CCC-NHC pincer metal complexes for organic light emitting diodes

Abstract

The presently-disclosed subject matter generally relates to symmetrical and unsymmetrical CCC-NHC pincer metal complexes, and methods of making and using the same. More specifically, the presently-disclosed subject matter relates to symmetrical and unsymmetrical bis(azolium) salts, the bis-N-heterocyclic carbenes derived thereof, and monoand bis-ligated CCC-NHC pincer metal complexes, and methods of making and using the same.

Description

CCC-NHC PINCER METAL COMPLEXES FOR ORGANIC LIGHT EMITTINGDIODESGOVERNMENT INTERESTThis invention was made with government support under grant numbers OIA - 1539035, TI-1743680, TI-1827686 awarded by the National Science Foundation. The government has certain rights in the invention.TECHNICAL FIELDThe presently-disclosed subject matter generally relates to symmetrical and unsymmetrical CCC-NHC pincer metal complexes, and methods of making and using the same. More specifically, the presently-disclosed subject matter relates to symmetrical and unsymmetrical bis(azolium) salts, the bis-N-heterocyclic carbenes derived thereof, and mono- and bis-ligated CCC-NHC pincer metal complexes, and methods of making and using the same.BACKGROUNDOrganic Light Emitting Diodes (OLEDs) hold the promise of being the most energy efficient light producing method and have gained increasing popularity in both academic and commercial research. Despite progress made in OLED technology, clear challenges still remain to make OLEDs the standard light source for all of society’s needs. These challenges include: 1) reducing bum-in problems with stable true-blue emitters that can be prepared at scale, 2) efficient and stable white OLEDs, 3) fabrication of an OLED device with a sufficient operational lifetime, 4) emitter materials that are available in sufficient supply, and 5) cost competitiveness. Current estimates are that OLEDs cost $100 / klm (kilolumens per square meter) and that commercial viability requires a cost of ~$10 / klm.Historically, the approach to dealing with such challenges has been the development of Ir(III) complexes and the study of their corresponding devices. However, these Ir(III) emitting materials are often formed from three bidentate ligands which lack the stability of higher denticity ligands. Ir(III) complexes bound to tridentate ligands are rarely studied for OLED applications due to their difficult synthesis or lack of desired photophysical properties. Also, there is the disadvantage that the supply of Ir available on the planet is limited, and it is listed as the least abundant at only 0.05 ppb in the upper crust and annual production is 3-4 tons. Other recent approaches use the metals of Pt and Pd which are an order of magnitudemore abundant than Ir with annual productions on the 100s of metric tons scale. Nevertheless, the metals of Pt and Pd are comparable in expense to Ir.SUMMARY OF THE DICLOSUREAn unprecedented approach to this challenge is disclosed herein and takes advantage of metals that are orders of magnitude less expensive than current metals due to their abundance. Described herein are emitters based on the earth abundant group 4 metals of Ti, Zr and Hf. For instance, a zirconium emitter would be less than 10% of the cost of current phosphorescent, precious, late transition metal emitters. The present disclosure relates to new white light emitters from compounds having the relatively abundant and inexpensive group 4 metals, including Zr which is the 4th most abundant transition metal with availability in the 10,000’s of tons per year. These complexes are the first solid state emitters comprising group 4 metals and open the possibility of producing for the first time a general white light solution that would be available globally using OLED technology instead of LEDs.In some embodiments, the CCC-NHC pincer complexes of Ti, Zr and Hf disclosed herein represent a new class of pincer metal complexes that demonstrate emission upon irradiation with UV light. In one embodiment, these complexes form highly efficient emitters of light in various portions of the light spectrum. In another embodiment, light emitting applications include, but are not limited to, photoluminescence (fluorescence or phosphorescence) and electroluminescence. Existing OLED devices, which are prevalent in flat panel displays that are found in cell phones, flat screen televisions, computer monitors, laptops, etc., have significant limitations in the blue region of the spectrum. In contrast thereto, one or more of the complexes disclosed herein provide highly efficient photoluminescence in the blue and other regions of the spectrum. As such, in a further embodiment, the symmetrical or unsymmetrical CCC-NHC pincer metal complexes disclosed herein may be used as emitters in modern organic light emitting diodes (OLEDs).1. In an aspect, the disclosure relates to an Organic Light Emitting Diode (OLED) device, comprising: an emissive layer in between a first electrode layer and a second electrode layer, wherein the emissive layer comprises a symmetrical or unsymmetrical mono-ligated CCC- NHC metal complex according to Formula (I) and / or a symmetrical or unsymmetrical bis- ligated CCC-NHC metal complex according to Formula (II):Formula I wherein n is the charge on the complex;M is titanium, zirconium or hafnium; R'-R9are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dialkyl amino having 1 to 33 carbon atoms, diarylamino having 12 to 33 carbons, alkylarylamino having 7 to 33 carbons, nitro, cyano, carboxy, CF3, thioether having 2 to 20 carbon atoms and 1 to 5 sulfur atoms, boronic ester having 1 to 33 carbon atoms and having two boron-oxygen bonds, silyl ether having 1 to 33 carbon atoms, silane having 1 to 33 carbon atoms, diazonium salt having a halo or tetrafluoroborate ion, ester having 1 to 33 carbon atoms, amide having 0 to 33 carbon atoms, aldehyde having 1 to 33 carbon atoms, imine having 1 to 33 carbon atoms, phosphine having 1 to 33 carbon atoms, phosphate ester having 1 to 33 carbon atoms, isocyanide, isocyanate, a substituted or unsubstituted alkyl group having 1 to 33 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 33 carbon atoms, a substituted or unsubstituted aryl group having 6 to 33 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 33carbon atoms, an alkylether having 2 to 33 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 33 carbon atoms or wherein one or more pair of R1and R2, R2and R3, R3and R4, R4and R5, R5and R6, R6and R7, R7and Rs, Rsand R9together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R10is C or N, wherein when R10is C, then ring A is a phenyl ring or a cyclohexyl ring, and when R10is N then Ring A is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;R11, R12and R13are each independently selected from a fluoro, chloro, bromo, iodo, - C=N, imine having 1 to 33 carbon atoms, carbazolyl, -CHi-aryl having 7 to 33 carbon atoms, alkyl having 1 to 50 carbon atoms, tetrahydrofuryl, dioxanyl, ether having 1 to 50 carbon atoms, polyether having 1 to 5 oxygen atoms and 2 to 33 carbon atoms, dialkyl amino having 1 to 33 carbon atoms, diarylamino having 12 to 33 carbons, alkylarylamino having 7 to 33 carbons, -OTf, -OAc, -O3SCH3, -O3SC6H5, -O2CCF3, -OMe, t-BuO-, EtO-, CF3CH2O-, and CF3CF2O-,-NCH, -Oaryl having 6 to 33 carbon atoms, alkyl having 1 to 33 carbon atoms, - CF3, phenyl,n” is 0 or 1 or 2, or 3, R100is selected from hydrogen, sulfonate, halogen, hydroxy, substituted-amino, substituted-amido, alkoxy, dimethylamino or amido, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms, y is 0, 1 or 2;X is a counterion and n' is the number of counterions;Z1and Z2are each independently selected from the group consisting of CH, CR14, and N; and wherein when Z1or Z2is CR14, R14is a C1-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH, then there is a double bond between the carbon in the Z position and the azole carbon attached thereto, and wherein whenZ1or Z2is CH2, then there is a single bond between the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R]-R9and R100is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms;Formula (II) wherein the definitions in Formula (II) for n, M, R'-R9, R10, R14, Ring A, X, n', Z1and Z2are identical to the definitions given in Formula (I) above,R15-R23are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms or wherein one or more pair of R15and R16, R16and R17, R17and R18, R18and R19, R19and R20, R20and R21, R21and R22, R22and R23together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R24is C or N, wherein when R24is C, then ring B is a phenyl ring, and when R24is N then Ring B is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;Z3and Z4are each independently selected from the group consisting of CH, CR140, and N; and wherein when Z3or Z4is CR140, R140is a C1-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R15-R23is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms.2. The OLED device of previously numbered sentence 1 , wherein M is zirconium, and X can be a strongly coordinating, weakly coordinating anion, or noncoordinating anion. Strongly coordinating anions include iodide, chloride, fluoride, bromide, Weakly coordinating anions include mesylate ( OMs), (triflate ( OTf), tetrafluoroborate (BF4-), hexafluorophosphate (PFe ), hexafluoroantimonate (SbFe )and perchlorate (CIO4 ). Weakly or non-coordinating anions include bistriflimido ( N(Tf)2), tetrakis[3,5- bis(trifluoromethyl)phenyl]borate ion, B[3,5-(CF3)2C6H3]4-, commonly abbreviated as B(ArF)4 and colloquially called "BARF," selected carborane anions and borane anions. These anions are far less coordinating than tetrafluoroborate, hexafluorophosphate, and perchlorate. Related tetrahedral anions include tetrakis(pentafluorophenyl)borate BiCeFsfl-, and A1[OC(CF3)3]4-.In the bulky borates and aluminates, the negative charge is symmetrically distributed over many electronegative atoms. Related anions can be derived from tris(pentafluorophenyl)boron BiCeFfl? by methyl abstraction for instance. Another advantageof these anions is that their salts are more soluble in non-polar organic solvents such as dichloromethane, toluene, and, in some cases, even alkanes.Neutral molecules that represent the parents to the non-coordinating anions are strong Lewis acids, e.g. boron trifluoride, BF3 and phosphorus pentafluoride, PF5. A notable Lewis acid of this type is tris(pentafluorophenyl)borane, B(CeFs)3, which can abstract alkyl ligands such as in the following reaction: (CsHshZ^CFL)? + B(CeF5)3[(C5H3)2Zr(CH3)]+[(CH3)B(C6F5)3]“.Another class of non-coordinating anions that can be used are derived from the carborane anion CBnHiz', and include the numerous derivatives where the hydrogens are replaced by halogens.Including the species discussed above, X can also include nitrite, sulfate, phosphate, bicarbonate, trifluoroacetate, pentafluoropropanoate, chloride, bromide, iodide, perchlorate, nitrate, benzenesulfonate, p-toluenesulfonate, methylsulfate, ethylsulfate, propylsulfate, tetrafluoroborate , tetraphenylborate, hexafluorophosphate, benzenesulfinate, acetate, trifluoroacetate, propionacetate, benzoate, oxalate, succinate, malonate, oleate, stearate, citrate, monohydrogen diphosphate, dihydrogen monophosphate, pentachlorostannate, chlorosulfonate, fluorosulfonate, trifluoromethansulfonate, hexafluoroarsenate, hexafluoroantimonate, molybdenate, tungstate, titanate, zirconate ions, or any combination thereof.3. The OLED device of any one of the previously numbered sentences, wherein M is zirconium, and X is tetraphenylborate, trifluoroacetate, pentafluoropropanoate, chloride, bromide, iodide, fluorosulfonate, or trifluoromethansulfonate.4. The OLED device of any one of the previously numbered sentences, wherein M is zirconium, and the emissive layer comprises a mono-ligated CCC-NHC metal complex according to Formula (I).5. The OLED device of any one of the previously numbered sentences, wherein M is zirconium, and the emissive layer comprises a mono-ligated CCC-NHC metal complex according to Formula (I) and the CCC-NHC ligand is symmetrical.6. The OLED device of any one of previously numbered sentences, wherein M is zirconium, and the emissive layer comprises a mono-ligated CCC-NHC metal complex according to Formula (I) and the CCC-NHC ligand is unsymmetrical.7. The OLED device of any one of the previously numbered sentences, wherein M is zirconium, and the emissive layer comprises a bis-ligated CCC-NHC metal complex according to Formula (II).8. The OLED device of any one of the previously numbered sentences, wherein the emissive layer comprises a mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and n is 1;R1and R9are each independently selected from an alkyl group having 1 to 6 carbon atoms, which is optionally substituted with a halogen, sulfonate, hydroxy, amino, nitro, cyano, or carboxy, or a phenyl group which is optionally substituted with a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy or an alky l group having 1 to 6 carbon atoms; andZ1and Z2are each CH and there is a double bond between the carbon in the Z position and the azole carbon attached thereto.9. The OLED device of any one of the previously numbered sentences, wherein the emissive layer comprises a mono-ligated CCC-NHC metal complex according to Formula(I), M is zirconium, and R4-R6are each hydrogen.10. The OLED device of any one of the previously numbered sentences, wherein the emissive layer comprises a bis-ligated CCC-NHC metal complex according to Formula(II), M is zirconium, and R4-R6and R18-R20are each hydrogen.11. The OLED device of any one of the previously numbered sentences, wherein the emissive layer comprises a mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R11, R12and R13are each independently selected from a chloro, dimethylamine, diethylamine, -OTf, 1 ,2,4-triazolyl, 1,2,3-triazolyl, imidazolyl, pyrazolyl, pyrrolyl, benzimidazolyl, or 6-methylindolyl; n” is 0 or 1.12. The OLED device of any one of the previously numbered sentences, wherein the emissive layer comprises a mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R11, R12and R13are each independently selected from a chloro, bromo, iodo, dimethylamine, diethylamine, methylphenylamine, ethylphenylamine, and diphenylamine; and n’" is 0 or 1.13. The OLED device of any one of the previously numbered sentences, wherein the emissive layer comprises:a mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R1and R9are each independently selected from methyl or ethyl; a bis-ligated CCC-NHC metal complex according to Formula (II) and R1, R9, R15and R23are each independently selected from methyl or ethyl.14. The OLED device of any one of the previously numbered sentences, wherein the emissive layer comprises: a mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R1and R9are each independently selected from methyl or ethyl.15. The OLED device of any one of the previously numbered sentences, wherein the emissive layer comprises: a mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R11, R12and R13are each independently selected from a chloro, bromo or iodo.16. The OLED device of any one of the previously numbered sentences, wherein Z1or Z2is CR14, and R14is a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, and the ring structure is aromatic or is a cyclohexyl ring with 0, 1 or 2 double bonds in the cyclohexyl ring.17. The OLED device of any one of the previously numbered sentences, wherein the emissive layer further comprises a host material; or wherein the emissive layer further comprises a host material and the host material is selected from:Poly(9-vinylcarbazole) (PVK)wherein n is sufficient to provide a weight average molecular weight of 10,000 to 500,000 grams per mole (g / mol).4,4',4-Tris(carbazol-9-yl)triphenylamine (TcTa)9-(3,5-Di(triphenylen-2-yl)phenyl)-9H -carbazole (DTP-mCP)18. The OLED device of any one of the previously numbered sentences, further comprising an electron injection layer, an electron transport / hole blocking layer, an electron blocking layer, a hole transport layer, a hole injection layer which are also between the first electrode layer and the second electrode layer.19. The OLED device of any one of the previously numbered sentences, wherein one of the first and second electrode layers is a cathode layer and the other is an anode layer, and the OLED has layers stacked in the following order: 1) cathode layer; 2) electroninjection layer; 3) electron transport / hole blocking layer; 4) emissive layer; 5) electron blocking layer; 6) hole transport layer; 7) hole injection layer; and 8) anode layer.20. The OLED device of any one of the previously numbered sentences, wherein the cathode layer comprises aluminum, the electron injection layer comprises LiF, the electron transport / hole