For polymer light-emitting diodes, developing highly efficient, stable, and saturated blue emitting polymer is essential in display and lighting applications and has long been a challenge. Here we report a concept for designing highly efficient electroluminescent polymers by introducing multiple charge transport moieties for efficient injection of charge carriers into spiro-polyfluorene (sPF). We integrate the triphenylamine (TPA) and carbazole (Cz) in the same side chain of sPF with logical spatial and energetic sequence of these moieties to establish graded route for more efficient hole injection and incorporate the electron transport moiety with strong electron-withdrawing capability, triazole (TAZ), on both chain ends to give favorable arrangement in space and energy for electron Injection. These two factors allow the corresponding single layer device to exhibit deep blue (db) emission with external quantum efficiency (eta(ext)) of 7.28%, which is the highest value among the db polymer fluorescent diodes ever documented.