Patent Description:
The present disclosure generally relates to organometallic compounds and formulations and their various uses including as emitters in devices such as organic light emitting diodes and related electronic devices.

Opto-electronic devices that make use of organic materials are becoming increasingly desirable for various 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.

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.

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 emissive layer (EML) device or a stack structure. Color may be measured using CIE coordinates, which are well known to the art.

<CIT> discloses an organometallic compound, an organic light-emitting device including the organometallic compound, and a diagnostic composition including the organometallic compound.

In one aspect, the present disclosure provides a compound of Formula I:
<CHM>
In Formula I:.

In another aspect, the present disclosure provides a formulation comprising a compound of Formula I as described herein.

In yet another aspect, the present disclosure provides an OLED having an organic layer comprising a compound of Formula I as described herein.

In yet another aspect, the present disclosure provides a consumer product comprising an OLED with an organic layer comprising a compound of Formula I as described herein.

Unless otherwise specified, the below terms used herein are defined as follows:
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.

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

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)-Rs).

The term "ester" refers to a substituted oxycarbonyl (-O-C(O)-Rs or -C(O)-O-Rs) radical.

The term "ether" refers to an -ORs radical.

The terms "sulfanyl" or "thio-ether" are used interchangeably and refer to a -SRs radical.

The term "selenyl" refers to a -SeRs radical.

The term "sulfinyl" refers to a -S(O)-Rs radical.

The term "sulfonyl" refers to a -SO<NUM>-Rs radical.

The term "phosphino" refers to a -P(Rs)<NUM> radical, wherein each Rs can be same or different.

The term "silyl" refers to a -Si(Rs)<NUM> radical, wherein each Rs can be same or different.

The term "germyl" refers to a -Ge(Rs)<NUM> radical, wherein each Rs can be same or different.

The term "boryl" refers to a -B(Rs)<NUM> radical or its Lewis adduct -B(Rs)<NUM> radical, wherein Rs can be same or different.

In each of the above, Rs 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 Rs 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, <NUM>-methylethyl, butyl, <NUM>-methylpropyl, <NUM>-methylpropyl, pentyl, <NUM>-methylbutyl, <NUM>-methylbutyl, <NUM>-methylbutyl, <NUM>,<NUM>-dimethylpropyl, <NUM>,<NUM>-dimethylpropyl, <NUM>,<NUM>-dimethylpropyl, and the like. Additionally, the alkyl group may be optionally substituted.

The term "cycloalkyl" refers to and includes monocyclic, polycyclic, and spiro alkyl radicals. Preferred cycloalkyl groups are those containing <NUM> to <NUM> ring carbon atoms and includes cyclopropyl, cyclopentyl, cyclohexyl, bicyclo[<NUM>. <NUM>]heptyl, spiro[<NUM>]decyl, spiro[<NUM>]undecyl, adamantyl, and the like. Additionally, the cycloalkyl group may be 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 may be 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 may be optionally substituted.

The term "alkynyl" refers to and includes both straight and branched chain alkyne radicals. Alkynyl groups are essentially alkyl groups that include at least one carbon-carbon triple bond in the alkyl chain. Preferred alkynyl groups are those containing two to fifteen carbon atoms. Additionally, the alkynyl group may be 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 may be 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 <NUM> to <NUM> 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 may be 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 <NUM> or <NUM> 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, 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, preferably dibenzothiophene, dibenzofuran, dibenzoselenophene, carbazole, indolocarbazole, imidazole, pyridine, triazine, benzimidazole, <NUM>,<NUM>-azaborine, <NUM>,<NUM>-azaborine, <NUM>,<NUM>-azaborine, borazine, and aza-analogs thereof. Additionally, the heteroaryl group may be 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, germyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, selenyl, 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, germyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, boryl, and combinations thereof.

In some instances, the More 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 Most Preferred General Substituents are selected from the group consisting of deuterium, fluorine, alkyl, cycloalkyl, aryl, heteroaryl, and combinations thereof.

The terms "substituted" and "substitution" refer to a substituent other than H that is bonded to the relevant position, e.g., a carbon or nitrogen. For example, when R<NUM> represents mono-substitution, then one R<NUM> must be other than H (i.e., a substitution). Similarly, when R<NUM> represents di-substitution, then two of R<NUM> must be other than H. Similarly, when R<NUM> represents zero or no substitution, R<NUM>, for example, can be a hydrogen for available valencies of ring atoms, as in carbon atoms for benzene and the nitrogen atom in pyrrole, or simply represents nothing for ring atoms with fully filled valencies, e.g., the nitrogen atom in pyridine. The maximum number of substitutions possible in a ring structure will depend on the total number of available valencies in the ring atoms.

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 aromatic ring 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, <CIT>, Patent Pub. No. <CIT>, and U. Application Pub. No. <CIT>, describe the making of deuterium-substituted organometallic complexes. Further reference is made to <NPL> and <NPL>, 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.

In some instance, a pair of adjacent substituents can be optionally joined or fused into a ring. The preferred ring is a five, six, or seven-membered carbocyclic or heterocyclic ring, includes both instances where the portion of the ring formed by the pair of substituents is saturated and where the portion of the ring formed by the pair of substituents is unsaturated. As used herein, "adjacent" means that the two substituents involved can be on the same ring next to each other, or on two neighboring rings having the two closest available substitutable positions, such as <NUM>, <NUM>' positions in a biphenyl, or <NUM>, <NUM> position in a naphthalene, as long as they can form a stable fused ring system.

any two substituents may be joined or fused to form a ring.

In some embodiments, each R, R', RA, RB, RC and RD is independently hydrogen or a substituent selected from the group consisting of the preferred general substituents defined herein. In some embodiments, each R, R', RA, RB, RC, and RD is independently hydrogen or a substituent selected from the group consisting of the more preferred general substituents defined herein. In some embodiments, each R, R', RA, RB, RC, and RD is independently hydrogen or a substituent selected from the group consisting of the most preferred general substituents defined herein.

In some embodiments, at least one of R<NUM> and R<NUM> is not hydrogen. In some embodiments, at least one of R<NUM> and R<NUM> is not hydrogen. In some embodiments, Formula Ia is directly attached to the associated ring. In some embodiments, Formula Ia is attached to the associated ring through an organic linker. In some such embodiments, the organic linker can be one or more unfused substituted or unsubstituted <NUM>-membered aromatic ring. In some such embodiments, the <NUM>-membered aromatic ring is phenyl.

In some embodiments, R* comprises two or more unfused phenyl rings, and at least one of the two or more unfused phenyl rings that is not directly attached to one of X<NUM> to X<NUM> or N* has an ortho substituent that is not hydrogen.

In some embodiments, R, R', or both are a substituent R*.

In some embodiments, at least one RA is a substituent R*.

In some embodiments, at least one RB is a substituent R*.

In some embodiments, at least one RC is a substituent R*.

In some embodiments, RD at X<NUM> is a substituent R*.

In some embodiments, at least two of R, R', RA, RB, RC, or RD are independently substituents R*. In some embodiments, exactly two of R, R', RA, RB, RC, or RD are independently substituents R*.

In some embodiments, R is a substituent R* and at least one RD is a substituent R*. In some embodiments, R is a substituent R* and exactly one RD is a substituent R*. In some such embodiments, RD at X<NUM> is the substituent R*.

In some embodiments, each of X<NUM> to X<NUM> is C. In some embodiments, each of X<NUM> to X<NUM> is C. In some embodiments, each of X<NUM> to X<NUM> is C. In some embodiments, each of X<NUM> to X<NUM> is C. In some embodiments, each of X<NUM> to X<NUM> is C.

In some embodiments, at least one of X<NUM> to X<NUM> is N. In some embodiments, at least one of X<NUM> to X<NUM> is N. In some embodiments, at least one of X<NUM> to X<NUM> is N. In some embodiments, at least one of X<NUM> to X<NUM> is N. In some embodiments, at least one of X<NUM> to X<NUM> is N.

In some embodiments, K<NUM> is a direct bond. In some embodiments, K<NUM> is O. In some embodiments, K<NUM> is S.

In some embodiments, Z<NUM> is C and Z<NUM> is N. In some embodiments, Z<NUM> is N and Z<NUM> is C.

