We studied the transient characteristics of poly(9,9-dioctylfluorene) (PFO)-based polymer light-emitting diodes (PLEDs) doped with red emissive phosphor tris(1-phenylisoquinoline) iridium (III) [Ir(piq)(3)] by applying the voltage pulse on the devices. The emission from the host was observed when the narrow pulse of 100 ns was applied. In order to change the electroluminescent (EL) spectrum, PFO-based white PLEDs have been demonstrated to utilize the pulse width and frequency. The maximum luminance reached 4800 cd/m(2) and the Commission Internationale de L'Eclairage (CIE) coordinates obtained the ideal white emission of (0.33, 0.35) at the pulse width and frequency of 100 ns and 1 kHz, respectively. (c) 2005 Elsevier B.V. All rights reserved.