blocking layer comprises PO15 which is a phosphine oxide based electron transport material, the electron blocking layer comprises TAPC, the hole transport layer comprises NPD, the hole injection layer comprises PEDOT:PSS and the anode comprises ITO.21. The OLED device of any one of the previously numbered sentences, wherein the anode layer is bonded to a substrate; or wherein the anode layer is bonded to a glass substrate.22. The OLED device of any one of the previously numbered sentences, excluding Ti, Zr and Hf compounds having the following CCC-NHC ligand or any NHC analog thereof23. The OLED device of any one of the previously numbered sentences, wherein R1- R9are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dialkyl amino having 1 to 20 carbon atoms, diarylamino having 12 to 20 carbons, alkylarylamino having 7 to 20 carbons, nitro, cyano, carboxy, CFs, thioether having 2 to 20 carbon atoms and 1 to 5 sulfur atoms, boronic ester having 1 to 20 carbon atoms and having two boron-oxygen bonds, silyl ether having 1 to 20 carbon atoms, silane having 1 to 20 carbon atoms, diazonium salt having a halo or tetrafluoroborate ion, ester having 1 to 20 carbon atoms, amide having 0 to 20 carbon atoms, aldehyde having 1 to 20 carbon atoms, imine having 1 to 20 carbon atoms, phosphine having 1 to 20 carbon atoms, phosphate ester having 1 to 20 carbon atoms, isocyanide, isocyanate, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms or wherein one or more pair of R1and R2, R2and R3, R3and R4, R4and Rs, Rsand R6, R6and R7, R7and R8, R8and R9together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R10is C or N, wherein when R10is C, then ring A is a phenyl ring or a cyclohexyl ring, and when R10is N then Ring A is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;R11, R12and R13are each independently selected from a fluoro, chloro, bromo, iodo, - C=N, imine having 1 to 20 carbon atoms, carbazolyl, -CfF-aryl having 7 to 20 carbon atoms, alkyl having 1 to 40 carbon atoms, tetrahydrofuryl, dioxanyl, ether having 1 to 40 carbon atoms, polyether having 1 to 5 oxygen atoms and 2 to 20 carbon atoms, dialkyl amino having 1 to 20 carbon atoms, diarylamino having 12 to 20 carbons, alkylarylamino having 7 to 20 carbons, -OTf, -OAc, -O3SCH3, -O3SC6H5, -O2CCF3, -OMe, t-BuO-, EtO-, CF3CH2O-, andCFSCF20-,-NCH, -Oaryl having 6 to 20 carbon atoms, alkyl having 1 to 20 carbon atoms, -CF3, phenyl,n” is 0 or 1 or 2, or 3, R100is selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstitutedheterocyclic group having 3 to 16 carhon atoms, an alkylether having 2 to 20 carhon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms, y is 0, 1 or 2;X is a counterion and n' is the number of counterions;Z1and Z2are each independently selected from the group consisting of CH, CR14, and N; and wherein when Z1or Z2is CR14, R14is a C'-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH, then there is a double bond between the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH2, then there is a single bond between the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R’-R9and R100is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms;R15-R23are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms or wherein one or more pair of R15and R16, R16and R17, R17and R18, R18and R19, R19and R20, R20and R21, R21and R22, R22and R23together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R24is C or N, wherein when R24is C, then ring B is a phenyl ring, and when R24is N then Ring B is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;Z3and Z4are each independently selected from the group consisting of CH, CR140, and N; and wherein when Z3or Z4is CR140, R140is a C1-C'1alkyl, Cs-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto,with the proviso that when any of R15-R23is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms.24. The OLED device of any one of the previously numbered sentences, wherein R1- R9are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dialkyl amino having 1 to 6 carbon atoms, diarylamino having 12 to 16 carbons, alkylarylamino having 7 to 16 carbons, nitro, cyano, carboxy, CF3, thioether having 2 to 6 carbon atoms and 1 to 5 sulfur atoms, boronic ester having 1 to 6 carbon atoms and having two boron-oxygen bonds, silyl ether having 1 to 6 carbon atoms, silane having 1 to 6 carbon atoms, diazonium salt having a halo or tetrafluoroborate ion, ester having 1 to 6 carbon atoms, amide having 0 to 6 carbon atoms, aldehyde having 1 to 6 carbon atoms, imine having 1 to 6 carbon atoms, phosphine having 1 to 6 carbon atoms, phosphate ester having 1 to 6 carbon atoms, isocyanide, isocyanate, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 6 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 6 carbon atoms, an alkylether having 2 to 6 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 6 carbon atoms or wherein one or more pair of R1and R2, R2and R3, R3and R4, R4and R5, R5and R6, R6and R7, R7and R8, R8and R9together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R10is C or N, wherein when R10is C, then ring A is a phenyl ring or a cyclohexyl ring, and when R10is N then Ring A is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;R11, R12and R13are each independently selected from a fluoro, chloro, bromo, iodo, - C=N, imine having 1 to 6 carbon atoms, carbazolyl, -CH2-aryl having 7 to 12 carbon atoms, alkyl having 1 to 30 carbon atoms, tetrahydrofuryl, dioxanyl, ether having 1 to 30 carbon atoms, polyether having 1 to 5 oxygen atoms and 2 to 6 carbon atoms, dialkyl amino having 1 to 6 carbon atoms, diarylamino having 12 to 16 carbons, alkylarylamino having 7 to 16 carbons, -OTf, -OAc, -O3SCH3, -O3SC6H5, -O2CCF3, -OMe, t-BuO-, EtO-, CF3CH2O-, and CF3CF2O-,-NCH, -Oaryl having 6 to 12 carbon atoms, alkyl having 1 to 6 carbon atoms, - CF3, phenyl,n” is 0 or 1 or 2, or 3, R100is selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 6 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 6 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 6 carbon atoms, y is 0, 1 or 2;X is a counterion and n' is the number of counterions;Z1and Z2are each independently selected from the group consisting of CH, CR14, and N; and wherein when Z1or Z2is CR14, R14is a C1-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH, then there is a double bond between the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH2, then there is a single bond between the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R]-R9and R100is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms;R1S-R23are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 6 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 6 carbon atoms, a substitutedor unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 6 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 6 carbon atoms or wherein one or more pair of R1Sand R16, R16and R17, R17and R18, R18and R19, R19and R20, R20and R21, R21and R22, R22and R23together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R24is C or N, wherein when R24is C, then ring B is a phenyl ring, and when R24is N then Ring B is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;Z3and Z4are each independently selected from the group consisting of CH, CR140, and N; and wherein when Z3or Z4is CR140, R140is a C’-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R15-R23is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms.25. The OLED device of any one of the previously numbered sentences having one or more of the following properties: a. Driving voltage (V) of 2.0-7.0; b. Efficiency (Cd / A, at driving voltage) of 13-88; c. CIE 1931 (at driving voltage) of (0.10-0.2, 0.21-0.42); d. Maximum efficiency (Cd / A) of 55.0-88.0; e. Maximum emission wavelength (nm) of 400-700; and f. Lifespan (hr, T95, at 6000 nit) of 3-7500.26. In another aspect, the disclosure relates to a symmetrical or unsymmetrical monoligated CCC-NHC metal complex according to Formula (I) and / or a symmetrical or unsymmetrical bis-ligated CCC-NHC metal complex according to Formula (II):Formula I wherein n is the charge on the complex:M is titanium, zirconium or hafnium; R'-R9are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dialkyl amino having 1 to 33 carbon atoms, diarylamino having 12 to 33 carbons, alkylarylamino having 7 to 33 carbons, nitro, cyano, carboxy, CF3, thioether having 2 to 20 carbon atoms and 1 to 5 sulfur atoms, boronic ester having 1 to 33 carbon atoms and having two boron-oxygen bonds, silyl ether having 1 to 33 carbon atoms, silane having 1 to 33 carbon atoms, diazonium salt having a halo or tetrafluoroborate ion, ester having 1 to 33 carbon atoms, amide having 0 to 33 carbon atoms, aldehyde having 1 to 33 carbon atoms, imine having 1 to 33 carbon atoms, phosphine having 1 to 33 carbon atoms, phosphate ester having 1 to 33 carbon atoms, isocyanide, isocyanate, a substituted or unsubstituted alkyl group having 1 to 33 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 33 carbon atoms, a substituted or unsubstituted aryl group having 6 to 33 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 33 carbon atoms, an alkylether having 2 to 33 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 33 carbon atoms or wherein one or more pair of R1and R2, R2and R3, R3and R4, R4and R5, R5and R6, R6and R7, R7and R8, R8and R9together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R10is C or N, wherein when R10is C, then ring A is a phenyl ring or a cyclohexyl ring, and when R10is N then Ring A is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;R11, R12and R13are each independently selected from a fluoro, chloro, bromo, iodo, - C=N, imine having 1 to 33 carbon atoms, carbazolyl, -CHz-aryl having 7 to 33 carbon atoms, alkyl having 1 to 50 carbon atoms, tetrahydrofuryl, dioxanyl, ether having 1 to 50 carbon atoms, polyether having 1 to 5 oxygen atoms and 2 to 33 carbon atoms, dialkyl amino having 1 to 33 carbon atoms, diarylamino having 12 to 33 carbons, alkylarylamino having 7 to 33 carbons, -OTf, -OAc, -O3SCH3, -O3SC6Hs, -O2CCF3, -OMe, t-BuO-, EtO-, CF3CH2O-, andCFSCF20-,-NCH, -Oaryl having 6 to 33 carbon atoms, alkyl having 1 to 33 carbon atoms, -CF3, phenyl,n” is 0 or 1 or 2, or 3, R100is selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms, y is 0, 1 or 2;X is a counterion and n' is the number of counterions;Z1and Z2are each independently selected from the group consisting of CH, CR14, and N; and wherein when Z1or Z2is CR14, R14is a C'-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH, then there is a double bond between the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH2, then there is a single bond between the carbon in the Z position and the azole carbon attached thereto,with the proviso that when any of R'-R9and R100is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms;Formula (II) wherein the definitions in Formula (II) for n, M, R'-Ry, R10, R14, Ring A, X, n', Z1and Z2are identical to the definitions given in Formula (I) above,R15-R23are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted orunsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms or wherein one or more pair of R15and R16, R16and R17, R17and R18, R18and R19, R19and R20, R20and R21, R21and R22, R22and R23together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R24is C or N, wherein when R24is C, then ring B is a phenyl ring, and when R24is N then Ring B is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;Z3and Z4are each independently selected from the group consisting of CH, CR140, and N; and wherein when Z3or Z4is CR140, R140is a C'-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R15-R23is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms; including complexes wherein: a) R11is dimethylamino, R12is dimethylamino and n” is 0; b) R11is dimethylamino, R12is dimethylamino, R13is dimethylamino and n” is 1; c) R11is chloro, R12is chloro and n” is 0; d) R11is chloro, R12is chloro, R13is chloro and n” is 1; and e) R11is dimethylamino, R12is chloro, R13is chloro and n” is 1, but excluding previously published examples.27. The metal complex according to any one of the previously numbered sentences, wherein M is zirconium, andX can be a strongly coordinating, weakly coordinating anion, or non-coordinating anion. Strongly coordinating anions include iodide, chloride, fluoride, bromide, Weakly coordinating anions include mesylate ( OMs), (triflate ( OTf), tetrafluoroborate (BFzf), hexafluorophosphate (PFs ), hexafluoroantimonate (SbFfi‘)and perchlorate (CIO4 ). Weakly or non-coordinating anions include bistriflimido ( N(Tf)2), tetrakis[3,5- bis(trifluoromethyl)phenyl]borate ion, B[3,5-(CF3)2CeH3]4-, commonly abbreviated as B(ArF)4" and colloquially called "BARF," selected carborane anions and borane anions. These anions are far less coordinating than tetrafluoroborate, hexafluorophosphate, and perchlorate. Related tetrahedral anions include tetrakis(pentafluorophenyl)borate B(C6F5)4~, and A1[OC(CF3)3]4“.In the bulky borates and aluminates, the negative charge is symmetrically distributed over many electronegative atoms. Related anions can be derived from tris(pentafluorophenyl)boron B(CeFs)3 by methyl abstraction for instance. Another advantage of these anions is that their salts are more soluble in non-polar organic solvents such as dichloromethane, toluene, and, in some cases, even alkanes.Neutral molecules that represent the parents to the non-coordinating anions are strong Lewis acids, e.g. boron trifluoride, BF3 and phosphorus pentafluoride, PFs. A notable Lewis acid of this type is tris(pentafluorophenyl)borane, B(C6Fs)3, which can abstract alkyl ligands such as in the following reaction: (CsHshZrCCFhh + B(C6Fs)3 [(C5H5)2Zr(CH3)]+[(CH3)B(C6F5)3]-.Another class of non-coordinating anions that can be used are derived from the carborane anion CB11H12 , and include the numerous derivatives where the hydrogens are replaced by halogens.Including the species discussed above, X can also include nitrite, sulfate, phosphate, bicarbonate, trifluoroacetate, pentafluoropropanoate, chloride, bromide, iodide, perchlorate, nitrate, benzenesulfonate, p-toluenesulfonate, methylsulfate, ethylsulfate, propylsulfate, tetrafluoroborate, tetraphenylborate, hexafluorophosphate, benzenesulfinate, acetate, trifluoroacetate, propionacetate, benzoate, oxalate, succinate, malonate, oleate, stearate, citrate, monohydrogen diphosphate, dihydrogen monophosphate, pentachlorostannate, chlorosulfonate, fluorosulfonate, trifluoromethansulfonate, hexafluoroarsenate, hexafluoroantimonate, molybdenate, tungstate, titanate, zirconate ions, or any combination thereof.28. The metal complex according to any one of the previously numbered sentences, wherein M is zirconium, and X is tetraphenylborate , trifluoroacetate, pentafluoropropanoate, chloride, bromide, iodide, fluorosulfonate, or trifluoromethansulfonate.29. The metal complex according to any one of the previously numbered sentences, wherein M is zirconium, and the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I).30. The metal complex according to any one of the previously numbered sentences, wherein M is zirconium, and the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I) and the CCC-NHC ligand is symmetrical.31 . The metal complex according to any one of the previously numbered sentences, wherein M is zirconium, and the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I) and the CCC-NHC ligand is unsymmetrical.32. The metal complex according to any one of the previously numbered sentences, wherein M is zirconium, and the metal complex is the bis-ligated CCC-NHC metal complex according to Formula (II).33. The metal complex according to any one of the previously numbered sentences, wherein the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and n is 1;R1and R9are each independently selected from an alkyl group having 1 to 6 carbon atoms, which is optionally substituted with a halogen, sulfonate, hydroxy, amino, nitro, cyano, or carboxy, or a phenyl group which is optionally substituted with a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy or an al ky 1 group having 1 to 6 carbon atoms; andZ1and Z2are each CH and there is a double bond between the carbon in the Z position and the azole carbon attached thereto.34. The metal complex according to any one of the previously numbered sentences, wherein the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R4-R6are each hydrogen.35. The metal complex according to any one of the previously numbered sentences, wherein the metal complex is the bis-ligated CCC-NHC metal complex according to Formula (II), M is zirconium, and R4-R6andR18-R20are each hydrogen.36. The metal complex according to any one of the previously numbered sentences, wherein the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R11, R12and R13are