Mixed excitation was observed based on solid-state cathodoluminescence (SSCL) structures under alternating-current (AC) applied voltages. and it combines charge carrier injection recombination and hot electron impact excitation. Under AC voltages of 500 Hz. the electroluminescence from an ITO/SiOx/MEH-PPV/SiOx/Al device contained two emission bands: a blue emission band peak at 3.02 eV (4 10 nm) and an orange emission band peak at 2.10 eV (590 nm). The source of these two emission bands was investigated. Our experimental results suggest that the orange emission comes from the recombination of MEH-PPV excitons, and the blue emission is from oxygen defects and interface states of SiOx. (c) 2005 Elsevier B.V. All rights reserved.