Self-doped polyaniline-modified anode for polymer light-emitting diode Original Research Article

Diphenylamine (DPA)–metanilic acid (MAA) copolymer (P(DPA-co-MAA))-coated indium–tin oxide (ITO) was used as the transparent anode and poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) was used as an electroluminescent layer in polymer light-emitting diode (PLED). The turn-on voltage of ITO/P(DPA-co-MAA)/MEH-PPV/Ca/Al device is reduced by 25% as compared with the ITO/MEH-PPV/Ca/Al device. The barrier height at the interface of P(DPA-co-MAA)/MEH-PPV is estimated to be 0.05 eV, approximately a quarter of that at the ITO/MEH-PPV interface.