We demonstrate that the phase aggregation process can be generally applied to the fabrication of polymer/CdSe double-layer light-emitting diodes (LEDs). The current and luminance characteristics of devices with aggregated CdSe nanoparticles are much better than those of devices with well-dispersed CdSc nanoparticles. It has been found that during the spinning process, aggregated nanoparticles are separated from the polymer and become attached to the polymer film. Aggregated nanoparticles between the emitting layer and the Al cathode can act as a buffer layer, enabling polymer/CdSe-based LEDs to exhibit better luminescence efficiency than that of neat polymer-based LED. (c) 2006 Elsevier B.V. All rights reserved.