D. Poelman et al., THE INFLUENCE OF SE-COEVAPORATION ON THE EMISSION-SPECTRA OF CAS-EU AND SRS-CE THIN-FILM ELECTROLUMINESCENT DEVICES, Journal of luminescence, 65(1), 1995, pp. 7-10
In order to reduce the number of sulphur vacancies in evaporated CaS:E
u and SrS:Ce electroluminescent thin films, Se-coevaporation can be pe
rformed. This process not only improves the brightness of the devices,
but also induces considerable changes in the emission spectra. The sh
ift of the electroluminescent spectra upon coevaporation was checked a
gainst semi-empirical molecular cluster energy calculations. In the ca
se of SrS:Ce, these spectral changes are seen to be entirely due to th
e effect of electron-phonon interactions, while for CaS:Eu, only cryst
al field effects play a role.