Light-Emitting Element

A light-emitting device comprising a light-emitting layer, the light-emitting layer comprising:

• a phosphorescent compound;
• and
• a substance exhibiting thermally activated delayed fluorescence,
• wherein a fluorescence spectrum of the substance exhibiting the 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 is lower than an energy value of a peak of the lowest-energy-side absorption band.

A light-emitting device comprising a light-emitting layer, the light-emitting layer comprising:

• a phosphorescent compound;
• and
• a substance exhibiting thermally activated delayed fluorescence,
• wherein a phosphorescence spectrum of the substance exhibiting the 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 is lower than an energy value of a peak of the lowest-energy-side absorption band.

A light-emitting device comprising a light-emitting layer, the light-emitting layer comprising:

• a phosphorescent compound;
• and
• a substance exhibiting thermally activated delayed fluorescence,
• wherein a fluorescence spectrum and a phosphorescence spectrum of the substance exhibiting the 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 and an energy value of a peak of the phosphorescence spectrum are lower than an energy value of a peak of the lowest-energy-side absorption band.