Synthesis of polyaniline as hole-injector layer in polymer light emitting diode

Polyaniline (PANI) was synthesized by in situ oxidative polymerization method using ammonium peroxydisulfate (APS) as oxidant and hydrochloric acid (HCl) as dopant. The prepared PANI has been used as hole-injection layer (HIL) in polymer light emitting diode (PLED). The PLED was composed by a thin layers of poly [2-methoxy-5- (2’-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and PANI sandwiched between indium tin oxide (ITO) and aluminum (Al) electrodes, resulting in the device structure ITO/PANI/MEH-PPV/Al. The improved performance of ITO/PANI/MEH-PPV/Al upon the fabricated devices including poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) as a HIL, ITO/PEDOT:PSS/MEH-PPV/Al, was investigated. According to the obtained results, it was shown that the PANI injection layer yields higher current and lower turn-on voltage. The hole injection barrier height () of the fabricated PLEDs was estimated using the Fowler-Nordheim (FN) field-emission tunneling theory