In some embodiments, Y is O. In some embodiments, Y is S. In some embodiments, Y is Se. In some embodiments, Y is N*R. In some embodiments, Y is CRR'. In some embodiments, Y is SiRR'. In some embodiments, Y is GeRR'.

In some embodiments, R* is selected from the group consisting of Formulas II,
<CHM>
<CHM>
In these structures:.

In some embodiments, L comprises at least one aryl or substituted aryl.

In some embodiments, R* has a structure of Formula II.

In some embodiments where R* has a structure of Formula II, each of X<NUM> to X<NUM> is C.

In some embodiments where R* has a structure of Formula II, at least one of X<NUM> to X<NUM> is N.

In some embodiments where R* has a structure of Formula II, L comprises at least one aryl or substituted aryl.

In some embodiments where R* has a structure of Formula II, L is bonded to X<NUM>.

In some embodiments where R* has a structure of Formula II, L is bonded to X<NUM> and X<NUM> and X<NUM> are N.

In some embodiments where R* has a structure of Formula II, L is bonded to X<NUM> and X<NUM>, X<NUM> and X<NUM> are N.

In some embodiments where R* has a structure of Formula II, RE comprises a moiety selected from the group consisting of alkyl, cycloalkyl, aryl, and heteroaryl.

In some embodiments, R* has a structure of Formula III.

In some embodiments where R* has a structure of Formula III, each of X<NUM> to X<NUM> is C.

In some embodiments where R* has a structure of Formula III, at least one of X<NUM> to X<NUM> is N.

In some embodiments where R* has a structure of Formula III, Z is N, and L is bonded to Z.

In some embodiments where R* has a structure of Formula III, Z is NRZ.

In some embodiments where R* has a structure of Formula III, Z is O.

In some embodiments where R* has a structure of Formula III, Z is S.

In some embodiments where R* has a structure of Formula III, Z is Se.

In some embodiments where R* has a structure of Formula III, Z is CRZRZ' or SiRZRZ'.

In some embodiments, R* has a structure of Formula IV.

In some embodiments where R* has a structure of Formula IV, L is bonded to X<NUM> and at least one of X<NUM> or X<NUM> is N. In some embodiments where R* has a structure of Formula IV, L is bonded to X<NUM> and either X<NUM> or X<NUM> is N.

In some embodiments where R* has a structure of Formula IV, L is bonded to X<NUM> and X<NUM> is N.

In some embodiments, R* comprises a <NUM>-membered or <NUM>-membered heterocyclic ring.

In some embodiments, R* comprises two or more unfused phenyl rings, and at least one of the two or more unfused phenyl rings that is not directly attached to one of X<NUM> to X<NUM> has an ortho substituent that is not hydrogen.

In some embodiments, R* is selected from the group consisting of:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
where:.

In some embodiments, the compound is selected from the group consisting of:
<CHM>
<CHM>
<CHM>
<CHM>
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and
<CHM>
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<CHM>
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<CHM>
<CHM>
<CHM>
<CHM>.

In some embodiments, the compound is selected from the group consisting of:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
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<CHM>
<CHM>
<CHM>
<CHM>
and
<CHM>.

In some embodiments, the compound having a structure of Formula I or otherwise described herein can be at least <NUM>% deuterated, at least <NUM>% deuterated, at least <NUM>% deuterated, at least <NUM>% deuterated, at least <NUM>% deuterated, at least <NUM>% deuterated, at least <NUM>% deuterated, at least <NUM>% deuterated, at least <NUM>% deuterated, or <NUM>% deuterated. As used herein, percent deuteration has its ordinary meaning and includes the percent of possible hydrogen atoms (e.g., positions that are hydrogen or deuterium) that are replaced by deuterium atoms.

In some embodiments of heteroleptic compound having the formula of M(LA)p(LB)q(LC)r as defined above, the ligand LA has a first substituent RI, where the first substituent RI has a first atom a-I that is the farthest away from the metal M among all atoms in the ligand LA. Additionally, the ligand LB, if present, has a second substituent RII, where the second substituent RII has a first atom a-II that is the farthest away from the metal M among all atoms in the ligand LB. Furthermore, the ligand LC, if present, has a third substituent RIII, where the third substituent RIII has a first atom a-III that is the farthest away from the metal M among all atoms in the ligand LC.

In such heteroleptic compounds, vectors VD1, VD2, and VD3 can be defined that are defined as follows. VD1 represents the direction from the metal M to the first atom a-I and the vector VD1 has a value D<NUM> that represents the straight line distance between the metal M and the first atom a-I in the first substituent RI. VD2 represents the direction from the metal M to the first atom a-II and the vector VD2 has a value D<NUM> that represents the straight line distance between the metal M and the first atom a-II in the second substituent RII. VD3 represents the direction from the metal M to the first atom a-III and the vector VD3 has a value D<NUM> that represents the straight line distance between the metal M and the first atom a-III in the third substituent RIII.

In such heteroleptic compounds, a sphere having a radius r is defined whose center is the metal M and the radius r is the smallest radius that will allow the sphere to enclose all atoms in the compound that are not part of the substituents RI, RII and RIII; and where at least one of D<NUM>, D<NUM>, and D<NUM> is greater than the radius r by at least <NUM>Å. In some embodiments, at least one of D<NUM>, D<NUM>, and D<NUM> is greater than the radius r by at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>Å.

In some embodiments of such heteroleptic compound, the compound has a transition dipole moment axis and angles are defined between the transition dipole moment axis and the vectors VD1, VD2, and VD3, where at least one of the angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 is less than <NUM>°. In some embodiments, at least one of the angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 is less than <NUM>°. In some embodiments, at least one of the angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 is less than <NUM>°. In some embodiments, at least one of the angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 is less than <NUM>°. In some embodiments, at least one of the angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 is less than <NUM>°. In some embodiments, at least two of the angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 are less than <NUM>°. In some embodiments, at least two of the angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 are less than <NUM>°. In some embodiments, at least two of the angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 are less than <NUM>°.

In some embodiments, all three angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 are less than <NUM>°. In some embodiments, all three angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 are less than <NUM>°. In some embodiments, all three angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 are less than <NUM>°.

In some embodiments of such heteroleptic compounds, the compound has a vertical dipole ratio (VDR) of <NUM> or less. In some embodiments of such heteroleptic compounds, the compound has a VDR of <NUM> or less. In some embodiments of such heteroleptic compounds, the compound has a VDR of <NUM> or less. In some embodiments of such heteroleptic compounds, the compound has a VDR of <NUM> or less. In some embodiments of such heteroleptic compounds, the compound has a VDR of <NUM> or less.

One of ordinarly skill in the art would readily understand the meaning of the terms transition dipole moment axis of a compound and vertical dipole ratio of a compound. Nevertheless, the meaning of these terms can be found in <CIT>. In <CIT>, horizontal dipole ratio (HDR) of a compound, rather than VDR, is discussed. However, one skilled in the art readily understands that VDR = <NUM> - HDR.

In another aspect, the present disclosure also provides an OLED device comprising a first organic layer that contains a compound as disclosed in the above compounds section of the present disclosure.

In some embodiments, the OLED comprises: an anode; a cathode; and an organic layer disposed between the anode and the cathode, where the organic layer comprises a compound of Formula I as described herein.

In some embodiments, the organic layer may be an emissive layer and the compound as described herein may be an emissive dopant or a non-emissive dopant.

In some embodiments, the emissive layer comprises one or more quantum dots.

In some embodiments, the organic layer may further comprise 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 CnH2n+<NUM>, OCnH2n+<NUM>, OAr<NUM>, N(CnH2n+<NUM>)<NUM>, N(Ar<NUM>)(Ar<NUM>), CH=CH-CnH2n+<NUM>, C≡CCnH2n+<NUM>, Ar<NUM>, Ar<NUM>-Ar<NUM>, CnH2n-Ar<NUM>, or no substitution, wherein n is an integer from <NUM> to <NUM>; and wherein Ar<NUM> and Ar<NUM> are independently selected from the group consisting of benzene, biphenyl, naphthalene, triphenylene, carbazole, and heteroaromatic analogs thereof.

