 mL 3-neck round bottom flask. in. The mixture was heated under reflux overnight in the presence of nitrogen. 80 mg (0.49 mmol) of iron (III) chloride was added and the mixture was bubbled directly into the cooled solution with air. After 3 hours, the solvent was evaporated and the residue was crystallised from methylene chloride. 6.56 g (37%) of product was obtained.

Synthesis of Compound 9. The triflate salt complex (2.06 g, 2.89 mmol), 1-(biphenyl-2-yl)-2-phenyl-1H-benzo[d]imidazole (4 g, 11.55 mmol), A 100 mL round bottom flask was added to 100 mL of ethanol. The mixture was heated under reflux overnight in the presence of nitrogen. The precipitate was collected by filtration and then purified by a column. 0.75 g of product was obtained.

Device instance

All example devices were fabricated by high vacuum (<10 ^-7 Torr) thermal evaporation. The anode electrode is ~800 on glass 1200 Or 2000 Indium tin oxide (ITO), or 800 Sapphire/IZO. Cathode system consists of 10 LiF with 1000 The composition of Al. All devices were packaged in an epoxy sealed glass cover in a nitrogen glove box (<1 ppm H ₂ O and O ₂ ) immediately after manufacture, and a moisture absorbent was incorporated into the package.

Device Stacks 1-10 Organic Stacked from ITO Surface (1200 From the sequence of 100 as a hole injection layer (HIL) Compound C, as a hole transport layer (HTL) 300 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (α-NPD), 300 as an emissive layer (EML) Doped body of the 7-10% dopant emitter (Inventive Compound 1-3), body-1 or body-2, as a barrier layer (BL) Or 100 Subject 1 or subject 2, and 400 as ETL Or 450 The composition of tris-8-hydroxyquinoline aluminum (Alq ₃ ).

Comparative Examples 1-4 were fabricated similarly to the device examples except that Compound B or Compound C was used as the emissive dopant.

As used herein, the following compounds have the following structure:

The present invention provides specific emissive dopants for an emissive layer of an OLED that can result in devices having particularly good properties. The materials of the emissive layer, and the materials and thicknesses of the BL and ETL of the device examples 1-10 are shown in Table 2. These devices were tested and the results obtained are provided in Table 3. A device having an emissive layer using Compounds 1-3 as an emissive dopant exhibits improved device efficiency and lifetime, and more saturated colors, which may be beneficial for such semi-symmetrical compounds.

From Device Examples 1-10, it can be seen that the compounds of the invention as emissive dopants in green phosphorescent OLEDs produce high device efficiencies, long operational lifetimes, and more saturated colors. As can be seen from Examples 1-4 and Comparative Example 3, Compounds 1 and 2 showed better efficiency, more saturated color, and longer life than Compound C. As can be seen from the device examples 5 and 6 and the comparative examples 1 and 2, the compound 3 has a longer life and higher efficiency than the compound B. Notably, as shown in Comparative Example 4, the device containing Compound 3 as an emissive dopant also showed a more saturated color and a narrower emission spectrum than Compound C.

These data show that phenylpyridine and phenylbenzimidazole containing semi-symmetric compounds are excellent emission dopants for phosphorescent OLEDs, which result in better color, longer lifetime, and higher efficiency.

The present invention provides specific emissive dopants for use in an emissive layer of an OLED. These dopants can provide devices with particularly good properties. The emissive layer materials of Device Examples 1-16, and the materials and thicknesses of BL and ETL are shown in Table 4. These devices were tested and the results obtained are provided in Table 5. A device having an emissive layer using Compounds 1-6, 8 and 9 as emissive dopants exhibits improved device efficiency and lifetime, and more saturated colors, which may be beneficial for such semi-symmetrical compounds.

From device examples 1-16, it can be seen that green light OLEDs comprising the inventive compound as an emissive dopant provide excellent properties. As can be seen from Device Examples 11-14 and Comparative Examples 1-4, Compounds 6, 8, and 9 exhibited more saturated colors, better efficiencies, and longer lifetimes than Compounds B and C. The device containing Compound 6 showed an improved lifetime over the device using Compound B or Compound C. The device using Compound 8 or Compound 9 showed a more saturated color, improved efficiency, and longer life than the device using Compound B or Compound C.

