Light-emitting element, light-emitting device, display device, electronic device, and lighting device
First Claim
Patent Images
1. A light-emitting element comprising:
- a first electrode;
a first light-emitting layer over the first electrode comprising;
a first phosphorescent compound; and
a first host material;
a second light-emitting layer over the first light-emitting layer comprising;
a second phosphorescent compound; and
a second host material;
a third light-emitting layer over the second light-emitting layer comprising;
a third phosphorescent compound; and
a third host material; and
a second electrode over the third light-emitting layer,wherein the first phosphorescent compound emits blue light,wherein ε
(λ
)λ
4 of the second phosphorescent compound has a peak within a wavelength range of 440 nm to 520 nm,wherein the second phosphorescent compound emits light with a wavelength longer than a wavelength of the light emitted from the first phosphorescent compound,wherein ε
(λ
)λ
4 of the third phosphorescent compound has a peak within a wavelength range of 520 nm to 600 nm,wherein the third phosphorescent compound emits light with a wavelength longer than the wavelength of the light emitted from the second phosphorescent compound,wherein λ
denotes a wavelength, andwherein ε
(λ
) denotes a molar absorption coefficient at the wavelength λ
.
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Abstract
An object is to provide a light-emitting element which uses a plurality of kinds of light-emitting dopants and has high emission efficiency. In one embodiment of the present invention, a light-emitting device, a light-emitting module, a light-emitting display device, an electronic device, and a lighting device each having reduced power consumption by using the above light-emitting element are provided. Attention is paid to Förster mechanism, which is one of mechanisms of intermolecular energy transfer. Efficient energy transfer by Förster mechanism is achieved by making an emission wavelength of a molecule which donates energy overlap with a local maximum peak on the longest wavelength side of a graph obtained by multiplying an absorption spectrum of a molecule which receives energy by a wavelength raised to the fourth power.
125 Citations
25 Claims
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1. A light-emitting element comprising:
-
a first electrode; a first light-emitting layer over the first electrode comprising; a first phosphorescent compound; and a first host material; a second light-emitting layer over the first light-emitting layer comprising; a second phosphorescent compound; and a second host material; a third light-emitting layer over the second light-emitting layer comprising; a third phosphorescent compound; and a third host material; and a second electrode over the third light-emitting layer, wherein the first phosphorescent compound emits blue light, wherein ε
(λ
)λ
4 of the second phosphorescent compound has a peak within a wavelength range of 440 nm to 520 nm,wherein the second phosphorescent compound emits light with a wavelength longer than a wavelength of the light emitted from the first phosphorescent compound, wherein ε
(λ
)λ
4 of the third phosphorescent compound has a peak within a wavelength range of 520 nm to 600 nm,wherein the third phosphorescent compound emits light with a wavelength longer than the wavelength of the light emitted from the second phosphorescent compound, wherein λ
denotes a wavelength, andwherein ε
(λ
) denotes a molar absorption coefficient at the wavelength λ
. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A light-emitting element comprising:
-
a first electrode; a first light-emitting layer over the first electrode comprising; a first phosphorescent compound; and a first host material; a second light-emitting layer over the first light-emitting layer comprising; a second phosphorescent compound; and a second host material; a third light-emitting layer over the second light-emitting layer comprising; a third phosphorescent compound; and a third host material; and a second electrode over the third light-emitting layer, wherein the first phosphorescent compound emits blue light, wherein ε
(λ
)λ
4 of the second phosphorescent compound has a peak within a wavelength range of 440 nm to 520 nm,wherein the second phosphorescent compound has a peak wavelength of phosphorescence within a range of 520 nm to 600 nm, wherein ε
(λ
)λ
4 of the third phosphorescent compound has a peak within a wavelength range of 520 nm to 600 nm,wherein the third phosphorescent compound emits light with a wavelength longer than the wavelength of the light emitted from the second phosphorescent compound, wherein λ
denotes a wavelength, andwherein ε
(λ
) denotes a molar absorption coefficient at the wavelength λ
. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
-
-
25. A light-emitting element comprising:
-
a first electrode; a first light-emitting layer over the first electrode comprising; a first phosphorescent compound; and a first host material; a second light-emitting layer over the first light-emitting layer comprising; a second phosphorescent compound; and a second host material; a third light-emitting layer over the second light-emitting layer comprising; a third phosphorescent compound; and a third host material; and a second electrode over the third light-emitting layer, wherein the first phosphorescent compound has a peak wavelength of phosphorescence within a range of 440 nm to 520 nm, wherein ε
(λ
)λ
4 of the second phosphorescent compound has a peak within a wavelength range of 440 nm to 520 nm,wherein the second phosphorescent compound has a peak wavelength of phosphorescence within a range of 520 nm to 600 nm, wherein ε
(λ
)λ
4 of the third phosphorescent compound has a peak within a wavelength range of 520 nm to 600 nm,wherein λ
denotes a wavelength, andwherein ε
(λ
) denotes a molar absorption coefficient at the wavelength λ
.
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Specification
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- Resources
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Current AssigneeSemiconductor Energy Laboratory Co., Ltd.
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Original AssigneeSemiconductor Energy Laboratory Co., Ltd.
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InventorsYamazaki, Shunpei, Seo, Satoshi, Hirakata, Yoshiharu, Ishisone, Takahiro
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Primary Examiner(s)Jahan, Bilkis
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Application NumberUS13/799,872Publication NumberTime in Patent Office342 DaysField of Search257/98, 257/99, 257/79US Class Current257/98CPC Class CodesB60Q 3/10 for dashboardsB60Q 3/208 Sun roofs; WindowsC09K 11/06 containing organic luminesc...C09K 2211/1007 Non-condensed systemsC09K 2211/1044 containing two nitrogen ato...C09K 2211/1059 containing three nitrogen a...C09K 2211/185 of the platinum group, i.e....F21S 6/002 Table lamps, e.g. for ambie...F21S 8/04 intended only for mounting ...F21Y 2115/10 Light-emitting diodes [LED]H01L 33/502 Wavelength conversion mater...H01L 33/504 Elements with two or more w...H05B 33/14 characterised by the chemic...H05B 33/145 Arrangements of the electro...H05B 33/20 characterised by the chemic...H10K 2101/10 Triplet emissionH10K 50/11 characterised by the electr...H10K 50/13 comprising stacked EL layer...