each independently selected from a chloro, dimethylamine, diethylamine, -OTf, 1 ,2,4-triazolyl, 1,2,3-triazolyl, imidazolyl, pyrazolyl, pyrrolyl, benzimidazolyl, or 6-methylindolyl; n” is 0 or 1.37. The metal complex according to any one of the previously numbered sentences, wherein the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R11, R12and R13are each independently selected from a chloro, bromo, iodo, dimethylamine, diethylamine, methylphenylamine, ethylphenylamine, and diphenylamine; and n” is 0 or 1.38. The metal complex according to any one of the previously numbered sentences, wherein the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R1and R9are each independently selected from methyl or ethyl; or a bis-ligated CCC-NHC metal complex according to Formula (II) and R1, R9, R15and R23are each independently selected from methyl or ethyl.39. The metal complex according to any one of the previously numbered sentences, wherein the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R1and R9are each independently selected from methyl or ethyl.40. The metal complex according to any one of the previously numbered sentences, wherein the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R11, R12and R13are each independently selected from a chloro, bromo or iodo.41. The metal complex according to any one of the previously numbered sentences, wherein Z1or Z2is CR14, and R14is a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, and the ring structure is aromatic or is a cyclohexyl ring with 0, 1 or 2 double bonds in the cyclohexyl ring.42. The OLED device of any one of the previously numbered sentences, excluding Ti, Zr and Hf compounds having the following CCC-NHC ligand:43. The metal complex of any one of the previously numbered sentences, wherein R1- R9are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dialkyl amino having 1 to 20 carbon atoms, diarylamino having 12 to 20 carbons, alkylarylamino having 7 to 20 carbons, nitro, cyano, carboxy, CF3, thioether having 2 to 20 carbon atoms and 1 to 5 sulfur atoms, boronic ester having 1 to 20 carbon atoms and havingtwo boron-oxygen bonds, silyl ether having 1 to 20 carbon atoms, silane having 1 to 20 carbon atoms, diazonium salt having a halo or tetrafluoroborate ion, ester having 1 to 20 carbon atoms, amide having 0 to 20 carbon atoms, aldehyde having 1 to 20 carbon atoms, imine having 1 to 20 carbon atoms, phosphine having 1 to 20 carbon atoms, phosphate ester having 1 to 20 carbon atoms, isocyanide, isocyanate, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms or wherein one or more pair of R1and R2, R2and R3, R3and R4, R4and R5, R5and R6, R6and R7, R7and Rs, Rsand R9together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R10is C or N, wherein when R10is C, then ring A is a phenyl ring or a cyclohexyl ring, and when R10is N then Ring A is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;R11, R12and R13are each independently selected from a fluoro, chloro, bromo, iodo, - C=N, imine having 1 to 20 carbon atoms, carbazolyl, -CFF-aryl having 7 to 20 carbon atoms, alkyl having 1 to 40 carbon atoms, tetrahydrofuryl, dioxanyl, ether having 1 to 40 carbon atoms, polyether having 1 to 5 oxygen atoms and 2 to 20 carbon atoms, dialkyl amino having 1 to 20 carbon atoms, diarylamino having 12 to 20 carbons, alkylarylamino having 7 to 20 carbons, -OTf, -OAc, -O3SCH3, -O3SC6H5, -O2CCF3, -OMe, t-BuO-, EtO-, CF3CH2O-, and CFjCFiO-rNCH, -Oaryl having 6 to 20 carbon atoms, alkyl having 1 to 20 carbon atoms, - CF3, phenyl,n” is 0 or 1 or 2, or 3, R100is selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms, y is 0, 1 or 2;X is a counterion and n' is the number of counterions;Z1and Z2are each independently selected from the group consisting of CH, CR14, and N; and wherein when Z1or Z2is CR14, R14is a C1-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH, then there is a double bond between the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH2, then there is a single bond between the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R]-R9and R100is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms;R15-R23are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms or wherein one or more pair of R15and R16, R16and R17, R17and R18, R18and R19, R19and R20, R20and R21, R21and R22, R22and R23together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R24is C or N, wherein when R24is C, then ring B is a phenyl ring, and when R24is N then Ring B is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;Z3and Z4are each independently selected from the group consisting of CH, CR140, and N; and wherein when Z3or Z4is CR140, R140is a C1-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R15-R23is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms.44. The metal complex of any one of the previously numbered sentences, wherein R1- R9are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dialkyl amino having 1 to 6 carbon atoms, diarylamino having 12 to 16 carbons, alkylarylamino having 7 to 16 carbons, nitro, cyano, carboxy, CF3, thioether having 2 to 6 carbon atoms and 1 to 5 sulfur atoms, boronic ester having 1 to 6 carbon atoms and having two boron-oxygen bonds, silyl ether having 1 to 6 carbon atoms, silane having 1 to 6 carbon atoms, diazonium salt having a halo or tetrafluoroborate ion, ester having 1 to 6 carbon atoms, amide having 0 to 6 carbon atoms, aldehyde having 1 to 6 carbon atoms, imine having 1 to 6 carbon atoms, phosphine having 1 to 6 carbon atoms, phosphate ester having 1 to 6 carbon atoms, isocyanide, isocyanate, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 6 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 6 carbon atoms, an alkylether having 2 to 6 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 6 carbon atoms or wherein one or more pair of R1and R2, R2and R3, R3and R4, R4and R5, R5and R6, R6and R7, R7and R8, R8and R9together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R10is C or N, wherein when R10is C, then ring A is a phenyl ring or a cyclohexyl ring, and when R10is N then Ring A is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;R11, R12and R13are each independently selected from a fluoro, chloro, bromo, iodo, - C=N, imine having 1 to 6 carbon atoms, carbazolyl, -CH2-aryl having 7 to 12 carbon atoms, alkyl having 1 to 30 carbon atoms, tetrahydrofuryl, dioxanyl, ether having 1 to 30 carbonatoms, polyether having 1 to 5 oxygen atoms and 2 to 6 carhon atoms, dialkyl amino having 1 to 6 carbon atoms, diarylamino having 12 to 16 carbons, alkylarylamino having 7 to 16 carbons, -OTf, -OAc, -O3SCH3, -O3SC6H5, -O2CCF3, -OMe, t-BuO-, EtO-, CF3CH2O-, and CF3CF2O-,-NCH, -Oaryl having 6 to 12 carbon atoms, alkyl having 1 to 6 carbon atoms, - CF3, phenyl,n” is 0 or 1 or 2, or 3, R100is selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 6 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 6 carhon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 6 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 6 carbon atoms, y is 0, 1 or 2;X is a counterion and n' is the number of counterions;Z1and Z2are each independently selected from the group consisting of CH, CR14, and N; and wherein when Z1or Z2is CR14, R14is a C]-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carhon attached thereto, and wherein when Z1or Z2is CH, then there is a double bond between the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH2, then there is a single bond between the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R'-R9and R100is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independentlyselected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carhoxy and an alkyl group having 1 to 6 carbon atoms;R15-R23are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 6 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 6 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 6 carbon atoms or wherein one or more pair of R15and R16, R16and R17, R17and R18, R18and R19, R19and R20, R20and R21, R21and R22, R22and R23together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R24is C or N, wherein when R24is C, then ring B is a phenyl ring, and when R24is N then Ring B is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;Z3and Z4are each independently selected from the group consisting of CH, CR140, and N; and wherein when Z3or Z4is CR140, R140is a C1-C6alkyl, Cs-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R15-R23is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms.45. A composition comprising the metal complex of any one of the previous sentences, wherein the concentration of the metal complex is higher than 10 ppm, or higher than 50 ppm, or higher than 100 ppm, or higher than 500 ppm, or higher than 1000 ppm, or higher than 0.1 wt.%, or higher than 1 wt.%, or higher than 2.5 wt%, or higher than 5 wt.%, or higher than 10 wt.%, or is higher than 10 ppm and less than 90 wt.%, or higher than 50 ppm and less than 90 wt.%, or higher than 100 ppm and less than 90 wt.%, or higher than 500 ppm and less than 90 wt.%, or higher than 1000 ppm and less than 90 wt.%, or higher than 0.1 wt.% and less than 90 wt.%, or higher than 1 wt.% and less than 90 wt.%, or higher than2.5 wt% and less than 90 wt.%, or higher than 5 wt.% and less than 90 wt.%, or higher than 10 wt.% and less than 90 wt.%, or is less than 50 wt.%, or is less than 20 wt.%.BRIEF DESCRIPTION OF THE DRAWINGSThe novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are used, and the accompanying drawings of which:FIG. 1 is an illustration of the modular approach to ligand design that affords control of coarse tuning elements and fine tuning elements.FIG. 2 is a schematic cross-sectional view of an organic light-emitting device according to an embodiment.FIG. 3 shows an exact mass determination spectrum of the tri chloro compound (12), showing peaks consistent with [(MeC1C1CMe)2Zr]2+.FIG. 4 shows a concentration dependent emission spectrum of the trichloro compound (12) [(MeC1C1CMe)2Zr]2+after excitation with 304 nm wavelength light.DETAILED DESCRIPTIONThe details of one or more embodiments of the presently-disclosed subject matter are set forth in this document. However, modifications to embodiments described in this document, and other embodiments, will be evident to those of ordinary skill in the art after a study of the information provided in this document. Additionally, it will be apparent to one of ordinary skill in the art that methods, devices, device elements, materials, procedures and techniques other than those specifically described herein can be applied without resort to undue experimentation. All such modifications, other embodiments, and art-known functional equivalents remain within the spirit and scope of the instant disclosure and are intended to be encompassed by this disclosure. The information provided in this document, and particularly the specific details of the described exemplary embodiments, is provided primarily for clearness of understanding and no unnecessary limitations are to be understood therefrom. In case of conflict, the specification of this document, including definitions, will control.While the terms used herein are believed to he well understood hy those of ordinary skill in the art, certain definitions are set forth to facilitate explanation of the presently disclosed subject matter.Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which the invention(s) belong.All patents, patent applications, published applications and publications, databases, websites, and other published materials referred to throughout the entire disclosure herein, unless noted otherwise, are incorporated by reference in their entirety.Where reference is made to a URL or other such identifier or address, it understood that such identifiers can change and particular information on the internet can come and go, but equivalent information can be found by searching the internet. Reference thereto evidences the availability and public dissemination of such information.Although any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of the presently-disclosed subject matter, representative methods, devices, and materials are described herein.The present application can "comprise" (open ended) or "consist essentially of the components of the present invention as well as other ingredients or elements described herein. As used herein, "comprising" is open ended and means the elements recited, or their equivalent in structure or function, plus any other element or elements which are not recited. The terms "having" and "including" are also to be construed as open ended unless the context suggests otherwise. The transitional phrase, “consists essentially of’ or “consisting essentially of” is intended to limit the scope of a sentence to the specified materials or steps "and those that do not materially affect the basic and novel characteristic(s)" of the claimed invention.When open-ended terms such as "including" or 'including, but not limited to" are used, there may be other non-enumerated members of a list that would be suitable for the making, using or sale of any embodiment thereof.Following long-standing patent law convention, the terms "a", "an", and "the" refer to "one or more" when used in this application, including the claims. Thus, for example, reference to "a ligand" includes a plurality of such ligands, and so forth.Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unlessindicated to the contrary, the numerical parameters set forth in this specification and claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently-disclosed subject matter.As used herein, the term "about," when referring to a value or to an amount of mass, weight, time, volume, concentration or percentage is meant to encompass variations of in some embodiments ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1 %, in some embodiments ±0.5%, and in some embodiments ±0.1 % from the specified amount, as such variations are appropriate to perform the disclosed method.As used herein, ranges can be expressed as from "about" one particular value, and / or to "about" another particular value. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as "about" that particular value in addition to the value itself. For example, if the value "10" is disclosed, then "about 10" is also disclosed. It is also understood that whenever a range is disclosed, all subranges and individual values are intended to be encompassed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.As used herein, "optional" or "optionally" means that the subsequently described event or circumstance does or does not occur and that the description includes instances where said event or circumstance occurs and instances where it does not. For example, an optionally variant portion means that the portion is variant or non-variant. The dashed lines in the various Formulas presented herein represent optional bonds or substituents.As used herein, the term “CCC-NHC pincer ligand” or “CCC-NHC ligand” is used to generically refer to the tridentate ligand used in Formulae I and II either free of metal or after the tridentate ligand is bound to the metal center. The bis(imidazolium salt) precursor that differs by three hydrogen atoms is routinely referred to as the “salt”, “bis-salt,” or proligand. The term “CCC-NHC pincer ligand complex” or “CCC-NHC complex” or “CCC-NHC pincer ligand compound” or “CCC-NHC compound” is used to generically refer to the tridentate ligand bound to a metal as used in Formulae I and II. The acronym “NHC” refers to N-heterocyclic carbenes.The present disclosure includes symmetrical or unsymmetrical compounds or salts. The NHC donors of the CCC-NHC pincer ligands can be systematically varied to produce symmetrical or unsymmetrical organometallic compounds or salts. Whether a compound or salt is symmetrical is exemplified in the 2-dimensional drawing of Figure 1. For instance, if an imaginary straight line is drawn through the middle of the phenyl ring to include thecarbon bonded to the X substituent as well as the X substituent, then a symmetrica] compound or salt would have identical atoms and chemical bonds on the tridentate ligand on both sides of the imaginary line, and an unsymmetrical compound or salt would not have identical atoms and / or chemical bonds on the tridentate ligand on both sides of the imaginary line.Process of Preparing the symmetrical or unsymmetrical mono-ligated CCC-NHC metal complex according to Formula (I) and / or a symmetrical or unsymmetrical bis-ligatedCCC-NHC metal complex according to Formula (II)The preparation of symmetrical and unsymmetrical CCC-NHC compounds is described in U.S. PgPub. No. 2020 / 0095228A1 and Box et al., "An efficient route to unsymmetrical bis(azolium) salts: CCC-NHC pincer ligand complex precursors" , Tetrahedron 