Heterocyclic compound and organic light-emitting diode and flat display device including the heterocyclic compound

A heterocyclic compound represented by Formula 1 below:

• wherein:
• A1 and A2 are each independently a substituted or unsubstituted fused pyridine cycle,
• R1 to R8 are each independently a hydrogen atom, a deuterium atom, a halogen atom, a hydroxyl group, a cyano group, a nitro group, a carboxyl group, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C2-C30 alkenyl group, a substituted or unsubstituted C2-C30 alkynyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C3-C30 cyclo alkyl group, a substituted or unsubstituted C3-C30 cyclo alkenyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C6-C30 aryloxy group, a substituted or unsubstituted C6-C30 arylthio group, a substituted or unsubstituted C3-C30 hetero aryl group, or a group represented by N(Q1)(Q2),
• wherein Q1, and Q2 are each independently a hydrogen atom, a deuterium atom, a halogen atom, a hydroxyl group, a cyano group, an amino group, a nitro group, a carboxyl group, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C2-C30 alkenyl group, a substituted or unsubstituted C2-C30 alkynyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C3-C30 cyclo alkyl group, a substituted or unsubstituted C3-C30 cyclo alkenyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C6-C30 aryloxy group, a substituted or unsubstituted C6-C30 arylthio group, or a substituted or unsubstituted C3-C30 hetero aryl group,
• L1 and L2 are each independently a substituted or unsubstituted C6-C30 arylene group or a substituted or unsubstituted C3-C30 heteroarylene group, and
• a and b are each independently an integer of 0 to 3.