Efficient deep‐blue organic light‐emitting diodes with double‐emission layers

Abstract Efficient deep‐blue organic light‐emitting diodes were demonstrated using 4,4'‐bis(9‐ethyl‐3‐carbazovinylene)‐1,1'‐biphenyl doped in double‐emission layers (D‐EMLs). The D‐EML system, which consists of 2‐methyl‐9,10‐di(2‐naphthyl)anthracene and 1,4‐(dinaphthalen‐2‐yl)‐naphthalene as blue hosts, was employed to broaden the recombination zone and to ensure the good confinement of the holes and electrons. The optimized device showed a peak current efficiency of 4.47 cd/A, a peak external quantum efficiency of 4.09%, and Commission Internationale de L'Eclairage coordinates of (0.16, 0.10).