2017, 73 (16), 2191-2195. These documents are incorporated herein by reference in their entirety.An aspect of the disclosure is a process of preparing a symmetrical or unsymmetrical mono-ligated CCC-NHC metal complex according to Formula (I) as recited any one of the previous claims, said process comprising:Formula (III)IFormula (IV)wherein M is Zr, Ti and Hf, and in Formulae (III) and Formula (IV), the definitions of n, M, R -Ry, R10, R14, R100, Ring A, X, Z1and Z2are identical to the definitions given in Formula (I); and in Formula (IV), the definition of y is 2 or 3; step (B) is an optional step and is a ligand exchange reaction wherein one or all of the NMe2 radicals attached to the M atom is replaced with the radicals of R11, R12and optionally R13to give the mono-ligated CCC-NHC metal complex according to Formula (I).In step (A), the reaction forming the metalated compounds of Formula (IV) can be done under relatively mild conditions. Initially, the CCC-NHC compound (a bis-salt) is combined with a strong base in an organic solvent. Any strong base can be chosen so long as the base is capable of deprotonating the CCC-NHC compound. Examples of such a strong base are benzyl potassium and KHMDS. The bis-salt can be combined with the strong base in a 1 :2 molar ratio. Any organic solvent can be used, including mixtures of organic solvents, so long as the organic solvent does not cause the percent yield to decrease to unacceptable levels. For instance, the organic solvent can be benzene, THF, or mixtures thereof. The reagents are allowed to react until a homogeneous solution is obtained that also routinely results in a colored solution. This is allowed to react about 5 minutes after which one equivalent of solid Zr(NMez)4 is added. The reaction was left overnight. Upon reduction of the solvent volume in vacuo crystals form and are collected.In an embodiment, x moles of CCC-NHC compound and 2x moles of benzyl potassium can be suspended in a mixture of benzene / THF (4: 1 volume ratio) in order to deprotonate the CCC-NHC compound. The mixture can be stirred for 30 minutes at room temperature.After deprotonation of the CCC-NHC compound, the metalation source is added. The metalation source can be a metal tetrakisdimethyl amido species, such as (Zr(NMe2)4 or Ti(NMe2)4 or Hf(NMe2)4). The initial metalation source may be added in any suitable amount depending upon the reagents and reaction conditions. Suitable amounts of the initial metalation source include, but are not limited to, between 1 and 10 molar equivalents, preferably 1 to 2.5 molar equivalents. The reaction can be performed at 18-180 Celsius, preferably at around room temperature (20-25 Celsius).An example of the metalation reaction is shown below:When a “non-coordinating counter ion” (including BPlu, PFe, BF4, or carboranes, for instance) is present in the salt, the metalation step produces the bis-amido complex as illustrated in the embodiment here.Step (B) is an optional step wherein there is a ligand exchange reaction that can be done under relatively mild conditions. Any organic solvent can be used, including mixtures of organic solvents, so long as the organic solvent does not cause the percent yield to reduce to unacceptable levels. For instance, the organic solvent can be benzene, THF or mixtures thereof. The reaction can be performed at 18-40 Celsius, preferably at around room temperature (20-25 Celsius).A generalized synthesis that is illustrative for the exchange reaction with the trisamido complex prepared in situ is shown below:Synthesis of tris-azole derivatives - The CCC-NHC Zr trisamido complexes derived from the procedure above and three equivalents of the azole was then added. Reaction times depended upon the specific azole and its characteristic acidity and steric hinderance. The product precipitated directly, upon reduction of the solvent volume, or upon addition of a second solvent.A generalized synthesis that is illustrative for the exchange reaction with the trisamido complex prepared in situ is shown below:wherein each XH can be substituted or unsubstituted. Each XH can be independently substituted with one or two R100radicals as defined above and 1,2,3-benzotriazole is included among these. The XH loses its proton on the nitrogen due to the basic conditions to allow for the formation of the Zr-N bond.Some examples of the formation of the tris-azole derivatives are given below.Linkage isomers are possible in this last example. In other words, the butyl groups can be replaced with any of the radicals at R1or R9of Formula (I).When a “non-coordinating counter ion” (including BPI14, PFe, BF4, or carboranes, for instance) is present in the salt the metalation step produces the bis-amido complex as illustrated in the embodiment here.Synthesis of bis-azole derivatives - A generalized synthesis involving ligand exchange on the zirconium atom of the bis-amido complex is shown below:wherein each XH can be substituted or unsubstituted. Each XH can be independently substituted with one or two R100radicals as defined above in Formula (I).The ligands remain facile for further exchange. In an embodiment, the ligand exchange reaction can be as follows:(11) (12)The ligand exchange reaction can be done under relatively mild conditions as shown above.The amido (11) is reacted with trimethylsilyl chloride in methylene chloride at room temperature with stirring for 2 hours to give the trichloro compound (12) at 73% yield.The trichloro compound (12) depicted above was tested in the solid state at 77K and 298K where it produced photoluminescent quantum yields of 25% and 1%, respectively.In an NMR tube, 5.0 mg (0.011 mmol, 1.0 eq) of (McC‘C1CMc)Zr(NMe2)3 was dissolved in 1 mL of CeDe. The solution was yellow. The white [(MeC1C1CMe)H3][BPh4]2 salt was added in one portion (9.5, 0.011 mmol, 1.0 eq) to the mixture and remained heterogeneous. After heating for 10 min to 70°C, the white powder slowly turned red and the color of the solution changed from yellow to colorless. The signals of (MeC1C‘CMe)Zr(NMe2)3 in CeDe disappeared and the signal of the dimethylamine grew in intensity. The solution presented a green-blue emission after irradiating under UV. After decanting the CeDe from the NMR tube, DCM was added. The red portion dissolved leaving a white solid. A sample of the solid was taken and diluted in acetonitrile. An exact mass determination of this acetonitrile solution yielded peaks consistent with z = 2 and the expected isotope pattern, [(MeCiCiCMe)2Zr][BPh4]2. ESI-MS (m / z) [M - 2 BPh4]+: [(MeCiCiCMe)2Zr]2+obs, 282.0658; calc, 282.0658. (A = 0.0 ppm). See Figure 3.The trichloro compound (12) was also found to produce a concentration dependent emission in solution that gave the following concentration dependent emission spectrum in THF after excitation with 304 nm wavelength light. At higher concentration, the low energy emission coupled with the higher energy emission effectively produces white light. At low concentrations the presumed excimer that produces the low energy emission is no longer present and a blue emission is observed. See Figure 4.In another embodiment, the trichloro compound (12) was used in a ligand exchange reaction to make the triflate compound (13) as shown below, which had a solid state emission with a photoluminescence quantum yield of 19% at 298 K. It also showed a concentration dependence similar to the trichloride complex.X Off(12) (13)The process can be altered to favor preparation of the bis-ligated species. In an aspect, is a process of preparing a symmetrical or unsymmetrical bis-ligated CCC-NHC metal complex according to Formula (II) as recited above: said process comprising reacting a molar amount of a compound of Formula (III) with a molar amount of M(NMe2)4:Fonnula (III)wherein M is Zr. Hf or Ti and the definitions of n. Rx-R9. R10, R14, R100, R140, Ring A, X, Z1and Z2are identical to the definitions given in Formula (II), and wherein the molar amount of M(NMe2)4 is at least twice the molar amount of the compound of Formula (III).PLED DesignThe CCC-NHC pincer compound or salt represented by Formulae (I) or (II) is suitable as, for example, a dopant in an emissive layer in an organic layer of an organic light-emittingdevice, and, according to another aspect of the disclosure, provided is an organic lightemitting device including: a first electrode layer; a second electrode layer; and an emissive layer (also referred to herein as an organic layer) disposed between the first electrode layer and the second electrode layer, wherein the emissive layer includes at least one of the symmetrical or unsymmetrical mono-ligated CCC-NHC metal complexes according to Formula (I) and / or at least one symmetrical or unsymmetrical bis-ligated CCC-NHC metal complex according to Formula (II).The organic light-emitting device includes the emissive layer comprising at least one of the symmetrical or unsymmetrical mono-ligated CCC-NHC metal complexes according to Formula (I) and / or at least one symmetrical or unsymmetrical bis-ligated CCC-NHC metal complex according to Formula (II) and thus may have low driving voltage, high efficiency, high electrical power, high quantum efficiency, long lifespan, and excellent color purity. The CCC-NHC metal complexes of the disclosure will emit in solution or solid state.The complexes represented by Formula (I) and / or Formula (II) may be used between a pair of electrodes in an organic light-emitting device. For example, the complexes represented by Formula (I) and / or Formula (II) may be included in the emissive layer. Here, the complexes of the disclosure serve as dopants, and the emissive layer may further include a host, wherein the amount of the complexes represented by Formula (I) and / or Formula (II) is smaller than the amount of the host.As used herein, the term “at least one CCC-NHC metal complex'’ denotes at least one of the symmetrical or unsymmetrical mono-ligated CCC-NHC metal complexes according to Formula (I) and / or at least one symmetrical or unsymmetrical bis-ligated CCC-NHC metal complex according to Formula (II) above.For example, the organic layer may include only Example 1 as the at least one CCC- NHC metal complex. In this regard, Example 1 may be included in the emissive layer of the organic light-emitting device. Alternatively, the organic layer may include Example 1 and Example 2 as the at least one CCC-NHC metal complex. In this regard, Example 1 and Example 2 may be included in the same layer (for example, both Example 1 and Example 2 may be included in the emissive layer).The first electrode may be an anode, which is a hole injection electrode, and the second electrode may be a cathode, which is an electron injection electrode. Alternatively, the first electrode may be a cathode, which is an electron injection electrode, and the second electrode may be an anode, which is a hole injection electrode.For example, the first electrode may be an anode, the second electrode may be a cathode, and the organic layer may include: i) a hole transport region disposed between the first electrode and the emissive layer, wherein the hole transport region may include at least one selected from a hole injection layer, a hole transport layer, and an electron blocking layer; and ii) an electron transport region disposed between the emissive layer and the second electrode, wherein the electron transport region may include at least one selected from a hole blocking layer, an electron transport layer, and an electron injection layer.As used herein, the terms “organic layer’- and “emissive layer’- refers to a single and / or a plurality of layers disposed between the first electrode and the second electrode in an organic light-emitting device. The “organic layer” and “emissive layer” may include not only organic compounds but also organometallic complexes including metals.FIG. 2 is a schematic view of an organic light-emitting device 10 according to an embodiment. Hereinafter, a structure and a method of manufacturing the organic light- emitting device according to an embodiment will be described with reference to FIG. 2. The organic light-emitting device 10 includes a first electrode 11, an organic layer 15, and a second electrode 19, which are sequentially layered in the stated order.A substrate may be additionally disposed under the first electrode 11 or on the second electrode 19. The substrate may be a conventional substrate that is used in an organic lightemitting device, such as glass substrate or a transparent plastic substrate, each having excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and water repellency.The first electrode 11 may be formed by vacuum-depositing or sputtering a material for forming the first electrode on the substrate. The first electrode 11 may be an anode. The material for the first electrode 11 may be selected from materials with a high work function for an easy hole injection. The first electrode 11 may be a reflective electrode, a semi- transmissive electrode, or a transmissive electrode. Examples of the material for the first electrode 1 1 may include indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO2), and zinc oxide (ZnO). Alternatively, a metal such as magnesium (Mg), aluminum (Al),aluminum-lithium (Al — Li), calcium (Ca), magnesium-indium (Mg — Tn), and magnesiumsilver (Mg — Ag) may be used.The first electrode 11 may have a single layer structure or a multi-layer structure including a plurality of layers. For example, the first electrode 11 may have a triple-layer structure of ITO / Ag / ITO, but embodiments are not limited thereto.The organic layer 15 may be disposed on the first electrode 11.The organic layer 15 may include a hole transport region, an emissive layer, and an electron transport region.The hole transport region may be disposed between the first electrode 11 and the emissive layer.The hole transport region may include at least one of a hole injection layer, a hole transport layer, an electron blocking layer, and a buffer layer.The hole transport region may only include a hole injection layer or a hole transport layer. Alternatively, the hole transport region may include a structure in which a hole injection layer / a hole transport layer or a hole injection layer / a hole transport layer / an electron blocking layer are sequentially layered on the first electrode 11.When the hole transport region includes a hole injection layer, the hole injection layer (HIL) may be formed on the first electrode 11 by using various methods such as vacuumdeposition, spin coating, casting, and Langmuir-Blodgett (LB) method.When the hole injection layer is formed using a vacuum deposition, vacuum deposition conditions may vary according to the compound that is used to form the hole injection layer, and the desired structure and thermal properties of the hole injection layer to be formed. For example, vacuum deposition may be performed at a temperature in a range of about 100° C. to about 500° C., a vacuum degree in a range of about 10-8 torr to about 10-3 torr, and a deposition rate in a range of about 0.01 Angstroms per second (A / sec) to about 100 A / sec. However, the deposition conditions are not limited thereto.When the hole injection layer is formed using spin coating, the coating conditions may vary according to the compound that is used to form the hole injection layer, and the desired structure and thermal properties of the hole injection layer to be formed. For example, the coating rate may be in a range of about 2,000 revolutions per minute (rpm) to about 5,000 rpm, and a temperature at which heat treatment is performed to remove a solvent after coating may be in a range of about 80° C. to about 200° C. However, the coating conditions are not limited thereto.The conditions for forming a hole transport layer and an electron blocking layer may be inferred based on the conditions for forming the hole injection layer.The hole transport region may include at least one selected from m-MTDATA, TDATA, 2-TNATA, NPB, p-NPB, TPD. a spiro-TPD. a spiro-NPB. methylated-NPB, TAPC, HMTPD, , polyaniline / dodecylbenzenesulfonic acid (Pani / DBSA), poly(3,4- ethylenedioxythiophene) / poly(4-styrenesulfonate) (PEDOT / PSS), polyaniline / camphor sulfonic acid (Pani / CSA), (polyaniline) / poly(4-styrenesulfonate) (PANI / PSS), polyvinylcarbazole - Poly(9-vinylcarbazole) (PVK)wherein n is sufficient to provide a weight average molecular weight of 10,000 to 500,000 grams per mole (g / mol),4,4',4-Tris(carbazol-9-yl)triphenylamine (TcTa)N,N-Bis(4-(9H-carbazol-9-yl)phenyl)-4-(3-(9,9-dimethylacridin-10(9H)-yl)-9H-carbazol-9- yl)aniline (TCTA-BP-DMAC)9-(3,5-Di(triphenylen-2-yl)phenyl)-9H -carbazole (DTP-mCP)4,4’-Bis(carbazol-9-yl)biphenyl (CBP)Moreover, the hole transport region may include at least one compound disclosed in paragraphs

