LIGHT-EMITTING ELEMENT, LIGHT-EMITTING DEVICE, ELECTRONIC APPARATUS, AND ILLUMINATION DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a light-emitting element with high external quantum efficiency, and a light-emitting element with long life.SOLUTION: A light-emitting element includes a light-emitting layer containing a guest material and a host material provided between a pair of electrodes. The emission spectrum of the host material overlaps with the absorption spectrum of the guest material. The excitation energy of the host material is converted into the excitation energy of the guest material and thus the phosphorescence is emitted. By using the overlapping between the emission spectrum of the host material and the absorption spectrum of the guest material, the energy shift from the host material to the guest material is smoothly carried out. Thus, the light-emitting element has the high energy shift efficiency. Therefore, the light-emitting element has the high external quantum efficiency.SELECTED DRAWING: Figure 1