Organic light-emitting devices (OLEDs) incorporating the copper phthalocyanine (CuPc)/N,N-'-bis-(1-naphthyl)-N,N-'-diphenyl-1,1(')-biphenyl-4,4(')-diamine composite hole transport layer have been fabricated. Under optimal condition, the highly efficient sky-blue OLED based on the aminosubstituted distyrylarylene fluorescent dye, doped in the stable diphenyanthracene blue host achieved a luminance efficiency of 16.2 cd/A with a Commission Internationale d' Eclairage (CIE)(x,y) color coordinate of [0.15, 0.29] at 6.4 V (20 mA/cm(2)) and an external quantum efficiency of 8.7%. (c) 2005 American Institute of Physics.