Efficient multilayer electrophosphorescence white polymer light-emitting diodes with aluminum cathodes

By simply doping Li(2)CO(3) in an alcohol soluble neutral conjugated polymer poly[9,9-bis(6'-diethoxylphosphorylhexyl)fluorene] (PF-EP), we demonstrate highly efficient multilayer electrophosphorescence white polymer light-emitting diodes with air-stable Al cathode. From the mechanism studies, we find that the phosphate groups can make Li ions movable in the PF-EP film, resulting in great improvement in the electron injection and transport ability of PF-EP. The hole-blocking ability is also strengthened. (C) 2010 Elsevier B. V. All rights reserved.