[0225] -

[0240] of U.S. PgPub. No. 2016 / 0181530A1 which is incorporated herein by reference.A thickness of the hole transport region may be in a range of about 100 Angstroms (A) to about 10,000 A, for example, about 100 A to about 1,000 A. When the hole transport region includes a hole injection layer and a hole transport layer, the thickness of the hole injection layer may be in a range of about 100 A to about 10,000 A, and for example, about 100 A to about 1 ,000 A, and the thickness of the hole transport layer may be in a range of about 50 A to about 2,000 A, and for example, about 100 A to about 1,500 A. When the thicknesses of the hole transport region, the hole injection layer, and the hole transport layer are within these ranges, excellent hole transport characteristics may be obtained without a substantial increase in driving voltage.The hole transport region may further include, in addition to the mentioned materials above, a charge-generating material to improve conductive properties. The charge-generating material may be homogeneously or non-homogeneously dispersed throughout the hole transport region.The charge-generating material may be, for example, a p-dopant. The p-dopant may be one selected from a quinone derivative, a metal oxide, and a cyano group-containing compound, but embodiments are not limited thereto. For example, non-limiting examples of the p-dopant are a quinone derivative, such as tetracyanoquinonedimethane (TCNQ) or2,3,5,6-tetrafluoro-tetracyano- l ,4-benzoquinonedimethane (F4-TCNQ); a metal oxide, such as a tungsten oxide or a molybdenum oxide; and a compound containing a cyano group, such as Compound HT-D1 illustrated below, but they are not limited thereto.Compound HT-D1F4-TCNQThe hole transport region may further include a buffer layer. The buffer layer may compensate for an optical resonance distance according to a wavelength of light emitted from the emissive layer, and thus may increase efficiency.The emissive layer may be formed on the hole transport region by using various methods, such as vacuum-deposition, spin coating, casting, or an LB method. When the emissive layer is formed by vacuum-deposition or spin coating, vacuum-deposition and coating conditions for the emissive layer may be generally similar to the conditions forforming a hole injection layer, though the conditions may vary depending on the compound used.When the hole transport region includes an electron blocking layer, a material for the electron blocking layer may be selected from a material that may be used in the hole transport region and a material for a host, but embodiments are not limited thereto. For example, when the hole transport region includes the electron blocking layer, the material for the electron blocking layer may be mCP.The emissive layer may include a host and a dopant, and the dopant includes the at least one CCC-NHC metal complex of the disclosure. Moreover, the emissive layer may also include at least one compound disclosed in paragraphs

[0249] -

[0266] of U.S. PgPub. No. 2016 / 0181530A1 which is incorporated herein by reference.When the organic light-emitting device is a full color organic light-emitting device, the emissive layer may be patterned into a red emissive layer, a green emissive layer, and a blue emissive layer. Alternatively, the emissive layer may have a structure in which the red emissive layer, the green emissive layer, and / or the blue emissive layer are layered to emit white light or other various embodiments are possible.When the emissive layer includes a host and a dopant, an amount of the dopant may be in a range of about 0.01 parts to about 15 parts by weight based on 100 parts by weight of the host, but embodiments are not limited thereto.A thickness of the emissive layer may be in a range of about 100 A to about 1,000 A, for example, about 200 A to about 600 A. When the thickness of the emissive layer is within this range, excellent light-emission characteristics may be obtained without a substantial increase in driving voltage.Then, an electron transport region may be disposed on the emissive layer. The electron transport region may include at least one selected from a hole blocking layer, an electron transport layer, and an electron injection layer, but is not limited thereto.For example, the electron transport region may have a structure of a hole blocking layer / an electron transport layer / an electron injection layer or an electron transport layer / an electron injection layer, but it is not limited thereto. The electron transport layer may have a single layer structure or a multi-layer structure including two or more different materials.The conditions for forming a hole blocking layer, an electron transport layer, and an electron injection layer may be inferred based on the conditions for forming the hole injection layer.When the electron transport region includes a hole blocking layer, the hole blocking layer may include, for example, at least one of BCP, Bphen and Balq, but embodiments are not limited thereto:A thickness of the hole blocking layer may be in a range of about 20 A to about 1 ,000 A, for example, about 30 A to about 300 A. When the thickness of the hole blocking layer is within this range, excellent hole blocking characteristics may be obtained without a substantial increase in driving voltage.The electron transport layer may further include at least one of BCP and Bphen above and Alqs, Balq, TAZ, and NT AZ below:Alternatively, the electron transport layer may include at least one selected from Compounds ET1 and ET2. but it is not limited thereto.ET!The thickness of the electron transport layer may be in a range of about 100 A to about 1,000 A, for example, about 150 A to about 500 A. When the thickness of the electron transport layer is within this range, excellent electron transport characteristics may be obtained without a substantial increase in driving voltage.The electron transport layer may further include a metal -containing material in addition to the materials described above.The metal-containing material may include a Li complex. The Li complex may include, for example, Compound ET-D1 (lithium quinolate. LiQ) or ET-D2.The electron transport region may include an electron injection layer (EIL) that facilitates electron injection from the second electrode 19.The electron injection layer may include at least one selected from LiF, Nad, CsF, Li2O, and BaO.A thickness of the electron injection layer may be in a range of about 1 A to about 100 A, for example, about 3 A to about 90 A. When the thickness of the electron injection layer is within this range, excellent electron injection characteristics may be obtained without a substantial increase in driving voltage.The second electrode 19 is disposed on the organic layer 15. The second electrode 19 may be a cathode. A material for the second electrode 19 may be a material having a relatively low work function, such as a metal, an alloy, an electrically conductive compound, and a mixture thereof. Detailed examples of the material for forming the second electrode 19 are lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al — Li), calcium (Ca), magnesium-indium (Mg — In), and magnesium-silver (Mg — Ag). Alternatively, ITO or IZO may be used to form a transmissive second electrode 19 to manufacture a top emission light-emitting device, and such a variation may be possible.Hereinbefore, the organic light-emitting device has been described with reference to FIG. 2, but embodiments are not limited thereto. For instance, the OLED can have the following configuration:The presently-disclosed subject matter is further illustrated by the following specific but non-limiting examples. The following examples may include compilations of data that are representative of data gathered at various times during the course of development and experimentation related to the presently-disclosed subject matter.EXAMPLESThe following examples relate to forming and testing various CCC-NHC complexes disclosed herein. Zirconium pincer compounds have been shown to emit when stimulated by UV light. Two families of pincer compounds have been demonstrated: the tris-amido complex family of complexes (1) and the bis-amido family of complexes (2).Example 1 - General synthesis of trisamido complexes (1).In a 10 mL flask, 0.125 mmol of the pincer salt and 2 eq. of benzyl potassium were suspended in a mixture of benzene / THF (4 mL / 1 mL). The mixture was stirred for 30 minutes at room temperature. A brown solid formed and the reaction gradually changed color from a bright red to brownish red. The reaction mixture was filtered through Celite. A transparent yellow filtrate was recovered. Zr(NMe2)4 was added to the filtrate and the vial was manually shaken. The mixture was left to rest for Ih. The mixture was concentrated to approximately 2 mL, and 8 mL of Et2O was added. The target product precipitates as a microcrystalline material.’H-NMR (500 MHz, C6D6): δ 7.09 (t, J = 7.7 Hz, IH), 6.82 (d, J = 7.8 Hz, 2H), 6.81 (d, J = 1.9 Hz, 2H), 6.01 (d, J = 1.8 Hz, 2H), 3.44 (s, 6H), 3.24 (s, 18H).13C-NMR (126 MHz, C6D6): δ 198.23, 147.99, 126.03, 120.41, 114.67, 109.05, 47.08, 37.29.Example 2 - Synthesis of 2-(l ,3-Bis(3'-butyl-imidazol-2'-ylidene)phenylene)(bis- dimethylamido) tetraphenylborate Zirconium(IV) (2)l,3-Bis(3'-butylimidazol-T-yl) benzene di-tetraphenylborate salt (1.0 g, 1.038 mmol), Zr(NMe2)4 (0.69 g, 2.56 mmol) and toluene (30 mL) were combined and stirred for 10 hours at 130°C in a sealed tube. After cooling to room temperature, a white crystal precipitated from the reaction mixture. The crystals were collected and dried under reduced pressure (0.075g, 88%). A crystal suitable for X-ray diffraction was selected from the solids. ’H NMR (500 MHz, CD2CI2) ) δ 7.47 (d, 7 =5, 2H ), 7.43 (t, J = 5 1H), 7.37 (s, 8H), 7.18 (d, J = 10 2 H), 7.06 (t, J = 5, 8H), 7.03 (d, 2H), 3.95 (t, J =10, 4H), 3.05 (s, 12H), 1.97 (m, 5H), 1.41 (m, 4H), 1.03(t, J = 10, 6H).Example 3 - Exchanging amidos on complex 2 with 1 ,2,4-triazole2-(l,3-Bis(3'-butyl-imidazole-2'-ylidene)phenylene)(bis-dimethyl amido) tetraphenylborate Zirconium(IV) (2) (50mg, 0.061mmol), 1 ,2,4-triazole (8.8mg, 0.128 mmol) and THF (1.5ml) were combined and stirred for 2 hours at room temperature in a vial. Thesolvent was removed through vacuum evaporation to give a white solid on the walls of the vial. The solid was washed with EbO and collected over a Buchner funnel (40.5mg 70%). The photograph is of a vial comprising a solvent and the product which is emitting light. The light was generated by stimulation with long wavelength UV (-365 nm) light.Example 4 - Exchanging amidos on complex 2 with 1,2,3-triazole2-(l,3-Bis(3'-butyl-imidazol-2'-ylidene)phenylene)(bis-dimethylamido) tetraphenylborate Zirconium(IV) (2) (lOmg, 0.012mmol), 1,2,3-triazole (2.2uL, 0.038 mmol) and dichloromethane (DCM) (1.0ml) were combined in NMR tube at room temperature. After 2 hours the solvent was evaporated through vacuum evaporation which left white solids on the wall of the vial. The photograph is of a vial comprising a solvent and the product which is emitting light. The light was generated by stimulation with long wavelength UV (~365 nm)light.Example 5 - Exchanging amidos on complex 2 with imidazole2-(l,3-Bis(3'-butyl-imidazol-2'-ylidene)phenylene)(bis-dimethylamido) tetraphenylborate Zirconium(IV) (2) (lOOmg, 0.121mmol), imidazole (26.92mg, 0.390 mmol) and THF (3ml) were combined and stirred for 2 hours at room temperature in a vial. The solvent was removed through vacuum evaporation to give white solid on the walls of the vial. The solid was washed with EtzO and collected over Buchner funnel (40.5mg 70%). The photograph is of an NMR tube comprising a solvent and the product which is emitting light. The light was generated by stimulation with long wavelength UV (-365 nm)light.Example 6 - Exchanging amidos on complex 2 with pyrazole2-(l,3-Bis(3'-butyl-imidazol-2'-ylidene)phenylene)(bis-dimethylamido) tetraphenylborate Zirconium(IV) (2) (lOmg, 0.012mmol), pyrazole (2.61mg, 0.038 mmol) and DCM ( 1.0ml) were combined in NMR tube at room temperature. After 2 hours the solvent was evaporated through vacuum evaporation which left colorless solids on the wall of the vial. The solid was washed with diethyl ether to give white solid. The photograph is of a vial comprising a solvent and the product which is emitting light. The light was generated by stimulation with long wavelength UV (-365 nm) light.Example 7 - Exchanging amidos on complex 2 with pyrrole2-(l,3-Bis(3'-butyl-imidazol-2'-ylidene)phenylene)(bis-dimethylamido) tetraphenylborate Zirconium(IV) (2) (lOmg, 0.012mmol), pyrrole (2.61uL, 0.038 mmol) and DCM (1.0ml) were combined in NMR tube at room temperature. After 4 minutes the solvent was evaporated through vacuum evaporation which left colorless solids on the wall of the vial. The solid was washed with diethyl ether to give white solid.Example 8 - Exchanging amidos on complex 2 with benzimidazole2-(l,3-Bis(3'-butyl-imidazol-2'-ylidene)phenylene)(bis-dimethylamido) tetraphenylborate Zirconium(IV) (2) (lOmg, 0.012mmol), benzimidazole (4.5mg, 0.038 mmol) and DCM (1.0ml) were combined in NMR tube at room temperature for 3 hours. The photograph is of the NMR tube comprising a solvent and the product which is emitting light. The light was generated by stimulation with long wavelength UV (~365 nm) light.Example 9 - Exchanging amidos on complex 2 with 6-methylindole2-(l,3-Bis(3'-butyl-imidazol-2'-ylidene)phenylene)(bis-dimethylamido) tetraphenylborate Zirconium(IV) (2) (lOmg, 0.012mmol), 6-methylindole (5.2mg, 0.040 mmol) and DCM (1.0ml) were combined in NMR tube at room temperature for 7 days. The photograph is of the NMR tube comprising a solvent and the product which is emitting light. The light was generated by stimulation with long wavelength UV (~365 nm) light.Process of Preparing an PLED (Prophetic)An ITO glass substrate (an anode) can be cut to a size of 50 millimeters (mm)x50 mmx0.5 mm, and then ultrasonicated in acetone, isopropyl alcohol, and pure water (for 15 minutes in each solvent), and then cleaned by UV ozone for 30 minutes.Then, m-MTDATA can be deposited on the glass substrate at a deposition rate of 1 Angstrom per second (A / sec) to form a hole injection layer having a thickness of 600 Angstroms (A) on the ITO electrode (anode), and a-NPD can be deposited on the hole injection layer at a deposition rate of 1 A / sec to form a hole transport layer having a thickness of 250 A.A CCC-NHC compound or salt of the present disclosure (a dopant) and CBP (a host) can be co-deposited on the hole transport layer at deposition rates of 0. 1 A / sec and 1 A / sec, respectively, to form an emissive layer having a thickness of 400 A.BAlq can be deposited on the emissive layer to form a hole blocking layer having a thickness of 50 A. Alq3 can be deposited on the hole blocking layer to form an electron transport layer having a thickness of 300 A. LiF can be deposited on the electron transport layer to form an electron injection layer having a thickness of 10 A, and Al can be deposited on the electroninjection layer to form a second electrode (a cathode) having a thickness of 1 ,200 A, thereby manufacturing an organic light-emitting device having a structure of ITO / m-MTDATA (600 A) / a-NPD (250 A) / CBP+10% (Compound 2) (400 A) / Balq (50 A) / Alq3 (300 A) / LiF (10 A) / A1 (1200 A).PLED CharacterizationThe organic light-emitting devices manufactured according to the present disclosure can be evaluated in terms of driving voltage, efficiency, power, color purity, quantum efficiency, and lifespan. This evaluation can be performed using a current- voltage meter (Keithley 2400) and luminance meter (Minolta Cs-IOOOA). Lifespan (T95, at 6000 nit) can be evaluated by measuring the amount of time that elapsed until luminance is reduced to 95% of the initial brightness of 100%.It is expected that the OLED of the present disclosure will have the following characteristics:

