| abstract |
An organic electroluminescence device is provided and includes containing a compound represented by the following formula (1a) and a compound represented by the following formula (1b). The molecular weight of the compound represented by formula (1a) is smaller than the molecular weight of the compound represented by formula (1b), and the content ratio of the compound represented by formula (1a) to the compound represented by formula (1b) is from 0.1 to 5,000 ppm. In formulae (1a) and (1b), A 1 , A 2 and X 1 to X 4 each represents a carbon atom or a nitrogen atom, Z 1 represents a 5-membered ring composed of a carbon atom and/or a heteroatom, Z 2 and Z 3 each represents an aromatic hydrocarbon ring or a heterocyclic ring, M represents a transition metal atom having an atomic weight of 40 or more and belonging to one of Groups 8 to 10 of the periodic table, n represents 1 or 2, m is 3 when M is a metal of Group 8 or 9, m is 2 when M is a metal of Group 10, L a and L b each represents a monodentate ligand,, and the ligand containing Z 1 to Z 3 has a structure with 18 p electrons in total. |