A metal complex comprising a partial structure represented by Formula 1: wherein Cy is a substituted or unsubstituted carbocyclic group or heterocyclic group having 5 to 24 aromatic ring atoms; wherein Cy is combined with M through a metal-carbon bond or a metal-nitrogen bond; wherein M is selected from the group consisting of copper, silver, gold, rhodium, ruthenium, palladium, osmium, iridium, and platinum; preferably, M is selected from iridium or platinum; wherein X is selected from O, S or Se; wherein X 1 to X 6 are independently selected from N or CR; and X 7 independently is CR; wherein R is selected from the group consisting of hydrogen, deuterium, halogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 3 to 30 carbon atoms, a substituted or unsubstituted alkylsilyl group having 3 to 20 carbon atoms, a substituted or unsubstituted arylsilyl group having 6 to 20 carbon atoms, a substituted or unsubstituted amino group having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, a nitrile group, an isonitrile group, a thioalkyl group, a sulfinyl group, a sulfonyl group, a phosphino group, and combinations thereof; two adjacent substitutions are optionally joined to form a ring; X 1 , X 2 , X 3 , or X 4 is connected to M through a metal-carbon bond or a metal-nitrogen bond; wherein Cy comprises a partial structure selected from the group consisting of: wherein Cy is a substituted or unsubstituted carbocyclic group or heterocyclic group having 5 to 24 aromatic ring atoms; wherein Cy is combined with M through a metal-carbon bond or a metal-nitrogen bond; wherein M is selected from the group consisting of copper, silver, gold, rhodium, ruthenium, palladium, osmium, iridium, and platinum; preferably, M is selected from iridium or platinum; wherein X is selected from O, S or Se; wherein X 1 to X 6 are independently selected from N or CR; and X 7 independently is CR; wherein R is selected from the group consisting of hydrogen, deuterium, halogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 3 to 30 carbon atoms, a substituted or unsubstituted alkylsilyl group having 3 to 20 carbon atoms, a substituted or unsubstituted arylsilyl group having 6 to 20 carbon atoms, a substituted or unsubstituted amino group having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, a nitrile group, an isonitrile group, a thioalkyl group, a sulfinyl group, a sulfonyl group, a phosphino group, and combinations thereof; two adjacent substitutions are optionally joined to form a ring; X 1 , X 2 , X 3 , or X 4 is connected to M through a metal-carbon bond or a metal-nitrogen bond; wherein Cy comprises a partial structure selected from the group consisting of: <EOS>