In some embodiments, the organic layer may further comprise a host, wherein host comprises at least one chemical group selected from the group consisting of triphenylene, carbazole, indolocarbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, 5λ2-benzo[d]benzo[<NUM>,<NUM>]imidazo[<NUM>,<NUM>-a]imidazole, <NUM>,<NUM>-dioxa-13b-boranaphtho[<NUM>,<NUM>,<NUM>-de]anthracene, triazine, boryl, silyl, aza-triphenylene, aza-carbazole, azaindolocarbazole, aza-dibenzothiophene, aza-dibenzofuran, aza-dibenzoselenophene, aza-5λ2-benzo[d]benzo[<NUM>,<NUM>]imidazo[<NUM>,<NUM>-a]imidazole, and aza-(<NUM>,<NUM>-dioxa-13b-boranaphtho[<NUM>,<NUM>,<NUM>-de]anthracene).

In some embodiments, the host may be selected from the HOST Group consisting of:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
and combinations thereof.

In some embodiments, the organic layer may further comprise a host, wherein the host comprises a metal complex.

In some embodiments, the emissive layer can comprise two hosts, a first host and a second host. In some embodiments, the first host is a hole transporting host, and the second host is an electron transporting host. In some embodiments, the first host and the second host can form an exciplex.

In some embodiments, the compound as described herein may be a sensitizer; wherein the device may further comprise an acceptor; and wherein the acceptor may be selected from the group consisting of fluorescent emitter, delayed fluorescence emitter, and combination thereof.

In yet another aspect, the OLED of the present disclosure may also comprise an emissive region containing a compound as disclosed in the above compounds section of the present disclosure.

In some embodiments, the emissive region can comprise a compound of Formula I as described herein.

In some embodiments, at least one of the anode, the cathode, or a new layer disposed over the organic emissive layer functions as an enhancement layer. The enhancement layer comprises a plasmonic material exhibiting surface plasmon resonance that non-radiatively couples to the emitter material and transfers excited state energy from the emitter material to non-radiative mode of surface plasmon polariton. The enhancement layer is provided no more than a threshold distance away from the organic emissive layer, wherein the emitter material has a total non-radiative decay rate constant and a total radiative decay rate constant due to the presence of the enhancement layer and the threshold distance is where the total non-radiative decay rate constant is equal to the total radiative decay rate constant. In some embodiments, the OLED further comprises an outcoupling layer. In some embodiments, the outcoupling layer is disposed over the enhancement layer on the opposite side of the organic emissive layer. In some embodiments, the outcoupling layer is disposed on opposite side of the emissive layer from the enhancement layer but still outcouples energy from the surface plasmon mode of the enhancement layer. The outcoupling layer scatters the energy from the surface plasmon polaritons. In some embodiments this energy is scattered as photons to free space. In other embodiments, the energy is scattered from the surface plasmon mode into other modes of the device such as but not limited to the organic waveguide mode, the substrate mode, or another waveguiding mode. If energy is scattered to the non-free space mode of the OLED other outcoupling schemes could be incorporated to extract that energy to free space. In some embodiments, one or more intervening layer can be disposed between the enhancement layer and the outcoupling layer. The examples for interventing layer(s) can be dielectric materials, including organic, inorganic, perovskites, oxides, and may include stacks and/or mixtures of these materials.

The enhancement layer modifies the effective properties of the medium in which the emitter material resides resulting in any or all of the following: a decreased rate of emission, a modification of emission line-shape, a change in emission intensity with angle, a change in the stability of the emitter material, a change in the efficiency of the OLED, and reduced efficiency roll-off of the OLED device. Placement of the enhancement layer on the cathode side, anode side, or on both sides results in OLED devices which take advantage of any of the above-mentioned effects. In addition to the specific functional layers mentioned herein and illustrated in the various OLED examples shown in the figures, the OLEDs according to the present disclosure may include any of the other functional layers often found in OLEDs.

The enhancement layer can be comprised of plasmonic materials, optically active metamaterials, or hyperbolic metamaterials. As used herein, a plasmonic material is a material in which the real part of the dielectric constant crosses zero in the visible or ultraviolet region of the electromagnetic spectrum. In some embodiments, the plasmonic material includes at least one metal. In such embodiments the metal may include at least one of Ag, Al, Au, Ir, Pt, Ni, Cu, W, Ta, Fe, Cr, Mg, Ga, Rh, Ti, Ru, Pd, In, Bi, Ca alloys or mixtures of these materials, and stacks of these materials. In general, a metamaterial is a medium composed of different materials where the medium as a whole acts differently than the sum of its material parts. In particular, we define optically active metamaterials as materials which have both negative permittivity and negative permeability. Hyperbolic metamaterials, on the other hand, are anisotropic media in which the permittivity or permeability are of different sign for different spatial directions. Optically active metamaterials and hyperbolic metamaterials are strictly distinguished from many other photonic structures such as Distributed Bragg Reflectors ("DBRs") in that the medium should appear uniform in the direction of propagation on the length scale of the wavelength of light. Using terminology that one skilled in the art can understand: the dielectric constant of the metamaterials in the direction of propagation can be described with the effective medium approximation. Plasmonic materials and metamaterials provide methods for controlling the propagation of light that can enhance OLED performance in a number of ways.

In some embodiments, the enhancement layer is provided as a planar layer. In other embodiments, the enhancement layer has wavelength-sized features that are arranged periodically, quasi-periodically, or randomly, or sub-wavelength-sized features that are arranged periodically, quasi-periodically, or randomly. In some embodiments, the wavelength-sized features and the sub-wavelength-sized features have sharp edges.

In some embodiments, the outcoupling layer has wavelength-sized features that are arranged periodically, quasi-periodically, or randomly, or sub-wavelength-sized features that are arranged periodically, quasi-periodically, or randomly. In some embodiments, the outcoupling layer may be composed of a plurality of nanoparticles and in other embodiments the outcoupling layer is composed of a pluraility of nanoparticles disposed over a material. In these embodiments the outcoupling may be tunable by at least one of varying a size of the plurality of nanoparticles, varying a shape of the plurality of nanoparticles, changing a material of the plurality of nanoparticles, adjusting a thickness of the material, changing the refractive index of the material or an additional layer disposed on the plurality of nanoparticles, varying a thickness of the enhancement layer, and/or varying the material of the enhancement layer. The plurality of nanoparticles of the device may be formed from at least one of metal, dielectric material, semiconductor materials, an alloy of metal, a mixture of dielectric materials, a stack or layering of one or more materials, and/or a core of one type of material and that is coated with a shell of a different type of material. In some embodiments, the outcoupling layer is composed of at least metal nanoparticles wherein the metal is selected from the group consisting of Ag, Al, Au, Ir, Pt, Ni, Cu, W, Ta, Fe, Cr, Mg, Ga, Rh, Ti, Ru, Pd, In, Bi, Ca, alloys or mixtures of these materials, and stacks of these materials. The plurality of nanoparticles may have additional layer disposed over them. In some embodiments, the polarization of the emission can be tuned using the outcoupling layer. Varying the dimensionality and periodicity of the outcoupling layer can select a type of polarization that is preferentially outcoupled to air. In some embodiments the outcoupling layer also acts as an electrode of the device.

In yet another aspect, the present disclosure also provides a consumer product comprising an organic light-emitting device (OLED) having an anode; a cathode; and an organic layer disposed between the anode and the cathode, wherein the organic layer may comprise a compound as disclosed in the above compounds section of the present disclosure.

In some embodiments, the consumer product comprises an OLED having an anode; a cathode; and an organic layer disposed between the anode and the cathode, wherein the organic layer may comprise a compound of Formula I as described herein.

In some embodiments, the consumer product can be one of a flat panel 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 laser printer, a telephone, a cell phone, tablet, a phablet, a personal digital assistant (PDA), a wearable device, a laptop computer, a digital camera, a camcorder, a viewfinder, a micro-display that is less than <NUM> inches (<NUM> inch = <NUM>) diagonal, a <NUM>-D display, a virtual reality or augmented reality display, a vehicle, a video wall comprising multiple displays tiled together, a theater or stadium screen, a light therapy device, and a sign.

