Light emitting device

A light emitting device, comprising:

• a first electrode;
• a second electrode facing the first electrode;
• and
• an emission layer disposed between the first electrode and the second electrode, wherein
• the emission layer comprises a host and a delayed fluorescence dopant,
• the host comprises a compound represented by Formula E-2a or Formula E-2b, and
• the delayed fluorescence dopant comprises a fused polycyclic compound represented by Formula 1:
• wherein in Formula 1,
• X1 and X2 are each independently N(R3), O, or S,
• when X1 is S then X2 is N(R3) and when X2 is S then X1 is N(R3),
• Y1 is B,
• R1 and R2 are each independently a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted amine group, a substituted or unsubstituted alkyl group of 1 to 30 carbon atoms, a substituted or unsubstituted aryl group of 6 to 60 ring-forming carbon atoms, or a substituted or unsubstituted heteroaryl group of 2 to 60 ring-forming carbon atoms,
• R3 is a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted alkyl group of 1 to 30 carbon atoms, a substituted or unsubstituted aryl group of 6 to 60 ring-forming carbon atoms, or a substituted or unsubstituted heteroaryl group of 2 to 60 ring-forming carbon atoms, or is combined with an adjacent group to form a ring,
• n1 and n2 are each independently an integer from 0 to 6, and
• Cy1 and Cy2 are each independently a substituted or unsubstituted aromatic hydrocarbon ring of 6 to 60 ring-forming carbon atoms, or a substituted or unsubstituted aromatic heterocycle of 2 to 60 ring-forming carbon atoms, or are combined with an adjacent group to form a ring:
• wherein in Formula E-2a,
• a is an integer from 0 to 10,
• La is a direct linkage, a substituted or unsubstituted arylene group of 6 to 30 ring-forming carbon atoms, or a substituted or unsubstituted heteroarylene group of 2 to 30 ring-forming carbon atoms,
• A1 to A5 are each independently N or C(Ri),
• Ra to Ri are each independently a hydrogen atom, a deuterium atom, a substituted or unsubstituted amine group, a substituted or unsubstituted thio group, a substituted or unsubstituted oxy group, a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group of 2 to 20 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 ring-forming carbon atoms, or a substituted or unsubstituted heteroaryl group of 2 to 30 ring-forming carbon atoms, or are combined with an adjacent group to form a ring, and
• two or three of A1 to A5 are N, and the remainder of A1 to A5 are C(Ri), and
• wherein in Formula E-2b,
• Cbz1 and Cbz2 are each independently an unsubstituted carbazole group, or a carbazole group substituted with an aryl group of 6 to 30 ring-forming carbon atoms,
• Lb is a direct linkage, a substituted or unsubstituted arylene group of 6 to 30 ring-forming carbon atoms, or a substituted or unsubstituted heteroarylene group of 2 to 30 ring-forming carbon atoms, and
• b is an integer from 0 to 10.

A display apparatus comprising a display panel, the display panel comprising at least one light emitting device, the light emitting device, comprising:

• a first electrode;
• a second electrode facing the first electrode;
• and
• an emission layer disposed between the first electrode and the second electrode,
• the emission layer comprising a fused polycyclic compound, the fused polycyclic compound comprising at least one selected from Compound Group 1:

A display apparatus comprising:

• a light emitting device, comprising:
• a first electrode;
• a hole transport region disposed on the first electrode;
• an emission layer disposed on the hole transport region;
• an electron transport region disposed on the emission layer;
• and
• a second electrode disposed on the electron transport region, wherein the emission layer comprises a fused polycyclic compound represented by Formula 1, and
• the hole transport region comprises a compound represented by Formula H-a:
• wherein in Formula 1,
• X1 and X2 are each independently N (R3), O, or S,
• when X1 is S then X2 is N (R3) and when X2 is S then X1 is N (R3),
• Y1 is B,
• R1 and R2 are each independently a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted amine group, a substituted or unsubstituted alkyl group of 1 to 30 carbon atoms, a substituted or unsubstituted aryl group of 6 to 60 ring-forming carbon atoms, or a substituted or unsubstituted heteroaryl group of 2 to 60 ring-forming carbon atoms,
• R3 is a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted alkyl group of 1 to 30 carbon atoms, a substituted or unsubstituted aryl group of 6 to 60 ring-forming carbon atoms, or a substituted or unsubstituted heteroaryl group of 2 to 60 ring-forming carbon atoms, or is combined with an adjacent group to form a ring,
• n1 and n2 are each independently an integer from 0 to 6, and
• Cy1 and Cy2 are each independently a substituted or unsubstituted aromatic hydrocarbon ring of 6 to 60 ring-forming carbon atoms, or a substituted or unsubstituted aromatic heterocycle of 2 to 60 ring-forming carbon atoms, or are combined with an adjacent group to form a ring:
• wherein in Formula H-a,
• Ya and Yb are each independently C (Re1) (Rf1), N (Rg1), O, or S, Ar1 is a substituted or unsubstituted aryl group of 6 to 30 ring-forming carbon atoms, or a substituted or unsubstituted heteroaryl group of 2 to 30 ring-forming carbon atoms,
• L1 and L2 are each independently a direct linkage, a substituted or unsubstituted arylene group of 6 to 30 ring-forming carbon atoms, or a substituted or unsubstituted heteroarylene group of 2 to 30 ring-forming carbon atoms, Ra1 to Rg1 are each independently a hydrogen atom, a deuterium atom, a substituted or unsubstituted amine group, a substituted or unsubstituted thio group, a substituted or unsubstituted oxy group, a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group of 2 to 20 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 ring-forming carbon atoms, or a substituted or unsubstituted heteroaryl group of 2 to 30 ring-forming carbon atoms, or are combined with an adjacent group to form a ring, na and nd are each independently an integer from 0 to 4, and nb and nc are each independently an integer from 0 to 3.