Organic electroluminescent materials and devices

This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 62/549,481, filed Aug. 24, 2017, the entire contents of which are incorporated herein by reference.

The present invention relates to compounds for use as emitters, and devices, such as organic light emitting diodes, including the same.

Opto-electronic devices that make use of organic materials are becoming increasingly desirable for a number of reasons. Many of the materials used to make such devices are relatively inexpensive, so organic opto-electronic devices have the potential for cost advantages over inorganic devices. In addition, the inherent properties of organic materials, such as their flexibility, may make them well suited for particular applications such as fabrication on a flexible substrate. Examples of organic opto-electronic devices include organic light emitting diodes/devices (OLEDs), organic phototransistors, organic photovoltaic cells, and organic photodetectors. For OLEDs, the organic materials may have performance advantages over conventional materials. For example, the wavelength at which an organic emissive layer emits light may generally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage is applied across the device. OLEDs are becoming an increasingly interesting technology for use in applications such as flat panel displays, illumination, and backlighting. Several OLED materials and configurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and 5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full color display. Industry standards for such a display call for pixels adapted to emit particular colors, referred to as “saturated” colors. In particular, these standards call for saturated red, green, and blue pixels. Alternatively the OLED can be designed to emit white light. In conventional liquid crystal displays emission from a white backlight is filtered using absorption filters to produce red, green and blue emission. The same technique can also be used with OLEDs. The white OLED can be either a single EML device or a stack structure. Color may be measured using CIE coordinates, which are well known to the art.

One example of a green emissive molecule is tris(2-phenylpyridine) iridium, denoted Ir(ppy) 3 , which has the following structure:

In this, and later figures herein, we depict the dative bond from nitrogen to metal (here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as well as small molecule organic materials that may be used to fabricate organic opto-electronic devices. “Small molecule” refers to any organic material that is not a polymer, and “small molecules” may actually be quite large. Small molecules may include repeat units in some circumstances. For example, using a long chain alkyl group as a substituent does not remove a molecule from the “small molecule” class. Small molecules may also be incorporated into polymers, for example as a pendent group on a polymer backbone or as a part of the backbone. Small molecules may also serve as the core moiety of a dendrimer, which consists of a series of chemical shells built on the core moiety. The core moiety of a dendrimer may be a fluorescent or phosphorescent small molecule emitter. A dendrimer may be a “small molecule,” and it is believed that all dendrimers currently used in the field of OLEDs are small molecules.

As used herein, “top” means furthest away from the substrate, while “bottom” means closest to the substrate. Where a first layer is described as “disposed over” a second layer, the first layer is disposed further away from substrate. There may be other layers between the first and second layer, unless it is specified that the first layer is “in contact with” the second layer. For example, a cathode may be described as “disposed over” an anode, even though there are various organic layers in between.

As used herein, “solution processible” means capable of being dissolved, dispersed, or transported in and/or deposited from a liquid medium, either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed that the ligand directly contributes to the photoactive properties of an emissive material. A ligand may be referred to as “ancillary” when it is believed that the ligand does not contribute to the photoactive properties of an emissive material, although an ancillary ligand may alter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled in the art, a first “Highest Occupied Molecular Orbital” (HOMO) or “Lowest Unoccupied Molecular Orbital” (LUMO) energy level is “greater than” or “higher than” a second HOMO or LUMO energy level if the first energy level is closer to the vacuum energy level. Since ionization potentials (IP) are measured as a negative energy relative to a vacuum level, a higher HOMO energy level corresponds to an IP having a smaller absolute value (an IP that is less negative). Similarly, a higher LUMO energy level corresponds to an electron affinity (EA) having a smaller absolute value (an EA that is less negative). On a conventional energy level diagram, with the vacuum level at the top, 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 such a diagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled in the art, a first work function is “greater than” or “higher than” a second work function if the first work function has a higher absolute value. Because work functions are generally measured as negative numbers relative to vacuum level, this means that a “higher” work function is more negative. On a conventional energy level diagram, with the vacuum level at the top, a “higher” work function is illustrated as further away from the vacuum level in the downward direction. Thus, the definitions of HOMO and LUMO energy levels follow a different convention than work functions.

More details on OLEDs, and the definitions described above, can be found in U.S. Pat. No. 7,279,704, which is incorporated herein by reference in its entirety.

There is a need in the art for novel emitter materials in organic electroluminescence device to improve device performance. The present invention addresses this need in the art.

A compound with that includes a Ligand L A of Formula I, which is coordinated to a metal M as represented by the dotted lines, shown below

wherein X 1 , X 2 , X 3 , and X 4 , and X 5 are independently selected from the group consisting of C and N; wherein if the 1,2,4-triazine ring is coordinated to the metal M through N, then X 5 is C, or if the triazine ring is coordinated to the metal M through C, then X 5 is N;

R 1 and R 2 represent mono to the maximum allowable substitution, or no substitution; and

each R 1 and R 2 are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; or optionally any two adjacent substituents R 1 and R 2 can be joined to form a ring;

wherein the metal M is selected from the group consisting of Ir, Rh, Re, Ru, Os, Pt, Au, and Cu; provided that if M is Pt or Cu, X 5 is C; and

L A may be joined with other ligands to form a tridentate, tetradentate, pentadentate, or hexadentate ligand.

An organic light emitting diode/device (OLED) that includes an anode, a cathode, and an organic layer disposed between the anode and the cathode. The organic layer includes a compound having a Ligand L A of Formula I. The OLED can be incorporated into one or more of a consumer product, an electronic component module, and/or a lighting panel

A formulation containing a compound having a Ligand L A of Formula I is provided.

A consumer product comprising the OLED is also disclosed.

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does not have a separate electron transport layer.

Generally, an OLED comprises at least one organic layer disposed between and electrically connected to an anode and a cathode. When a current is applied, the anode injects holes and the cathode injects electrons into the organic layer(s). The injected holes and electrons each migrate toward the oppositely charged electrode. When an electron and hole localize on the same molecule, an “exciton,” which is a localized electron-hole pair having an excited energy state, is formed. Light is emitted when the exciton relaxes via a photoemissive mechanism. In some cases, the exciton may 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 used emissive molecules that emitted light from their singlet states (“fluorescence”) as disclosed, for example, in U.S. Pat. No. 4,769,292, which is incorporated by reference in its entirety. Fluorescent emission generally occurs in a time frame of less than 10 nanoseconds.

More recently, OLEDs having emissive materials that emit light from triplet states (“phosphorescence”) have been demonstrated. Baldo et al., “Highly Efficient Phosphorescent Emission from Organic Electroluminescent Devices,” Nature, vol. 395, 151-154, 1998; (“Baldo-I”) and Baldo et al., “Very high-efficiency green organic light-emitting devices based on electrophosphorescence,” Appl. Phys. Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), are incorporated by reference in their entireties. Phosphorescence is described in more detail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporated by reference.

FIG. 1 shows an organic light emitting device 100 . The figures are not necessarily drawn to scale. Device 100 may 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 , an electron transport layer 145 , an electron injection layer 150 , a protective layer 155 , a cathode 160 , and a barrier layer 170 . Cathode 160 is a compound cathode having a first conductive layer 162 and a second conductive layer 164 . Device 100 may be fabricated by depositing the layers described, in order. The properties and functions of these various layers, as well as example materials, are described in more detail in U.S. Pat. No. 7,279,704 at cols. 6-10, which are incorporated by reference.

More examples for each of these layers are available. For example, a flexible and transparent substrate-anode combination is disclosed in U.S. Pat. No. 5,844,363, which is incorporated by reference in its entirety. An example of a p-doped hole transport layer is m-MTDATA doped with F 4 -TCNQ at a molar ratio of 50:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. Examples of emissive and host materials are disclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which is incorporated by reference in its entirety. An example of an n-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 by reference in its entirety. U.S. Pat. Nos. 5,703,436 and 5,707,745, which are incorporated by reference in their entireties, disclose examples of cathodes including compound cathodes having a thin layer of metal such as Mg:Ag with an overlying transparent, electrically-conductive, sputter-deposited ITO layer. The theory and use of blocking layers is described in more detail in U.S. Pat. No. 6,097,147 and U.S. Patent Application Publication No. 2003/0230980, which are incorporated by reference in their entireties. Examples of injection layers are provided in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety. A description of protective layers may be found in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety.

