Identification of the components of the electroluminescence spectrum of PEexcited in uniform fields

The electroluminescence (EL) of insulating polymers is a subject of great i nterest because it gives insight into aging and breakdown processes. While most of the studies performed on polyolefins are under divergent field conf igurations, a uniform field is used more and more. However, a convincing in terpretation of the emission spectrum has not been given up to now, and som e discrepancies have appeared between the spectra recorded under divergent and uniform fields. Wavelength-resolved EL spectra are carried out on metal ized polymeric films biased under different ac and de voltage levels. We sh ow that the light emission consists of two different components with typica l field dependence and spectral distribution. One is associated with the lu minescence of the polymer, the other is due to photon emission from the met allic layers through the radiative decay of surface plasmons excited by the injection current. The proposed interpretation reconciliates the observati ons made under divergent and uniform fields and allows us to discuss the na ture of the chromophores involved in EL.