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.