Organic light-emitting diode

An organic light-emitting device comprising:

• a first electrode;
• a second electrode;
• an organic layer between the first electrode and the second electrode;
• and
• a light efficiency-improvement layer disposed on the first electrode or the second electrode,
• wherein the light efficiency-improvement layer comprises a heterocyclic compound represented by Formula 1 below:
• wherein R1 to R4 are, each independently, a hydrogen atom, a deuterium, a substituted or unsubstituted C5 to C60 alkyl group, a substituted or unsubstituted C6 to C60 aryl group, or a substituted or unsubstituted C6 to C60 condensed polycyclic group;
• L1 and L2 are, each independently, a single bond, a substituted or unsubstituted C6 to C60 aryl group, a substituted or unsubstituted C3 to C60 heteroaryl group, or a substituted or unsubstituted C6 to C60 condensed polycyclic group;
• Ar1 and Ar2 are, each independently, a substituted or unsubstituted C6 to C60 aryl group, a substituted or unsubstituted C3 to C60 heteroaryl group, or a substituted or unsubstituted C6 to C60 condensed polycyclic group;
• A, B, C, and D represent, each independently, —CH═ or —N═,
• provided that A, B, C, and D are not all —CH═ at the same time;
• and
• m and n are, each independently, an integer of 0 to 3,
• provided that m and n are not both 0 at the same time.