Highly efficient solution-processed blue thermally activated delayed fluorescent (TADF) devices are developed by designing soluble blue TADF emitters. The solubility and emission color could be managed by introducing F as an electron withdrawing unit instead of CN. Two soluble blue TADF emitters are synthesized and show a high external quantum efficiency of 20.0% with a color coordinate of (0.16,0.26), and it is the best quantum efficiency reported in solution-processed TADF devices. The device performances of the solution-processed blue TADF devices are comparable to those of vacuum-processed blue TADF devices.