FIG. 2 shows an inverted OLED 200 . The device includes a substrate 210 , a cathode 215 , an emissive layer 220 , a hole transport layer 225 , and an anode 230 . Device 200 may be fabricated by depositing the layers described, in order. Because the most common OLED configuration has a cathode disposed over the anode, and device 200 has cathode 215 disposed under anode 230 , device 200 may be referred to as an “inverted” OLED. Materials similar to those described with respect to device 100 may be used in the corresponding layers of device 200 . FIG. 2 provides one example of how some layers may be omitted from the structure of device 100 .

The simple layered structure illustrated in FIGS. 1 and 2 is provided by way of non-limiting example, and it is understood that embodiments of the invention may be used in connection with a wide variety of other structures. The specific materials and structures described are exemplary in nature, and other materials and structures may be used. Functional OLEDs may be achieved by combining the various layers described in different ways, or layers 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. Although many of the examples provided herein describe various layers as comprising a single material, it is understood that combinations of materials, such as a mixture of host and dopant, or more generally a mixture, may be used. Also, the layers may have various sublayers. The names given to the various layers herein are not intended to be strictly limiting. 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 may be described as having an “organic layer” disposed between a cathode and an anode. This organic layer may comprise a single layer, or may further comprise multiple layers of different organic materials as described, for example, with respect to FIGS. 1 and 2 .

Structures and materials not specifically described may also be used, such as OLEDs comprised of polymeric materials (PLEDs) such as disclosed in U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated by reference in its entirety. By way of further example, OLEDs having a single organic layer may be used. OLEDs may be stacked, for example as described in U.S. Pat. No. 5,707,745 to Forrest et al, which is incorporated by reference in its entirety. The OLED structure may deviate from the simple layered structure illustrated in FIGS. 1 and 2 . For example, the substrate may include an angled reflective surface to improve out-coupling, such as a mesa structure as described in U.S. Pat. No. 6,091,195 to Forrest et al., and/or a pit structure as described in U.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated by reference in their entireties.

Unless otherwise specified, any of the layers of the various embodiments may be deposited by any suitable method. For the organic layers, preferred methods include thermal evaporation, ink-jet, such as described in U.S. Pat. Nos. 6,013,982 and 6,087,196, which are incorporated by reference in their entireties, organic vapor phase deposition (OVPD), such as described in U.S. Pat. No. 6,337,102 to Forrest et al., which is incorporated by reference in its entirety, and deposition by organic vapor jet printing (OVJP), such as described in U.S. Pat. No. 7,431,968, which is incorporated by reference in its entirety. Other suitable deposition methods include spin coating and other solution based processes. Solution based processes are preferably carried out in nitrogen or an inert atmosphere. For the other layers, preferred methods include thermal evaporation. Preferred patterning methods include deposition through a mask, cold welding such as described in U.S. Pat. Nos. 6,294,398 and 6,468,819, which are incorporated by reference in their entireties, and patterning associated with some of the deposition methods such as ink jet and organic vapor jet printing (OVJP). Other methods may also be used. The materials to be deposited may be modified to make them compatible with a particular deposition method. For example, substituents such as alkyl and aryl groups, branched or unbranched, and preferably containing at least 3 carbons, may be used in small molecules to enhance their ability to undergo solution processing. Substituents having 20 carbons or more may be used, and 3-20 carbons is a preferred range. Materials with asymmetric structures may have better solution processibility than those having symmetric structures, because asymmetric materials may have a lower tendency to recrystallize. Dendrimer substituents may be used to enhance the ability of small molecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the present invention may further optionally comprise a barrier layer. One purpose of the barrier layer is to protect the electrodes and organic layers from damaging exposure to harmful species in the environment including moisture, vapor and/or gases, etc. The barrier layer may be deposited over, under or next to a substrate, an electrode, or over any other parts of a device including an edge. The barrier layer may comprise a single layer, or multiple layers. The barrier layer may be formed by various known chemical vapor deposition techniques and may include compositions having a single phase as well as compositions having multiple phases. Any suitable material or combination of materials may be used for the barrier layer. The barrier layer may incorporate an inorganic or an organic compound or both. The preferred barrier layer comprises a mixture of a polymeric material and a non-polymeric material as described in U.S. Pat. No. 7,968,146, PCT Pat. Application Nos. PCT/US2007/023098 and PCT/US2009/042829, which are herein incorporated by reference in their entireties. To be considered a “mixture”, the aforesaid polymeric and non-polymeric materials comprising the barrier layer should be deposited under the same reaction conditions and/or at the same time. The weight ratio of polymeric to non-polymeric material may be in the range of 95:5 to 5:95. The polymeric material and the non-polymeric material may be created from the same precursor material. In one example, the mixture of a polymeric material and a non-polymeric material consists essentially of polymeric silicon and inorganic silicon.

Devices fabricated in accordance with embodiments of the invention can be incorporated into a wide variety of electronic component modules (or units) that can be incorporated into a variety of electronic products or intermediate components. Examples of such electronic products or intermediate components include display screens, lighting devices such as discrete light source devices or lighting panels, etc. that can be utilized by the end-user product manufacturers. Such electronic component modules can optionally include the driving electronics and/or power source(s). Devices fabricated in accordance with embodiments of the invention can be incorporated into a wide variety of consumer products that have one or more of the electronic component modules (or units) incorporated therein. A consumer product comprising an OLED that includes the compound of the present disclosure in the organic layer in the OLED is disclosed. Such consumer products would include any kind of products that include one or more light source(s) and/or one or more of some type of visual displays. Some examples of such consumer products include flat panel displays, curved displays, computer monitors, medical monitors, televisions, billboards, lights for interior or exterior illumination and/or signaling, heads-up displays, fully or partially transparent displays, flexible displays, rollable displays, foldable displays, stretchable displays, laser printers, telephones, mobile phones, tablets, phablets, personal digital assistants (PDAs), wearable devices, laptop computers, digital cameras, camcorders, viewfinders, micro-displays (displays that are less than 2 inches diagonal), 3-D displays, virtual reality or augmented reality displays, vehicles, video walls comprising multiple displays tiled together, theater or stadium screen, and a sign. Various control mechanisms may be used to control devices fabricated in accordance with the present invention, including passive matrix and active matrix. Many of the devices are intended for use in a temperature range comfortable to humans, such as 18 degrees C. to 30 degrees C., and more preferably at room temperature (20-25 degrees C.), but could be used outside this temperature range, for example, from −40 degree C. to +80 degree C.

The materials and structures described herein may have applications in devices other than OLEDs. For example, other optoelectronic devices such as organic solar cells and organic photodetectors may employ the materials and structures. More generally, organic devices, such as organic transistors, may employ the materials and structures.

The terms “halo,” “halogen,” and “halide” are used interchangeably and refer to fluorine, chlorine, bromine, and iodine.

The term “acyl” refers to a substituted carbonyl radical (C(O)—R s ).

The term “ester” refers to a substituted oxycarbonyl (—O—C(O)—R s or —C(O)—O—R s ) radical.

The term “ether” refers to an —OR s radical.

The terms “sulfanyl” or “thio-ether” are used interchangeably and refer to a —SR s radical.

The term “sulfinyl” refers to a —S(O)—R s radical.

The term “sulfonyl” refers to a —SO 2 —R s radical.

The term “phosphino” refers to a —P(R s ) 3 radical, wherein each R s can be same or different.

The term “silyl” refers to a —Si(R s ) 3 radical, wherein each R s can be same or different.

In each of the above, R s can be hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, and combination thereof. Preferred R s is selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and combination thereof.

The term “alkyl” refers to and includes both straight and branched chain alkyl radicals. Preferred alkyl groups are those containing from one to fifteen carbon atoms and includes methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, and the like. Additionally, the alkyl group is optionally substituted.

The term “cycloalkyl” refers to and includes monocyclic, polycyclic, and spiro alkyl radicals. Preferred cycloalkyl groups are those containing 3 to 12 ring carbon atoms and includes cyclopropyl, cyclopentyl, cyclohexyl, bicyclo[3.1.1]heptyl, spiro[4.5]decyl, spiro[5.5]undecyl, adamantyl, and the like. Additionally, the cycloalkyl group is optionally substituted.

