Light-emitting element, light-emitting device, and electronic device
View Patent ↗A light-emitting element is provided, including a first electrode and a second electrode, a first layer including first and second organic compounds, the first layer being formed between the first electrode and the second electrode wherein the first organic compound is capable of emitting a first light and the second organic compound has an electron transporting property, and a second layer including third and fourth organic compounds, the second layer being formed between the first layer and the second electrode wherein the third organic compound is capable of emitting a second light and has an electron trap property and the fourth organic compound has an electron transporting property.
1. A light-emitting element comprising:
an anode;
a first light-emitting layer over the anode, the first light-emitting layer comprising a first organic compound having light-emitting property and a second organic compound having electron transporting property;
a second light-emitting layer over and in contact with the first light-emitting layer, the second light-emitting layer comprising a third organic compound having light-emitting property and a fourth organic compound; and
a cathode over the second light-emitting layer,
wherein a LUMO level of the third organic compound is lower than a LUMO level of the fourth organic compound by 0.3 eV or more, and
wherein the third organic compound is dispersed in the fourth organic compound.
2. The light-emitting element according to claim 1 , further comprising a hole transporting layer,
wherein the hole transporting layer is formed between the anode and the first light-emitting layer.
3. The light-emitting element according to claim 1 , wherein the fourth organic compound has electron transporting property.
4. The light-emitting element according to claim 1 ,
wherein the first organic compound exhibits emission of bluish light, and
wherein the third organic compound exhibits emission of blue to blue green light.
5. The light-emitting element according to claim 1 , wherein a difference between a peak value of an emission spectrum of the first organic compound and a peak value of an emission spectrum of the third organic compound is 0 nm or more and less than 30 nm.
6. A lighting device comprising the light-emitting element according to claim 1 .
7. An electronic device comprising:
a display device,
wherein the display device comprises the light-emitting element according to claim 1 .
8. A light-emitting element comprising:
an anode;
a first light-emitting layer over the anode, the first light-emitting layer comprising a first organic compound having light-emitting property and a second organic compound having electron transporting property;
a second light-emitting layer over and in contact with the first light-emitting layer, the second light-emitting layer comprising a third organic compound having light-emitting property and a fourth organic compound;
an electron transporting layer over the second light-emitting layer; and
a cathode over the electron transporting layer,
wherein a LUMO level of the third organic compound is lower than a LUMO level of the fourth organic compound by 0.3 eV or more, and
wherein the third organic compound is dispersed in the fourth organic compound.
9. The light-emitting element according to claim 8 , further comprising a hole transporting layer,
wherein the hole transporting layer is formed between the anode and the first light-emitting layer.
10. The light-emitting element according to claim 8 , wherein the fourth organic compound has electron transporting property.
11. The light-emitting element according to claim 8 ,
wherein the first organic compound exhibits emission of bluish light, and
wherein the third organic compound exhibits emission of blue to blue green light.
12. The light-emitting element according to claim 8 , wherein a difference between a peak value of an emission spectrum of the first organic compound and a peak value of an emission spectrum of the third organic compound is 0 nm or more and less than 30 nm.
13. A lighting device comprising the light-emitting element according to claim 8 .
14. An electronic device comprising:
a display device,
wherein the display device comprises the light-emitting element according to claim 8 .