Change in quantum efficiency of self-assembled films based on PPV and ionic salt added PSS

Abstract

Electrical characteristics of self-assembled devices based on Poly(p-phenylene vinylene) (PPV), Poly(sodium 4-styrenesulfonate) (PSS) and carrageenan (CARRA) were investigated. Relative quantum efficiency-of ITO/(PPV/PSS)(20)/Al device was significantly decreased with the increase of ionic strength of the PSS solution. In contrast, the relative quantum efficiency of ITO/(PPV/PSS)(5)/(PPV/CARRA)(15)/Al device prepared by inserting (PPV/CARRA)(15) bilayers between the (PPV/PSS)(5) film and Al electrode were increased with the increase of ionic strength in the PSS solution. The performance improvement of ITO/(PPV/PSS)(5)/(PPV/CARRA)(15)/Al device is believed to be due to the formation of a stable interface between the (PPV/CARRA) and the Al electrode as well as the enhancement of hole transporting characteristics of (PPV/PSS) bilayers with added ion salt.