Light-emitting element, light-emitting device, display device, and electronic apparatus

1. A light-emitting element comprising:

an anode;

a cathode;

a luminescent layer disposed between the anode and the cathode so that excitons are generated therein, the luminescent layer containing a luminescent material that emits light by applying a current between the anode and the cathode, and a host material helping the luminescent layer emit light;

a first luminescence-assisting layer disposed in contact with the luminescent layer between the anode and the luminescent layer, the first luminescence-assisting layer containing a first luminescence-assisting material having characteristics the same as or similar to the host material and having a function of preventing the excitons from being deactivated; and

a second luminescence-assisting layer disposed in contact with the luminescent layer between the cathode and the luminescent layer, the second luminescence-assisting layer containing a second luminescence-assisting material having characteristics the same as or similar to the host material and having a function of preventing the excitons from being deactivated,

wherein the luminescent layer and the first luminescence-assisting layer each contain a high-molecular-weight material.

2. The light-emitting element according to claim 1 , further comprising a hole transport layer capable of transporting holes between the anode and the first luminescence-assisting layer, wherein the first luminescence-assisting layer has a function of preventing the excitons from reaching the hole transport layer.

3. The light-emitting element according to claim 1 , further comprising an electron transport layer capable of transporting electrons between the cathode and the second luminescence-assisting layer, wherein the second luminescence-assisting layer has a function of preventing the excitons from reaching the electron transport layer.

4. The light-emitting element according to claim 1 , wherein the high-molecular-weight material has a cross-linked structure.

5. The light-emitting element according to claim 4 , wherein the high-molecular-weight material is an amine compound.

6. The light-emitting element according to claim 1 , wherein at least one of the first luminescence-assisting material and the second luminescence-assisting material is the same as the host material.

7. The light-emitting element according to claim 1 , wherein the luminescent layer has a thickness in the range of 10 to 50 nm.

8. The light-emitting element according to claim 7 , wherein the first luminescence-assisting layer and the second luminescence-assisting layer each have a thickness in the range of 5 to 25 nm.

9. The light-emitting element according to claim 7 , wherein the total thickness of the luminescent layer, the first luminescence-assisting layer and the second luminescence-assisting layer is in the range of 40 to 80 nm.

10. The light-emitting element according to claim 1 , wherein the second luminescence-assisting layer further contains a high-molecular-weight material.

11. A light-emitting device comprising the light-emitting element as set forth in claim 1 .

12. A light-emitting device comprising the light-emitting element as set forth in claim 2 .

13. A light-emitting device comprising the light-emitting element as set forth in claim 3 .

14. A light-emitting device comprising the light-emitting element as set forth in claim 4 .

15. A light-emitting device comprising the light-emitting element as set forth in claim 5 .

16. A light-emitting device comprising the light-emitting element as set forth in claim 6 .

17. A light-emitting device comprising the light-emitting element as set forth in claim 7 .

18. A light-emitting device comprising the light-emitting element as set forth in claim 8 .

19. A display device comprising the light-emitting element as set forth in claim 1 .

20. An electronic apparatus comprising the light emitting element as set forth in claim 1 .