Light-emitting element
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorSatoshi Seo
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Abstract
Provided is a light-emitting element with high external quantum efficiency and a low drive voltage. The light-emitting element includes a light-emitting layer which contains a phosphorescent compound and a material exhibiting thermally activated delayed fluorescence between a pair of electrodes, wherein a peak of a fluorescence spectrum and/or a peak of a phosphorescence spectrum of the material exhibiting thermally activated delayed fluorescence overlap(s) with a lowest-energy-side absorption band in an absorption spectrum of the phosphorescent compound, and wherein the phosphorescent compound exhibits phosphorescence in the light-emitting layer by voltage application between the pair of electrodes.
Claims34
A light-emitting device comprising:
- a first electrode and a second electrode;
- and
- a light-emitting layer between the first electrode and the second electrode,
- wherein the light-emitting layer comprises a phosphorescent compound and a material exhibiting thermally activated delayed fluorescence,
- wherein the material exhibiting thermally activated delayed fluorescence comprises a π-electron deficient heteroaromatic ring,
- wherein a fluorescence spectrum of the material exhibiting thermally activated delayed fluorescence overlaps with the lowest-energy-side absorption band in an absorption spectrum of the phosphorescent compound, and
- wherein an energy value of a peak of the fluorescence spectrum of the material exhibiting thermally activated delayed fluorescence is lower than an energy value of a peak of the lowest-energy-side absorption band in the absorption spectrum of the phosphorescent compound.
A light-emitting device comprising:
- a first electrode and a second electrode;
- and
- a light-emitting layer between the first electrode and the second electrode,
- wherein the light-emitting layer comprises a phosphorescent compound and a material,
- wherein the material comprises a π-electron deficient heteroaromatic ring,
- wherein a difference between a lowest triplet excitation energy and a lowest singlet excitation energy of the material is 0.3 eV or less,
- wherein a fluorescence spectrum of the material overlaps with the lowest-energy-side absorption band in an absorption spectrum of the phosphorescent compound, and
- wherein an energy value of a peak of the fluorescence spectrum of the material is lower than an energy value of a peak of the lowest-energy-side absorption band in the absorption spectrum of the phosphorescent compound.
A light-emitting device comprising:
- a first electrode and a second electrode;
- and
- a light-emitting layer between the first electrode and the second electrode,
- wherein the light-emitting layer comprises a phosphorescent compound and a material exhibiting thermally activated delayed fluorescence,
- wherein the material exhibiting thermally activated delayed fluorescence comprises a π-electron deficient heteroaromatic ring, and
- wherein an energy value of a peak of a fluorescence spectrum of the material exhibiting thermally activated delayed fluorescence is lower than an energy value of a peak of the lowest-energy-side absorption band in an absorption spectrum of the phosphorescent compound.
A light-emitting device comprising:
- a first electrode and a second electrode;
- and
- a light-emitting layer between the first electrode and the second electrode,
- wherein the light-emitting layer comprises a phosphorescent compound and a material,
- wherein the material comprises a π-electron deficient heteroaromatic ring,
- wherein a difference between a lowest triplet excitation energy and a lowest singlet excitation energy of the material is 0.3 eV or less, and
- wherein an energy value of a peak of a fluorescence spectrum of the material is lower than an energy value of a peak of the lowest-energy-side absorption band in an absorption spectrum of the phosphorescent compound.
Dependencies are inferred from the claim text.