Light-emitting element, display device, electronic device, and lighting device
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsShunsuke Hosoumi, Takahiro Ishisone, Tatsuyoshi Takahashi, Satoshi Seo
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Abstract
A light-emitting element containing a fluorescent material and having high emission efficiency is provided. The light-emitting element contains the fluorescent material and a host material. The host material contains a first organic compound and a second organic compound. The first organic compound and the second organic compound can form an exciplex. The minimum value of a distance between centroids of the fluorescent material and at least one of the first organic compound and the second organic compound is 0.7 nm or more and 5 nm or less.
Claims10
A light-emitting device emitting green light, comprising:
- a pair of electrodes over a substrate;
- and
- a light-emitting layer between the pair of electrodes,
- wherein the light-emitting layer comprises:
- a fluorescent material as a guest material;
- and
- an organic compound as a host material,
- wherein the fluorescent material comprises at least two branched alkyl groups each having 3 to 10 carbon atoms, at least two cyclic hydrocarbon groups each having 3 to 10 carbon atoms, or at least two bridged cyclic hydrocarbon groups each having 3 to 10 carbon atoms,
- wherein an emission peak of the organic compound overlaps with an absorption band of the fluorescent material on the lowest energy side, and
- wherein the organic compound is a thermally activated delayed fluorescence (TADF) material.
A light-emitting device emitting blue light, comprising:
- a pair of electrodes over a substrate;
- and
- a light-emitting layer between the pair of electrodes,
- wherein the light-emitting layer comprises:
- a fluorescent material as a guest material;
- and
- an organic compound as a host material,
- wherein the fluorescent material comprises at least two branched alkyl groups each having 3 to 10 carbon atoms, at least two cyclic hydrocarbon groups each having 3 to 10 carbon atoms, or at least two bridged cyclic hydrocarbon groups each having 3 to 10 carbon atoms,
- wherein an emission peak of the organic compound overlaps with an absorption band of the fluorescent material on the lowest energy side, and
- wherein the organic compound is a thermally activated delayed fluorescence (TADF) material.
Dependencies are inferred from the claim text.