Claims

Claims:

1. An Organic Light Emitting Diode (OLED) device, comprising an emissive layer in between a first electrode layer and a second electrode layer, wherein the emissive layer comprises a symmetrical or unsymmetrical mono-ligated CCC-NHC metal complex according to Formula (I) and / or a symmetrical or unsymmetrical bis-ligated CCC- NHC metal complex according to Formula (II):Formula I wherein n is the charge on the complex;M is titanium, zirconium or hafnium; R'-R9are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dialkyl amino having 1 to 33 carbon atoms, diarylamino having 12 to 33 carbons, alkylarylamino having 7 to 33 carbons, nitro, cyano, carboxy, CF3, thioether having 2 to 20 carbon atoms and 1 to 5 sulfur atoms, boronic ester having 1 to 33 carbon atoms and having two boron-oxygen bonds, silyl ether having 1 to 33 carbon atoms, silane having 1 to 33 carbon atoms, diazonium salt having a halo or tetrafluoroborate ion, ester having 1 to 33 carbon atoms, amide having 0 to 33 carbon atoms, aldehyde having 1 to 33 carbon atoms, imine having 1 to 33 carbon atoms, phosphine having 1 to 33 carbon atoms, phosphate ester having 1 to 33 carbon atoms, isocyanide, isocyanate, a substituted or unsubstituted alkyl group having 1 to 33 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 33 carbon atoms, a substituted or unsubstituted aryl group having 6 to 33 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 33carbon atoms, an alkylether having 2 to 33 carbon atoms and 1 to 5 oxygen atoms, and an alkoxygroup having 1 to 33 carbon atoms or wherein one or more pair of R1and R2, R2and R3, R3and R4, R4and R5, R5and R6, R6and R7, R7and R8, R8and R9together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R10is C or N, wherein when R10is C, then ring A is a phenyl ring or a cyclohexyl ring, and when R10is N then Ring A is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;R11, R12and R13are each independently selected from a fluoro, chloro, bromo, iodo, - C=N, imine having 1 to 33 carbon atoms, carbazolyl, -CH 2-ary I having 7 to 33 carbon atoms, alkyl having 1 to 50 carbon atoms, tetrahydrofuryl, dioxanyl, ether having 1 to 50 carbon atoms, polyether having 1 to 5 oxygen atoms and 2 to 33 carbon atoms, dialkyl amino having 1 to 33 carbon atoms, diarylamino having 12 to 33 carbons, alkylarylamino having 7 to 33 carbons, -OTf, -OAc, -O3SCH3, -O3SC6H5, -O2CCF3, -OMe, t-BuO-, EtO-, CF3CH2O-, andCFsCFiO-rNCH, -Oaryl having 6 to 33 carbon atoms, alkyl having 1 to 33 carbon atoms, -CF3, phenyl,n” is 0 or 1 or 2, or 3, R100is selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms, y is 0, 1 or 2;X is a counterion and n' is the number of counterions;Z1and Z2are each independently selected from the group consisting of CH, CR14, andN; andwherein when Z1or Z2is CR14, R14is a C'-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH, then there is a double bond between the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH2, then there is a single bond between the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R]-R9and R100is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms;Formula (II) wherein the definitions in Formula (II) for n, M, R'-R9, R10, R14, Ring A, X, n', Z1and Z2are identical to the definitions given in Formula (I) above, ligand A and ligand B can be the same or can be different, they can be symmetrical or unsymmetrical ligands and one of them can bereplaced by a completely different pincer type ligand, for instance a classical PCP type pincer ligand or any other mono-, di-, or trianionic, tridentate pincer ligand including ones derived from combinations of the azoles listed for Formula I.R1S-R23are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms or wherein one or more pair of R15and R16, R16and R17, R17and R18, R18and R19, R19and R20, R20and R21, R21and R22, R22and R23together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R24is C or N, wherein when R24is C, then ring B is a phenyl ring, and when R24is N then Ring B is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;Z3and Z4are each independently selected from the group consisting of CH, CR140, and N; and wherein when Z3or Z4is CR140, R140is a C1-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R1S-R23is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms.

2. The OLED device of claim 1 , wherein M is zirconium, andX can be a strongly coordinating, weakly coordinating anion, or non-coordinating anion. Strongly coordinating anions include iodide, chloride, fluoride, bromide, Weakly coordinating anions include mesylate ( OMs), (Inflate ( OTf), tetrafluoroborate (BFC), hexafluorophosphate (PFe ), hexafluoroantimonate (SbFe land perchlorate (CIO4 ). Weakly or non-coordinating anions include bistriflimido ( N(Tf)2), tetrakis[3,5- bis(trifluoromethyl)phenyl]borate ion, B[3,5-(CF3)2C6H3]4-, commonly abbreviated asB(ArF)4" and colloquially called "BARF," selected carborane anions and borane anions. These anions are far less coordinating than tetrafluoroborate, hexafluorophosphate, and perchlorate. Related tetrahedral anions include tetrakis(pentafluorophenyl)borate B(CeF5)4-, and A1[OC(CF3)3]T.In the bulky borates and aluminates, the negative charge is symmetrically distributed over many electronegative atoms. Related anions can be derived from tris(pentafluorophenyl)boron B(CeFs)3by methyl abstraction for instance. Another advantage of these anions is that their salts are more soluble in non-polar organic solvents such as dichloromethane, toluene, and, in some cases, even alkanes.Neutral molecules that represent the parents to the non-coordinating anions are strong Lewis acids, e.g. boron trifluoride, BF3and phosphorus pentafluoride, PF5. A notable Lewis acid of this type is tris(pentafluorophenyl)borane, B(C6Fs)3, which can abstract alkyl ligands such as in the following reaction: (CsHs)2Zr(CH3)2 + B(C6Fs)3[(C5H5)2Zr(CH3)]+[(CH3)B(C6F5)3]-.Another class of non-coordinating anions that can be used are derived from the carborane anion CB11H12" and include the numerous derivatives where the hydrogens are replaced by halogens.Including the species discussed above, X can also include nitrite, sulfate, phosphate, bicarbonate, trifluoroacetate, pentafluoropropanoate, chloride, bromide, iodide, perchlorate, nitrate, benzenesulfonate, p-toluenesulfonate, methylsulfate, ethylsulfate, propylsulfate, tetrafluoroborate, tetraphenylborate, hexafluorophosphate, benzenesulfinate, acetate, trifluoroacetate, propionacetate, benzoate, oxalate, succinate, malonate, oleate, stearate, citrate, monohydrogen diphosphate, dihydrogen monophosphate, pentachlorostannate, chlorosulfonate, fluorosulfonate, trifluoromethansulfonate, hexafluoroarsenate, hexafluoroantimonate, molybdenate, tungstate, titanate, zirconate ions, or any combination thereof.

3. The OLED device of any one of the previous claims, wherein M is zirconium, and X is tetraphenylborate, trifluoroacetate, pentafluoropropanoate, chloride, bromide, iodide, fluorosulfonate, or trifluoromethansulfonate.

4. The OLED device of any one of the previous claims, wherein M is zirconium, and the emissive layer comprises a mono-ligated CCC-NHC metal complex according to Formula (I).

5. The OLED device of any one of the previous claims, wherein M is zirconium, and the emissive layer comprises a mono-ligated CCC-NHC metal complex according to Formula (I) and the CCC-NHC ligand is symmetrical.

6. The OLED device of any one of claims 1-4, wherein M is zirconium, and the emissive layer comprises a mono-ligated CCC-NHC metal complex according to Formula (I) and the CCC-NHC ligand is unsymmetrical.

7. The OLED device of any one of the previous claims, wherein M is zirconium, and the emissive layer comprises a bis-ligated CCC-NHC metal complex according to Formula (II).

8. The OLED device of any one of the previous claims, wherein the emissive layer comprises a mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and n is i;R1and R9are each independently selected from an alkyl group having 1 to 6 carbon atoms, which is optionally substituted with a halogen, sulfonate, hydroxy, amino, nitro, cyano, or carboxy, or a phenyl group which is optionally substituted with a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy or an alkyl group having 1 to 6 carbon atoms; andZ1and Z2are each CH and there is a double bond between the carbon in the Z position and the azole carbon attached thereto.

9. The OLED device of any one of the previous claims, wherein the emissive layer comprises a mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R4-R6are each hydrogen.

