Blue electroluminescence mechanism of polyester derivative blend films

Abstract

A new polymer of polyester derivative (PE) blend with poly(N-vinycarbazole) (PVK) and compound of PBD at various weight ratio were used as emitter in unilayer electroluminescence (EL) devices with indium cathode. Analyses of fluorescence and EL spectra imply common emission energy states are formed in the blend films, by which to explain the possibility of maximum EL efficiency in blend films higher than that in either of PE and PVK. The PL and EL spectra show the maximum emission band shifts red slightly between 430 nm and 450 nm as increasing the ratio of PE, meanwhile the half width increases and a new peak around 525 nm appears. The new peak is confirmed originating from the dimer formed by coupling of interchains in polymer PE. Both of PE and PVK can give rise to PL emission under UV light. The origin of PC and EL emission is analysed.