Two blue fluorophores with excellent hybridized local and charge-transfer(HLCT) and "hot exciton" properties were developed as the blue emitter and the host of orange-red phosphor to achieve highly efficient fluorescent/phosphorescent (F/P) hybrid white organic light-emitting diodes (WOLEDs) in a single-emissive-layer single-dopant(single-EML-SD) architecture even at a high concentration of phosphorescent dopant.In the devices, part of the triplet excitons of the blue fluorophores can be utilized to realize reverse intersystem crossing from the triplet excited states to the singlet excited states for blue emission, and the diffusion volume range of the triplet excitons is reduced significantly.When the concentration of the phosphorescent dopant is up to 1.0 wt%,which is ten times higher than the traditional single-EML-SD F/P hybrid WOLEDs,highly efficient white emission was still achieved with maximum total external quantum efficiency (EQE) of 23.8%, current efficiency (CE) of 56.1 cd A-1, and power efficiency(PE) of 62.9 lm W-1.It opens a new avenue for achieving high performance F/P hybrid WOLEDs in a single-EML-SD architecture with easily controllable doping concentration.