Organic compound, light-emitting element, light-emitting device, electronic device, and lighting device
摘要
說明書
When a difference between the singlet excitation energy level and the triplet excitation energy level is small, with low thermal energy at 100° C. or lower, preferably at approximately room temperature, the triplet excitation energy can be upconverted to the singlet excitation energy by reverse intersystem crossing. Therefore, the compound of one embodiment of the present invention is suitably used as a compound that has a function of converting the triplet excitation energy into the singlet excitation energy or a compound that has a function of converting the triplet excitation energy into the singlet excitation energy and converting it into light emission. For efficient reverse intersystem crossing, the difference between the singlet excitation energy level and the triplet excitation energy level is preferably greater than 0 eV and less than or equal to 0.3 eV, more preferably greater than 0 eV and less than or equal to 0.2 eV, still more preferably greater than 0 eV and less than or equal to 0.1 eV.
Note that when the region where the HOMO is distributed and the region where the LUMO is distributed overlap each other and transition dipole moment between the HOMO level and the LUMO level is larger than 0, light emission can be obtained from an excited state related to the HOMO level and the LUMO level (e.g., the lowest singlet excited state). Therefore, the compound of one embodiment of the present invention is suitable as a light-emitting material that has a function of converting the triplet excitation energy into the singlet excitation energy; in other words, the compound is suitable as a thermally activated delayed fluorescence material.
A film of the compound of this embodiment can be formed by an evaporation method (including a vacuum evaporation method), an inkjet method, a coating method, gravure printing, or the like.