10. The OLED device of any one of the previous claims, wherein the emissive layer comprises a bis-ligated CCC-NHC metal complex according to Formula (II), M is zirconium, and R4-R6and R18-R20are each hydrogen.1 1 . The OLED device of any one of the previous claims, wherein the emissive layer comprises a mono-ligated CCC-NHC metal complex according to Formula (I), M iszirconium, and R11, R12and R13are each independently selected from a chloro, dimethylamine, diethylamine, -OTf, 1 ,2,4-triazolyl, 1,2,3-triazolyl, imidazolyl, pyrazolyl, pyrrolyl, benzimidazolyl, or 6-methylindolyl; n” is 0 or 1.

12. The OLED device of any one of the previous claims, wherein the emissive layer comprises a mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R11, R12and R13are each independently selected from a chloro, bromo, iodo, dimethylamine, diethylamine, methylphenylamine, ethylphenyl amine, and diphenylamine; and n” is 0 or 1.

13. The OLED device of any one of the previous claims, wherein the emissive layer comprises: a mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R1and R9are each independently selected from methyl or ethyl; a bis-ligated CCC-NHC metal complex according to Formula (II) and R1, R9, R15and R23are each independently selected from methyl or ethyl.

14. The OLED device of any one of the previous claims, wherein the emissive layer comprises: a mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R1and R9are each independently selected from methyl or ethyl.

15. The OLED device of any one of the previous claims, wherein the emissive layer comprises: a mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R11, R12and R13are each independently selected from a chloro, bromo or iodo.

16. The OLED device of any one of the previous claims, wherein Z1or Z2is CR14, and R14is a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, and the ring structure is aromatic or is a cyclohexyl ring with 0, 1 or 2 double bonds in the cyclohexyl ring.

17. The OLED device of any one of the previous claims, wherein the emissive layer further comprises a host material; or wherein the emissive layer further comprises a host material and the host material is selected from:Poly(9-vinylcarbazole) (PVK)wherein n is sufficient to provide a weight average molecular weight of 10,000 to 500,000 grams per mole (g / mol),4,4',4-Tris(carbazol-9-yl)triphenylamine (TcTa)N,N-Bis(4-(9H-carbazol-9-yl)phenyl)-4-(3-(9,9-dimethylacridin-10(9H)-yl)-9H- carbazol-9-yl)aniline (TCTA-BP-DMAC)9-(3,5-Di(triphenylen-2-yl)phenyl)-9H -carbazole (DTP-mCP)4,4’-Bis(carbazol-9-yl)biphenyl (CBP)18. The OLED device of any one of the previous claims, further comprising an electron injection layer, an electron transport / hole blocking layer, an electron blocking layer, a hole transport layer, a hole injection layer which are also between the first electrode layer and the second electrode layer.

19. The OLED device of any one of the previous claims, wherein one of the first and second electrode layers is a cathode layer and the other is an anode layer, and the OLED has layers stacked in the following order: 1) cathode layer; 2) electron injection layer; 3) electron transport / hole blocking layer; 4) emissive layer; 5) electron blocking layer; 6) hole transport layer; 7) hole injection layer; and 8) anode layer.

20. The OLED device of any one of the previous claims, wherein the cathode layer comprises aluminum, the electron injection layer comprises LiF, the electron transport / hole blocking layer comprises PO15 which is a phosphine oxide based electron transport material, the electron blocking layer comprises TAPC, the hole transport layer comprises NPD, the hole injection layer comprises PEDOT:PSS and the anode comprises ITO.

21. The OLED device of any one of the previous claims, wherein the anode layer is bonded to a substrate; or wherein the anode layer is bonded to a glass substrate.

22. The OLED device of any one of the previous claims, excluding Ti, Zr and Hf compounds having the following CCC-NHC ligand:

23. The OLED device of any one of the previous claims, wherein Rj-R9are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dialkyl amino having 1 to 20 carbon atoms, diarylamino having 12 to 20 carbons, alkylarylamino having 7 to 20 carbons, nitro, cyano, carboxy, CF3, thioether having 2 to 20 carbon atoms and 1 to 5 sulfur atoms, boronic ester having 1 to 20 carbon atoms and having two boron-oxygen bonds, silyl ether having 1 to 20 carbon atoms, silane having 1 to 20 carbon atoms, diazonium salt having a halo or tetrafluoroborate ion, ester having 1 to 20 carbon atoms, amide having 0 to 20 carbon atoms, aldehyde having 1 to 20 carbon atoms, imine having 1 to 20 carbon atoms, phosphine having 1 to 20 carbon atoms, phosphate ester having 1 to 20 carbon atoms, isocyanide, isocyanate, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms or wherein one or more pair of R1and R2, R2and R3, R3and R4, R4and R5, R5and R6, R6and R7, R7and R8, R8and R9together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R10is C or N, wherein when R10is C, then ring A is a phenyl ring or a cyclohexyl ring, and when R10is N then Ring A is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;R11, R12and R13are each independently selected from a fluoro, chloro, bromo, iodo, - C=N, imine having 1 to 20 carbon atoms, carbazolyl, -CBE-aryl having 7 to 20 carbon atoms, alkyl having 1 to 40 carbon atoms, tetrahydrofuryl, dioxanyl, ether having 1 to 40 carbon atoms, polyether having 1 to 5 oxygen atoms and 2 to 20 carbon atoms, dialkyl amino having1 to 20 carbon atoms, diarylamino having 12 to 20 carbons, alkylarylamino having 7 to 20 carbons, -OTf, -OAc, -O3SCH3, -O3SC6H5, -O2CCF3, -OMe, t-BuO-, EtO-, CF3CH2O-, and CF3CF2O-,-NCH, -Oaryl having 6 to 20 carbon atoms, alkyl having 1 to 20 carbon atoms, - CF3, phenyl,n” is 0 or 1 or 2, or 3, R100is selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms, y is 0, 1 or 2;X is a counterion and n' is the number of counterions;Z1and Z2are each independently selected from the group consisting of CH, CR14, and N; and wherein when Z1or Z2is CR14, R14is a C1-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH, then there is a double bond between the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH2, then there is a single bond between the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R]-R9and R100is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms;R15-R23are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms or wherein one or more pair of R1Sand R16, R16and R17, R17and R1S, R18and R19, R19and R20, R20and R21, R21and R22, R22and R23together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R24is C or N, wherein when R24is C, then ring B is a phenyl ring, and when R24is N then Ring B is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;Z3and Z4are each independently selected from the group consisting of CH, CR140, and N; and wherein when Z3or Z4is CR140, R140is a C1-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R15-R23is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms.

24. The OLED device of any one of the previous claims, wherein R'-R9are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dialkyl amino having 1 to 6 carbon atoms, diarylamino having 12 to 16 carbons, alkylarylamino having 7 to 16 carbons, nitro, cyano, carboxy, CFs, thioether having 2 to 6 carbon atoms and 1 to 5 sulfur atoms, boronic ester having 1 to 6 carbon atoms and having two boron-oxygen bonds, silyl ether having 1 to 6 carbon atoms, silane having 1 to 6 carbon atoms, diazonium salt having a halo or tetrafluoroborate ion, ester having 1 to 6 carbon atoms, amide having 0 to 6 carbon atoms, aldehyde having 1 to 6 carbon atoms, imine having 1 to 6 carbon atoms, phosphine having 1 to 6 carbon atoms, phosphate ester having 1 to 6 carbon atoms, isocyanide, isocyanate, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, asubstituted or unsubstituted alkenyl group having 2 to 6 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 6 carbon atoms, an alkylether having 2 to 6 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 6 carbon atoms or wherein one or more pair of R1and R2, R2and R3, R3and R4, R4and R5, R5and R6, R6and R7, R7and R8, R8and R9together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R10is C or N, wherein when R10is C, then ring A is a phenyl ring or a cyclohexyl ring, and when R10is N then Ring A is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;R11, R12and R13are each independently selected from a fluoro, chloro, bromo, iodo, - C=N, imine having 1 to 6 carbon atoms, carbazolyl, -CHj-aryl having 7 to 12 carbon atoms, alkyl having 1 to 30 carbon atoms, tetrahydrofuryl, dioxanyl, ether having 1 to 30 carbon atoms, polyether having 1 to 5 oxygen atoms and 2 to 6 carbon atoms, dialkyl amino having 1 to 6 carbon atoms, diarylamino having 12 to 16 carbons, alkylarylamino having 7 to 16 carbons, -OTf, -OAc, -O3SCH3, -O3SC6H5, -O2CCF3, -OMe, t-BuO-, EtO-, CF3CH2O-, and CFsCFiO-rNCH, -Oaryl having 6 to 12 carbon atoms, alkyl having 1 to 6 carbon atoms, - CF3, phenyl,n” is 0 or 1 or 2, or 3, R100is selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 6 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstitutedheterocyclic group having 3 to 16 carhon atoms, an alkylether having 2 to 6 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 6 carbon atoms, y is 0, 1 or 2;X is a counterion and n' is the number of counterions;Z1and Z2are each independently selected from the group consisting of CH, CR14, and N; and wherein when Z1or Z2is CR14, R14is a C'-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH, then there is a double bond between the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH2, then there is a single bond between the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R’-R9and R100is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms;R15-R23are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 6 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 6 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 6 carbon atoms or wherein one or more pair of R15and R16, R16and R17, R17and R18, R18and R19, R19and R20, R20and R21, R21and R22, R22and R23together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R24is C or N, wherein when R24is C, then ring B is a phenyl ring, and when R24is N then Ring B is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;Z3and Z4are each independently selected from the group consisting of CH, CR140, and N; and wherein when Z3or Z4is CR140, R140is a C1-C'1alkyl, Cs-C12aryl or a substituted or unsuhstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto,with the proviso that when any of R15-R23is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms.

25. The OLED device of any one of the previous claims having one or more of the following properties: g. Driving voltage (V) of 2.0-7.0; h. Efficiency (Cd / A, at driving voltage) of 13-88; i. CIE 1931 (at driving voltage) of (0.10-0.2, 0.21-0.42); j. Maximum efficiency (Cd / A) of 55.0-88.0; k. Maximum emission wavelength (nm) of 400-700; and l. Lifespan (hr, T95, at 6000 nit) of 3-7500.

26. A symmetrical or unsymmetrical mono-ligated CCC-NHC metal complex according to Formula (I) and / or a symmetrical or unsymmetrical bis-ligated CCC-NHC metal complex according to Formula (II):Formula I wherein n is the charge on the complex;M is titanium, zirconium or hafnium; R -R9are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dialkyl amino having 1 to 33 carbon atoms,diarylamino having 12 to 33 carbons, alkylarylamino having 7 to 33 carbons, nitro, cyano, carboxy, CF3, thioether having 2 to 20 carbon atoms and 1 to 5 sulfur atoms, boronic ester having 1 to 33 carbon atoms and having two boron-oxygen bonds, silyl ether having 1 to 33 carbon atoms, silane having 1 to 33 carbon atoms, diazonium salt having a halo or tetrafluoroborate ion, ester having 1 to 33 carbon atoms, amide having 0 to 33 carbon atoms, aldehyde having 1 to 33 carbon atoms, imine having 1 to 33 carbon atoms, phosphine having 1 to 33 carbon atoms, phosphate ester having 1 to 33 carbon atoms, isocyanide, isocyanate, a substituted or unsubstituted alkyl group having 1 to 33 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 33 carbon atoms, a substituted or unsubstituted aryl group having 6 to 33 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 33 carbon atoms, an alkylether having 2 to 33 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 33 carbon atoms or wherein one or more pair of R1and R2, R2and R3, R3and R4, R4and R5, R5and R6, R6and R7, R7and R8, R8and R9together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R10is C or N, wherein when R10is C, then ring A is a phenyl ring or a cyclohexyl ring, and when R10is N then Ring A is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;R11, R12and R13are each independently selected from a fluoro, chloro, bromo, iodo, - C=N, imine having 1 to 33 carbon atoms, carbazolyl, -CHz-aryl having 7 to 33 carbon atoms, alkyl having 1 to 50 carbon atoms, tetrahydrofuryl, dioxanyl, ether having 1 to 50 carbon atoms, polyether having 1 to 5 oxygen atoms and 2 to 33 carbon atoms, dialkyl amino having 1 to 33 carbon atoms, diarylamino having 12 to 33 carbons, alkylarylamino having 7 to 33 carbons, -OTf, -OAc, -O3SCH3, -O3SC6H5, -O2CCF3, -OMe, t-BuO-, EtO-, CF3CH2O-, and CF3CF2O-,-NCH, -Oaryl having 6 to 33 carbon atoms, alkyl having 1 to 33 carbon atoms, - CF3, phenyl,n” is 0 or 1 or 2, or 3, R100is selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms, y is 0, 1 or 2;X is a counterion and n' is the number of counterions;Z1and Z2are each independently selected from the group consisting of CH, CR14, and N; and wherein when Z1or Z2is CR14, R14is a C]-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH, then there is a double bond between the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH2, then there is a single bond between the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R]-R9and R100is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms;Formula (II) wherein the definitions in Formula (II) for n, M, R'-R9, R10, R14, Ring A, X, n', Z1and Z2are identical to the definitions given in Formula (I) above,R15-R23are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms or wherein one or more pair of R1Sand R16, R16and R17, R17and R18, R18and R19, R19and R20,R20and R21, R21and R22, R22and R23together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R24is C or N, wherein when R24is C, then ring B is a phenyl ring, and when R24is N then Ring B is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;Z3and Z4are each independently selected from the group consisting of CH, CR140, and N; and wherein when Z3or Z4is CR140, R140is a C'-C6alkyl, Cs-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R15-R23is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms; including complexes wherein: a) R11is dimethylamino, R12is dimethylamino and n” is 0; b) R11is dimethylamino, R12is dimethylamino, R13is dimethylamino and n” is 1; c) R11is chloro, R12is chloro and n” is 0; d) Rnis chloro, R12is chloro, R13is chloro and n” is 1; and e) R11is dimethylamino, R12is chloro, R13is chloro and n” is 1 and excluding previously published complexes.

