Organic electroluminescent materials and devices

wherein:

• each of rings A, B, C, and D is independently a 5-membered or 6-membered carbocyclic or heterocyclic ring with the proviso that none of rings A, B, C and D is pyrazole;
• each of X1 to X8 is independently C or N;
• each of Z1, Z2, Z3, and Z4 is each independently C or N;
• each of L1, L2, L3, and L4 is each independently selected from the group consisting of a direct bond, BRe, BReRf, NRe, PRe, P(O)Re, O, S, Se, C═O, C═S, C═Se, C═NRe, C═CReRf, S═O, SO2, CReRf, SiReRf, and GeReRf,
• each of a, b, c, and d is independently 0 or 1;
• a+b+c+d=3 or 4;
• two of K1, K2, K3, and K4 are dative bonds, and the remainder are covalent bonds, O, or S;
• each of RA, RB, RC, and RD is independently represent mono to the maximum allowable substitution, or no substitution;
• each Re, Rf, R1, R2, R3, RA, RB, RC, and RD is independently a hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, boryl, arylalkyl, alkoxy, aryloxy, amino, silyl, germyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, selenyl, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;
• the compound has a highest occupied molecular orbital (HOMO) energy (EHOMO) and a lowest unoccupied molecular orbital (LUMO) energy (ELUMO);
• the ELUMO is equal to or greater than −1.98 eV;
• the gap energy between the HOMO and the LUMO is at least 3.0 eV;
• the compound emits light upon photoexcitation at room temperature;
• the emitted light has an emission spectrum characterized by a peak emission wavelength Amax when measured at a mass concentration of 1% in a PMMA film;
• and
• the full width at half maximum of the emission at λmax is equal to or less than 30 nm.

An organic light emitting device (OLED) comprising:

• an anode;
• a cathode;
• and
• an organic layer disposed between the anode and the cathode, wherein the organic layer comprises a compound of
• wherein:
• M is Pt or Pd;
• the bond between the metal M and the ring having RD in Formula IIa and IIb is a metal-carbene bond;
• rings A, B, and C are each independently a 5-membered or 6-membered carbocyclic or heterocyclic ring;
• each of X1 to X6 and X9 to X12 is independently C or N;
• each of Z1, Z2, and Z3 is independently C or N;
• each of L1, L2, L3, and L4 is independently selected from the group consisting of a direct bond, BRe, BReRf, NRe, PRe, P(O)Re, O, S, Se, C═O, C═S, C═Se, C═NRe, C═CReRf, S═O, SO2, CReRf, SiReRf, and GeReRf, alky, cycloalkyl, aryl, and heteroaryl;
• each of a, b, c, and d is independently 0 or 1;
• a+b+c+d=3 or 4;
• each K1, K2, and K3 is independently selected from the group consisting of a dative carbene bond, a covalent bond, O, and S;
• when Z1 is N, ring A in Formula I is not a pyridine or pyrazole;
• each of Z1, Z2, and Z3 is C if its respective K1, K2, or K3 forms a dative carbene bond to Pt;
• each of RA, RB, RC, and RD independently represents mono to the maximum allowable substitution, or no substitution;
• L5 is a direct bond or an organic linker;
• Y is selected from the group consisting of amino, alkoxy, aryloxy, or SiR1R2R3,
• when Y is SiR1R2R3, L2 is not BR;
• each Re, Rf, R1, R2, R3, RA, RB, RC, and RD is independently a hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, boryl, arylalkyl, alkoxy, aryloxy, amino, silyl, germyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, selenyl, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, and
• any two substituents may be joined or fused together to form a ring, with the proviso that Y does not comprise carbazole or dibenzofuran.

A consumer product comprising an organic light-emitting device (OLED) comprising:

• an anode;
• a cathode;
• and
• an organic layer disposed between the anode and the cathode, wherein the organic layer comprises a compound of
• wherein:
• M is Pt or Pd;
• the bond between the metal M and the ring having RD in Formula IIa and IIb is a metal-carbene bond;
• rings A, B, and C are each independently a 5-membered or 6-membered carbocyclic or heterocyclic ring;
• each of X1 to X6 and X9 to X12 is independently C or N;
• each of Z1, Z2, and Z3 is independently C or N;
• each of L1, L2, L3, and L4 is independently selected from the group consisting of a direct bond, BRe, BReRf, NRe, PRe, P(O)Re, O, S, Se, C═O, C═S, C═Se, C═NRe, C═CReRf, S═O, SO2, CReRf, SiReRf, and GeReRf, alky, cycloalkyl, aryl, and heteroaryl;
• each of a, b, c, and d is independently 0 or 1;
• a+b+c+d=3 or 4;
• each K1, K2, and K3 is independently selected from the group consisting of a dative carbene bond, a covalent bond, O, and S;
• when Z1 is N, ring A in Formula I is not a pyridine or pyrazole;
• each of Z1, Z2, and Z3 is C if its respective K1, K2, or K3 forms a dative carbene bond to Pt;
• each of RA, RB, RC, and RD independently represents mono to the maximum allowable substitution, or no substitution;
• L5 is a direct bond or an organic linker;
• Y is selected from the group consisting of amino, alkoxy, aryloxy, or SiR1R2R3, when Y is SiR1R2R3, L2 is not BR;
• each Re, Rf, R1, R2, R3, RA, RB, RC, and RD is independently a hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, boryl, arylalkyl, alkoxy, aryloxy, amino, silyl, germyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, selenyl, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;
• and
• any two substituents may be joined or fused together to form a ring, with the proviso that Y does not comprise carbazole or dibenzofuran.