Polyaniline as a transparent electrode for polymer light-emitting diodes: Lower operating voltage and higher efficiency

Abstract

We demonstrate that by using polyaniline (PANI) or a combination of (PANI) and indium/tin oxide (ITO) as the transparent anode of a polymer light-emitting diode with poly[2-methoxy-5-(2'-ethyl- hexyloxy)-1,4-phenylene vinylene] (MEH-PPV), as the active layer, device performance can be significantly improved. The operating voltage can be reduced by ∼30%-50% and the quantum efficiency can be increased by ∼30%-40% with respect to the devices using ITO alone as the hole-injecting anode. The barrier height at the PANI/MEH-PPV interface is estimated to be ∼0.08-0.12 eV, approximately half of that at the ITO/MEH-PPV interface.