COMPOSITION AND LIGHT-EMITTING ELEMENT COMPRISING THE SAME

1 . A composition comprising: a compound having residues of at least two kinds of nitrogen-containing compounds selected from the group consisting of nitrogen-containing compounds represented by formulas (1-1), (1-2), (1-3) and (1-4) given below:

wherein R each represents a hydrogen atom or a substituent; and more than one R may be the same or different; and a phosphorescent compound.

2 . The composition according to claim 1 , wherein the compound having residues of at least two kinds of nitrogen-containing compounds is a compound having residues of at least two kinds of nitrogen-containing compounds selected from the group consisting of nitrogen-containing compounds represented by the formulas (1-2), (1-3) and (1-4) given above.

3 . The composition according to claim 1 , wherein at least one of the R is an alkyl group, an alkoxy group, an aryl group that may have a substituent or a heteroaryl group that may have a substituent.

4 . The composition according to claim 3 , wherein at least one of the R is a substituent having 3 or more atoms in total except hydrogen.

5 . The composition according to claim 4 , wherein at least one of the R is an alkyl group having 3 to 10 carbon atoms or an alkoxy group having 3 to 10 carbon atoms.

6 . The composition according to claim 1 , wherein the compound having residues of at least two kinds of nitrogen-containing compounds is a compound represented by formula (A-1) or (A-2) given below:

Z 1 —(Y 1 ) m —Z 2   (A-1)

Z 1 —(Y 2 ) n —Z 2   (A-2)

wherein Z 1 and Z 2 each independently represent a residue of a nitrogen-containing compound represented by the above formula (1-1), (1-2), (1-3) or (1-4); Y 1 represents —C(R a )(R b )—, —N(R c )—, —O—, —Si(R d )(R e )—, —P(R f )— or —S—; R a to R f each independently represent a hydrogen atom or a substituent; m is an integer of 0 to 5; when there is more than one Y 1 , they may be the same or different; Y 2 represents an arylene group that may have a substituent; n is an integer of 1 to 5; and when there is more than one Y 2 , these may be same or different, or a compound having a residue of the foregoing compound.

7 . The composition according to claim 6 , wherein the compound having a residue of a compound represented by the above formula (A-1) is a compound represented by a formula (A-1-1) given below:

wherein R is as defined above.

8 . The composition according to claim 1 , wherein the compound having residues of at least two kinds of nitrogen-containing compounds is a polymer compound.

9 . The composition according to claim 8 , wherein the compound having residues of at least two kinds of nitrogen-containing compounds is a polymer compound having a repeating unit comprising a residue of a compound represented by the above formula (A-1) or (A-2).

10 . The composition according to claim 9 , wherein the polymer compound having a repeating unit containing a residue of a compound represented by the above formula (A-1) is a polymer compound having a repeating unit represented by a formula (A-1-2) given below:

wherein, R is as defined above.

11 . The composition according to claim 1 , wherein the lowest triplet excitation energy value of the compound having residues of at least two kinds of nitrogen-containing compounds as calculated by a computational scientific approach is 3.0 eV or more.

12 . The composition according to claim 1 , wherein the absolute value of the lowest unoccupied molecular orbital energy level of the compound having residues of at least two kinds of nitrogen-containing compounds as calculated by a computational scientific approach is 1.5 eV or more.

13 . The composition according to claim 1 , wherein a lowest triplet excitation energy value (ETH) of the compound having residues of at least two kinds of nitrogen-containing compounds and the lowest triplet excitation energy value (ETG) of the phosphorescent compound satisfy the expression given below:

ETH>ETG (eV).

14 . The composition according to claim 8 , wherein the compound having residues of at least two kinds of nitrogen-containing compounds is a compound having a heterocyclic structure constituting the nitrogen-containing compounds and a partial structure adjacent to the heterocyclic structure, the partial structure having at least two π-conjugated electrons, wherein the dihedral angle between the heterocyclic structure and the partial structure is 40° or more.

15 . The composition according to claim 1 , wherein the phosphorescent compound is an iridium complex or a platinum complex.

16 . The composition according to claim 15 , wherein the phosphorescent compound is a metal complex having iridium or platinum as a central metal and, having 8-quinolinol or a derivative thereof, benzoquinolinol or a derivative thereof, or 2-phenyl-pyridine or a derivative thereof as a ligand.

17 . A polymer compound comprising: residues of at least two kinds of nitrogen-containing compounds selected from the group consisting of nitrogen-containing compounds represented by formulas (1-1), (1-2), (1-3) and (1-4) given below:

wherein R represents a hydrogen atom or a substituent; and more than one R may be the same or different; and a residue of a phosphorescent compound.

18 . A film prepared by using the composition according to claim 1 .

19 . A light-emitting device prepared by using the composition according to claim 1 .

20 . A planar light source comprising the light-emitting device according to claim 19 .

21 . A display comprising the light-emitting device according to claim 19 .

22 . A light comprising the light-emitting device according to claim 19 .

23 . A film prepared by using the polymer compound according to claim 17 .

24 . A light-emitting device prepared by using the polymer compound according to claim 17 .