Role of ionic species in determining characteristics of polymer LEDs

Even traces of ionic species in the emissive polymer layer in Al/MEH-PPV/ITO LEDs or in the non-emissive emeraldine base, “EB” layer, in Al/MEH-PPV/EB/ITO LEDs are shown to dramatically change the characteristics of the LEDs including improved quantum yield and/or operation in both forward and reverse bias modes due to reduction of electron/hole injection energies facilitated by ion diffusion phenomenon.