This data shows that semi-symmetric compounds containing phenylpyridine and phenylbenzimidazole are excellent emission dopants for phosphorescent OLED systems. These compounds provide devices with improved efficiency, improved color, and longer life.

Figure 3 shows solution photoluminescence (PL) spectra of Compound 3, Compound A, and Compound B. The fully symmetrical complex compound A exhibits an electronic vibration structure. The semi-symmetric compound 3 has a shape similar to that of the compound B. However, the emission of Compound 3 is narrower than that of Compound B, which indicates that both ligands contribute to the emission. In addition, Compound 3 can be evaporated under high vacuum at less than 220 ° C, which is about 20 degrees lower than Compound B and about 60 degrees lower than Compound A.

Figure 4 shows a typical phosphorescent organic light-emitting device.

Figure 5 shows a phosphorescent organic light-emitting device having an emissive layer containing an inventive compound as an emissive dopant. The device of Figure 5 comprises a compound C of 100 Thick hole injection layer, an NPD 300 Thick hole transport layer, 300 of a host material doped with X% of the inventive compound Thick emissive layer, a body-1 or a body-2 of 50 Or 100 Thick barrier, and an Alq ₃ of 400 Or 450 A thick electron transport layer and a LiF/Al cathode. X is 7% or 10%.

Figure 6 shows a semi-symmetric compound containing phenylpyridine and phenylbenzimidazole.

It is understood that the various embodiments described herein are by way of example only and are not intended to limit the scope of the invention. For example, many of the materials and structures described herein may be substituted by other materials and structures without departing from the spirit of the invention. As will be apparent to those skilled in the art, the present invention may be embodied in the specific embodiments and the preferred embodiments described herein. It should be understood that various theories as to why the invention is effective are not intended to be limiting.

100. . . Organic light emitting device

110. . . Substrate

115. . . anode

120. . . Hole injection layer

125. . . Hole transport layer

130. . . Electronic barrier

135. . . Emissive layer

140. . . Hole barrier

145. . . Electronic transport layer

150. . . Electron injection layer

155. . . The protective layer

160. . . cathode

162. . . First conductive layer

164. . . Second conductive layer

200. . . Inverted OLED

210. . . Substrate

215. . . cathode

220. . . Emissive layer

225. . . Hole transport layer

230. . . anode

Figure 1 shows an organic light emitting device.

Figure 2 shows an inverted organic light-emitting device without a separate electron transport layer.

Figure 3 shows the solution photoluminescence spectra of fully symmetric and semi-symmetrical compounds.

Figure 4 shows the structure of a phosphorescent organic light-emitting device.

Figure 5 shows a phosphorescent organic light-emitting device containing a compound of the invention.

Figure 6 shows a half symmetrical compound.

(no component symbol description)

Claims (25)

