Light-emitting element, lighting device, light-emitting device, and electronic device
View Patent ↗A light-emitting element with high emission efficiency is provided. A light-emitting element with a long lifetime is provided. The light-emitting element includes an anode; a hole-transport layer over the anode, containing a hole-transport compound and a compound; a light-emitting layer over the hole-transport layer, containing a host material and a guest material; and a cathode over the light-emitting layer. The host material is an electron-transport compound. The guest material and the compound are each independently a phosphorescent compound or a thermally activated delayed fluorescence material. A peak of an emission spectrum of the compound is on a shorter wavelength side than a peak of an emission spectrum of the guest material. Only the guest material emits light.
1. A light-emitting element comprising:
an anode;
a hole-transport layer over the anode, the hole-transport layer containing a hole-transport compound and a first compound;
a light-emitting layer over the hole-transport layer, the light-emitting layer containing a host material and a guest material; and
a cathode over the light-emitting layer,
wherein the first compound is any one of a phosphorescent compound and a thermally activated delayed fluorescence material,
wherein the host material is an electron-transport compound,
wherein the guest material is any one of a phosphorescent compound and a thermally activated delayed fluorescence material,
wherein a peak of an emission spectrum of the first compound is on a shorter wavelength side than a peak of an emission spectrum of the guest material, and
wherein only the guest material emits light.
2. The light-emitting element according to claim 1 , wherein the hole-transport compound has an electron-blocking property.
3. The light-emitting element according to claim 1 ,
wherein the electron-transport compound has a hole-blocking property.
4. The light-emitting element according to claim 1 ,
wherein the electron-transport compound forms an exciplex in combination with the first compound.
5. The light-emitting element according to claim 1 ,
wherein the first compound and the guest material are each an organometallic complex containing iridium.
6. The light-emitting element according to claim 1 ,
wherein the peak of the emission spectrum of the first compound is determined by a photoluminescence method in a solvent, and
wherein the peak of the emission spectrum of the first compound is determined by a photoluminescence method in the solvent.
7. A lighting device comprising the light-emitting element according to claim 1 .
8. A light-emitting element comprising:
an anode;
a hole-transport layer over the anode, the hole-transport layer containing a hole-transport compound and a first compound;
a light-emitting layer over and in contact with the hole-transport layer, the light-emitting layer containing a host material and a guest material; and
a cathode over the light-emitting layer,
wherein the first compound is any one of a phosphorescent compound and a thermally activated delayed fluorescence material,
wherein the host material is an electron-transport compound,
wherein the guest material is any one of a phosphorescent compound and a thermally activated delayed fluorescence material,
wherein a peak of an emission spectrum of the first compound is on a shorter wavelength side than a peak of an emission spectrum of the guest material, and
wherein only the guest material emits light.
9. The light-emitting element according to claim 8 ,
wherein the hole-transport compound has an electron-blocking property.
10. The light-emitting element according to claim 8 ,
wherein the electron-transport compound has a hole-blocking property.
11. The light-emitting element according to claim 8 ,
wherein the electron-transport compound forms an exciplex in combination with the first compound.
12. The light-emitting element according to claim 8 ,
wherein the first compound and the guest material are each an organometallic complex containing iridium.
13. The light-emitting element according to claim 8 ,
wherein the peak of the emission spectrum of the first compound is determined by a photoluminescence method in a solvent, and
wherein the peak of the emission spectrum of the first compound is determined by a photoluminescence method in the solvent.
14. A lighting device comprising the light-emitting element according to claim 8 .