The terms “heteroalkyl” or “heterocycloalkyl” refer to an alkyl or a cycloalkyl radical, respectively, having at least one carbon atom replaced by a heteroatom. Optionally the at least one heteroatom is selected from O, S, N, P, B, Si and Se, preferably, O, S or N. Additionally, the heteroalkyl or heterocycloalkyl group is optionally substituted.

The term “alkenyl” refers to and includes both straight and branched chain alkene radicals. Alkenyl groups are essentially alkyl groups that include at least one carbon-carbon double bond in the alkyl chain. Cycloalkenyl groups are essentially cycloalkyl groups that include at least one carbon-carbon double bond in the cycloalkyl ring. The term “heteroalkenyl” as used herein refers to an alkenyl radical having at least one carbon atom replaced by a heteroatom. Optionally the at least one heteroatom is selected from O, S, N, P, B, Si, and Se, preferably, O, S, or N. Preferred alkenyl, cycloalkenyl, or heteroalkenyl groups are those containing two to fifteen carbon atoms. Additionally, the alkenyl, cycloalkenyl, or heteroalkenyl group is optionally substituted.

The term “alkynyl” refers to and includes both straight and branched chain alkyne radicals. Preferred alkynyl groups are those containing two to fifteen carbon atoms. Additionally, the alkynyl group is optionally substituted.

The terms “aralkyl” or “arylalkyl” are used interchangeably and refer to an alkyl group that is substituted with an aryl group. Additionally, the aralkyl group is optionally substituted.

The term “heterocyclic group” refers to and includes aromatic and non-aromatic cyclic radicals containing at least one heteroatom. Optionally the at least one heteroatom is selected from O, S, N, P, B, Si, and Se, preferably, O, S, or N. Hetero-aromatic cyclic radicals may be used interchangeably with heteroaryl. Preferred hetero-non-aromatic cyclic groups are those containing 3 to 7 ring atoms which includes at least one hetero atom, and includes cyclic amines such as morpholino, piperidino, pyrrolidino, and the like, and cyclic ethers/thio-ethers, such as tetrahydrofuran, tetrahydropyran, tetrahydrothiophene, and the like. Additionally, the heterocyclic group may be optionally substituted.

The term “aryl” refers to and includes both single-ring aromatic hydrocarbyl groups and polycyclic aromatic ring systems. The polycyclic rings may have two or more rings in which two carbons are common to two adjoining rings (the rings are “fused”) wherein at least one of the rings is an aromatic hydrocarbyl group, e.g., the other rings can be cycloalkyls, cycloalkenyls, aryl, heterocycles, and/or heteroaryls. Preferred aryl groups are those containing six to thirty carbon atoms, preferably six to twenty carbon atoms, more preferably six to twelve carbon atoms. Especially preferred is an aryl group having six carbons, ten carbons or twelve carbons. Suitable aryl groups include phenyl, biphenyl, triphenyl, triphenylene, tetraphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, and azulene, preferably phenyl, biphenyl, triphenyl, triphenylene, fluorene, and naphthalene. Additionally, the aryl group is optionally substituted.

The term “heteroaryl” refers to and includes both single-ring aromatic groups and polycyclic aromatic ring systems that include at least one heteroatom. The heteroatoms include, but are not limited to O, S, N, P, B, Si, and Se. In many instances, O, S, or N are the preferred heteroatoms. Hetero-single ring aromatic systems are preferably single rings with 5 or 6 ring atoms, and the ring can have from one to six heteroatoms. The hetero-polycyclic ring systems can have two or more rings in which two atoms are common to two adjoining rings (the rings are “fused”) wherein at least one of the rings is a heteroaryl, e.g., the other rings can be cycloalkyls, cycloalkenyls, aryl, heterocycles, and/or heteroaryls. The hetero-polycyclic aromatic ring systems can have from one to six heteroatoms per ring of the polycyclic aromatic ring system. Preferred heteroaryl groups are those containing three to thirty carbon atoms, preferably three to twenty carbon atoms, more preferably three to twelve carbon atoms. Suitable heteroaryl groups include dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocathazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine, preferably dibenzothiophene, dibenzofuran, dibenzoselenophene, carbazole, indolocathazole, imidazole, pyridine, triazine, benzimidazole, 1,2-azaborine, 1,3-azaborine, 1,4-azaborine, borazine, and aza-analogs thereof. Additionally, the heteroaryl group is optionally substituted.

Of the aryl and heteroaryl groups listed above, the groups of triphenylene, naphthalene, anthracene, dibenzothiophene, dibenzofuran, dibenzoselenophene, carbazole, indolocarbazole, imidazole, pyridine, pyrazine, pyrimidine, triazine, and benzimidazole, and the respective aza-analogs of each thereof are of particular interest.

The terms alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aralkyl, heterocyclic group, aryl, and heteroaryl, as used herein, are independently unsubstituted, or independently substituted, with one or more general substituents.

In many instances, the general substituents are selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

In some instances, the preferred general substituents are selected from the group consisting of deuterium, fluorine, alkyl, cycloalkyl, heteroalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, and combinations thereof.

In some instances, the preferred general substituents are selected from the group consisting of deuterium, fluorine, alkyl, cycloalkyl, alkoxy, aryloxy, amino, silyl, aryl, heteroaryl, sulfanyl, and combinations thereof.

In yet other instances, the more preferred general substituents are selected from the group consisting of deuterium, fluorine, alkyl, cycloalkyl, aryl, heteroaryl, and combinations thereof.

The term “substituted” refers to a substituent other than H that is bonded to the relevant position, e.g., a carbon. For example, where R 1 represents mono-substituted, then one R 1 must be other than H. Similarly, where R 1 represents di-substituted, then two of R 1 must be other than H. Similarly, where R 1 is unsubstituted, R 1 is hydrogen for all available positions. The maximum number of substitutions possible in a structure (for example, a particular ring or fused ring system) will depend on the number of atoms with available valencies.

As used herein, “combinations thereof” indicates that one or more members of the applicable list are combined to form a known or chemically stable arrangement that one of ordinary skill in the art can envision from the applicable list. For example, an alkyl and deuterium can be combined to form a partial or fully deuterated alkyl group; a halogen and alkyl can be combined to form a halogenated alkyl substituent; and a halogen, alkyl, and aryl can be combined to form a halogenated arylalkyl. In one instance, the term substitution includes a combination of two to four of the listed groups. In another instance, the term substitution includes a combination of two to three groups. In yet another instance, the term substitution includes a combination of two groups. Preferred combinations of substituent groups are those that contain up to fifty atoms that are not hydrogen or deuterium, or those which include up to forty atoms that are not hydrogen or deuterium, or those that include up to thirty atoms that are not hydrogen or deuterium. In many instances, a preferred combination of substituent groups will include up to twenty atoms that are not hydrogen or deuterium.

The “aza” designation in the fragments described herein, i.e. aza-dibenzofuran, aza-dibenzothiophene, etc. means that one or more of the C—H groups in the respective fragment can be replaced by a nitrogen atom, for example, and without any limitation, azatriphenylene encompasses both dibenzo[f,h]quinoxaline and dibenzo[f,h]quinoline. One of ordinary skill in the art can readily envision other nitrogen analogs of the aza-derivatives described above, and all such analogs are intended to be encompassed by the terms as set forth herein.

As used herein, “deuterium” refers to an isotope of hydrogen. Deuterated compounds can be readily prepared using methods known in the art. For example, U.S. Pat. No. 8,557,400, Patent Pub. No. WO 2006/095951, and U.S. Pat. Application Pub. No. US 2011/0037057, which are hereby incorporated by reference in their entireties, describe the making of deuterium-substituted organometallic complexes. Further reference is made to Ming Yan, et al., Tetrahedron 2015, 71, 1425-30 and Atzrodt et al., Angew. Chem. Int. Ed. ( Reviews ) 2007, 46, 7744-65, which are incorporated by reference in their entireties, describe the deuteration of the methylene hydrogens in benzyl amines and efficient pathways to replace aromatic ring hydrogens with deuterium, respectively.

It is to be understood that when a molecular fragment is described as being a substituent or otherwise attached to another moiety, its name may be written as if it were a fragment (e.g. phenyl, phenylene, naphthyl, dibenzofuryl) or as if it were the whole molecule (e.g. benzene, naphthalene, dibenzofuran). As used herein, these different ways of designating a substituent or attached fragment are considered to be equivalent.

