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 having a first substituent and a second substituent,
wherein each of the first substituent and the second substituent comprises a 9-phenylcarbazole group,
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 the first substituent and the second substituent have the same structure.
5 . The compound according to claim 1 , wherein the compound does not include amine.
6 . 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 having a first substituent and a second substituent,
wherein each of the first substituent and the second substituent comprises a 9-phenylcarbazole group,
wherein the second compound has an anthracene skeleton, and
wherein the hole-transport layer is in contact with the light-emitting layer.
7 . The light-emitting device according to claim 6 , wherein the second compound is a host material.
8 . The light-emitting device according to claim 6 , wherein a HOMO level of the first compound is deeper than or equal to a HOMO level of the second compound.
9 . The light-emitting device according to claim 6 , wherein the first substituent and the second substituent have the same structure.
10 . The light-emitting device according to claim 6 , wherein the first compound does not include amine.
11 . An electronic device comprising the light-emitting device according to claim 6 .
12 . A lighting device comprising the light-emitting device according to claim 6 .