Light-emitting element, light-emitting device, and electronic device
It is an object to provide a light-emitting element having long lifetime. A light-emitting element is provided, in which a light-emitting layer, a first layer, and a second layer are provided between a first electrode and a second electrode; the first layer is provided between the light-emitting layer and the first electrode; the second layer is provided between the light-emitting layer and the second electrode; the first layer is a layer for controlling the hole transport; the second layer is a layer for controlling the electron transport; and light emission is obtained from the light-emitting layer by applying voltage to the first electrode and the second electrode such that the potential of the first electrode is higher than that of the second electrode.
1. A light-emitting element comprising:
a first electrode;
a hole-transporting layer over the first electrode;
a light-emitting layer over the hole-transporting layer;
an electron-transporting layer over the light-emitting layer;
a second electrode over the electron-transporting layer;
a first layer between the first electrode and the hole-transporting layer; and
a second layer between the light-emitting layer and the electron-transporting layer,
wherein the first layer comprises a first organic compound having a hole-transporting property and a second organic compound having an electron-transporting property,
wherein the second layer comprises a third organic compound having an electron-transporting property and a fourth organic compound having a hole-transporting property,
wherein the light-emitting layer consists essentially of a host material and a light-emitting material,
wherein the light-emitting material is a first phosphorescent compound,
wherein the host material is different from the third organic compound,
wherein the fourth organic compound is a second phosphorescent compound different from the first phosphorescent compound, and
wherein the hole-transporting layer consists essentially of the first organic compound.
2. The light-emitting element according to claim 1 , wherein the second organic compound is any one of an oxadiazole derivative, a triazole derivative, and a phenanthroline derivative.
3. The light-emitting element according to claim 1 , wherein a concentration of the second organic compound in the first layer is greater than or equal to 1 wt % and less than or equal to 20 wt %.
4. The light-emitting element according to claim 1 , wherein a thickness of the first layer is greater than or equal to 1 nm and less than or equal to 20 nm.
5. The light-emitting element according to claim 1 , wherein a concentration of the fourth organic compound in the second layer is greater than or equal to 0.1 wt % and less than or equal to 5 wt %.
6. The light-emitting element according to claim 1 , wherein the second organic compound decreases a hole-transporting property of the first layer.
7. The light-emitting element according to claim 1 , wherein the third organic compound is a metal complex.
8. The light-emitting element according to claim 1 , wherein the second organic compound has a molecular structure having a heterocyclic.
9. The light-emitting element according to claim 1 , wherein the fourth organic compound decreases an electron-transporting property of the second layer.
10. The light-emitting element according to claim 1 , wherein the second organic compound is a substance to which a hole is not injected.
11. The light-emitting element according to claim 1 , wherein a thickness of the second layer is greater than or equal to 5 nm and less than or equal to 20 nm.
12. The light-emitting element according to claim 1 ,
wherein the first layer is in contact with the hole-transporting layer, and
wherein the second layer is in contact with the light-emitting layer and the electron-transporting layer.
13. A light-emitting device comprising the light-emitting element according to claim 1 and a control unit configured to control light emission of the light-emitting element.
14. An electronic device comprising a display portion, the display portion comprising the light-emitting element according to claim 1 and a control unit configured to control light emission of the light-emitting element.
15. A light-emitting element comprising:
a first electrode;
a hole injection layer over the first electrode;
a hole-transporting layer over the hole injection layer;
a light-emitting layer over the hole-transporting layer;
an electron-transporting layer over the light-emitting layer;
a second electrode over the electron-transporting layer;
a first layer between the hole injection layer and the hole-transporting layer; and
a second layer between the light-emitting layer and the electron-transporting layer,
wherein the first layer comprises a first organic compound having a hole-transporting property and a second organic compound having an electron-transporting property,
wherein the second layer comprises a third organic compound having an electron-transporting property and a fourth organic compound having a hole-transporting property,
wherein the light-emitting layer consists essentially of a host material and a light-emitting material,
wherein the light-emitting material is a first phosphorescent compound,
wherein the host material is different from the third organic compound,
wherein the fourth organic compound is a second phosphorescent compound,
wherein the hole-transporting layer consists essentially of the first organic compound, and
wherein a difference between a peak wavelength of an emission spectrum of the fourth organic compound and that of the light-emitting layer is within 30 nm.
16. The light-emitting element according to claim 15 , wherein the second organic compound is any one of an oxadiazole derivative, a triazole derivative, and a phenanthroline derivative.
17. The light-emitting element according to claim 15 , wherein a concentration of the second organic compound in the first layer is greater than or equal to 1 wt % and less than or equal to 20 wt %.