We describe novel transition metal complexes with a ligand that includes a 1,2,4-triazine ring and a derivative thereof coordinated to a metal M. The complexes can be useful as emitter materials in organic electroluminescence device to improve the performance, e.g., OLED stability (lifetime) or efficiency.

The transition metal complexes include a Ligand L A of Formula I, which is coordinated to a metal M as represented by the dotted lines:

wherein X 1 , X 2 , X 3 , and X 4 , and X 5 are independently selected from the group consisting of C and N; wherein if the 1,2,4-triazine ring is coordinated to the metal M through N, then X 5 is C, or if the triazine ring is coordinated to the metal M through C, then X 5 is N;

R 1 and R 2 represent mono to the maximum allowable substitution, or no substitution; and

each R 1 and R 2 are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; or optionally any two adjacent substituents R 1 and R 2 can be joined to form a ring;

wherein the metal M is selected from the group consisting of Ir, Rh, Re, Ru, Os, Pt, Au, and Cu; provided that if M is Pt or Cu, X 5 is C; and

L A may be joined with other ligands to form a tridentate, tetradentate, pentadentate, or hexadentate ligand.

In one embodiment, R 1 and R 2 are each independently selected from the group consisting of hydrogen, deuterium, fluorine, alkyl, cycloalkyl, heteroalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, and combinations thereof. In one embodiment, R 1 and R 2 are each independently selected from the group consisting of hydrogen, deuterium, fluorine, alkyl, cycloalkyl, alkoxy, aryloxy, amino, silyl, aryl, heteroaryl, sulfanyl, and combinations thereof.

In one embodiment, at least one of R 1 is selected from alkyl, which is optionally fully or partially deuterated, aryl, which is optionally fully or partially deuterated, cycloalkyl, which is optionally fully or partially deuterated, heteroaryl, which is optionally fully or partially deuterated, and combinations thereof.

In one embodiment, at least two adjacent R 2 join to form an aromatic ring. In one embodiment, at least two adjacent R 1 join to form an aromatic ring.

In one embodiment, M is Os, Ir or Pt. In one embodiment, M is Ir or Pt.

The compound is homoleptic, or the compound is heteroleptic.

In one embodiment, each of X 1 , X 2 , X 3 , X 4 , and X 5 is C.

In one embodiment, each of X 1 , X 2 , X 3 , X 4 , and X 5 is C, and the 1,2,4-triazine ring is coordinated to the metal M through the 1-N or 2-N of the 1,2,4-triazine.

In one embodiment, one to three of X 1 , X 2 , X 3 , X 4 , and X 5 is N. In one embodiment, at least one of X 1 , X 2 , X 3 , X 4 , and X 5 is N.

In one embodiment, the compound is of Formula II, Formula III, or Formula IV

wherein A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , A 7 and A 8 are independently selected from CR 3 or N;

each R 3 is independently selected from the group consisting of hydrogen, deuterium, fluorine, alkyl, cycloalkyl, heteroalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, and combinations thereof, or optionally, two adjacent R 3 can join to form an aromatic ring;

W is selected from CR w1 R w2 , O, S, Se, or NR N ;

wherein R w1 , R w2 , and R N are independently selected from the group consisting of hydrogen, deuterium, fluorine, alkyl, cycloalkyl, heteroalkyl, aryl, heteroaryl, and combinations thereof; and

the hash bond in Formula III represents a fused bond with ring 2.

In one embodiment, L A is selected from the group consisting of

In one embodiment, the Ligand L A is selected from the group consisting of:

In one embodiment, the compound has a formula of M(L A ) x (L B ) y (L C ) wherein L B and L C are each a bidentate ligand; and x is 1, 2, or 3; y is 1, or 2; z is 0, 1, or 2; and x+y+z is the oxidation state of the metal M. In one embodiment, the bidentate ligands L B and L C are independently selected from the group consisting of

wherein each R a , R b , and R c may independently represent from mono substitution to the maximum possible number of substitution, or no substitution;

wherein each R a , R b , and R c is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and

wherein any two adjacent substituents of R a , R b , and R c are optionally fused or joined to form a ring or form a multidentate ligand.

In one embodiment, L B is selected from the group consisting of:

In one embodiment, the compound is the Compound Ax having the formula Ir(L Ai ) 3 ; wherein x=i; and i is an integer from 1 to 212.

In one embodiment, the compound is the Compound By having the formula Ir(L Ai )(L Bj ) 2 ; wherein y=468i+j−468; i is an integer from 1 to 212, and j is an integer from 1 to 468.

In one embodiment, the compound is the Compound Cz having the formula Ir(L Ai ) 2 (L Ck ); wherein z=1260i+k−1260; i is an integer from 1 to 212, and k is an integer from 1 to 1260; and wherein L Ck is selected from the group consisting of the following structures: L C1 through L C1260 are based on a structure of Formula X,

in which R 1 , R 2 , and R 3 are defined as:

wherein R D1 to R D21 has the following structures:

In one embodiment, the compound has a formula selected from the group consisting of Ir(L A ) 3 , Ir(L A )(L B ) 2 , Ir(L A ) 2 (L B ), Ir(L A ) 2 (L C ), Ir(L A ) (L C ) 2 , and Ir(L A )(L B )(L C ); and wherein L A , L B , and L C are different from each other. In one embodiment, the compound has a formula of Pt(L A )(L B ); and wherein L A and L B can be the same or different. In one embodiment, L A and L B are connected to form a tetradentate ligand. In one embodiment, L A and L B are connected at two places to form a macrocyclic tetradentate ligand.

In one embodiment, L B and L C are each independently selected from the group consisting of:

wherein each Y 1 to Y 1 are independently selected from the group consisting of carbon and nitrogen;

wherein Y′ is selected from the group consisting of BR e , NR e , PR e , O, S, Se, C═O, S═O, SO 2 , CR e R f , SiR e R f , and GeR e R f ;

wherein R e and R f are optionally fused or joined to form a ring;

wherein each R a , R b , R c , and R d may independently represent from mono substitution to the maximum possible number of substitution, or no substitution;

wherein each R a , R b , R c , R d , R e , and R f is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and

wherein any two adjacent substituents of R a , R b , R c , and R d are optionally fused or joined to form a ring or form a multidentate ligand.

The present invention also includes an organic light emitting device (OLED). The OLED may include an anode, a cathode, and an organic layer disposed between the anode and the cathode. In one embodiment, the organic layer includes a compound that includes a Ligand L A of Formula I.

In one embodiment, the organic layer further comprises a host, wherein the host comprises a triphenylene containing benzo-fused thiophene or benzo-fused furan;

wherein any substituent in the host is an unfused substituent independently selected from the group consisting of C n H 2n+1 , OC n H 2n+1 , OAr 1 , N(C n H 2n+1 ) 2 , N(Ar 1 )(Ar 2 ), CH═CH'C n H 2n+1 , Ar 1 , Ar 1 —Ar 2 , C n H 2n —Ar 1 , or no substitution;

wherein n is from 1 to 10; and

wherein Ar 1 and Ar e are independently selected from the group consisting of benzene, biphenyl, naphthalene, triphenylene, carbazole, and heteroaromatic analogs thereof.

In one embodiment, the organic layer further comprises a host, wherein the host comprises a metal complex.

In one embodiment, the organic layer further comprises a host, wherein the host comprises at least one chemical group selected from the group consisting of triphenylene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, azatriphenylene, azacarbazole, aza-dibenzothiophene, aza-dibenzofuran, and aza-dibenzoselenophene.

In one embodiment, the host is selected from the group consisting of:

and combinations thereof.

The present invention also includes a consumer product that includes an organic light emitting device (OLED). The OLED may include an anode, a cathode, and an organic layer disposed between the anode and the cathode. In one embodiment, the organic layer includes a compound that includes a Ligand L A of Formula I.

In one embodiment, the consumer product is selected from the group consisting of a flat panel display, a curved display, a computer monitor, a medical monitor, a television, a billboard, a light for interior or exterior illumination and/or signaling, a heads-up display, a fully or partially transparent display, a flexible display, a rollable display, a foldable display, a stretchable display, a laser printer, a telephone, a mobile phone, a tablet, a phablet, a personal digital assistant (PDA), a wearable device, a laptop computer, a digital camera, a camcorder, a viewfinder, a micro-display (display that is less than 2 inches diagonal), a 3-D display, a virtual reality or augmented reality display, a vehicle, a video wall comprising multiple displays tiled together, a theater or stadium screen, and a sign.

