The effect of a metal electrode on PPV electroluminescence processes

Abstract

Two metal electrodes of aluminum (Al) and calcium (Ca), which have different work functions, were used to fabricate EL devices based on poly(p-phenylene vinylene) (PPV) with single-layer structure. A new experimental phenomenon is discovered. The electroluminescent (EL) spectra are different in EL devices with metal electrode of Al and Ca. The feature is expressed as a variation of the ratio of intensity from the peak at 550 nm to the peak at 510 nm. From this, we discussed the main type of carrier moving in PPV film with Al and Ca electrodes, respectively, By comparing the processes between EL and photoluminescence (PL), a reason for the difference in EL spectra with Al and Ca electrodes was analyzed.