Improvement in electroluminescent characteristics of SrS : Ce thin-film devices by doping of divalent elements

Abstract

To compensate Sr vacancies, divalent transition elements such as Zn and Cd were doped for SrS : Ce thin film electroluminescent (TFEL) devices. By Zn or Cd doping, EL emission spectra sift to blue region. Current spike, which results from a generation of a space charge in the SrS : Ce phosphor layer, is also reduced. However, a conduction charge and the EL luminance is decreased by the Zn or Cd doping. To increase a conduction charge and a luminance, Na doped SrS : Ce TFEL devices having ZnS buffer layers were prepared. The devices show a luminance of 1000 cd/m^2 and EL efficiency of 0.8 lm/W at 1 kHz.