In some embodiments, the OLED has one or more characteristics selected from the group consisting of being flexible, being rollable, being foldable, being stretchable, and being curved. In some embodiments, the OLED is transparent or semi-transparent. In some embodiments, the OLED further comprises a layer comprising carbon nanotubes.

In some embodiments, the OLED further comprises a layer comprising a delayed fluorescent emitter. In some embodiments, the OLED comprises a RGB pixel arrangement or white plus color filter pixel arrangement. In some embodiments, the OLED is a mobile device, a hand held device, or a wearable device. In some embodiments, the OLED is a display panel having less than 10 inch diagonal or 50 square inch area. In some embodiments, the OLED is a display panel having at least 10 inch diagonal or 50 square inch area. In some embodiments, the OLED is a lighting panel.

In some embodiments, the compound can be an emissive dopant. In some embodiments, the compound can produce emissions via phosphorescence, fluorescence, thermally activated delayed fluorescence, i.e., TADF (also referred to as E-type delayed fluorescence; see, e.g., U.S. application Ser. No. 15/700,352, which is hereby incorporated by reference in its entirety), triplet-triplet annihilation, or combinations of these processes.

According to another aspect, a formulation comprising the compound described herein is also disclosed.

The OLED disclosed herein can be incorporated into one or more of a consumer product, an electronic component module, and a lighting panel. The organic layer can be an emissive layer and the compound can be an emissive dopant in some embodiments, while the compound can be a non-emissive dopant in other embodiments.

The organic layer can also include a host. In some embodiments, two or more hosts are preferred. In some embodiments, the hosts used maybe a) bipolar, b) electron transporting, c) hole transporting or d) wide band gap materials that play little role in charge transport. In some embodiments, the host can include a metal complex. The host can be a triphenylene containing benzo-fused thiophene or benzo-fused furan. Any substituent in the host can be an unfused substituent independently selected from the group consisting of C n H 2n+1 , OC n H 2n+1 , OAr 1 , N(C n H 2n+1 ) 2 , N(Ar 1 )(Ar 2 ), CH═CH—C n H 2n+1 , C≡C—C n H 2n+1 , Ar 1 , Ar 1 —Ar 2 , and C n H 2n —Ar 1 , or the host has no substitutions. In the preceding substituents n can range from 1 to 10; and Ar 1 and Ar 2 can be independently selected from the group consisting of benzene, biphenyl, naphthalene, triphenylene, carbazole, and heteroaromatic analogs thereof. The host can be an inorganic compound. For example a Zn containing inorganic material e.g. ZnS.

The host can be a compound comprising at least one chemical group selected from the group consisting of triphenylene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, azatriphenylene, azacarbazole, aza-dibenzothiophene, aza-dibenzofuran, and aza-dibenzoselenophene. The host can include a metal complex. The host can be, but is not limited to, a specific compound selected from the group consisting of:

and combinations thereof.

Additional information on possible hosts is provided below.

In yet another aspect of the present disclosure, a formulation that comprises the novel compound disclosed herein is described. The formulation can include one or more components selected from the group consisting of a solvent, a host, a hole injection material, hole transport material, electron blocking material, hole blocking material, and an electron transport material, disclosed herein.

Combination with Other Materials

The materials described herein as useful for a particular layer in an organic light emitting device may be used in combination with a wide variety of other materials present in the device. For example, emissive dopants disclosed herein may be used in conjunction with a wide variety of hosts, transport layers, blocking layers, injection layers, electrodes and other layers that may be present. The materials described or referred to below are non-limiting examples of materials that may be useful in combination with the compounds disclosed herein, and one of skill in the art can readily consult the literature to identify other materials that may be useful in combination.

Conductivity Dopants:

A charge transport layer can be doped with conductivity dopants to substantially alter its density of charge carriers, which will in turn alter its conductivity. The conductivity is increased by generating charge carriers in the matrix material, and depending on the type of dopant, a change in the Fermi level of the semiconductor may also be achieved. Hole-transporting layer can be doped by p-type conductivity dopants and n-type conductivity dopants are used in the electron-transporting layer.

Non-limiting examples of the conductivity dopants that may be used in an OLED in combination with materials disclosed herein are exemplified below together with references that disclose those materials: EP01617493, EP01968131, EP2020694, EP2684932, US20050139810, US20070160905, US20090167167, US2010288362, WO06081780, WO2009003455, WO2009008277, WO2009011327, WO2014009310, US2007252140, US2015060804, US20150123047, and US2012146012.

A hole injecting/transporting material to be used in the present invention is not particularly limited, and any compound may be used as long as the compound is typically used as a hole injecting/transporting material. Examples of the material include, but are not limited to: a phthalocyanine or porphyrin derivative; an aromatic amine derivative; an indolocarbazole derivative; a polymer containing fluorohydrocarbon; a polymer with conductivity dopants; a conducting polymer, such as PEDOT/PSS; a self-assembly monomer derived from compounds such as phosphoric acid and silane derivatives; a metal oxide derivative, such as MoO x ; a p-type semiconducting organic compound, such as 1,4,5,8,9,12-Hexaazatriphenylenehexacarbonitrile; a metal complex, and a cross-linkable compounds.

Examples of aromatic amine derivatives used in HIL or HTL include, but not limit to the following general structures:

Each of Ar 1 to Ar 9 is selected from the group consisting of aromatic hydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl, triphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, and azulene; the group consisting of aromatic heterocyclic compounds such as dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine; and the group consisting of 2 to 10 cyclic structural units which are groups of the same type or different types selected from the aromatic hydrocarbon cyclic group and the aromatic heterocyclic group and are bonded to each other directly or via at least one of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom, chain structural unit and the aliphatic cyclic group. Each Ar may be unsubstituted or may be substituted by a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acids, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

In one aspect, Ar 1 to Ar 9 is independently selected from the group consisting of:

wherein k is an integer from 1 to 20; X 101 to X 108 is C (including CH) or N; Z 101 is Ar 1 , O, or S; Ar 1 has the same group defined above.

Examples of metal complexes used in HIL or HTL include, but are not limited to the following general formula:

wherein Met is a metal, which can have an atomic weight greater than 40; (Y 101 Y 102 ) is a bidentate ligand, Y 101 and Y 102 are independently selected from C, N, O, P, and S; L 101 is an ancillary ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal; and k′+k″ is the maximum number of ligands that may be attached to the metal.

In one aspect, (Y 101 -Y 102 ) is a 2-phenylpyridine derivative. In another aspect, (Y 101 -Y 102 ) is a carbene ligand. In another aspect, Met is selected from Ir, Pt, Os, and Zn. In a further aspect, the metal complex has a smallest oxidation potential in solution vs. Fc + /Fc couple less than about 0.6 V.

Non-limiting examples of the HIL and HTL materials that may be used in an OLED in combination with materials disclosed herein are exemplified below together with references that disclose those materials: CN102702075, DE102012005215, EP01624500, EP01698613, EP01806334, EP01930964, EP01972613, EP01997799, EP02011790, EP02055700, EP02055701, EP1725079, EP2085382, EP2660300, EP650955, JP07-073529, JP2005112765, JP2007091719, JP2008021687, JP2014-009196, KR20110088898, KR20130077473, TW201139402, U.S. Ser. No. 06/517,957, US20020158242, US20030162053, US20050123751, US20060182993, US20060240279, US20070145888, US20070181874, US20070278938, US20080014464, US20080091025, US20080106190, US20080124572, US20080145707, US20080220265, US20080233434, US20080303417, US2008107919, US20090115320, US20090167161, US2009066235, US2011007385, US20110163302, US2011240968, US2011278551, US2012205642, US2013241401, US20140117329, US2014183517, U.S. Pat. Nos. 5,061,569, 5,639,914, WO05075451, WO07125714, WO08023550, WO08023759, WO2009145016, WO2010061824, WO2011075644, WO2012177006, WO2013018530, WO2013039073, WO2013087142, WO2013118812, WO2013120577, WO2013157367, WO2013175747, WO2014002873, WO2014015935, WO2014015937, WO2014030872, WO2014030921, WO2014034791, WO2014104514, WO2014157018.

