Highly efficient and stable blue-light-emitting materials consisting of oligofluorenyl blocks and charge transporting segments are synthesized. The external quantum efficiencies of the solution-processed light-emitting diodes were of up to 6.1% and 8.6% for undoped and doped devices, respectively. The exceedingly high efficiency and excellent stability of these devices suggest that these new developed materials are very promising for deep-blue-light OLEDs.