Light-emitting element, light-emitting device, electronic device, and lighting device
Objects of the present invention are to provide: a light-emitting element having a long lifetime and good emission efficiency and drive voltage. One embodiment of the invention is a light-emitting element including, between an anode and a cathode, at least a stack structure in which a first layer, a second layer, and a light-emitting layer are provided in order from the anode side. The first layer includes a first organic compound and an electron-accepting compound. The second layer includes a second organic compound having a HOMO level differing from the HOMO level of the first organic compound by from −0.2 eV to +0.2 eV. The light-emitting layer includes a third organic compound having a HOMO level differing from the HOMO level of the second organic compound by from −0.2 eV to +0.2 eV and a light-emitting substance having a hole-trapping property with respect to the third organic compound.
1. A light-emitting element comprising:
between an anode and a cathode, at least a stack structure including a first layer, a second layer, and a light-emitting layer, wherein the first layer is between the anode and the second layer, the second layer is between the first layer and the light-emitting layer, and the light-emitting layer is between the second layer and the cathode,
wherein the first layer comprises a first organic compound,
wherein the second layer comprises a second organic compound,
wherein the light-emitting layer comprises a third organic compound and a light-emitting sub stance,
wherein the first organic compound and the second organic compound each separately comprises a skeleton of at least any one of an aromatic amine, a π-excessive heteroaromatic ring, a tricyclic condensed aromatic hydrocarbon ring, and a tetracyclic condensed aromatic hydrocarbon ring,
wherein the third organic compound comprises an anthracene skeleton,
wherein the second organic compound differs from the first organic compound,
wherein the light-emitting substance comprises an aromatic amine skeleton and a pyrene skeleton, and
wherein a HOMO level of the light-emitting substance is higher than a HOMO level of the third organic compound by 0.3 eV or more.
2. The light-emitting element according to claim 1 , wherein a HOMO level of the first organic compound is greater than or equal to −6.0 eV and less than or equal to −5.7 eV.
3. A light-emitting device comprising the light-emitting element according to claim 1 .
4. An electronic device comprising a display portion having the light-emitting device according to claim 3 .
5. A lighting device comprising a lighting portion having the light-emitting device according to claim 3 .
6. A light-emitting element comprising:
between an anode and a cathode, at least a stack structure including a first layer, a second layer, and a light-emitting layer, wherein the first layer is between the anode and the second layer, the second layer is between the first layer and the light-emitting layer, and the light-emitting layer is between the second layer and the cathode,
wherein the first layer comprises a first organic compound and an electron-accepting compound,
wherein the second layer comprises a second organic compound,
wherein the light-emitting layer comprises a third organic compound and a light-emitting sub stance,
wherein the first organic compound and the second organic compound each separately comprises a skeleton of at least any one of an aromatic amine, a π-excessive heteroaromatic ring, a tricyclic condensed aromatic hydrocarbon ring, and a tetracyclic condensed aromatic hydrocarbon ring,
wherein the third organic compound comprises an anthracene skeleton,
wherein a HOMO level of the light-emitting substance is higher than a HOMO level of the third organic compound by 0.3 eV or more, and
wherein the light-emitting substance comprises an aromatic amine skeleton and a pyrene skeleton.
7. The light-emitting element according to claim 6 , wherein a HOMO level of the first organic compound is greater than or equal to −6.0 eV and less than or equal to −5.7 eV.
8. A light-emitting device comprising the light-emitting element according to claim 6 .
9. An electronic device comprising a display portion having the light-emitting device according to claim 8 .
10. A lighting device comprising a lighting portion having the light-emitting device according to claim 8 .
11. A light-emitting element comprising:
between an anode and a cathode, at least a stack structure including a first layer, a second layer, and a light-emitting layer, wherein the first layer is between the anode and the second layer, the second layer is between the first layer and the light-emitting layer, and the light-emitting layer is between the second layer and the cathode,
wherein the first layer comprises a first organic compound and an electron-accepting compound,
wherein the second layer comprises a second organic compound,
wherein the light-emitting layer comprises a third organic compound and a light-emitting sub stance,
wherein the first organic compound and the second organic compound each separately comprises a skeleton of at least any one of an aromatic amine, a π-excessive heteroaromatic ring, a tricyclic condensed aromatic hydrocarbon ring, and a tetracyclic condensed aromatic hydrocarbon ring,
wherein the third organic compound comprises an anthracene skeleton,
wherein a HOMO level of the light-emitting substance is higher than a HOMO level of the third organic compound by 0.3 eV or more, and
wherein the light-emitting substance comprises iridium.
12. The light-emitting element according to claim 11 , wherein a HOMO level of the first organic compound is greater than or equal to −6.0 eV and less than or equal to −5.7 eV.
13. A light-emitting device comprising the light-emitting element according to claim 11 .
14. An electronic device comprising a display portion having the light-emitting device according to claim 13 .
15. A lighting device comprising a lighting portion having the light-emitting device according to claim 13 .