Several OLED materials and configurations are described in <CIT>, <CIT>, and <CIT>.

More examples for each of these layers are available. For example, a flexible and transparent substrate-anode combination is disclosed in <CIT>. An example of a p-doped hole transport layer is m-MTDATA doped with F<NUM>-TCNQ at a molar ratio of <NUM>:<NUM>, as disclosed in <CIT>. Examples of emissive and host materials are disclosed in <CIT>. An example of an n-doped electron transport layer is BPhen doped with Li at a molar ratio of <NUM>:<NUM>, as disclosed in <CIT>. <CIT> and <CIT>, 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 <CIT> and <CIT>. Examples of injection layers are provided in <CIT>. A description of protective layers may be found in <CIT>.

The simple layered structure illustrated in <FIG> and <FIG> is provided by way of non-limiting example, and it is understood that embodiments of the present disclosure 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 <NUM>, hole transport layer <NUM> transports holes and injects holes into emissive layer <NUM>, 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 <FIG> and <FIG>.

Structures and materials not specifically described may also be used, such as OLEDs comprised of polymeric materials (PLEDs) such as disclosed in <CIT>. By way of further example, OLEDs having a single organic layer may be used. OLEDs may be stacked, for example as described in <CIT> The OLED structure may deviate from the simple layered structure illustrated in <FIG> and <FIG>. For example, the substrate may include an angled reflective surface to improve outcoupling, such as a mesa structure as described in <CIT>, and/or a pit structure as described in <CIT>.

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 <CIT> and <CIT>, organic vapor phase deposition (OVPD), such as described in <CIT>, and deposition by organic vapor jet printing (OVJP, also referred to as organic vapor jet deposition (OVJD)), such as described in <CIT>. 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 <CIT> and <CIT>, 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 <NUM> carbons, may be used in small molecules to enhance their ability to undergo solution processing. Substituents having <NUM> carbons or more may be used, and <NUM>-<NUM> carbons are a preferred range. Materials with asymmetric structures may have better solution processability 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 disclosure 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 <CIT>, PCT Pat. Application Nos. <CIT> and <CIT>. 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 <NUM>:<NUM> to <NUM>:<NUM>. 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 present disclosure 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 present disclosure 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 <NUM> inches (<NUM> inch = <NUM>) diagonal), <NUM>-D displays, virtual reality or augmented reality displays, vehicles, video walls comprising multiple displays tiled together, theater or stadium screen, a light therapy device, and a sign. Various control mechanisms may be used to control devices fabricated in accordance with the present disclosure, including passive matrix and active matrix. Many of the devices are intended for use in a temperature range comfortable to humans, such as <NUM> degrees C. to <NUM> degrees C. , and more preferably at room temperature (<NUM>-<NUM>), but could be used outside this temperature range, for example, from -<NUM> degree C to + <NUM>.

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 <NUM> inch (<NUM> inch = <NUM>) diagonal or <NUM> square inch (<NUM> square inch = <NUM>,<NUM><NUM>) area. In some embodiments, the OLED is a display panel having at least <NUM> inch (<NUM> inch = <NUM>) diagonal or <NUM> square inch (<NUM> square inch = <NUM>,<NUM><NUM>) 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.,<CIT>), triplet-triplet annihilation, or combinations of these processes. In some embodiments, the emissive dopant can be a racemic mixture, or can be enriched in one enantiomer. In some embodiments, the compound can be homoleptic (each ligand is the same). In some embodiments, the compound can be heteroleptic (at least one ligand is different from others). When there are more than one ligand coordinated to a metal, the ligands can all be the same in some embodiments. In some other embodiments, at least one ligand is different from the other ligands. In some embodiments, every ligand can be different from each other. This is also true in embodiments where a ligand being coordinated to a metal can be linked with other ligands being coordinated to that metal to form a tridentate, tetradentate, pentadentate, or hexadentate ligands. Thus, where the coordinating ligands are being linked together, all of the ligands can be the same in some embodiments, and at least one of the ligands being linked can be different from the other ligand(s) in some other embodiments.

In some embodiments, the compound can be used as a phosphorescent sensitizer in an OLED where one or multiple layers in the OLED contains an acceptor in the form of one or more fluorescent and/or delayed fluorescence emitters. In some embodiments, the compound can be used as one component of an exciplex to be used as a sensitizer. As a phosphorescent sensitizer, the compound must be capable of energy transfer to the acceptor and the acceptor will emit the energy or further transfer energy to a final emitter. The acceptor concentrations can range from <NUM>% to <NUM>%. The acceptor could be in either the same layer as the phosphorescent sensitizer or in one or more different layers. In some embodiments, the acceptor is a TADF emitter. In some embodiments, the acceptor is a fluorescent emitter. In some embodiments, the emission can arise from any or all of the sensitizer, acceptor, and final emitter.

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.

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.

The present disclosure encompasses any chemical structure comprising the novel compound of the present disclosure, or a monovalent or polyvalent variant thereof. In other words, the inventive compound, or a monovalent or polyvalent variant thereof, can be a part of a larger chemical structure. Such chemical structure can be selected from the group consisting of a monomer, a polymer, a macromolecule, and a supramolecule (also known as supermolecule). As used herein, a "monovalent variant of a compound" refers to a moiety that is identical to the compound except that one hydrogen has been removed and replaced with a bond to the rest of the chemical structure. As used herein, a "polyvalent variant of a compound" refers to a moiety that is identical to the compound except that more than one hydrogen has been removed and replaced with a bond or bonds to the rest of the chemical structure. In the instance of a supramolecule, the inventive compound can also be incorporated into the supramolecule complex without covalent bonds.

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.

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: <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>. <CHM>
<CHM>
<CHM>
<CHM>
<CHM>.

A hole injecting/transporting material to be used in the present disclosure 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 phosphonic acid and silane derivatives; a metal oxide derivative, such as MoOx; a p-type semiconducting organic compound, such as <NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>-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:
<CHM>.

Each of Ar<NUM> to Ar<NUM> 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 <NUM> to <NUM> 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<NUM> to Ar<NUM> is independently selected from the group consisting of:
<CHM>
<CHM>
wherein k is an integer from <NUM> to <NUM>; X<NUM> to X<NUM> is C (including CH) or N; Z<NUM> is NAr<NUM>, O, or S; Ar<NUM> 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:
<CHM>
wherein Met is a metal, which can have an atomic weight greater than <NUM>; (Y<NUM>-Y<NUM>) is a bidentate ligand, Y<NUM> and Y<NUM> are independently selected from C, N, O, P, and S; L<NUM> is an ancillary ligand; k' is an integer value from <NUM> 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<NUM>-Y<NUM>) is a <NUM>-phenylpyridine derivative. In another aspect, (Y<NUM>-Y<NUM>) 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 <NUM> 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: <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>. <CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
and
<CHM>.

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.

The light emitting layer of the organic EL device of the present disclosure 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:
<CHM>
wherein Met is a metal; (Y<NUM>-Y<NUM>) is a bidentate ligand, Y<NUM> and Y<NUM> are independently selected from C, N, O, P, and S; L<NUM> is an another ligand; k' is an integer value from <NUM> 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:
<CHM>
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<NUM>-Y<NUM>) is a carbene ligand.

In one aspect, the host compound contains at least one of the following groups 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 <NUM> to <NUM> 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:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
and
<CHM>
wherein R<NUM> 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 <NUM> to <NUM> or <NUM> to <NUM>. X<NUM> to X<NUM> are independently selected from C (including CH) or N. Z<NUM> and Z<NUM> are independently selected from NR<NUM>, 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: <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>,
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
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<CHM>
<CHM>
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<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>.

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: <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>. <CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>.

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:
<CHM>
wherein k is an integer from <NUM> to <NUM>; L<NUM> is another ligand, k' is an integer from <NUM> to <NUM>.

Electron transport layer (ETL) 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 ETL 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:
<CHM>
<CHM>
wherein R<NUM> 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<NUM> to Ar<NUM> has the similar definition as Ar's mentioned above. k is an integer from <NUM> to <NUM>. X<NUM> to X<NUM> 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:
<CHM>
wherein (O-N) or (N-N) is a bidentate ligand, having metal coordinated to atoms O, N or N, N; L<NUM> is another ligand; k' is an integer value from <NUM> 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: <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>,
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>.