A semi-symmetric bismuth compound Ir(L1) _n (L2) _3-n having the following formula: Where n=1 or 2; L1; where Is L2; wherein R ₂ , R ₃ , R ₄ and R ₅ may represent mono-, di-, tri- or tetra-substituted; wherein R ₂ , R ₃ , R ₄ and R _{5 are} each independently selected from hydrogen, alkyl, heterocycloalkane a group consisting of a aryl group, an aryl group, a substituted aryl group, a heteroaryl group, and a substituted heteroaryl group; and wherein R ₁ is selected from the group consisting of alkyl, heteroalkyl, aryl, heteroaryl, substituted aryl a group of substituted and substituted heteroaryl groups; and wherein R ₁ does not form a conjugated system with L1. The compound of claim 1, wherein n=1. The compound of claim 1, wherein the compound has the formula: Wherein R4 is hydrogen or methyl. The compound of claim 1, wherein the R ₁ is Wherein X ₁ and X ₂ are independently selected from C and N; wherein Y _{1 is} not hydrogen; and wherein Y ₁ may be bonded to other substituents on the aryl ring. The compound of claim 1, wherein each of R ₂ , R ₃ and R _{5 is} hydrogen. The compound of claim 1, wherein the L1 is selected from the group consisting of: The compound of claim 1, wherein the L2 is selected from the group consisting of: The compound of claim 6, wherein the L2 is selected from the group consisting of: The compound of claim 1, wherein the L1 is selected from the group consisting of: The compound of claim 1, wherein the L2 is selected from the group consisting of: The compound of claim 9, wherein the L2 is selected from the group consisting of: The compound of claim 1, wherein the compound is selected from the group consisting of: The compound of claim 1, wherein the compound is selected from the group consisting of: The compound of claim 1, wherein the compound is selected from the group consisting of: The compound of claim 1, wherein the compound is a green emitting dopant. An organic light-emitting device comprising: an anode; a cathode; and an organic layer disposed between the anode and the cathode, the organic layer further comprising a semi-symmetric bismuth compound Ir(L1) _n (L2) having the following formula _3-n compound: Where n=1 or 2; Is L1; Is L2; wherein R ₂ , R ₃ , R ₄ and R ₅ may represent mono-, di-, tri- or tetra-substituted; wherein R ₂ , R ₃ , R ₄ and R _{5 are} each independently selected from hydrogen, alkyl, heterocycloalkane a group consisting of a aryl group, an aryl group, a substituted aryl group, a heteroaryl group, and a substituted heteroaryl group; and wherein R ₁ is selected from the group consisting of alkyl, heteroalkyl, aryl, heteroaryl, substituted aryl a group of substituted and substituted heteroaryl groups; and wherein R ₁ does not form a conjugated system with L1. The device of claim 16, wherein the organic layer is an emissive layer and has the formula This compound is an emissive compound. The device of claim 16, wherein R ₁ is Wherein X ₁ and X ₂ are independently selected from C and N; wherein Y _{1 is} not hydrogen; and wherein Y ₁ may be bonded to other substituents on the aryl ring. The device of claim 16, wherein the compound is selected from the group consisting of: The device of claim 16, wherein the compound is selected from the group consisting of: The device of claim 16, wherein the compound is selected from the group consisting of: The device of claim 16, wherein the emissive layer further comprises a body. The device of claim 22, wherein the subject has the following formula: Wherein R ₁ and R ₂ independently represent a mono-, di-, tri- or tetra-substituted group selected from alkyl, alkoxy, amino, alkenyl, alkynyl, aralkyl, aryl and heteroaryl groups, or none a substituent; and wherein at least one of R ₁ and R ₂ comprises a co-triphenyl group. The device of claim 22, wherein the subject has the following formula: Wherein R ₁ , R ₂ and R _{3 are} each independently hydrogen, a non-fused aryl group or a non-fused heteroaryl group having one or more meta substituents, wherein at least one of R ₁ , R ₂ and R ₃ Not hydrogen; and each meta-substituent thereof is optionally a non-fused aryl or heteroaryl group substituted with a further substituent selected from the group consisting of a non-fused aryl group, a non-fused heteroaryl group, and an alkyl group. . A consumer product comprising a device, the device further comprising: an anode; a cathode; and an organic layer disposed between the anode and the cathode, the organic layer further comprising a semi-symmetric bismuth compound Ir (L1) ) _n (L2) _3-n compound: Where n=1 or 2; L1; where Is L2; wherein R ₂ , R ₃ , R ₄ and R ₅ may represent mono-, di-, tri- or tetra-substituted; wherein R ₂ , R ₃ , R ₄ and R _{5 are} each independently selected from hydrogen, alkyl, heterocycloalkane a group consisting of a aryl group, an aryl group, a substituted aryl group, a heteroaryl group, and a substituted heteroaryl group; and wherein R ₁ is selected from the group consisting of alkyl, heteroalkyl, aryl, heteroaryl, substituted aryl a group of substituted and substituted heteroaryl groups; and wherein R ₁ does not form a conjugated system with L1.