Highly efficient polymer white-light-emitting diodes based on lithium salts doped electron transporting layer

Highly efficient polymer organic white-light emitting diodes (OWLED) derived from the Li₂CO₃-doped water/alcohol-soluble neutral conjugated polymer PF-OH was reported. The 5 wt% Li₂CO ₃-doped PF-OH films exhibit a slightly rougher surface, with a root-mean-square surface roughness of 0.75 nm, compared to that of the undoped PF-OH films. The increased current density and lowered turn-on voltage indicate that the transporting ability of PF-OH electron-transport/injection layer (ETL) is enhanced upon doping with Li₂CO₃. The greatly improved performance of doped devices should be mainly due to the enhanced charge-transporting ability of PF-OH ETL upon doping. The results of hole-dominated device show that the current density of the hole carriers in PF-OH ETLs significantly decreases upon doping.