In any above-mentioned compounds used in each layer of the OLED device, the hydrogen atoms can be partially or fully deuterated. The minimum amount of hydrogen of the compound being deuterated is selected from the group consisting of <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, and <NUM>%. 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.

Step <NUM>: <NUM>-Bromo-<NUM>-(<NUM>-chlorophenyl) pyridine: <NUM>-bromo-<NUM>-iodopyridine (<NUM>, <NUM> mmol, <NUM> equiv), (<NUM>-chlorophenyl) boronic acid (<NUM>, <NUM> mmol, <NUM> equiv), potassium carbonate (<NUM>, <NUM> mmol, <NUM> equiv), toluene (<NUM>) and water (<NUM>) were added to a <NUM> round-bottom flask, equipped with a reflux condenser and stir bar. The mixture was sparged with nitrogen for <NUM> minutes. Bis(triphenylphosphine)palladium (II) chloride (<NUM>, <NUM> mmol, <NUM> equiv) was added, sparging continued for <NUM> minutes, then the reaction mixture was heated at reflux for <NUM> hours. TLC analysis showed almost complete consumption of the starting electrophile. The mixture was cooled to room temperature (RT), diluted with saturated brine (<NUM>) and the phases were separated. The aqueous phase was extracted with ethyl acetate (<NUM>). The combined organic phases were dried over anhydrous sodium sulfate (<NUM>) and dry-loaded onto Celite (diatomaceous earth) (<NUM>). The crude material was partially purified by chromatography on silica gel (<NUM>), eluting with a gradient of <NUM>:<NUM>:<NUM> to <NUM>:<NUM>:<NUM> ethyl acetate/ dichloromethane/heptanes to afford a yellow solid. The solid was recrystallized from acetonitrile (<NUM>) to afford light pink crystals. The mother liquor was concentrated under reduced pressure and repurified by chromatography on silica gel (<NUM>), eluting with a gradient of <NUM>:<NUM>:<NUM> to <NUM>:<NUM>:<NUM> ethyl acetate/ dichloromethane/heptanes. The recovered material was combined with the previous batch of crystals to afford <NUM>-bromo-<NUM>-(<NUM>-chlorophenyl) pyridine (<NUM>, <NUM>% yield) as an off-white solid.

Step <NUM>: <NUM>-(<NUM>-bromo-<NUM>-(tert-butyl) phenyl)-<NUM>-(<NUM>-chlorophenyl) pyridine: <NUM>-bromo-<NUM>-(<NUM>-chlorophenyl)pyridine (<NUM>, <NUM> mmol, <NUM> equiv), (<NUM>-bromo-<NUM>-(tert-butyl)phenyl)boronic acid (<NUM>, <NUM> mmol, <NUM> equiv), sodium carbonate (<NUM>, <NUM> mmol, <NUM> equiv), toluene (<NUM>), ethanol (<NUM>) and water (<NUM>) were added to a <NUM> round-bottom flask, equipped with a reflux condenser and stir bar. The mixture was sparged with nitrogen for <NUM> minutes. Bis(tri-phenylphosphine) palladium (II) chloride (<NUM>, <NUM> mmol, <NUM> equiv) was added, sparging continued for <NUM> minutes, then the reaction mixture was heated at reflux for <NUM> hours. GCMS analysis of the reaction mixture showed complete consumption of the starting electrophile. The mixture was cooled to room temperature, diluted with saturated brine (<NUM>) and the phases were separated. The aqueous phase was extracted with dichloromethane (<NUM>) and the combined organic phases were dried over anhydrous sodium sulfate (<NUM>). The suspension was passed through a pad of silica gel (<NUM>), rinsing the pad with <NUM>% ethyl acetate in dichloromethane (<NUM>). The filtrate was concentrated under reduced pressure. The crude material was partially purified by chromatography on silica gel (<NUM>), eluting with a gradient of <NUM>:<NUM>:<NUM> to <NUM>:<NUM>:<NUM> ethyl acetate/dichloro-methane/heptanes to afford a yellow solid. The solid (<NUM>) was recrystallized from acetonitrile (<NUM>) to afford light yellow crystals. The crystallization (mother) liquor was concentrated under reduced pressure and chromatographed on silica gel (<NUM> × <NUM>), eluting with a gradient of <NUM>:<NUM>:<NUM> to <NUM>:<NUM>:<NUM> ethyl acetate/dichloromethane/heptanes to give additional product. The material was combined with the previous crystals to give <NUM>-(<NUM>-bromo-<NUM>-(tert-butyl) phenyl)-<NUM>-(<NUM>-chlorophenyl) pyridine (<NUM>, <NUM>% yield) as yellow crystals.

Step <NUM>: <NUM>-(<NUM>-(tert-Butyl)-<NUM>-(<NUM>,<NUM>,<NUM>,<NUM>-tetramethyl-<NUM>,<NUM>,<NUM>-dioxaborolan-<NUM>-yl)phenyl)-<NUM>-(<NUM>-chlorophenyl)pyridine: <NUM>-(<NUM>-bromo-<NUM>-(tert-butyl)phenyl)-<NUM>-(<NUM>-chlorophenyl)pyridine (<NUM>, <NUM> mmol, <NUM> equiv), bis(pinacolato) diboron (<NUM>, <NUM> mmol, <NUM> equiv), potassium acetate (<NUM>, <NUM> mmol, <NUM> equiv), and toluene (<NUM>) were added to a <NUM> round-bottom flask, equipped with a reflux condenser and stir bar. The mixture was sparged with nitrogen for <NUM> minutes. ([<NUM>,<NUM>'-Bis(diphenylphosphino)ferrocene] dichloropalladium (II), complex with dichloromethane) (<NUM>, <NUM> mmol, <NUM> equiv) was added, sparging continued for <NUM> minutes, then the reaction mixture was heated at reflux for <NUM> hours. The cooled mixture was passed through a pad of silica gel (<NUM>), and the pad washed with <NUM>% ethyl acetate in hexanes (<NUM>). The filtrate was concentrated under reduced pressure. The mixture was passed through a second silica gel (<NUM>) pad, eluting with <NUM>% ethyl acetate in hexanes (<NUM>) to give <NUM>-(<NUM>-(tert-butyl)-<NUM>-(<NUM>,<NUM>,<NUM>,<NUM>-tetramethyl-<NUM>,<NUM>,<NUM>-dioxaborolan-<NUM>-yl) phenyl)-<NUM>-(<NUM>-chlorophenyl) pyridine (<NUM>, <NUM>% yield, <NUM>% GCMS purity) as a semi-solid.

Step <NUM>: <NUM>,<NUM>-Di-tert-butyl-<NUM>-(<NUM>-(<NUM>-(tert-butyl)-<NUM>-(<NUM>-(<NUM>-chlorophenyl)pyridin-<NUM>-yl)phenyl)-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>H-benzo[d]imidazol-<NUM>-yl)phenol : <NUM>-(<NUM>-bromo-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>-benzo[d] imidazol-<NUM>-yl)-<NUM>,<NUM>-di-tert-butylphenol (<NUM>, <NUM> mmol, <NUM> equiv), <NUM>-(<NUM>-(tert-butyl)-<NUM>-(<NUM>,<NUM>,<NUM>,<NUM>-tetramethyl-<NUM>,<NUM>,<NUM>-dioxaborolan-<NUM>-yl)phenyl)-<NUM>-(<NUM>-chlorophenyl)pyridine (<NUM>, <NUM> mmol, <NUM> equiv), potassium carbonate (<NUM>, <NUM> mmol, <NUM> equiv), <NUM>,<NUM>-dioxane (<NUM>), and water (<NUM>) were added to a <NUM> round-bottom flask, equipped with a reflux condenser and stir bar. The mixture was sparged with nitrogen for <NUM> minutes. Bis(triphenylphosphine)palladium (II) chloride (<NUM>, <NUM> mmol, <NUM> equiv) was added, sparging continued for <NUM> minutes, then the reaction mixture was heated at reflux for <NUM> hours. The mixture was cooled to room temperature, diluted with saturated brine (<NUM>) and ethyl acetate (<NUM>), then the phases were separated. The aqueous phase was extracted with ethyl acetate (<NUM>). The combined organic phases were dried over anhydrous sodium sulfate (<NUM>) and concentrated under reduced pressure. Hexanes (<NUM>) was added to the crude residue resulting in formation of a precipitate. The suspension was filtered and the solid washed with hexanes (<NUM>). The solid was dissolved in dichloromethane (<NUM>) and dry-loaded onto Celite (diatomaceous earth) (<NUM>). The crude material was chromatographed on silica gel (<NUM>), eluting with a gradient of <NUM>:<NUM>:<NUM> to <NUM>:<NUM>:<NUM> ethyl acetate/dichloro-methane/hexanes to afford an off-white solid. The solid was triturated with methanol (<NUM>) to give <NUM>,<NUM>-di-tert-butyl-<NUM>-(<NUM>-(<NUM>-(tert-butyl)-<NUM>-(<NUM>-(<NUM>-chloro-phenyl) pyridin-<NUM>-yl) phenyl)-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>H-benzo[d] imidazol-<NUM>-yl) phenol (<NUM>, <NUM>% yield, <NUM>% UHPLC purity) as an off-white solid.

