Organic electroluminescent element
An organic EL device includes a pair of electrodes and an organic compound layer between pair of electrodes. The organic compound layer includes an emitting layer including a first material, a second material and a third material, in which singlet energy EgS(H) of the first material, singlet energy EgS(H2) of the second material, and singlet energy EgS(D) of the third material satisfy a specific relationship.
1. An organic electroluminescence device comprising a pair of electrodes and an organic compound layer therebetween, the organic compound layer comprising an emitting layer comprising: a first material; a second material; and a third material, wherein
singlet energy EgS(H1) of the first material, singlet energy EgS(H2) of the second material, and singlet energy EgS(D) of the third material satisfy a relationship of numerical formulae (1) and (2) below,
the singlet energy EgS(H1) of the first material and the singlet energy EgS(H2) of the second material satisfy a relationship of numerical formula (8) below,
a difference ΔST(H1) between the singlet energy EgS(H1) of the first material and an energy gap Eg 77K (H1) at 77K of the first material satisfies a relationship of a numerical formula (3) below, and
the third material is a fluorescent material,
EgS(H1)>EgS(D) (1)
EgS(H2)>EgS(D) (2)
ΔST(H1)=EgS(H1)−Eg 77K (H1)<0.3 [eV] (3)
EgS(H2)≥EgS(H1) (8).
2. The organic electroluminescence device according to claim 1 , wherein
the difference ΔST(H1) between the singlet energy EgS(H1) of the first material and the energy gap Eg 77K (H1) at 77K of the first material satisfies a relationship of a numerical formula (4) below,
ΔST(H1)=EgS(H1)−Eg 77K (H1)<0.2 [eV] (4).
3. The organic electroluminescence device according to claim 1 , wherein
the energy gap Eg 77K (H1) at 77K of the first material and the energy gap Eg 77K (D) at 77K of the third material satisfy a relationship of a numerical formula (7) below,
Eg 77K (H1)−Eg 77K (D)>0.5 [eV] (7).
4. The organic electroluminescence device according to claim 1 , wherein
the organic electroluminescence device exhibits a delayed fluorescence ratio larger than 37.5%.
5. The organic electroluminescence device according to claim 1 , wherein
the organic electroluminescence device exhibits a residual intensity ratio larger than 36.0% after an elapse of 1 μs after voltage removal in a transitional EL measurement.
6. The organic electroluminescence device according to claim 1 , wherein
a half bandwidth of a photoluminescence spectrum of the first material is 50 nm or more.
7. The organic electroluminescence device according to claim 1 , wherein
an emission peak wavelength of the third material is in a range of 500 nm to 600 nm.
8. The organic electroluminescence device according to claim 1 , wherein
the singlet energy EgS(H1) of the first material and the singlet energy EgS(H2) of the second material satisfy a relationship of numerical formula (9) below,
EgS(H2)>EgS(H1) (9)
9. The organic electroluminescence device according to claim 1 , wherein the emitting layer does not comprise a heavy-metal complex.
10. The organic electroluminescence device according to claim 1 , wherein the first material exhibits a delayed fluorescence.
11. The organic electroluminescence device according to claim 2 , wherein a half bandwidth of a photoluminescence spectrum of the first material is 50 nm or more, and the emitting layer does not comprise a heavy-metal complex.
12. The organic electroluminescence device according to claim 2 , wherein a half bandwidth of a photoluminescence spectrum of the first material is 50 nm or more, and the first material exhibits a delayed fluorescence.
13. The organic electroluminescence device according to claim 2 , wherein the emitting layer does not comprise a heavy-metal complex, and the first material exhibits a delayed fluorescence.
14. The organic electroluminescence device according to claim 2 , wherein a half bandwidth of a photoluminescence spectrum of the first material is 50 nm or more, the emitting layer does not comprise a heavy-metal complex, and the first material exhibits a delayed fluorescence.
