Abstract
The mechanism which enabled wide-range color-tuning for multilayer polymer light-emitting diodes (LED) based on poly(p-phenylene vinylene) (PPV) and polyfluorene (PF) was investigated. The wide-range low-voltage continuous color tuning was achieved in multilayer LED by using the high-efficiency electroluminescent conjugated polymers. The color of the emitted photon depended on position of the electron-hole recombination which consisted of three layers for red, green and blue emission with one extra layer for electron blocking. The recombination zone was pushed away from the cathode and concentrated in different emissive layers due to the stronger field dependence of electron mobility relative to hole mobility.