Patent ID: 11864403
Assignee: SEMICONDUCTOR ENERGY LABORATORY CO., LTD.
Field: nan (nan)
Classification: CPC H | IPC H

Claim 1:
2. A light-emitting device comprising:
a first electrode;
a first light-emitting layer over the first electrode;
a second light-emitting layer over the first light-emitting layer;
a third light-emitting layer over the second light-emitting layer;
a second electrode over the third light-emitting layer; and
an electron-transport material, a Group 1 metal or a compound of the Group 1 metal, a hole-transport material, and a first organic compound which are between the second light-emitting layer and the third light-emitting layer,
wherein the first organic compound comprises at least one of a halogen group and a cyano group,
wherein the first light-emitting layer comprises a first host material and a first fluorescent material,
wherein the second light-emitting layer comprises a second organic compound, a third organic compound which forms an exciplex together with the second organic compound, and a phosphorescent material,
wherein the third light-emitting layer comprises a second host material and a second fluorescent material,
wherein an emission spectrum peak of the exciplex overlaps with an adsorption band on a longest wavelength side in an absorption spectrum of the phosphorescent material,
wherein the first fluorescent material and the second fluorescent material are the same material,
wherein the second organic compound is one of a triazole derivative, a dibenzofuran derivative, a pyrimidine derivative, a triazine derivative, a pyridine derivative, a bipyridine derivative, and a phenanthroline derivative,
wherein the first host material is an anthracene derivative or a tetracene derivative,
wherein the light-emitting device is configured to emit white light,
wherein a level of the lowest triplet excited state of the first fluorescent material is higher than a level of the lowest triplet excited state of the first host material, and
wherein a level of the lowest singlet excited state of the first host material is higher than a level of the lowest singlet excited state of the first fluorescent material.