Effect of hole transporting layer doped with organic salts on performance of polymer electroluminescent devices

Poly(p-phenylene vinylene) has studied as not only emissive material but also hole transporting material in light-emitting diodes. Because PPV is non-soluble polymer at any solvent, it can be used as hole transporting layer (HTL) in multilayer structure of electroluminescent devices. After thermal conversion of PPV precursor into PPV, we spin-coated polydioctylfluorene (PDOF) as emitting layer on it. EL devices using the PPV doped with organic salts, tetra-n-butylammonium tetrafluoroborate (TBABF4), as HTL showed great luminance efficiency. The organic salts in PPV polymer chains formed local dipoles under the electrical field and it affected the performance of the EL devices.