Organic electroluminescent device

1. An organic electroluminescent device comprising:

a pair of electrodes;

an organic layer including a light emitting layer between the electrodes, wherein the organic layer contains a compound represented by formula (V):

wherein R 51 represents a methyl or ethyl group and R 55 represents a hydrogen atom, a substituted or unsubstituted alkyl group, a cyano group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group.

2. The organic electroluminescent device according to claim 1 , wherein R 55 is a hydrogen atom.

3. The organic electroluminescent device according to claim 1 , wherein the compound represented by formula (V) has T 1 of 61 kcal/mol or greater.

4. The organic electroluminescent device according to claim 1 , wherein the compound represented by formula (V) has a molecular weight of from 450 to 1200.

5. The organic electroluminescent device according to claim 1 , wherein the light emitting layer further contains at least one phosphorescent metal complex containing a metal having an atomic weight of 40 or greater and a monoanionic bidentate ligand represented by one of formulae (A1) to (A4):

wherein E 1a to E 1q each independently represents a carbon atom or a hetero atom, R 1a to R 1i each independently represents a hydrogen atom or a substituent, and skeletons represented by the formulae (A1) to (A4) each has a 18π electronic structure in total.

6. The organic electroluminescent device according to claim 1 , wherein the light emitting layer further contains at least one tetradentate platinum complex represented by formula (1):

wherein X 1 , X 2 , X 3 , and X 4 each independently represents a carbon atom or a nitrogen atom, with the proviso that at least one of X 1 , X 2 , X 3 , and X 4 represents a nitrogen atom, X 5 , X 6 , X 7 , X 8 , X 9 , and X 10 each independently represents a carbon atom or a nitrogen atom, X 11 and X 12 each independently represents a carbon atom or a nitrogen atom, X 13 , X 14 , and X 15 each independently represents a carbon atom, a nitrogen atom, an oxygen atom, or a sulfur atom, with the proviso that the number of nitrogen atoms contained in a 5-membered ring skeleton represented by X 11 , X 12 , X 13 , X 14 , and X 15 is 2 or less, and L represents a single bond or a divalent linking group.

7. An organic electroluminescent device comprising:

a pair of electrodes;

an organic layer including a light emitting layer between the electrodes, wherein the organic layer contains a compound represented by formula (X):

wherein R 101 represents a methyl or ethyl group, R 105 and R 109 each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, a cyano group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group.

8. The organic electroluminescent device according to claim 7 , wherein each of R 105 and R 109 is a hydrogen atom.

9. The organic electroluminescent device according to claim 7 , wherein the light emitting layer contains a compound represented by formula (a):

wherein R 1 to R 4 each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group, an alkoxy group, an acyl group, an acyloxy group, an amino group, a nitro group, a cyano group, an ester group, an amide group, a halogen group, a perfluoroalkyl group, or a silyl group, with the proviso that at least one of R 1 to R 4 is a group having a double bond or a triple bond, and X 1 to X 12 each independently represents a hydrogen atom, an alkyl group, an alkynyl group, an aryl group, a heteroaryl group, an alkoxy group, an acyl group, an acyloxy group, an amino group, a nitro group, a cyano group, an ester group, an amide group, a halogen group, a perfluoroalkyl group, or a silyl group.

10. The organic electroluminescent device according to claim 7 , wherein the compound represented by formula (X) has T 1 of 61 kcal/mol or greater.

11. The organic electroluminescent device according to claim 7 , wherein the compound represented by formula (X) has a molecular weight of from 450 to 1200.

12. The organic electroluminescent device according to claim 7 , wherein the light emitting layer further contains at least one phosphorescent metal complex containing a metal having an atomic weight of 40 or greater and a monoanionic bidentate ligand represented by one of formulae (A1) to (A4):

wherein E 1a to E 1q each independently represents a carbon atom or a hetero atom, R 1a to R 1i each independently represents a hydrogen atom or a substituent, and skeletons represented by the formulae (A1) to (A4) each has a 18π electronic structure in total.

13. The organic electroluminescent device according to claim 7 , wherein the light emitting layer further contains at least one tetradentate platinum complex represented by formula (1):

wherein X 1 , X 2 , X 3 , and X 4 each independently represents a carbon atom or a nitrogen atom, with the proviso that at least one of X 1 , X 2 , X 3 , and X 4 represents a nitrogen atom, X 5 , X 6 , X 7 , X 8 , X 9 , and X 10 each independently represents a carbon atom or a nitrogen atom, X 11 and X 12 each independently represents a carbon atom or a nitrogen atom, X 13 , X 14 , and X 15 each independently represents a carbon atom, a nitrogen atom, an oxygen atom, or a sulfur atom, with the proviso that the number of nitrogen atoms contained in a 5-membered ring skeleton represented by X 11 , X 12 , X 13 , X 14 , and X 15 is 2 or less, and L represents a single bond or a divalent linking group.