18. The light-emitting element according to claim 15 , wherein a thickness of the first layer is greater than or equal to 1 nm and less than or equal to 20 nm.
19. The light-emitting element according to claim 15 , wherein a concentration of the fourth organic compound in the second layer is greater than or equal to 0.1 wt % and less than or equal to 5 wt %.
20. The light-emitting element according to claim 15 , wherein the second organic compound decreases a hole-transporting property of the first layer.
21. The light-emitting element according to claim 15 , wherein the third organic compound is a metal complex.
22. The light-emitting element according to claim 15 , wherein the second organic compound has a molecular structure having a heterocyclic.
23. The light-emitting element according to claim 15 , wherein the fourth organic compound decreases an electron-transporting property of the second layer.
24. The light-emitting element according to claim 15 , wherein the hole injection layer comprises the first organic compound.
25. The light-emitting element according to claim 15 , wherein the second organic compound is a substance to which a hole is not injected.
26. The light-emitting element according to claim 15 , wherein a thickness of the second layer is greater than or equal to 5 nm and less than or equal to 20 nm.
27. The light-emitting element according to claim 15 ,
wherein the first layer is in contact with the hole injection layer and the hole-transporting layer, and
wherein the second layer is in contact with the light-emitting layer and the electron-transporting layer.
28. A light-emitting device comprising the light-emitting element according to claim 15 and a control unit configured to control light emission of the light-emitting element.
29. An electronic device comprising a display portion, the display portion comprising the light-emitting element according to claim 15 and a control unit configured to control light emission of the light-emitting element.
30. A light-emitting element comprising:
a first electrode;
a hole injection layer over the first electrode;
a hole-transporting layer over the hole injection layer;
a light-emitting layer over the hole-transporting layer;
an electron-transporting layer over the light-emitting layer;
a second electrode over the electron-transporting layer;
a first layer between the hole injection layer and the hole-transporting layer; and
a second layer between the light-emitting layer and the electron-transporting layer,
wherein the first layer comprises a first organic compound having a hole-transporting property and a second organic compound having an electron-transporting property,
wherein the second layer comprises a third organic compound having an electron-transporting property and a fourth organic compound having a hole-transporting property,
wherein the hole injection layer comprises a fifth organic compound and a metal oxide;
wherein the light-emitting layer consists essentially of a host material and a light-emitting material,
wherein the light-emitting material is a first phosphorescent compound,
wherein the host material is different from the third organic compound,
wherein the fourth organic compound is a second phosphorescent compound,
wherein the electron-transporting layer contains neither the third organic compound nor the fourth organic compound, and
wherein the hole-transporting layer consists essentially of the first organic compound.
31. The light-emitting element according to claim 30 , wherein the second organic compound is any one of an oxadiazole derivative, a triazole derivative, and a phenanthroline derivative.
32. The light-emitting element according to claim 30 , wherein a concentration of the second organic compound in the first layer is greater than or equal to 1 wt % and less than or equal to 20 wt %.
33. The light-emitting element according to claim 30 , wherein a thickness of the first layer is greater than or equal to 1 nm and less than or equal to 20 nm.
34. The light-emitting element according to claim 30 , wherein a concentration of the fourth organic compound in the second layer is greater than or equal to 0.1 wt% and less than or equal to 5 wt %.
35. The light-emitting element according to claim 30 , wherein the second organic compound decreases a hole-transporting property of the first layer.
36. The light-emitting element according to claim 30 , wherein the third organic compound is a metal complex.
37. The light-emitting element according to claim 30 , wherein the second organic compound has a molecular structure having a heterocyclic.
38. The light-emitting element according to claim 30 , wherein the fourth organic compound decreases an electron-transporting property of the second layer.
39. The light-emitting element according to claim 30 , wherein the fifth organic compound contained in the hole injection layer is the first organic compound.
40. The light-emitting element according to claim 30 , wherein the second organic compound is a substance to which a hole is not injected.
41. The light-emitting element according to claim 30 , wherein a thickness of the second layer is greater than or equal to 5 nm and less than or equal to 20 nm.
42. The light-emitting element according to claim 30 ,
wherein the first layer is in contact with the hole injection layer and the hole-transporting layer, and
wherein the second layer is in contact with the light-emitting layer and the electron-transporting layer.
43. A light-emitting device comprising the light-emitting element according to claim 30 and a control unit configured to control light emission of the light-emitting element.
44. An electronic device comprising a display portion, the display portion comprising the light-emitting element according to claim 30 and a control unit configured to control light emission of the light-emitting element.