An electron blocking layer (EBL) may be used to reduce the number of electrons and/or excitons that leave the emissive layer. The presence of such a blocking layer in a device may result in substantially higher efficiencies, and/or longer lifetime, as compared to a similar device lacking a blocking layer. Also, a blocking layer may be used to confine emission to a desired region of an OLED. In some embodiments, the EBL material has a higher LUMO (closer to the vacuum level) and/or higher triplet energy than the emitter closest to the EBL interface. In some embodiments, the EBL material has a higher LUMO (closer to the vacuum level) and/or higher triplet energy than one or more of the hosts closest to the EBL interface. In one aspect, the compound used in EBL contains the same molecule or the same functional groups used as one of the hosts described below.

Host:

The light emitting layer of the organic EL device of the present invention preferably contains at least a metal complex as light emitting material, and may contain a host material using the metal complex as a dopant material. Examples of the host material are not particularly limited, and any metal complexes or organic compounds may be used as long as the triplet energy of the host is larger than that of the dopant. Any host material may be used with any dopant so long as the triplet criteria is satisfied.

Examples of metal complexes used as host are preferred to have the following general formula:

wherein Met is a metal; (Y 103 -Y 104 ) is a bidentate ligand, Y 103 and Y 104 are independently selected from C, N, O, P, and S; L 101 is an another ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal; and k′+k″ is the maximum number of ligands that may be attached to the metal.

In one aspect, the metal complexes are:

wherein (O—N) is a bidentate ligand, having metal coordinated to atoms O and N.

In another aspect, Met is selected from Ir and Pt. In a further aspect, (Y 103 -Y 104 ) is a carbene ligand.

Examples of other organic compounds used as host are selected from the group consisting of aromatic hydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl, triphenylene, tetraphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, and azulene; the group consisting of aromatic heterocyclic compounds such as dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine; and the group consisting of 2 to 10 cyclic structural units which are groups of the same type or different types selected from the aromatic hydrocarbon cyclic group and the aromatic heterocyclic group and are bonded to each other directly or via at least one of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom, chain structural unit and the aliphatic cyclic group. Each option within each group may be unsubstituted or may be substituted by a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acids, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

In one aspect, the host compound contains at least one of the following groups in the molecule:

wherein R 101 is selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acids, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, and when it is aryl or heteroaryl, it has the similar definition as Ar's mentioned above. k is an integer from 0 to 20 or 1 to 20. X 101 to X 108 are independently selected from C (including CH) or N. Z 101 and Z 102 are independently selected from NR 101 , O, or S.

Non-limiting examples of the host materials that may be used in an OLED in combination with materials disclosed herein are exemplified below together with references that disclose those materials: EP2034538, EP2034538A, EP2757608, JP2007254297, KR20100079458, KR20120088644, KR20120129733, KR20130115564, TW201329200, US20030175553, US20050238919, US20060280965, US20090017330, US20090030202, US20090167162, US20090302743, US20090309488, US20100012931, US20100084966, US20100187984, US2010187984, US2012075273, US2012126221, US2013009543, US2013105787, US2013175519, US2014001446, US20140183503, US20140225088, US2014034914, U.S. Pat. No. 7,154,114, WO2001039234, WO2004093207, WO2005014551, WO2005089025, WO2006072002, WO2006114966, WO2007063754, WO2008056746, WO2009003898, WO2009021126, WO2009063833, WO2009066778, WO2009066779, WO2009086028, WO2010056066, WO2010107244, WO2011081423, WO2011081431, WO2011086863, WO2012128298, WO2012133644, WO2012133649, WO2013024872, WO2013035275, WO2013081315, WO2013191404, WO2014142472, US20170263869, US20160163995, U.S. Pat. No. 9,466,803,

Additional Emitters:

One or more additional emitter dopants may be used in conjunction with the compound of the present disclosure. Examples of the additional emitter dopants are not particularly limited, and any compounds may be used as long as the compounds are typically used as emitter materials. Examples of suitable emitter materials include, but are not limited to, compounds which can produce emissions via phosphorescence, fluorescence, thermally activated delayed fluorescence, i.e., TADF (also referred to as E-type delayed fluorescence), triplet-triplet annihilation, or combinations of these processes.

Non-limiting examples of the emitter materials that may be used in an OLED in combination with materials disclosed herein are exemplified below together with references that disclose those materials: CN103694277, CN1696137, EB01238981, EP01239526, EP01961743, EP1239526, EP1244155, EP1642951, EP1647554, EP1841834, EP1841834B, EP2062907, EP2730583, JP2012074444, JP2013110263, JP4478555, KR1020090133652, KR20120032054, KR20130043460, TW201332980, U.S. Ser. No. 06/699,599, U.S. Ser. No. 06/916,554, US20010019782, US20020034656, US20030068526, US20030072964, US20030138657, US20050123788, US20050244673, US2005123791, US2005260449, US20060008670, US20060065890, US20060127696, US20060134459, US20060134462, US20060202194, US20060251923, US20070034863, US20070087321, US20070103060, US20070111026, US20070190359, US20070231600, US2007034863, US2007104979, US2007104980, US2007138437, US2007224450, US2007278936, US20080020237, US20080233410, US20080261076, US20080297033, US200805851, US2008161567, US2008210930, US20090039776, US20090108737, US20090115322, US20090179555, US2009085476, US2009104472, US20100090591, US20100148663, US20100244004, US20100295032, US2010102716, US2010105902, US2010244004, US2010270916, US20110057559, US20110108822, US20110204333, US2011215710, US2011227049, US2011285275, US2012292601, US20130146848, US2013033172, US2013165653, US2013181190, US2013334521, US20140246656, US2014103305, U.S. Pat. Nos. 6,303,238, 6,413,656, 6,653,654, 6,670,645, 6,687,266, 6,835,469, 6,921,915, 7,279,704, 7,332,232, 7,378,162, 7,534,505, 7,675,228, 7,728,137, 7,740,957, 7,759,489, 7,951,947, 8,067,099, 8,592,586, 8,871,361, WO06081973, WO06121811, WO07018067, WO07108362, WO07115970, WO07115981, WO08035571, WO2002015645, WO2003040257, WO2005019373, WO2006056418, WO2008054584, WO2008078800, WO2008096609, WO2008101842, WO2009000673, WO2009050281, WO2009100991, WO2010028151, WO2010054731, WO2010086089, WO2010118029, WO2011044988, WO2011051404, WO2011107491, WO2012020327, WO2012163471, WO2013094620, WO2013107487, WO2013174471, WO2014007565, WO2014008982, WO2014023377, WO2014024131, WO2014031977, WO2014038456, WO2014112450.

A hole blocking layer (HBL) may be used to reduce the number of holes and/or excitons that leave the emissive layer. The presence of such a blocking layer in a device may result in substantially higher efficiencies and/or longer lifetime as compared to a similar device lacking a blocking layer. Also, a blocking layer may be used to confine emission to a desired region of an OLED. In some embodiments, the HBL material has a lower HOMO (further from the vacuum level) and/or higher triplet energy than the emitter closest to the HBL interface. In some embodiments, the HBL material has a lower HOMO (further from the vacuum level) and/or higher triplet energy than one or more of the hosts closest to the HBL interface.

In one aspect, compound used in HBL contains the same molecule or the same functional groups used as host described above.

In another aspect, compound used in HBL contains at least one of the following groups in the molecule:

wherein k is an integer from 1 to 20; L 101 is an another ligand, k′ is an integer from 1 to 3.

Electron transport layer (En) may include a material capable of transporting electrons. Electron transport layer may be intrinsic (undoped), or doped. Doping may be used to enhance conductivity. Examples of the En material are not particularly limited, and any metal complexes or organic compounds may be used as long as they are typically used to transport electrons.

In one aspect, compound used in ETL contains at least one of the following groups in the molecule:

wherein R 101 is selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acids, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, when it is aryl or heteroaryl, it has the similar definition as Ar's mentioned above. Ar 1 to Ar 3 has the similar definition as Ar's mentioned above. k is an integer from 1 to 20. X 101 to X 108 is selected from C (including CH) or N.

In another aspect, the metal complexes used in ETL contains, but not limit to the following general formula:

wherein (O—N) or (N—N) is a bidentate ligand, having metal coordinated to atoms O, N or N, N; L 101 is another ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal.

