A light-emitting device including an material, wherein KISC/KFL(original) of the emitting material is about 100 or greater, KRISC/KPH(original) of the emitting material is about 100 or greater, KISC/KRISC of the emitting material is about 0.9 or greater and about 1,000 or less, wherein, among all emission components of the emitting material, a ratio of a phosphorescent emission component that is emitted by a radiative transition of a triple exciton to a ground state is 90% or greater, wherein the KISC, the KRISC, the KFL(original), the KPH(original) are the same as described in the specification, and wherein the ratio of the phosphorescent emission component are evaluated from a transient photoluminescence (PL) spectrum per temperature of the emitting material.