Step <NUM>: <NUM>,<NUM>-Di-tert-butyl-<NUM>-(<NUM>-(<NUM>-(tert-butyl)-<NUM>-(<NUM>-(<NUM>',<NUM>',<NUM>'-tris(methyl-d<NUM>)-[<NUM>,<NUM>'-biphenyl] -<NUM>-yl)pyridin-<NUM>-yl)phenyl)-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>H-benzo[d] imidazol-<NUM>-yl)phenol: <NUM>,<NUM>-di-tert-butyl-<NUM>-(<NUM>-(<NUM>-(tert-butyl)-<NUM>-(<NUM>-(<NUM>-chlorophenyl)pyridin-<NUM>-yl)phenyl)-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>H-benzo[d]imidazol-<NUM>-yl)phenol (<NUM>, <NUM> mmol, <NUM> equiv), <NUM>,<NUM>,<NUM>,<NUM>-tetramethyl-<NUM>-(<NUM>,<NUM>,<NUM>-tris(methyl-d<NUM>)phenyl)-<NUM>,<NUM>,<NUM>-dioxaborolane (<NUM>, <NUM> mmol, <NUM> equiv), potassium carbonate (<NUM>, <NUM> mmol, <NUM> equiv), <NUM>,<NUM>-dioxane (<NUM>) and water (<NUM>) were added to a <NUM> round-bottom flask, equipped with a reflux condenser and stir bar. The mixture was sparged with nitrogen for <NUM> minutes. Palladium (II) acetate (<NUM>, <NUM> mmol, <NUM> equiv) and <NUM>-dicyclohexylphosphino-<NUM>',<NUM>'-dimethoxybiphenyl (SPhos) (<NUM>, <NUM> mmol, <NUM> equiv) were added, sparging continued for <NUM> minutes, then the reaction mixture was heated at <NUM> for <NUM> hours. The mixture was cooled to room temperature. Ethyl acetate (<NUM>) and saturated brine (<NUM>) were added, and the phases were separated. The aqueous phase was extracted with dichloromethane (<NUM>). The combined organic phases were dried over anhydrous sodium sulfate (<NUM>) then filtered through a silica gel (<NUM>) pad, rinsing with <NUM>% ethyl acetate in dichloromethane (<NUM>). The filtrates were concentrated under reduced pressure to afford <NUM>,<NUM>-di-tert-butyl-<NUM>-(<NUM>-(<NUM>-(tert-butyl)-<NUM>-(<NUM>-(<NUM>',<NUM>',<NUM>'-tris(methyl-d<NUM>)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)pyridin-<NUM>-yl)phenyl)-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>H-benzo[d] imidazol-<NUM>-yl)phenol (<NUM>, ><NUM>% yield) as a yellow semi-solid.

Step <NUM>: <NUM>-(tert-Butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-amine: A mixture of <NUM>-bromo-<NUM>-(tert-butyl) aniline (<NUM>, <NUM> mmol, <NUM> equiv), phenylboronic acid (<NUM>, <NUM> mmol, <NUM> equiv) and potassium carbonate (<NUM>, <NUM> mmol, <NUM> equiv) in toluene (<NUM>) and water (<NUM>) was sparged with nitrogen for <NUM> minutes. Tetrakis(triphenylphosphine)palladium (<NUM>) (<NUM>, <NUM> mmol, <NUM> equiv) was added, then the mixture was sparged with nitrogen for <NUM> minutes then heated at reflux for <NUM> hour. The reaction mixture was cooled to room temperature and saturated brine (<NUM>) was added. Ethyl acetate (<NUM>) was added, and the phases separated. The organic phase was filtered through silica gel (<NUM>), rinsing with ethyl acetate (<NUM>). The filtrate was concentrated under reduced pressure to give a brown oil. The oil was triturated with methanol (<NUM>) at room temperature for <NUM> hour to give <NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-amine (<NUM>, <NUM>% yield) as a light brown solid. The mother liquor was retained for future use.

Step <NUM>: N-(<NUM>-Bromo-<NUM>-nitrophenyl)-<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-amine (<NUM>-<NUM>-<NUM>): A mixture of <NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-amine (<NUM>, <NUM> mmol, <NUM> equiv) in anhydrous tetrahydrofuran (<NUM>) was cooled to -<NUM>. 5M_n-Butyllithium in hexanes (<NUM>, <NUM> mmol, <NUM> equiv) was added dropwise over <NUM> minutes. A copious amount of yellow solid formed. The reaction mixture was stirred at -<NUM> for <NUM> hour. <NUM>-Bromo-<NUM>-fluoro-<NUM>-nitrobenzene (<NUM>, <NUM> mmol, <NUM> equiv) in anhydrous tetrahydrofuran (<NUM>) was added and the reaction mixture was stirred for <NUM> hour while warming from -<NUM> to -<NUM>. The reaction mixture was quenched with water (<NUM>). Saturated brine (<NUM>) and ethyl acetate (<NUM>) were added, and the phases separated. The aqueous phase was extracted with ethyl acetate (<NUM>). The combined organic phases were washed with saturated brine (<NUM>) and filtered through silica gel (<NUM>), rinsing with ethyl acetate (<NUM>). The filtrate was concentrated under reduced pressure to give N-(<NUM>-Bromo-<NUM>-nitrophenyl)-<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-amine (~<NUM>% yield) as a brown oil which was used directly in the next step.

Step <NUM>: <NUM>-Bromo-N<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl) benzene-<NUM>,<NUM>-diamine: Iron (<NUM>, <NUM> mmol, <NUM> equiv) was added to a solution of crude N-(<NUM>-bromo-<NUM>-nitrophenyl)-<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-amine (<NUM>, ~<NUM> mmol, <NUM> equiv) in acetic acid (<NUM>). The reaction mixture was heated at <NUM> for <NUM> hour. Extensive gas evolution occurred, and the heating mantle was removed. LCMS analysis of the reaction mixture indicated the starting material was consumed. The cooled reaction mixture was filtered through Celite (<NUM>), washing the solids washed with ethyl acetate (<NUM>). The filtrate was concentrated under reduced pressure to a heel then saturated brine (<NUM>) and ethyl acetate (<NUM>) added. The organic phase was washed with saturated aqueous sodium carbonate (<NUM>) and saturated brine (<NUM>). The organic phase, containing some solids, was filtered through silica gel (<NUM>), rinsing with ethyl acetate (<NUM>). The filtrate was concentrated under reduced pressure to give a brown oil. The residue was purified by chroma-tography on silica gel (<NUM>), eluting with <NUM>% dichloromethane in heptanes. Product fractions were concentrated to give <NUM> - bromo-N<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-bi-phenyl]-<NUM>-yl) benzene-<NUM>,<NUM>-diamine (<NUM>, <NUM>% yield over <NUM> steps) as a yellow solid.

