This study presents the influences of dye doping and hole blocking layer insertion on the electroluminescent properties of the blue organic light-emitting diode (OLED). The luminance of the device was significantly improved by 1,4-bis[2-(3-N-ethhycarbazoryl)vinyl]benzene (BCzVB) doping because of the utilization of effective Forester energy transfer and the improvement of carrier injection and trapping; a BCzVB dominant emission was observed. When a 2.9-dimethyl-4,7-diphenyl-1,10 phenanthroline (BCP) hold blocking layer was inserted between the N,N'-di(napthalene-1-yl)-N,N'-diphenyl-benzidine (NPB) and 3-tert-butyl-9,10-di(napth-2-yl)anthracene (TBADN) layers, the high energy barrier hindered the injection of holes into the emitting layer. A decrease in current density and an increase in turn-on voltage were observed. However, the luminance definitely improved when the device involved an undoped emission layer together with a 3 nm thick BCP layer insertion. Furthermore, when a BCP layer was inserted between the TBADN:BCzVB and Alq(3) layers, a thin BCP layer insertion enhanced the injection of electrons and improved the luminance of the device. In contrast, a thick BCP layer insertion caused a delay in electron transport. resulting in a decrease in current density and a deterioration in luminance. (c) 2009 The Electrochemical Society. [DOI: 10.1149/1.3054385] All rights reserved.