Organic electroluminescent device and display device
View Patent ↗An electroluminescent device is provided with an anode, a cathode, and an organic layer having at least a light-emitting layer and held between the anode and the cathode. A layer with a nitrogen-containing heterocycle derivative therein is arranged between the anode and the light-emitting layer. The layer with the nitrogen-containing heterocycle derivative contained therein has a thickness greater than a hole supply layer arranged between the anode and the light-emitting layer.
1. An electroluminescent device comprising:
an anode;
a cathode; and
an organic layer held between said anode and said cathode, the organic layer including
a light-emitting layer,
a hole supply layer arranged between said anode and the light-emitting layer and having a thickness ranging from 30 to 40 nm, the hole supply layer including a hole injection layer and a hole transport layer, and
an electron supply layer containing at least one layer including a nitrogen-containing heterocycle derivative that is a benzimidazole derivative that is arranged between said cathode and said light-emitting layer, the electron supply layer having a thickness greater than a combined thickness of the hole supply layer and the light-emitting layer,
wherein the electron supply layer and said organic layer are formed to satisfy the following relationship:
0.90 >d 1 /d 2 >0.30
where d 1 is the thickness of the electron supply layer and d 2 is a thickness of said organic layer,
wherein a combined thickness of the at least one layer including the nitrogen-containing heterocycle derivative ranges from 70 nm to 130 nm, and
wherein the electroluminescent device has a current efficiency of at least 6.0 cd/A.
2. The electroluminescent device according to claim 1 , wherein said benzimidazole derivative is represented by the following formula (1), (2) or (3):
wherein,
R represents a hydrogen atom, a substituted or unsubstituted C 6 -C 60 aryl group, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted quinolyl group, a substituted or unsubstituted C 1 -C 20 alkyl group or a substituted or unsubstituted C 1 -C 20 alkoxy group, and n stands for an integer of from 0 to 4;
R 1 represents a substituted or unsubstituted C 6 -C 60 aryl group, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted quinolyl group, a substituted or unsubstituted C 1 -C 20 alkyl group or a substituted or unsubstituted C 1 -C 20 alkoxy group;
R 2 and R 3 each independently represent a hydrogen atom, a substituted or unsubstituted C 6 -C 60 aryl group, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted quinolyl group, a substituted or unsubstituted C 1 -C 20 alkyl group or a substituted or unsubstituted C 1 -C 20 alkoxy group;
L represents a substituted or unsubstituted C 6 -C 60 arylene group, a substituted or unsubstituted pyridinylene group, a substituted or unsubstituted quinolinylene group or a substituted or unsubstituted fluolenylene group;
Ar 1 represents a substituted or unsubstituted C 6 -C 60 arylene group, a substituted or unsubstituted pyridinylene group or a substituted or unsubstituted quinolinylene group;
Ar 2 represents a substituted or unsubstituted C 6 -C 60 aryl group, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted quinolyl group, a substituted or unsubstituted C 1 -C 20 alkyl group or a substituted or unsubstituted C 1 -C 20 alkoxy group; and
Ar 3 represents a substituted or unsubstituted C 6 -C 60 aryl group, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted quinolyl group, a substituted or unsubstituted C 1 -C 20 alkyl group, a substituted or unsubstituted C 1 -C 20 alkoxy group, or a group represented by—Ar 1 -Ar 2 in which Ar 1 and Ar 2 have the same meanings as defined above.
3. The electroluminescent device according to claim 1 , further comprising:
a layer containing an azatriphenylene derivative and arranged on a side of an interface between said hole supply layer and said anode.
4. A display device comprising:
a substrate; and
organic electroluminescent devices formed in an array on said substrate, each of said organic electroluminescent devices including an anode, a cathode and an organic layer held between said anode and said cathode, the organic layer including
a light-emitting layer,
a hole supply layer arranged between said anode and the light-emitting layer and having a thickness ranging from 30 to 40 nm, the hole supply layer including a hole injection layer and a hole transport layer, and
an electron supply layer containing at least one layer including a nitrogen-containing heterocycle derivative that is a benzimidazole derivative that is arranged between said cathode and said light-emitting layer, the electron supply layer having a thickness greater than a combines thickness of the hole supply layer and the light-emitting layer,
wherein the electron supply layer and said organic layer are formed to satisfy the following relationship:
0.90 >d 1 /d 2 >0.30
where d 1 is the thickness of the electron supply layer and d 2 is a thickness of said organic layer,
wherein a combined thickness of the at least one layer including the nitrogen-containing heterocycle derivative ranges from 70 nm to 130 nm,
wherein the electroluminescent device has a current efficiency of at least 6.0 cd/A.