We have demonstrated efficient deep-blue organic light emitting diodes using 4,4'-bis(9-ethyl-3-carbazovinylene)-1,1'-biphenyl (BCzVBi) doped in 4'-(dinaphthalen-2-yl)-1,10-binaphthyl (DNBN) as emitting layer. There is more overlap between the photoluminescence (PL) spectrum of DNBN and ultra violet (UV)/visible absorption spectrum of BCzVBi than PL spectrum of 2-methyl-9,10-di(2-naphthyl) anthracene (MADN) and UV/visible absorption of BCzVBi, resulting in efficient energy transfer from DNBN to BCzVBi. The optimized deep-blue device showed a peak current efficiency of 5.12 cd/A, peak external quantum efficiency (EQE) of 4.72%, and as Commission Internationale d'Eclairage coordinates of (0.15, 0.12). The device using blue host, DNBN, exhibited higher EQE of 1.6 times at 1 mA/cm(2) than control device using blue host, MADN.