Non-limiting examples of the ETL materials that may be used in an OLED in combination with materials disclosed herein are exemplified below together with references that disclose those materials: CN103508940, EP01602648, EP01734038, EP01956007, JP2004-022334, JP2005149918, JP2005-268199, KR0117693, KR20130108183, US20040036077, US20070104977, US2007018155, US20090101870, US20090115316, US20090140637, US20090179554, US2009218940, US2010108990, US2011156017, US2011210320, US2012193612, US2012214993, US2014014925, US2014014927, US20140284580, U.S. Pat. Nos. 6,656,612, 8,415,031, WO2003060956, WO2007111263, WO2009148269, WO2010067894, WO2010072300, WO2011074770, WO2011105373, WO2013079217, WO2013145667, WO2013180376, WO2014104499, WO2014104535,

Charge Generation Layer (CGL)

In tandem or stacked OLEDs, the CGL plays an essential role in the performance, which is composed of an n-doped layer and a p-doped layer for injection of electrons and holes, respectively. Electrons and holes are supplied from the CGL and electrodes. The consumed electrons and holes in the CGL are refilled by the electrons and holes injected from the cathode and anode, respectively; then, the bipolar currents reach a steady state gradually. Typical CGL materials include n and p conductivity dopants used in the transport layers.

In any above-mentioned compounds used in each layer of the OLED device, the hydrogen atoms can be partially or fully deuterated. Thus, any specifically listed substituent, such as, without limitation, methyl, phenyl, pyridyl, etc. may be undeuterated, partially deuterated, and fully deuterated versions thereof. Similarly, classes of substituents such as, without limitation, alkyl, aryl, cycloalkyl, heteroaryl, etc. also may be undeuterated, partially deuterated, and fully deuterated versions thereof.

DFT Calculations

Table 1 shows that by using the triazine with nitrogen atoms at the 1, 2 and 4 positions instead of 1, 3, and 5 positions, a considerable bathochromic shift of the emission of the final metal complex can be achieved. Moreover, the 1,2,4-triazine enhances the possibility that additional aromatic rings fused to the triazine will provide even more potential for red shift of the color of the resulting metal complexes.

Materials Synthesis

All reactions were carried out under nitrogen atmosphere unless specified otherwise. All solvents for reactions were anhydrous and used as received from commercial sources.

Synthesis of 3-Amino-5-methylbenzo[e][1,2,4]triazine 1-oxide

To a stirred solution of sodium hydroxide (41.5 g, 1038 mmol) in refluxing EtOH (1 L) was added guanidine hydrochloride (99 g, 1031 mmol). The suspension was stirred at rt for 3 h. The solid was removed by filtration and the filtrate was concentrated under reduced pressure. The residue was dissolved in THF (800 mL) and 2-fluoro-1-methyl-3-nitrobenzene (20 g, 129 mmol) was added. The reaction mixture was stirred at 80° C. overnight. Potassium tert-butoxide (73 g, 651 mmol) was added and the mixture was stirred at the same temperature for 4 h. After cooling, the mixture was acidified to pH 6 with 1 M aq. HCl solution, with ice being periodically added to maintain the temperature below 30° C. The resultant yellow solid was collected by filtration under reduced pressure and washed with water (500 mL). The solid was dried in vacuo at 45° C. to afford 3-amino-5-methylbenzo[e][1,2,4]triazine 1-oxide (14.6 g, 64%) as a yellow solid.

Synthesis of 3-Hydroxy-5-methylbenzo[e][1,2,4]triazine 1-oxide

To a stirred solution of 3-amino-5-methylbenzo[e][1,2,4]triazine 1-oxide (14.6 g, 83.0 mmol) in TFA (290 mL) at 0° C. was added sodium nitrite (6.30 g, 91.0 mmol). The solution was stirred for 1 h at 0° C. and then 4 h at room temperature. The reaction was quenched with water (500 mL) and the mixture stirred for 30 mins. The resultant yellow solid was collected by filtration under reduced pressure, washed with water (3×50 mL) and dried in vacuo at 40° C. to afford 3-hydroxy-5-methylbenzo[e][1,2,4]triazine 1-oxide (12.7 g, 85%) as a yellow solid.

Synthesis of 3-Chloro-5-methylbenzo[e][1,2,4]triazine 1-oxide

A stirred suspension of 3-hydroxy-5-methylbenzo[e][1,2,4]triazine 1-oxide (12.7 g, 71.7 mmol) in POCl 3 (50 mL, 536 mmol) was heated to 100° C. and stirred for 4 h. After cooling, the solution was poured slowly into water and stirred for 10 mins. The resultant solid was collected by filtration, washed with water and dried in vacuo at 40° C. to afford 3-chloro-5-methylbenzo[e][1,2,4]triazine 1-oxide

Synthesis of 5-Methyl-3-phenylbenzo[e][1,2,4]triazine 1-oxide

A stirred mixture of 3-chloro-5-methylbenzo[e][1,2,4]triazine 1-oxide (4.00 g, 20.5 mmol), phenylboronic acid (2.80 g, 23.0 mmol), tetrakis(triphenylphosphine)palladium(0) (1.20 g, 1.04 mmol) and potassium carbonate (6.00 g, 43.4 mmol) in dioxane (100 mL) and water (100 mL) was heated to 100° C. and stirred for 3 h. After cooling, water (500 mL) was added. The resultant solid was collected by filtration under reduced pressure and dried in vacuo at 40° C. to afford 5-methyl-3-phenylbenzo[e][1,2,4]triazine 1-oxide (4.10 g, 82%) as a green solid.

Synthesis of 5-Methyl-3-phenylbenzo[e][1,2,4]triazine (Ligand=L A173 )

A stirred mixture of 5-methyl-3-phenylbenzo[e][1,2,4]triazine 1-oxide (4) (4.10 g, 17.3 mmol) and 5% Pd/C (0.400 g, 0.188 mmol) in EtOH (250 mL) was hydrogenated under 1 bar of hydrogen at rt for 2 h. The reaction mixture was stirred under an air atmosphere over the weekend and then air was bubbled through the mixture for 5 h. The reaction mixture was filtered through a pad of Celite, washing with DCM (400 mL), and concentrated under reduced pressure. The crude material was purified by chromatography on silica gel (330 g, 0-70% DCM/isohexane) and then triturated with refluxing isohexane (25 mL) to afford 5-methyl-3-phenylbenzo[e][1,2,4]triazine (3.10 g, 80%) as a yellow solid.

Synthesis of Compound B 81212

A flask was charged with the iridium triflate salt (1.50 g, 2.02 mmol), 5-methyl-3-phenylbenzo[e][1,2,4]triazine (0.72 g, 3.24 mmol), and then ethanol (81 mL) was added and the reaction solution was degassed with nitrogen. The clear yellow solution was heated to 75° C. for 48 hrs. The reaction solution was cooled to room temperature and filtered. The black solids obtained were washed with EtOH, dissolved in DCM and passed through a plug of silica w/˜1 L DCM. The filtrate was concentrated to ˜1.3 g black solids. The black solids were recrystallized from xylenes to afford 0.65 g of the desired product (43%).

Synthesis of 3-(3,5-Dimethylphenyl)-5-methylbenzo[e][1,2,4]triazine 1-oxide

A stirred mixture of 3-chloro-5-methylbenzo[e][1,2,4]triazine 1-oxide (4.00 g, 20.5 mmol), (3,5-dimethylphenyl)boronic acid (3.40 g, 22.7 mmol), tetrakis(triphenylphosphine)palladium(0) (1.20 g, 1.04 mmol) and potassium carbonate (6.00 g, 43.4 mmol) in dioxane (100 mL) and water (100 mL) was heated to 100° C. and stirred for 2.5 h. The mixture was allowed to cool to rt and stirred overnight. The reaction mixture was diluted with water (250 mL) and stirred for 10 mins. The resultant solid was collected by filtration and dried in vacuo at 40° C. to afford 3-(3,5-dimethylphenyl)-5-methylbenzo[e][1,2,4]triazine 1-oxide (5.30 g, 88%) as pale brown solid.

Synthesis of 3-(3,5-Dimethylphenyl)-5-methylbenzo[e][1,2,4]triazine (Ligand=L A174 )

A stirred mixture of 3-(3,5-dimethylphenyl)-5-methylbenzo[e][1,2,4]triazine 1-oxide (5.30 g, 20.0 mmol) and 5% Pd/C (0.500 g, 0.235 mmol) in DCM (250 mL) was hydrogenated under 1 bar of hydrogen at rt for 24 h. Air was bubbled through the stirred mixture for 3 h. The reaction mixture was filtered through a pad of Celite, washing with DCM (500 mL) and concentrated under reduced pressure. The crude material was purified by chromatography on silica gel (330 g column, 0-70% DCM/isohexane) to afford 3-(3,5-dimethylphenyl)-5-methylbenzo[e][1,2,4]triazine (3.7 g, 74%) as a yellow solid.

