Light-emitting element, light-emitting device, display device, electronic appliance, and lighting device
A multicolor light-emitting element using fluorescence and phosphorescence, which has a small number of manufacturing steps owing to a relatively small number of layers to be formed and is advantageous for practical application can be provided. In addition, a multicolor light-emitting element using fluorescence and phosphorescence, which has favorable emission efficiency is provided. A light-emitting element which includes a light-emitting layer having a stacked-layer structure of a first light-emitting layer exhibiting light emission from a first exciplex and a second light-emitting layer exhibiting phosphorescence is provided.
1. A light-emitting element comprising:
an anode;
a hole-transport layer over the anode;
a first light-emitting layer over the hole-transport layer, the first light-emitting layer comprising a first organic compound and a second organic compound;
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 and a phosphorescent compound;
an electron-transport layer over the second light-emitting layer; and
a cathode over the electron-transport layer,
wherein each of a triplet excited level of the first organic compound and the second organic compound is higher than a triplet excited level of the phosphorescent compound,
wherein a combination of the first organic compound and the second organic compound forms a first exciplex,
wherein light emitted from the first light-emitting layer has an emission peak at 500 nm to 600 nm, and
wherein light emitted from the second light-emitting layer has an emission peak at 600 nm to 700 nm.
2. The light-emitting element according to claim 1 , wherein the first light-emitting layer further comprises a dopant.
3. The light-emitting element according to claim 2 , wherein the dopant is a light-emitting substance.
4. A light-emitting module including the light-emitting element according to claim 1 , the light-emitting module comprising:
a current controlling transistor electrically connected to the light-emitting element.
5. A display module including the light-emitting element according to claim 1 in a display portion, the display module comprising:
a current controlling transistor electrically connected to the light-emitting element.
6. A lighting device including the light-emitting element according to claim 1 .
7. A light-emitting device comprising:
the light-emitting element according to claim 1 ; and
a current controlling transistor electrically connected to the light-emitting element.
8. A display device comprising:
the light-emitting element according to claim 1 in a display portion; and
a current controlling transistor electrically connected to the light-emitting element.
9. An electronic appliance comprising the light-emitting element according to claim 1 .
10. A light-emitting element comprising:
an anode;
a hole-transport layer over the anode;
a first light-emitting layer over the hole-transport layer, the first light-emitting layer comprising a first organic compound and a second organic compound;
a second light-emitting layer between the hole-transport layer and the first light-emitting layer, the second light-emitting layer comprising a third organic compound and a phosphorescent compound;
an electron-transport layer over the second light-emitting layer; and
a cathode over the electron-transport layer,
wherein the second light-emitting layer is in contact with the first light-emitting layer,
wherein each of a triplet excited level of the first organic compound and the second organic compound is higher than a triplet excited level of the phosphorescent compound,
wherein a combination of the first organic compound and the second organic compound forms a first exciplex,
wherein light emitted from the first light-emitting layer has an emission peak at 500 nm to 600 nm, and
wherein light emitted from the second light-emitting layer has an emission peak at 600 nm to 700 nm.
11. The light-emitting element according to claim 10 , wherein the first light-emitting layer further comprises a dopant.
12. The light-emitting element according to claim 11 , wherein the dopant is a light-emitting substance.
13. A light-emitting module including the light-emitting element according to claim 10 , the light-emitting module comprising:
a current controlling transistor electrically connected to the light-emitting element.
14. A display module including the light-emitting element according to claim 10 in a display portion, the display module comprising:
a current controlling transistor electrically connected to the light-emitting element.
15. A lighting device including the light-emitting element according to claim 10 .
16. A light-emitting device comprising:
the light-emitting element according to claim 10 ; and
a current controlling transistor electrically connected to the light-emitting element.
17. A display device comprising:
the light-emitting element according to claim 10 in a display portion; and
a current controlling transistor electrically connected to the light-emitting element.
18. An electronic appliance comprising the light-emitting element according to claim 10 .