A compound of Formula I,is provided. In Formula I,
moiety A is a monocyclic ring or a polycyclic fused ring
system; each of X1 to X2 and Z1 to Z3 is independently C or N; Y1 is C, N, O, S, Se, P, or As; K is a direct bond or a
linker; each of A1 and A2 is C, Si, N, P, or As; each of L1, L2, and L3 is absent, a direct bond, or a
linker; at least one of L1 to L4 is present; when L3 is present, X11 is C, whereas if L3 is absent, X11 is C or N; M is Pt or Pd; each R1, R2, RA, RB, RC, RD, Rα, and Rβ is
hydrogen or a General
Substituent defined herein and R* is a General
Substituent defined herein. Formulations, OLEDs, and
consumer products containing the compound are also provided.