15. The organic electroluminescence device according to claim 1 , wherein the first material is represented by a formula (101) below,
A 1 and A 2 is independently represent:
a hydrogen atom;
a halogen atom;
a cyano group;
a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 ring carbon atoms;
a substituted or unsubstituted aromatic heterocyclic group having 2 to 30 ring carbon atoms;
a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms;
a substituted or unsubstituted cycloalkyl group having 3 to 30 ring carbon atoms;
a substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms;
a substituted or unsubstituted aralkyl group having 7 to 30 carbon atoms;
a substituted or unsubstituted aryloxy group having 6 to 30 ring carbon atoms; or
a substituted or unsubstituted silyl group,
Y 1 to Y 4 and Y 13 to Y 16 each independently represent C(R) or a nitrogen atom,
Y 5 to Y 8 each independently represent C(R), a nitrogen atom or a carbon atom bonded to one of Y 9 to Y 12 ,
Y 9 to Y 12 each independently represent C(R), a nitrogen atom or a carbon atom bonded to one of Y 5 to Y 8 ,
R independently represents a hydrogen atom or a substituent, the substituent for R being the same as the substituent for A 1 and A 2 , and
L 1 and L 2 each independently represent: a single bond; a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 30 ring carbon atoms; a substituted or unsubstituted divalent aromatic heterocyclic group having 2 to 30 ring carbon atoms; or a group formed by bonding the above divalent aromatic hydrocarbon group and the above divalent aromatic heterocyclic group.
16. The organic electroluminescence device according to claim 15 , wherein at least one of A 1 and A 2 is a cyano group.
17. The organic electroluminescence device according to claim 15 , wherein A 1 and A 2 each independently represent a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 ring carbon atoms or a substituted or unsubstituted aromatic heterocyclic group having 2 to 30 ring carbon atoms.
18. The organic electroluminescence device according to claim 15 , wherein
A 1 represent a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 ring carbon atoms and A 2 represent a substituted or unsubstituted aromatic heterocyclic group having 2 to 30 ring carbon atoms or
A 1 represent a substituted or unsubstituted aromatic heterocyclic group having 2 to 30 ring carbon atoms and A 2 represent a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 ring carbon atoms.
19. The organic electroluminescence device according to claim 15 , wherein
Y 1 to Y 4 and Y 13 to Y 16 independently represent C(R),
Y 5 to Y 8 independently represent C(R) or a carbon atom to be bonded to one of Y 9 to Y 12 ,
Y 9 to Y 12 independently represent C(R) or a carbon atom to be bonded to one of Y 5 to Y 8 , and
R independently represents a hydrogen atom or a substituent.
20. The organic electroluminescence device according to claim 15 , wherein
one of L 1 and L 2 represents a single bond, and
the other of L 1 and L 2 is represented by a formula (a) below,
where, in the formula (a), Y 21 to Y 25 each independently represent C(R a ), a nitrogen atom or a carbon atom bonded to L 3 ,
R a independently represents a hydrogen atom or a substituent, the substituent for R a being the same as the substituent for A 1 and A 2 , and
L 3 and L 4 each independently represent: a single bond; a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 30 ring carbon atoms; a substituted or unsubstituted divalent aromatic heterocyclic group having 2 to 30 ring carbon atoms; or a group formed by bonding the above divalent aromatic hydrocarbon group and the above divalent aromatic heterocyclic group.
21. The organic electroluminescence device according to claim 15 , wherein
one of L 1 and L 2 represents a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 30 ring carbon atoms, a substituted or unsubstituted divalent aromatic heterocyclic group having 2 to 30 ring carbon atoms, or a group formed by bonding the substituted or unsubstituted divalent aromatic hydrocarbon group and the substituted or unsubstituted divalent aromatic heterocyclic group, and
the other of L 1 and L 2 is represented by a formula (a) below,
where, in the formula (a), Y 21 to Y 25 each independently represent C(R a ), a nitrogen atom or a carbon atom bonded to L 3 ,
R a independently represents a hydrogen atom or a substituent, the substituent for R a being the same as the substituent for A 1 and A 2 , and
L 3 and L 4 each independently represent: a single bond; a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 30 ring carbon atoms; a substituted or unsubstituted divalent aromatic heterocyclic group having 2 to 30 ring carbon atoms; or a group formed by bonding the above divalent aromatic hydrocarbon group and the above divalent aromatic heterocyclic group.
