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

By simply doping Li2CO3 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.

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► We demonstrate efficient multilayer electrophosphorescence white PLEDs with Al cathode.
► We find that the phosphate groups can make Li ions movable in the PF-EP film.
► The movable Li ions great improve the electron injection and transport ability of PF-EP.
► The hole-blocking ability is also strengthened.