Light-emitting element, light-emitting device, electronic device, lighting device, and pyrene-based compound
A highly efficient light-emitting element capable of providing a plurality of emission colors is provided, which does not easily deteriorate and can minimize a decrease in external quantum efficiency even when a light-emitting layer has a stacked structure. A light-emitting device, an electronic device, and a lighting device which have low power consumption and long lifetime are provided. A light-emitting element includes a plurality of light-emitting layers stacked between a pair of electrodes. The light-emitting layers each contain a host material and a guest material. The guest materials of the light-emitting layers are substances which have different HOMO levels but have substantially the same LUMO levels and emit light of different colors. A light-emitting device, an electronic device, and a lighting device are fabricated using the light-emitting element.
1. A light-emitting element comprising a light-emitting layer between a pair of electrodes,
wherein the light-emitting layer comprises a bipolar material as a host material and at least two kinds of pyrene-based compounds having different HOMO levels but having substantially the same LUMO levels as guest materials,
wherein one of the two kinds of pyrene-based compounds is represented by a formula (G1):
wherein Ar represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms,
wherein α represents a substituted or unsubstituted phenylene group,
wherein R 1 to R 12 separately represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms,
wherein R 13 to R 20 separately represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and
wherein n is 0 or 1.
2. The light-emitting element according to claim 1 , wherein the LUMO levels of the two kinds of pyrene-based compounds are within a range of ±0.1 eV.
3. The light-emitting element according to claim 1 , wherein the bipolar material is a material comprising condensed aromatic hydrocarbon.
4. The light-emitting element according to claim 1 , wherein the bipolar material comprises anthracene, pyrene, phenanthrene, triphenylene, or fluoranthene.
5. The light-emitting element according to claim 1 , wherein one of the two kinds of pyrene-based compounds is represented by a formula (G2):
wherein Ar represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms,
wherein R 1 to R 12 separately represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and
wherein R 13 to R 20 separately represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
6. The light-emitting element according to claim 1 ,
wherein one of the two kinds of pyrene-based compounds is represented by a formula (G3):
wherein R 1 to R 12 and R 21 to R 25 separately represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
7. The light-emitting element according to claim 1 ,
wherein one of the two kinds of pyrene-based compounds is represented by a formula (100):
8. A light-emitting device comprising the light-emitting element according to claim 1 .
9. An electronic device comprising the light-emitting device according to claim 8 .
10. A lighting device comprising the light-emitting device according to claim 8 .
11. A light-emitting element comprising a light-emitting layer between a pair of electrodes,
wherein the light-emitting layer comprises a first light-emitting layer comprising a bipolar material and a first pyrene-based compound and a second light-emitting layer comprising the bipolar material and a second pyrene-based compound,
wherein the first pyrene-based compound and the second pyrene-based compound have different HOMO levels but have substantially the same LUMO levels,
wherein at least one of the first pyrene-based compound and the second pyrene-based compound is represented by a formula (G1):
wherein Ar represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms,
wherein α represents a substituted or unsubstituted phenylene group,
wherein R 1 to R 12 separately represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms,
wherein R 13 to R 20 separately represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and
wherein n is 0 or 1.
12. The light-emitting element according to claim 11 , wherein the LUMO levels of the first pyrene-based compound and the second pyrene-based compound are within a range of ±0.1 eV.
13. The light-emitting element according to claim 11 , wherein the bipolar material is a material comprising condensed aromatic hydrocarbon.
14. The light-emitting element according to claim 11 , wherein the bipolar material comprises anthracene, pyrene, phenanthrene, triphenylene, or fluoranthene.
15. The light-emitting element according to claim 11 ,
wherein one of the first pyrene-based compound and the second pyrene-based compound is represented by a formula (G2):
wherein Ar represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms,
wherein R 1 to R 12 separately represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and
wherein R 13 to R 20 separately represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
16. The light-emitting element according to claim 11 , wherein one of the first pyrene-based compound and the second pyrene-based compound is represented by a formula (G3):
wherein R 1 to R 12 and R 21 to R 25 separately represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
17. The light-emitting element according to claim 11 , wherein one of the first pyrene-based compound and the second pyrene-based compound is represented by a formula (100):
18. A light-emitting device comprising the light-emitting element according to claim 11 .
19. An electronic device comprising the light-emitting device according to claim 18 .
20. A lighting device comprising the light-emitting device according to claim 18 .
21. A pyrene-based compound represented by a formula (G1):
wherein Ar represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms,
wherein α represents a substituted or unsubstituted phenylene group,
wherein R 1 to R 12 separately represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms,
wherein R 13 to R 20 separately represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and
wherein n is 0 or 1.
22. The pyrene-based compound according to claim 21 , wherein the pyrene-based compound is represented by a formula (G2):
23. The pyrene-based compound according to claim 21 , wherein the pyrene-based compound is represented by a formula (G3):
wherein R 21 to R 25 separately represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
24. The pyrene-based compound according to claim 21 , wherein the pyrene-based compound represented by a formula (100):