Light-emitting element, light-emitting device, electronic device, and lighting device
A novel light-emitting element is provided. A light-emitting element with a long lifetime is provided. A light-emitting element with high emission efficiency is provided. In the light-emitting element, an EL layer includes a hole-injection layer, a first hole-transport layer, a second hole-transport layer, a third hole-transport layer, a light-emitting layer, a first electron-transport layer, and a second electron-transport layer in this order; the hole-injection layer includes an organic acceptor; the LUMO level of the host material is higher than that of the first electron-transport layer; the LUMO level of the second electron-transport layer is higher than that of the first electron-transport layer; the host material is a substance including a condensed aromatic ring skeleton; and the first and second electron-transport layers each include a substance having a heteroaromatic ring skeleton.
1. A compound comprising:
a naphthalene group substituted with two carbazole groups,
wherein the compound has a hole-transport property, and
wherein the compound is used in a first layer being in contact with a light-emitting layer comprising a first compound comprising an anthracene skeleton.
2. The compound according to claim 1 , wherein the first compound is a host material.
3. The compound according to claim 1 , wherein a HOMO level of the compound is deeper than or equal to a HOMO level of the first compound.
4. The compound according to claim 1 ,
wherein each of the two carbazole groups is a phenylcarbazole skeleton, and
wherein the compound has two phenylcarbazole skeletons.
5. The compound according to claim 1 , wherein the compound does not include amine.
6. The compound according to claim 1 , wherein the compound is represented by the following formula:
7. A light-emitting device comprising:
a hole-transport layer comprising a first compound; and
a light-emitting layer comprising a second compound,
wherein the first compound has a naphthalene group substituted with two carbazole groups,
wherein the second compound has an anthracene skeleton, and
wherein the hole-transport layer is in contact with the light-emitting layer.
8. The light-emitting device according to claim 7 , wherein the second compound is a host material.
9. The light-emitting device according to claim 7 , wherein a HOMO level of the first compound is deeper than or equal to a HOMO level of the second compound.
10. The light-emitting device according to claim 7 ,
wherein each of the two carbazole groups is a phenylcarbazole skeleton, and
wherein the first compound has two phenylcarbazole skeletons.
11. The light-emitting device according to claim 7 , wherein the first compound does not include amine.
12. The light-emitting device according to claim 7 , wherein the first compound is represented by the following formula:
13. An electronic device comprising the light-emitting device according to claim 7 .
14. A lighting device comprising the light-emitting device according to claim 7 .