Light-emitting element, display device, electronic device, and lighting device
First Claim
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1. A light-emitting device comprising:
- a pair of electrodes over a substrate; and
a first light-emitting layer and a second light-emitting layer between the pair of electrodes,a charge generation layer between the first light-emitting layer and the second light-emitting layer,wherein at least one of the first light-emitting layer and the second light-emitting layer comprises;
a fluorescent material as a guest material; and
a first organic compound and a second organic compound capable of forming an exciplex as a host material,wherein the fluorescent material comprises at least two substituents and condensed aromatic hydrocarbon having at least three rings,wherein the two substituents comprise any one of branched alkyl groups each having 3 to 10 carbon atoms, cyclic hydrocarbon groups each having 3 to 10 carbon atoms, bridged cyclic hydrocarbon groups each having 3 to 10 carbon atoms, andwherein light emitted from the exciplex has a region overlapping with an absorption band of the fluorescent material on the lowest energy side.
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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.
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Citations
18 Claims
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1. A light-emitting device comprising:
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a pair of electrodes over a substrate; and a first light-emitting layer and a second light-emitting layer between the pair of electrodes, a charge generation layer between the first light-emitting layer and the second light-emitting layer, wherein at least one of the first light-emitting layer and the second light-emitting layer comprises; a fluorescent material as a guest material; and a first organic compound and a second organic compound capable of forming an exciplex as a host material, wherein the fluorescent material comprises at least two substituents and condensed aromatic hydrocarbon having at least three rings, wherein the two substituents comprise any one of branched alkyl groups each having 3 to 10 carbon atoms, cyclic hydrocarbon groups each having 3 to 10 carbon atoms, bridged cyclic hydrocarbon groups each having 3 to 10 carbon atoms, and wherein light emitted from the exciplex has a region overlapping with an absorption band of the fluorescent material on the lowest energy side. - View Dependent Claims (2, 3, 4, 5, 6, 7, 15, 16)
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8. A light-emitting device comprising:
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a pair of electrodes over a substrate; and a first light-emitting layer and a second light-emitting layer between the pair of electrodes, a charge generation layer between the first light-emitting layer and the second light-emitting layer, wherein at least one of the first light-emitting layer and the second light-emitting layer comprises; a fluorescent material as a guest material; and a first organic compound and a second organic compound capable of forming an exciplex as a host material, wherein the fluorescent material has a fluorescence quantum yield of 70% or higher, and wherein the fluorescent material comprises at least two substituents and condensed aromatic hydrocarbon having at least three rings, wherein the two substituents comprise any one of branched alkyl groups each having 3 to 10 carbon atoms, cyclic hydrocarbon groups each having 3 to 10 carbon atoms, bridged cyclic hydrocarbon groups each having 3 to 10 carbon atoms, and wherein light emitted from the exciplex has a region overlapping with an absorption band of the fluorescent material on the lowest energy side. - View Dependent Claims (9, 10, 11, 12, 13, 14, 17, 18)
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Specification