Temperature-dependent electroluminescence spectra of poly(phenylene-vinylene) derivatives-based polymer light-emitting diodes

Abstract

This study reports on the temperature dependence of electroluminescence spectra of polymer light-emitting diodes based on poly[2,5-bis(3′,7′-dimethyl-octyloxy)1,4-phenylene-vinylene] and poly[2-methoxy-5(2′-ethyl-hexoxy)1,4-phenylene-vinylene]. Temperatures from 80to350K were investigated. A vibronic structure of electroluminescence spectra has been observed. The electroluminescence spectra were then fitted with multiple Gaussian peaks. A blueshift of the zero-phonon line has been reported with increasing temperature, while the full width at half maximum of electroluminescence peaks increased. We propose a model of thermally activated statistic occupation of excited states to fully describe the experimental data. Finally, these electroluminescence changes with temperature only imply a negligible variation of the emitted color.