Organic electroluminescent materials and devices

A compound, having a structure represented by Formula 1:

• wherein
• L is, at each occurrence identically or differently, selected from
• or any combination thereof;
• ring AA is a conjugated structure having 4 to 30 ring atoms and at least one intra-ring double bond;
• n is, at each occurrence identically or differently, selected from an integer from 0 to 10;
• Y is, at each occurrence identically or differently, selected from the group consisting of CRL and N;
• ring A is, at each occurrence identically or differently, a 5-membered heterocyclic ring, and the 5-membered heterocyclic ring comprises an intra-ring double bond, at least one N atom, and at least one W;
• W is, at each occurrence identically or differently, selected from the group consisting of O, S, Se, and NRN;
• X is, at each occurrence identically or differently, selected from the group consisting of Se, NR′, and CR″R′″;
• R and RL represent, at each occurrence identically or differently, mono-substitution, multiple substitutions or non-substitution;
• R, R′, R″, R′″, RL, and RN are, at each occurrence identically or differently, selected from the group consisting of:
• hydrogen, deuterium, halogen, a nitroso group, a nitro group, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, a cyano group, an isocyano group, SCN, OCN, SF5, a boranyl group, a sulfinyl group, a sulfonyl group, a phosphoroso group, a hydroxyl group, a sulfanyl group, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted aralkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted alkynyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, and combinations thereof;
• when L is selected from
• and n=0, at least one of substituents R and RN is a group having at least one electron-withdrawing group;
• when X is selected from NR′ or CR″R′″, at least one of R′, R″ and R′″ is a group having at least one electron-withdrawing group;
• adjacent substituents R″, R′″ can be optionally joined to form a ring;
• and
• adjacent substituents R, RL can be optionally joined to form a ring;
• when adjacent substituents RL are joined to form a ring, the resulting ring has at least 4 ring atoms;
• and when adjacent substituents R are joined to form a ring, the resulting ring has at least 6 ring atoms.