Organic electroluminescent materials and devices

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 having the structure of Formula I:
• wherein:
• moiety AA is a monocyclic ring or a polycyclic fused ring system, wherein the monocyclic ring or each ring of the polycyclic fused ring system is independently a 5-membered to 10-membered carbocyclic or heterocyclic ring;
• moiety CC is a monocyclic 5-membered to 10-membered carbocyclic or heterocyclic ring;
• Z1 is C or N;
• X7′ and X8′ are each independently C or N;
• each of K1 and K2 is independently selected from the group consisting of a direct bond, O, S, Se, N(Rα), P(Rα), B(Rα), C(Rα)(Rβ), and Si(Rα)(Rβ);
• RAA, RBB, and RCC each independently represent mono to the maximum allowable substitutions, or no substitutions;
• each Rα, Rβ, RAA, RBB, and RCC is independently hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, germyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, selenyl, and combinations thereof, at least one RBB or RCC comprises a silyl group or a germyl group;
• LAA is coordinated to a metal M;
• the metal M is Ir, Rh, Re, Ru, Os, Pt, Pd, Au, Ag, or Cu;
• the metal M may be coordinated to other ligands;
• LA may be joined with other ligands to form a tridentate, tetradentate, pentadentate, or hexadentate ligand;
• and
• any two of Rα, Rβ, RAA, RBB, and RCC may be joined or fused to form a ring.

A compound, or a neutral molecular form thereof, or a monovalent or polyvalent form thereof, or a monomeric or polymeric form thereof, or a macromolecular or supramolecular form thereof, wherein the compound has a first ligand LA comprising a structure of Formula I:

• wherein:
• moiety AA is a monocyclic ring or a polycyclic fused ring system, wherein the monocyclic ring or each ring of the polycyclic fused ring system is independently a 5-membered to 10-membered carbocyclic or heterocyclic ring;
• moiety CC is a monocyclic 5-membered to 10-membered carbocyclic or heterocyclic ring;
• Z1 is C or N;
• X7′ and X8′ are each independently C or N;
• each of K1 and K2 is independently selected from the group consisting of a direct bond, O, S, Se, N(Rα), P(Rα), B(Rα), C(R)(Rβ), and Si(Rα)(Rβ);
• RAA, RBB, and RCC each independently represent mono to the maximum allowable substitutions, or no substitutions;
• each Rα, Rβ, RAA, RBB, and RCC is independently hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, germyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, selenyl, and combinations thereof;
• at least one RBB or RCC comprises a silyl group or a germyl group;
• LAA is coordinated to a metal M;
• the metal M is Ir, Rh, Re, Ru, Os, Pt, Pd, Au, Ag, or Cu;
• the metal M may be coordinated to other ligands;
• LA may be joined with other ligands to form a tridentate, tetradentate, pentadentate, or hexadentate ligand;
• and
• any two of Rα, Rβ, RAA, RBB, and RCC may be joined or fused to form a ring.