Step <NUM>: <NUM>-(<NUM>-Bromo-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>H-benzo[d]imidazol-<NUM>-yl)-<NUM>,<NUM>-di-tertbutylphenol: Sodium meta-bisulfite (<NUM>, <NUM> mmol, <NUM> equiv) was added to a solution of <NUM>-bromo-N<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)benzene-<NUM>,<NUM>-diamine (<NUM>, <NUM> mmol, <NUM> equiv) and <NUM>,<NUM>-di-tert-butyl-<NUM>-hydroxybenzaldehyde (<NUM>, <NUM> mmol, <NUM> equiv) in N,N-dimethylform-amide (<NUM>) then the reaction mixture was heated at <NUM> for <NUM> hours. Water (<NUM>) was added to the cooled reaction mixture. The suspension was filtered and the sticky solid washed with water (<NUM>). The solid was triturated with methanol (<NUM> × <NUM>) to give <NUM>-(<NUM>-bromo-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>H-benzo[d]imidazol-<NUM>-yl)-<NUM>,<NUM>-di-tertbutylphenol (<NUM>, <NUM>% yield) as an off-white solid.

Platinum complex of <NUM>,<NUM>-di-tert-butyl-<NUM>-(<NUM>-(<NUM>-(tert-butyl)-<NUM>-(<NUM>-(<NUM>',<NUM>',<NUM>'-tris (methyl-d<NUM>)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)pyridin-<NUM>-yl)phenyl)-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>-benzo[d]imidazol-<NUM>-yl) phenol: <NUM>,<NUM>-Di-tert-butyl-<NUM>-(<NUM>-(<NUM>-(tert-butyl)-<NUM>-(<NUM>-(<NUM>',<NUM>',<NUM>'-tris(methyl-d<NUM>)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)pyridin-<NUM>-yl)phenyl)-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>H-benzo[d]imidazol-<NUM>-yl)phenol (<NUM>, <NUM> mmol, <NUM> equiv), platinum(II) acetylacetonate (<NUM>, <NUM> mmol, <NUM> equiv) and acetic acid (<NUM>) were sequentially added to a <NUM> round-bottom flask equipped with a stir bar. The mixture was sparged with nitrogen for <NUM> minutes then heated at <NUM> for <NUM> hours. After cooling to room temperature, the mixture was diluted with methanol (<NUM>), the suspension filtered, and the solids washed with methanol (<NUM>). The solids were dissolved in dichloromethane (<NUM>) and dry-loaded onto Celite (<NUM>). The crude material was purified by flash chromatography (<NUM> silica gel), eluting with <NUM>:<NUM>:<NUM> to <NUM>:<NUM>:<NUM> ethyl acetate/dichloromethane/hexanes to afford a yellow solid. This solid was dissolved in dichloromethane (<NUM>) and precipitated by the slow addition of methanol (<NUM>). The suspension was filtered, and the solids washed with methanol (<NUM>). The precipitation procedure was repeated once more and the solids dried in a vacuum oven at <NUM> for <NUM> hours to give the platinum complex of <NUM>,<NUM>-di-tert-butyl-<NUM>-(<NUM>-(<NUM>-(tert-butyl)-<NUM>-(<NUM>-(<NUM>',<NUM>',<NUM>'-tris (methyl-d<NUM>)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)pyridin-<NUM>-yl)phenyl)-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>-benzo[d]imidazol-<NUM>-yl) phenol (<NUM>, <NUM>% yield) as a yellow solid.

Step <NUM>: <NUM>-(<NUM>-(<NUM>-Bromopyridin-<NUM>-yl) phenyl)-<NUM>-carbazole: A mixture of <NUM>-bromo-<NUM>-iodopyridine (<NUM>, <NUM> mmol, <NUM> equiv) and (<NUM>-(<NUM>-carbazol-<NUM>-yl) phenyl) boronic acid (<NUM>, <NUM> mmol, <NUM> equiv) in toluene (<NUM>) and <NUM> aqueous potassium carbonate (<NUM>), was sparged with nitrogen for <NUM> minutes. Trans-dichlorobis(triphenylphosphine)palladium (II) (<NUM>, <NUM> mmol, <NUM> equiv) was added, sparging continued for <NUM> minutes, then the reaction mixture was heated at reflux for <NUM> hours. The mixture was cooled to room temperature and the layers separated. The aqueous phase was extracted with ethyl acetate (<NUM> × <NUM>). The combined organic phases were washed with saturated brine (<NUM>), dried over sodium sulfate, filtered, and concentrated under reduced pressure. The crude material (<NUM>) was dissolved in dichloromethane (<NUM>) and dry-loaded onto Celite. The crude material was chromatographed on silica gel (<NUM>), eluting with <NUM>-<NUM>% ethyl acetate in heptanes, then holding at <NUM>% ethyl acetate until all products had eluted. The cleanest product containing fractions, along with the ethyl acetate final rinse were combined and concentrated to give a yellow solid. The recovered material (<NUM>) was triturated with acetonitrile (<NUM>) for <NUM> hours at room temperature, then the suspension filtered. The solid was dried in a vacuum oven at <NUM> for <NUM> hours to give <NUM>-(<NUM>-(<NUM>-bromopyridin-<NUM>-yl) phenyl)-<NUM>H-carbazole (<NUM>, <NUM>% yield) as a pale-yellow solid.

Step <NUM>: <NUM>-(<NUM>-(<NUM>-(<NUM>-Bromo-<NUM>-(tert-butyl)phenyl)pyridin-<NUM>-yl)phenyl)-<NUM>H-carbazole: A mixture of <NUM>-(<NUM>-(<NUM>-bromopyridin-<NUM>-yl)phenyl)-<NUM>H-carbazole (<NUM>, <NUM> mmol, <NUM> equiv), <NUM>-bromo-<NUM>-tert-butylphenylboroinc acid (<NUM>, <NUM> mmol, <NUM> equiv) and sodium carbonate (<NUM>, <NUM> mmol, <NUM> equiv) in toluene (<NUM>), ethanol (<NUM>) and water (<NUM>) was sparged with nitrogen for <NUM> minutes. Trans-dichlorobis(triphenylphosphine)palladium (II) (<NUM>, <NUM> mmol, <NUM> equiv) was added, sparging continued for <NUM> minutes, then the reaction mixture was heated at reflux for <NUM> hours. LCMS analysis showed complete conversion of the starting material to product. The mixture was cooled, and the layers separated. The aqueous phase was extracted with toluene (<NUM> × <NUM>). The combined organic phases were washed with saturated brine (<NUM>) and concentrated under reduced pressure. The residue was suspended in <NUM>% ethyl acetate in heptanes (<NUM>), then passed through a pad of silica gel (<NUM>), rinsing the pad with <NUM>% ethyl acetate in heptanes (<NUM> × <NUM>). The filtrate was concentrated under reduced pressure to give <NUM>-(<NUM>-(<NUM>-(<NUM>-bromo-<NUM>-(tert-butyl) phenyl) pyridin-<NUM>-yl) phenyl)-<NUM>H-carbazole (<NUM>, <NUM>% yield) as an off-white solid.

Step <NUM>: <NUM>-(<NUM>-(<NUM>-(<NUM>-(tert-Butyl)-<NUM>-(<NUM>,<NUM>,<NUM>,<NUM>-tetramethyl-<NUM>,<NUM>,<NUM>-dioxaborolan-<NUM>-yl)phenyl) pyridin-<NUM>-yl)phenyl)-<NUM>-carbazole: A mixture of <NUM>-(<NUM>-(<NUM>-(<NUM>-bromo-<NUM>-(tert-butyl)phenyl)pyridin-<NUM>-yl)phenyl)-<NUM>H-carbazole (<NUM>, <NUM> mmol, <NUM> equiv), bis(pinacolato)diboron (<NUM>, <NUM> mmol, <NUM> equiv) and potassium acetate (<NUM>, <NUM> mmol, <NUM> equiv) in toluene (<NUM>), was sparged with nitrogen for <NUM> minutes. Bis(diphenylphosphinoferrocene)palladium (II) dichloride dichloromethane adduct (<NUM>, <NUM> mmol, <NUM> equiv) was added, sparging continued for <NUM> minutes, then the reaction mixture heated at reflux for <NUM> hours. LCMS and <NUM>H NMR analyses showed complete conversion to product. The cooled mixture was filtered through a pad of silica gel (<NUM>), rinsing the pad with toluene (<NUM> × <NUM>). The filtrate was concentrated under reduced pressure to give a black semi-solid. The residue (<NUM>) was triturated with methanol (<NUM>) for <NUM> minutes, the suspension filtered, and the solid washed with methanol (<NUM> × <NUM>). The solid was air-dried to give <NUM>-(<NUM>-(<NUM>-(<NUM>-(tert-butyl)-<NUM>-(<NUM>,<NUM>,<NUM>,<NUM>-tetra-methyl-<NUM>,<NUM>,<NUM>-dioxaborolan-<NUM>-yl) phenyl) pyridin-<NUM>-yl) phenyl)-<NUM>H-carbazole (<NUM>, <NUM>% yield, <NUM>% purity) as a light grey solid. Attempts at recrystallization and trituration did not improve the purity.