Synthesis of Iridium Dimer

A flask was charged with 3-(3,5-dimethylphenyl)-5-methylbenzo[e][1,2,4]triazine (1.01 g, 4.05 mmol), 2-EtOEtOH (17 mL), and water (6 mL), and then degassed with nitrogen. Iridium (III) chloride tetrahydrate (0.50 g, 1.35 mmol) was added and the reaction mixture was heated to 105° C. overnight. The suspension was cooled to room temperature and filtered, washed with MeOH and dried in vacuo (0.95 g, 97%). The material was used as is in the next step.

Synthesis of Compound C 218002

A flask was charged with iridium dimer (0.92 g, 0.64 mmol), 2-EtOEtOH (21.17 nil), and 3,7-diethylnonane-4,6-dione (1.011 g, 4.76 mmol), and then degassed with nitrogen. Potassium carbonate (0.66 g, 4.76 mmol) was added and the reaction was stirred at room temperature overnight. The reaction mixture was diluted with MeOH and filtered through a plug of celite. The solids were washed with MeOH. The dark solids were then collected by washing with DCM. The product was concentrated and recrystallized from DCM/MeOH provided 0.6 g (53%) of desired product.

Synthesis of 3-(4-(tert-Butyl)naphthalen-2-yl)-5-methylbenzo[e][1,2,4]triazine 1-oxide

A suspension of 3-chloro-5-methylbenzo[e][1,2,4]triazine 1-oxide (4.50 g, 23.0 mmol), potassium carbonate (6.74 g, 48.8 mmol) and 2-(4-(tert-butyl)naphthalen-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (7.99 g, 25.8 mmol) in dioxane (100 mL) and water (100 mL) was degassed with bubbling nitrogen for 20 min. Tetrakis(triphenylphosphine)palladium(0) (1.33 g, 1.15 mmol) was added and the mixture was heated to 100° C. and stirred overnight. After cooling to rt, water (500 mL) was added and the mixture stirred at rt for 1 h. The resultant solid was collected by filtration. The solid was triturated with isohexane (10 mL) and then dried in vacuo at 50° C. to afford 3-(4-(tert-butypnaphthalen-2-yl)-5-methylbenzo[e][1,2,4]triazine 1-oxide (7.84 g, 97%) as a yellow solid.

Synthesis of 3-(4-(tert-Butyl)naphthalen-2-yl)-5-methylbenzo[e][1,2,4]triazine (Ligand=L A187 )

A mixture of 3-(4-(tert-butyl)naphthalen-2-yl)-5-methylbenzo[e][1,2,4]triazine 1-oxide (7.85 g, 22.9 mmol) and 5% Pd/C (800 mg, 0.376 mmol) in ethanol (250 mL) was hydrogenated under 1 bar of hydrogen overnight. The reaction mixture was filtered through a pad of Celite, washing with DCM (250 mL). 5% Pd/C (800 mg, 0.376 mmol) was added to the filtrate and the mixture hydrogenated under 3 bar of hydrogen until complete consumption of starting material. Air was bubbled through the mixture for 2 h. The reaction mixture was filtered through a pad of Celite, washing with DCM (200 mL). The crude product was purified by chromatography on silica gel (330 g, 0-60% DCM/isohexane) and then triturated with isohexane (20 mL) to afford 3-(4-(tert-butyl)naphthalen-2-yl)-5-methylbenzo[e][1,2,4]triazine (3.60 g, 48%) as a yellow solid.

Synthesis of Iridium Dimer

A flask was charged with 3-(4-(tert-butyl)naphthalen-2-yl)-5-methylbenzo[e][1,2,4]triazine (2.44 g, 7.45 mmol), 2-EtOEtOH (60 mL), and water (20 mL), and then degassed with nitrogen. Iridium (III) chloride tetrahydrate (1.20 g, 3.24 mmol) was added and the reaction mixture was heated to 105° C. overnight. The suspension was cooled to room temperature and filtered, washed with MeOH and dried in vacuo (1.10 g, 39%). The product was used as is in the next step.

Synthesis of Compound C 234361

A flask was charged with iridium dimer (1.00 g, 0.57 mmol), 2-EtOEtOH (60 mL), and pentane-2,4-dione (0.57 g, 5.68 mmol), and degassed with nitrogen. Potassium carbonate (0.79 g, 5.68 mmol) was added and the reaction was stirred at room temperature overnight. The reaction mixture was diluted with MeOH and filtered through a plug of celite. The solids were washed with MeOH. The dark solids were then collected by washing with DCM. The product was concentrated and recrystallized from DCM/MeOH provided 0.39 g (36%) of desired product.

Synthesis of 5-Methyl-3-(naphthalen-1-yl)benzo[e][1,2,4]triazine 1-oxide

A mixture of 3-chloro-5-methylbenzo[e][1,2,4]triazine 1-oxide (3.30 g, 16.9 mmol), potassium carbonate (4.94 g, 35.8 mmol) and naphthalen-1-ylboronic acid (3.25 g, 18.9 mmol) in dioxane (50 mL) and water (50 mL) was degassed with bubbling nitrogen for 20 mins. Tetrakis(triphenylphosphine)palladium(0) (0.98 g, 0.84 mmol) was added and the mixture heated to 100° C. and stirred for 2 h. After cooling to rt, water (200 mL) was added and the mixture stirred at rt for 1 h. The resultant solid was collected by filtration and dried in vacuo to afford 5-methyl-3-(naphthalen-1-yl)benzo[e][1,2,4]triazine 1-oxide (4.75 g, 97%) as a yellow solid.

Synthesis of 5-Methyl-3-(naphthalen-1-yl)benzo[e][1,2,4]triazine (Ligand=L A186 )

A mixture of 5-methyl-3-(naphthalen-2-yl)benzo[e][1,2,4]triazine 1-oxide (1) (4.75 g, 16.5 mmol) and 10% Pd/C (0.475 g, 4.46 mmol) in EtOH (100 mL) and DCM (100 mL) was hydrogenated under 3 bar of hydrogen at rt for 4 h. Air was bubbled through the reaction mixture for 2 h. The reaction mixture was diluted with DCM, filtered through a short pad of Celite and concentrated under reduced pressure. The crude product was purified by successive chromatography on silica gel (80 g, 0-30% EtOAc/isohexane; 80 g, 0-50% DCM/isohexane) to afford the 5-methyl-3-(naphthalen-1-yl)benzo[e][1,2,4]triazine (2.35 g, 52%) as a yellow solid.

Synthesis of Iridium Dimer

A flask was charged with 3-(4-(tert-butyl)naphthalen-2-yl)-5-methylbenzo[e][1,2,4]triazine (2.20 g, 8.09 mmol), 2-EtOEtOH (60 mL), and water (20 mL), and then degassed with nitrogen. Iridium (III) chloride tetrahydrate (1.20 g, 3.24 mmol) was added and the reaction mixture was heated to 105° C. overnight. The suspension was cooled to room temperature and filtered, washed with MeOH and dried in vacuo (2.53 g, Quant.). The product was used as is in the next step.

Synthesis of Compound C 233122

A flask was charged with iridium dimer (2.55 g, 1.66 mmol), 2-EtOEtOH (60 mL), and 3,7-diethylnonane-4,6-dione (3.52 g, 16.6 mmol), and then degassed with nitrogen. Potassium carbonate (2.29 g, 16.6 mmol) was added and the reaction was stirred at room temperature overnight. The reaction mixture was diluted with MeOH and filtered through a plug of celite. The solids were washed with MeOH. The dark solids were then collected by washing with DCM. The product was concentrated and recrystallized from DCM/MeOH provided 2.10 g (85%) of desired product.

Photoluminescent data confirm that the inventive compounds can emit in deep red and infra-red part of the spectrum.

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 with other materials and structures without deviating from the spirit of the invention. The present invention as claimed may therefore include variations from the particular examples and preferred embodiments described herein, as will be apparent to one of skill in the art. It is understood that various theories as to why the invention works are not intended to be limiting.