US Patent 9082994 Light-emitting element, light-emitting device, electronic device, and lighting device

Provided is a light-emitting element having a light-emitting layer which contains at least a host material and a plurality of guest materials, where the host material has a lower T1 level than that of at least one of the plurality of guest materials. The emission of the one of the plurality of guest materials exhibits a multicomponent decay curve, and the lifetime thereof is less than or equal to 15 μsec, preferably less than or equal to 10 μsec, more preferably less than or equal to 5 μsec, where the lifetime is defined as a time for the emission to decrease in intensity to 1/100 of its initial intensity.