THIN-FILM ELECTROLUMINESCENCE OF ZNS-TB-3+

Light conversion efficiencies up to 2 lm/W can be reached in ZnS:Tb thin film electroluminescence devices. Rapid degradation, however, is caused by such extreme overdoping. In general the decrease of efficiency during aging has no counterparts in changing spectra or in carrier acceleration/center excitation, so that it should be related to a diminishing content of excitable centers, possibly by segregation to existing clusters and/or Tb-rich phases. Rather stable operation can be achieved in the 0.5-0.8 lm/W range. © 1989.