Heterocyclic compound, organic light-emitting diode comprising the heterocyclic compound, and flat panel display device comprising the organic light-emitting diode

A heterocyclic compound represented by Formula 1 below:

• wherein X is *—Ar1 or
• wherein Ar1 is a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted pentalenyl, a substituted or unsubstituted indenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted azulenyl group, a substituted or unsubstituted heptalenyl group, a substituted or unsubstituted indacenyl group, a substituted or unsubstituted acenaphtyl group, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted spiro-fluorenyl group, a substituted or unsubstituted phenalenyl group, a substituted or unsubstituted phenanthrenyl group, a substituted or unsubstituted anthryl group, a substituted or unsubstituted fluoranthenyl group, a substituted or unsubstituted triphenylenyl group, a substituted or unsubstituted pyrenyl group, a substituted or unsubstituted chrysenyl group, a substituted or unsubstituted naphthacenyl group, a substituted or unsubstituted picenyl group, a substituted or unsubstituted perylenyl group, a substituted or unsubstituted pentaphenyl group, a substituted or unsubstituted hexacenyl group, a substituted or unsubstituted pyrrolyl group, a substituted or unsubstituted imidazolyl group, a substituted or unsubstituted benzoimidazolyl group, a substituted or unsubstituted phenylbenzoimidazolyl group, a substituted or unsubstituted pyrazolyl group, a substituted or unsubstituted pyridinyl group, a substituted or unsubstituted phenylpyridinyl group, a substituted or unsubstituted phenylimidazopyridinyl group, a substituted or unsubstituted pyrazinyl group, a substituted or unsubstituted pyrimidinyl group, a substituted or unsubstituted phenylimidazopyrimidinyl group, a substituted or unsubstituted pyridazinyl group, a substituted or unsubstituted indolyl group, a substituted or unsubstituted isoindolyl group, a substituted or unsubstituted indazolyl group, a substituted or unsubstituted purinyl group, a substituted or unsubstituted quinolinyl group, a substituted or unsubstituted benzoquinolinyl group, a substituted or unsubstituted phthalazinyl group, a substituted or unsubstituted naphthyridinyl group, a substituted or unsubstituted quinoxalinyl group, a substituted or unsubstituted quinazolinyl group, a substituted or unsubstituted cinnolinyl group, a substituted or unsubstituted carbazolyl group, a substituted or unsubstituted phenanthridinyl group, a substituted or unsubstituted acridinyl group, a substituted or unsubstituted phenanthrolinyl group, a substituted or unsubstituted phenazinyl group, a substituted or unsubstituted furanyl group, a substituted or unsubstituted benzofuranyl group, a substituted or unsubstituted dibenzofuranyl group, a substituted or unsubstituted thiophenyl group, a substituted or unsubstituted benzo[b]thiophenyl group, a substituted or unsubstituted dibenzothiophenyl, a substituted or unsubstituted thiazolyl group, a substituted or unsubstituted isothiazolyl group, a substituted or unsubstituted benzothiazolyl group, a substituted or unsubstituted oxazolyl group, a substituted or unsubstituted isoxazolyl group, a substituted or unsubstituted benzooxazolyl group, a substituted or unsubstituted triazolyl group, a substituted or unsubstituted phenyltriazolyl group, a substituted or unsubstituted tetrazolyl group, a substituted or unsubstituted oxadiazolyl group, a substituted or unsubstituted phenyloxadiazolyl group, a substituted or unsubstituted diphenylethynyl group, a substituted or unsubstituted phenylethynylfluorenyl group, or a substituted or unsubstituted phenylethynylnaphthyl group;
• Ar2 is a substituted or unsubstituted C6-C60 arylene group, a substituted or unsubstituted C6-C60 aryleneoxy group, a substituted or unsubstituted C6-C60 arylenethio group, a substituted or unsubstituted C2-C60 heteroarylene group, or a substituted or unsubstituted C2-C60 polycyclic condensed group;
• * indicates a binding site;
• Y1, Y2, Y3 and Y4 are each independently NR7, O, or S;
• a, b, c and d are each independently an integer of 0 or 1, wherein a+b=1 and c+d=1;
• and
• R1, R2, R3, R4, R5, R6 and R7 are each independently a hydrogen atom, a deuterium, a tritium, a halogen atom, a hydroxyl group, a cyano group, a nitro group, a carboxyl group, a silyl group, a substituted or unsubstituted C1-C50 alkyl group, a substituted or unsubstituted C2-C50 alkenyl group, a substituted or unsubstituted C2-C50 alkynyl group, a substituted or unsubstituted C1-C50 alkoxy group, a substituted or unsubstituted C3-C50 cycloalkyl group, a substituted or unsubstituted C3-C50 cycloalkenyl group, a substituted or unsubstituted C6-C60 aryl group, a substituted or unsubstituted C6-C60 aryloxy group, a substituted or unsubstituted C6-C60 arylthio group, a substituted or unsubstituted C2-C60 heteroaryl group, a substituted or unsubstituted C2-C60 polycyclic condensed group, or N(Q1)(Q2), and Q1 and Q2 are each independently a hydrogen atom, a deuterium, a tritium, a halogen atom, a hydroxyl group, a cyano group, a nitro group, a carboxyl group, a silyl group, a substituted or unsubstituted C1-C50 alkyl group, a substituted or unsubstituted C2-C50 alkenyl group, a substituted or unsubstituted C2-C50 alkynyl group, a substituted or unsubstituted C1-C50 alkoxy group, a substituted or unsubstituted C3-C50 cycloalkyl group, a substituted or unsubstituted C3-C50 cycloalkenyl group, a substituted or unsubstituted C6-C60 aryl group, a substituted or unsubstituted C6-C60 aryloxy group, a substituted or unsubstituted C6-C60 arylthio group, a substituted or unsubstituted C2-C60 heteroaryl group, and a substituted or unsubstituted C2-C60 polycyclic condensed group, wherein at least two of R1, R2, R3, R4, R5, R6, and R7 which are adjacent to each other bind to each other to form a saturated or unsaturated ring.