27. The metal complex according to any one of the previous claims, wherein M is zirconium, and X can be a strongly coordinating, weakly coordinating anion, or noncoordinating anion. Strongly coordinating anions include iodide, chloride, fluoride, bromide, Weakly coordinating anions include mesylate ( OMs), (triflate ( OTf), tetrafluoroborate (BF4-), hexafluorophosphate (PFe ), hexafluoroantimonate (SbFe'land perchlorate (CIO4 ). Weakly or non-coordinating anions include bistriflimido ( NiTI’h), tetrakis[3,5- bis(trifluoromethyl)phenyl]borate ion, B|3,5-(CT3hG1H3|.T. commonly abbreviated as B(ArF)4" and colloquially called "BARF," selected carborane anions and borane anions. These anions are far less coordinating than tetrafluoroborate, hexafluorophosphate, and perchlorate. Related tetrahedral anions include tetrakis(pentafluorophenyl)borate B(C6Fs)4_, and A1[OC(CF3)3]4“.In the bulky borates and aluminates, the negative charge is symmetrically distributed over many electronegative atoms. Related anions can be derived fromtris(pentafluorophenyl)boron BiCeFA? by methyl abstraction for instance. Another advantage of these anions is that their salts are more soluble in non-polar organic solvents such as dichloromethane, toluene, and, in some cases, even alkanes.Neutral molecules that represent the parents to the non-coordinating anions are strong Lewis acids, e.g. boron trifluoride, BF3 and phosphorus pentafluoride, PFs. A notable Lewis acid of this type is tris(pentafluorophenyl)borane, BiCeFsp, which can abstract alkyl ligands such as in the following reaction: (CiHipZiiCHik + BiCLFib — > [(C5H5)2Zr(CH3)]+[(CH3)B(C6F5)3]-.Another class of non-coordinating anions that can be used are derived from the carborane anion CB11H12", and include the numerous derivatives where the hydrogens are replaced by halogens.Including the species discussed above, X can also include nitrite, sulfate, phosphate, bicarbonate, trifluoroacetate, pentafluoropropanoate, chloride, bromide, iodide, perchlorate, nitrate, benzenesulfonate, p-toluenesulfonate, methylsulfate, ethylsulfate, propylsulfate, tetrafluoroborate, tetraphenylborate, hexafluorophosphate, benzenesulfinate, acetate, trifluoroacetate, propionacetate, benzoate, oxalate, succinate, malonate, oleate, stearate, citrate, monohydrogen diphosphate, dihydrogen monophosphate, pentachlorostannate, chlorosulfonate, fluorosulfonate, trifluoromethansulfonate, hexafluoroarsenate, hexafluoroantimonate, molybdenate, tungstate, titanate, zirconate ions, or any combination thereof.

28. The metal complex according to any one of the previous claims, wherein M is zirconium, and X is tetraphenylborate, trifluoroacetate, pentafluoropropanoate, chloride, bromide, iodide, fluorosulfonate, or trifluoromethansulfonate.

29. The metal complex according to any one of the previous claims, wherein M is zirconium, and the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I).

30. The metal complex according to any one of the previous claims, wherein M is zirconium, and the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I) and the CCC-NHC ligand is symmetrical.31 . The metal complex according to any one of the previous claims, wherein M is zirconium, and the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I) and the CCC-NHC ligand is unsymmetrical.

32. The metal complex according to any one of the previous claims, wherein M is zirconium, and the metal complex is the bis-ligated CCC-NHC metal complex according to Formula (II).

33. The metal complex according to any one of the previous claims, wherein the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and n is i;R1and R9are each independently selected from an alkyl group having 1 to 6 carbon atoms, which is optionally substituted with a halogen, sulfonate, hydroxy, amino, nitro, cyano, or carboxy, or a phenyl group which is optionally substituted with a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy or an alky l group having 1 to 6 carbon atoms; andZ1and Z2are each CH and there is a double bond between the carbon in the Z position and the azole carbon attached thereto.

34. The metal complex according to any one of the previous claims, wherein the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R4-R6are each hydrogen.

35. The metal complex according to any one of the previous claims, wherein the metal complex is the bis-ligated CCC-NHC metal complex according to Formula (II), M is zirconium, and R4-R6and R18-R20are each hydrogen.

36. The metal complex according to any one of the previous claims, wherein the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R11, R12and R13are each independently selected from a chloro, dimethyl amine, diethylamine, -OTf, 1 ,2,4-triazolyl, 1 ,2,3-triazolyl, imidazolyl, pyrazolyl, pyrrolyl, benzimidazolyl, or 6-methylindolyl; n” is 0 or 1.

37. The metal complex according to any one of the previous claims, wherein the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R11, R12and R1’ are each independently selected from a chloro, bromo, iodo, dimethylamine, diethylamine, methylphenylamine, ethylphenylamine, and diphenylamine; and n” is 0 or 1.

38. The metal complex according to any one of the previous claims, wherein the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R1and R9are each independently selected from methyl or ethyl; or a bis-ligated CCC-NHC metal complex according to Formula (II) and R1, R9, R13and R23are each independently selected from methyl or ethyl.

39. The metal complex according to any one of the previous claims, wherein the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R1and R9are each independently selected from methyl or ethyl.

40. The metal complex according to any one of the previous claims, wherein the metal complex is the mono-ligated CCC-NHC metal complex according to Formula (I), M is zirconium, and R11, R12and R13are each independently selected from a chloro, bromo or iodo.

41. The metal complex according to any one of the previous claims, wherein Z1or Z2is CR14, and R14is a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, and the ring structure is aromatic or is a cyclohexyl ring with 0, 1 or 2 double bonds in the cyclohexyl ring.

42. The OLED device of any one of the previous claims, excluding Ti, Zr and Hf compounds having the following CCC-NHC ligand:

43. The metal complex of any one of the previous claims, wherein R'-R9are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dialkyl amino having 1 to 20 carbon atoms, diarylamino having 12 to 20 carbons, alkylarylamino having 7 to 20 carbons, nitro, cyano, carboxy, CF3, thioether having 2 to 20 carbon atoms and 1 to 5 sulfur atoms, boronic ester having 1 to 20 carbon atoms and having two boron-oxygen bonds, silyl ether having 1 to 20 carbon atoms, silane having 1 to 20 carbon atoms, diazonium salt having a halo or tetrafluoroborate ion, ester having 1 to 20 carbon atoms, amide having 0 to 20 carbon atoms, aldehyde having 1 to 20 carbon atoms, imine having 1 to 20 carbon atoms, phosphine having 1 to 20 carbon atoms, phosphate ester having 1 to 20 carbon atoms, isocyanide, isocyanate, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms or wherein one or more pair of R1and R2, R2and R3, R3and R4, R4and R5, R5and R6, R6and R7, R7and R8, R8and R9together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R10is C or N, wherein when R10is C, then ring A is a phenyl ring or a cyclohexyl ring, and when R10is N then Ring A is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;R11, R12and R13are each independently selected from a fluoro, chloro, bromo, iodo, - C=N, imine having 1 to 20 carbon atoms, carbazolyl, -ClF-aryl having 7 to 20 carbon atoms, alkyl having 1 to 40 carbon atoms, tetrahydrofuryl, dioxanyl, ether having 1 to 40 carbon atoms, polyether having 1 to 5 oxygen atoms and 2 to 20 carbon atoms, dialkyl amino having 1 to 20 carbon atoms, diarylamino having 12 to 20 carbons, alkylarylamino having 7 to 20 carbons, -OTf, -OAc, -O3SCH3, -O3SC6H5, -O2CCF3, -OMe, t-BuO-, EtO-, CF3CH2O-, and CFiCFiO-rNCH, -Oaryl having 6 to 20 carbon atoms, alkyl having 1 to 20 carbon atoms, - CF3, phenyl,n” is 0 or 1 or 2, or 3, R100is selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms, y is 0, 1 or 2;X is a counterion and n' is the number of counterions;Z1and Z2are each independently selected from the group consisting of CH, CR14, and N; and wherein when Z1or Z2is CR14, R14is a C]-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH, then there is a double bond between the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH2, then there is a single bond between the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R]-R9and R100is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms;R1S-R23are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 20 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 20 carbon atoms or wherein one or more pair of R1Sand R16, R16and R17, R17and R18, R18and R19, R19and R20, R20and R21, R21and R22, R22and R23together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R24is C or N, wherein when R24is C, then ring B is a phenyl ring, and when R24is N then Ring B is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;Z3and Z4are each independently selected from the group consisting of CH, CR140, and N; and wherein when Z3or Z4is CR140, R140is a C’-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R15-R23is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms.

44. The metal complex of any one of the previous claims, wherein R' -R9are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dialkyl amino having 1 to 6 carbon atoms, diarylamino having 12 to 16 carbons, alkylarylamino having 7 to 16 carbons, nitro, cyano, carboxy, CF3, thioether having 2 to 6 carbon atoms and 1 to 5 sulfur atoms, boronic ester having 1 to 6 carbon atoms and having two boron-oxygen bonds, silyl ether having 1 to 6 carbon atoms, silane having 1 to 6 carbon atoms, diazonium salt having a halo or tetrafluoroborate ion, ester having 1 to 6 carbon atoms, amide having 0 to 6 carbon atoms, aldehyde having 1 to 6 carbon atoms, imine having 1 to 6 carbon atoms, phosphine having 1 to 6 carbon atoms, phosphate ester having 1 to 6 carbon atoms, isocyanide, isocyanate, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 6 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 6 carbon atoms, an alkylether having 2 to 6 carbon atoms and 1 to 5 oxygen atoms, and analkoxy group having 1 to 6 carbon atoms or wherein one or more pair of R1and R2, R2and R3, R3and R4, R4and R5, R5and R6, R6and R7, R7and R8, R8and R9together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R10is C or N, wherein when R10is C, then ring A is a phenyl ring or a cyclohexyl ring, and when R10is N then Ring A is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;R11, R12and R13are each independently selected from a fluoro, chloro, bromo, iodo, - C=N, imine having 1 to 6 carbon atoms, carbazolyl, -CH2-aryl having 7 to 12 carbon atoms, alkyl having 1 to 30 carbon atoms, tetrahydrofuryl, dioxanyl, ether having 1 to 30 carbon atoms, polyether having 1 to 5 oxygen atoms and 2 to 6 carbon atoms, dialkyl amino having 1 to 6 carbon atoms, diarylamino having 12 to 16 carbons, alkylarylamino having 7 to 16 carbons, -OTf, -OAc, -O3SCH3, -O3SC6H5, -O2CCF3, -OMe, t-BuO-, EtO-, CF3CH2O-, andCFsCFiO-rNCH, -Oaryl having 6 to 12 carbon atoms, alkyl having 1 to 6 carbon atoms, -CF3, phenyl,n” is 0 or 1 or 2, or 3, R100is selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 6 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 6 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 6 carbon atoms, y is 0, 1 or 2;X is a counterion and n' is the number of counterions;Z1and Z2are each independently selected from the group consisting of CH, CR14, andN; andwherein when Z1or Z2is CR14, R14is a C'-C6alkyl, C5-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH, then there is a double bond between the carbon in the Z position and the azole carbon attached thereto, and wherein when Z1or Z2is CH2, then there is a single bond between the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R]-R9and R100is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms;R15-R23are each independently selected from hydrogen, sulfonate, halogen, hydroxy, amino, dimethylamino, nitro, cyano, carboxy, CF3, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 6 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 16 carbon atoms, an alkylether having 2 to 6 carbon atoms and 1 to 5 oxygen atoms, and an alkoxy group having 1 to 6 carbon atoms or wherein one or more pair of R15and R16, R16and R17, R17and R18, R18and R19, R19and R20, R20and R21, R21and R22, R22and R23together with the carbons they are attached form a saturated or unsaturated 6 membered ring;R24is C or N, wherein when R24is C, then ring B is a phenyl ring, and when R24is N then Ring B is a pyridine ring or a piperidine ring which optionally has 1 or 2 double bonds between ring carbons;Z3and Z4are each independently selected from the group consisting of CH, CR140, and N; and wherein when Z3or Z4is CR140, R140is a C'-C6alkyl, Cs-C12aryl or a substituted or unsubstituted C4 alkyl forming a ring structure with the carbon in the Z position and the azole carbon attached thereto, with the proviso that when any of R15-R23is a substituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group, then the substituent is independently selected from a halogen, sulfonate, hydroxy, amino, nitro, cyano, carboxy and an alkyl group having 1 to 6 carbon atoms.

45. A process of preparing the symmetrical or unsymmetrical mono-ligated CCC-NHC metal complex according to Formula (I) as recited any one of the previous claims, said process comprising:Formula (III)wherein M is Zr, Ti and Hf, and in Formulae (III) and Formula (IV), the definitions of n, M, R’-R9, R10, R14, R100, y, Ring A, X, Z1and Z2are identical to the definitions given in Formula (I); and in Formula (IV), the definition of y’ is 2 or 3; andstep (B) is an optional step and is a ligand exchange reaction wherein one or all of the NMe2 radicals attached to the M atom is replaced with the radicals of R11, R12and optionally R13to give the mono-ligated CCC-NHC metal complex according to Formula (I).

46. A process of preparing the symmetrical or unsymmetrical bis-ligated CCC-NHC metal complex according to Formula (II) as recited in any one of the previous claims: said process comprising reacting a molar amount of a compound of Formula (III) with a molar amount of M(NMe2)4:Formula (III)wherein M is Zr, Hf or Ti and the definitions of n, R'-R9, R10, R14, R100, R140, y, Ring A, X, Z1and Z2are identical to the definitions given in Formula (II), and wherein the molar amount of M(NMe2)4 is at least twice the molar amount of the compound of Formula (III).

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