Influences of an inserted hole-blocking bathocuproine (BC) layer were investigated on electroluminescence (EL) performances of organic light emitting devices with a configuration of ITO/BC/Alq(3)/Mg-Ag, where Alq(3) is tris(8-quinolinolato)aluminum(III). Variations in the thickness of organic layers and bias voltages were found to alternate the emissive region from the BC layer to the Alq(3) layer, resulting in shift of the emission wavelength in the EL spectra of the devices. (C) 2003 Elsevier B.V. All rights reserved.