Light-emitting device and material therefor

DETAILED DESCRIPTION OF THE INVENTION The heterocyclic compound having at least two hetero atoms is a monocyclic, polycyclic or condensed-ring compound having two or more atoms other than a carbon atom and a hydrogen atom in its heterocyclic skeleton.
The heterocyclic skeleton preferably contains two or more hetero atoms selected from nitrogen, oxygen and sulfur.
A still preferred heterocyclic skeleton is an aromatic heterocyclic ring having at least one nitrogen atom, particularly two or more nitrogen atoms in the nucleus.
The hetero atoms can be at either a condensed position or a non-condensed position.
Examples of the heterocyclic skeleton having at least two hetero atoms are pyrazole, imidazole, pyrazine, pyrimidine, indazole, purine, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, phenanthroline, pyrroloimidazole, pyrrolotriazole, pyrazoloimidazole, pyrazolotriazole, pyrazolopyrimidine, pyrazolotriazine, imidazoimidazole, imidazopyridazine, imidazopyridine, imidazopyrazine, triazolopyridine, benzimidazole, naphthimidazole, benzoxazole, naphthoxazole, benzothiazole, naphthothiazole, benzotriazole, tetraazaindene, and triazine.
Preferred of them are imidazopyridazine, imidazopyridine, imidazopyrazine, benzimidazole, naphthimidazole, benzoxazole, naphtoxazole, benzothiazole, naphthothiazole, and triazine.
Still preferred are imidazopyridine, imidazopyrazine, benzimidazole, naphthimidazole, and triazine.
Particularly preferred are imidazopyridine, benzimidazole, naphthimidazole, and triazine.
Imidazopyridine and triazine are the most preferred.
The heterocyclic compounds having at least two hetero atoms are preferably those represented by formula (I): ##STR7## wherein R represents a hydrogen atom or a substituent; X represents --O--, --S--, .
dbd.
N-- or .
dbd.
N--R.
sup.
a ; R.
sup.
a represents a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group; and Q represents an atomic group necessary for forming a hetero ring together with N and X; R and X or Q may be connected together to form a ring