| abstract |
To provide a light-emitting element which uses a fluorescent material as a light-emitting substance and has higher luminous efficiency. To provide a light-emitting element which includes a mixture of a thermally activated delayed fluorescent substance and a fluorescent material. By making the emission spectrum of the thermally activated delayed fluorescent substance overlap with an absorption band on the longest wavelength side in absorption by the fluorescent material in an S 1 level of the fluorescent material, energy at an S 1 level of the thermally activated delayed fluorescent substance can be transferred to the S 1 of the fluorescent material. Alternatively, it is also possible that the S 1 of the thermally activated delayed fluorescent substance is generated from part of the energy of a T 1 level of the thermally activated delayed fluorescent substance, and is transferred to the S 1 of the fluorescent material. |