Step <NUM>: <NUM>-(<NUM>-(<NUM>-(<NUM>-(<NUM>-(<NUM>H-Carbazol-<NUM>-yl)phenyl)pyridin-<NUM>-yl)-<NUM>-(tert-butyl)phenyl)-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>H-benzo[d]imidazol-<NUM>-yl)-<NUM>,<NUM>-di-tert-butyl-phenol : A mixture <NUM>-(<NUM>-bromo-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>H-benzo[d]imidazol-<NUM>-yl)-<NUM>,<NUM>-di-tert-butylphenol (<NUM>, <NUM> mmol, <NUM> equiv), <NUM>-(<NUM>-(<NUM>-(<NUM>-(tert-butyl)-<NUM>-(<NUM>,<NUM>,<NUM>,<NUM>-tetramethyl-<NUM>,<NUM>,<NUM>-dioxaborolan-<NUM>-yl)phenyl)pyridin-<NUM>-yl)phenyl)-<NUM>H-carbazole (<NUM>, <NUM> mmol, <NUM> equiv) and potassium carbonate (<NUM>, <NUM> mmol, <NUM> equiv) in <NUM>,<NUM>-dioxane (<NUM>) and water (<NUM>) was sparged with nitrogen for <NUM> minutes. Palladium (II) acetate (<NUM>, <NUM> mmol, <NUM> equiv) and dicyclohexyl(<NUM>',<NUM>'-dimethoxy-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl) phosphine (SPhos) (<NUM>, <NUM> mmol, <NUM> equiv) were added, sparging continued for <NUM> minutes, then the reaction mixture was heated at reflux for <NUM> hours. Ethyl acetate (<NUM>) and saturated brine (<NUM>) were added. The organic layer was separated, dried over sodium sulfate (<NUM>), filtered through a pad of silica gel (<NUM>) and concentrated to give crude <NUM>-(<NUM>-(<NUM>-(<NUM>-(<NUM>-(<NUM>H-carbazol-<NUM>-yl)phenyl)pyridin-<NUM>-yl)-<NUM>-(tert-butyl)phenyl)-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>H-benzo[d]imidazol-<NUM>-yl)-<NUM>,<NUM>-di-tert-butyl-phenol (<NUM>, <NUM>% yield) as a brown solid.

Platinum complex of <NUM>-(<NUM>-(<NUM>-(<NUM>-(<NUM>-(<NUM>H-carbazol-<NUM>-yl)phenyl)pyridin-<NUM>-yl)-<NUM>-(tert-butyl)phenyl)-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>H-benzo[d]imidazol-<NUM>-yl)-<NUM>,<NUM>-di-tert-butylphenol: A mixture of <NUM>-(<NUM>-(<NUM>-(<NUM>-(<NUM>-(<NUM>H-carbazol-<NUM>-yl)phenyl)pyridin-<NUM>-y1)-<NUM>-(tert-butyl)phenyl)-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>H-benzo[d]imidazol-<NUM>-yl)-<NUM>,<NUM>-di-tert-butylphenol (<NUM>, <NUM> mmol, <NUM> equiv) and platinum(II) acetylacetonate (<NUM>, <NUM> mmol, <NUM> equiv) in acetic acid (<NUM>) was sparged with nitrogen for <NUM> minutes then heated at <NUM> for <NUM> hours. LCMS analysis showed ~<NUM>% product (~<NUM>%) and starting material (<NUM>%). The cooled yellow suspension was filtered and the solid was washed with methanol (<NUM> × <NUM>). The solid was purified on an Interchim automated chromatography system (<NUM> silica gel cartridge), eluting with a gradient of <NUM>-<NUM>% dichloromethane in heptanes. The recovered impure product was triturated with dichloromethane in methanol (<NUM>/<NUM>) at <NUM> for <NUM> hour. The suspension was filtered and the solid washed with methanol (<NUM> × <NUM>). The solid was dried in vacuum oven at <NUM> for <NUM> hours to give the platinum complex of <NUM>-(<NUM>-(<NUM>-(<NUM>-(<NUM>-(<NUM>H-carbazol-<NUM>-yl)phenyl)pyridin-<NUM>-yl)-<NUM>-(tert-butyl)phenyl)-<NUM>-(<NUM>-(tert-butyl)-[<NUM>,<NUM>'-biphenyl]-<NUM>-yl)-<NUM>H-benzo[d]imidazol-<NUM>-yl)-<NUM>,<NUM>-di-tert-butylphenol (<NUM>, <NUM>% yield, ><NUM>% UPLC purity) as a yellow solid.

All example devices were fabricated by high vacuum (<<NUM>-<NUM> Torr (wherein <NUM> Torr = <NUM> Pa)) thermal evaporation. The anode was <NUM>Å of indium tin oxide (ITO). The cathode consisted of <NUM>Å of Liq (<NUM>-hydroxyquinoline lithium) followed by <NUM>,<NUM>Å of Al. All devices were encapsulated with a glass lid sealed with an epoxy resin in a nitrogen glove box (<<NUM> ppm of H<NUM>O and O<NUM>) immediately after fabrication with a moisture getter incorporated inside the package. The organic stack of the device examples consisted of, sequentially from the ITO Surface: 100Å of HATCN as the hole injection layer (HIL); <NUM>Å of HTM as a hole transporting layer (HTL); emissive layer (EML) with thickness <NUM>Å. Emissive layer containing H-host (H1): E-host (H2) in <NUM>:<NUM> ratio and <NUM>% of green emitter. <NUM>Å of Liq (<NUM>-hydroxyquinoline lithium) doped with <NUM>% of ETM as the ETL. The schematic structure of the devices is provided in the Table <NUM> below. The chemical structures of the device materials are shown below. <CHM>
<CHM>
<CHM>
<CHM>.

Upon fabrication the devices have been measured EL, JVL and life tested at DC <NUM> mA/cm<NUM>. LT97 at <NUM>,<NUM> nits ( wherein <NUM> nit = <NUM> cd/m2) was calculated from <NUM> mA/cm2 LT data assuming acceleration factor <NUM>. Device performance data is shown in the Table <NUM> below.

Claim 1:
A compound of Formula I,
<CHM>
wherein:
M is Pd or Pt;
each of X<NUM> to X<NUM> is independently C or N;
one of Z<NUM> and Z<NUM> is C and the other is N;
Y is selected from the group consisting of O, S, Se, N*R, CRR', SiRR', and GeRR';
K<NUM> is selected from the group consisting of a direct bond, O, and S;
each of RA, RB, RC, and RD independently represents mono to the maximum allowable substitution, or no substitution;
each R, R', RA, RB, RC, and RD is independently hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, germyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, boryl, selenyl, and combinations thereof;
at least one of R, R', RA, RB, RC, or RD is a substituent R*; wherein at least one RD is a substituent R*;
one of the following two statements is true:
(i) R* comprises a <NUM>-membered or <NUM>-membered heterocyclic ring;
(ii) R* comprises Formula Ia,
<CHM>
wherein each of RY and RZ independently represents mono to the maximum allowable substitution, or no substitution;
R<NUM>, R<NUM>, R<NUM>, R<NUM>, RY and RZ is independently hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, germyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, boryl, selenyl, and combinations thereof; wherein at least one of R<NUM>, R<NUM>, R<NUM>, and R<NUM> is not hydrogen; and
any two substituents may be joined or fused to form a ring.