A quantum efficiency improving device approach to harvest singlet excitons of fluorescent emitters was developed by sequential deposition of sensitizer-doped emitting layer and fluorescent emitter doped emitting layer. The sequentially deposited emitting layer structure was intended to emit mostly by the Forster energy transfer process from the sensitizer to the fluorescent emitter while suppressing Dexter energy transfer by spatially separating the fluorescent emitter from the sensitizer. The multilayered emitting layer structure improved the EQE of the fluorescent devices from 13.1% to 18.8% by separating the sensitizing layer and fluorescent emitting layer.