22. The organic electroluminescence device according to claim 15 , wherein
at least one of L 1 and L 2 is represented by a formula (a) below,
where, in the formula (a), Y 21 to Y 25 each independently represent C(R a ) or a carbon atom bonded to L 3 ,
R a independently represents a hydrogen atom or a substituent, the substituent for R a being the same as the substituent for A 1 and A 2 , and
L 3 and L 4 each independently represent: a single bond; a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 30 ring carbon atoms; a substituted or unsubstituted divalent aromatic heterocyclic group having 2 to 30 ring carbon atoms; or a group formed by bonding the above divalent aromatic hydrocarbon group and the above divalent aromatic heterocyclic group.
23. The organic electroluminescence device according to claim 15 , wherein
A 1 is a cyano group,
L 1 is represented by a formula (a) below,
where, in the formula (a), Y 21 to Y 25 each independently represent C(R a ), a nitrogen atom or a carbon atom bonded to L 3 ,
R a independently represents a hydrogen atom or a substituent, the substituent for R a being the same as the substituent for A 1 and A 2 , and
L 3 and L 4 each independently represent: a single bond; a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 30 ring carbon atoms; a substituted or unsubstituted divalent aromatic heterocyclic group having 2 to 30 ring carbon atoms; or a group formed by bonding the above divalent aromatic hydrocarbon group and the above divalent aromatic heterocyclic group.
24. The organic electroluminescence device according to claim 23 , wherein
A 2 is a substituted or unsubstituted aromatic hydrocarbon group having 6 ring carbon atoms,
L 2 is a single bond,
Y 1 to Y 4 and Y 13 to Y 16 each independently represent C(R),
Y 5 to Y 8 each independently represent C(R) or a carbon atom bonded to one of Y 9 to Y 12 , and
Y 9 to Y 12 each independently represent C(R) or a carbon atom bonded to one of Y 5 to Y 8 .
25. The organic electroluminescence device according to claim 24 , wherein
the difference ΔST(H1) between the singlet energy EgS(H1) of the first material and the energy gap Eg 77K (H1) at 77K of the first material satisfies formula (4) below:
ΔST(H1)=EgS(H1)−Eg 77K (H1)<0.2 [eV] (4),
a half bandwidth of a photoluminescence spectrum of the first material is 50 nm or more,
the emitting layer does not comprise a heavy-metal complex,
the first material exhibits a delayed fluorescence.
26. The organic electroluminescence device according to claim 15 , wherein
A 1 is a substituted or unsubstituted pyrimidine or a substituted or unsubstituted triazine.
27. The organic electroluminescence device according to claim 26 , wherein
A 2 is a substituted or unsubstituted aromatic hydrocarbon group having 6 ring carbon atoms,
L 1 is a single bond,
L 2 is a single bond,
Y 1 to Y 4 and Y 13 to Y 16 each independently represent C(R),
Y 5 to Y 8 each independently represent C(R) or a carbon atom bonded to one of Y 9 to Y 12 , and
Y 9 to Y 12 each independently represent C(R) or a carbon atom bonded to one of Y 5 to Y 8 .
28. The organic electroluminescence device according to claim 27 , wherein
the difference ΔST(H1) between the singlet energy EgS(H1) of the first material and the energy gap Eg 77K (H1) at 77K of the first material satisfies formula (4) below:
ΔST(H1)=EgS(H1)−Eg 77K (H1)<0.2 [eV] (4),
a half bandwidth of a photoluminescence spectrum of the first material is 50 nm or more,
the emitting layer does not comprise a heavy-metal complex,
the first material exhibits a delayed fluorescence.