Stabilization of bluish-green luminescent Ce3+ Centers by Rb doping in SrS:Ce thin film electroluminescent devices

It is revealed that the electroluminescence (EL) spectra of bluish-green luminescent Ce3+ centers can be stabilized by Rb doping in SrS:Ce thin film EL devices prepared by an electron-beam evaporation method. It is also found that Rb doping results in reduction of the current spike of EL devices, indicating suppression of Ce3+-V-Sr complex center formation. For the transparent SrS:Ce,Rb device, even without postdeposition annealing, the bluish-green EL corresponding to the Commission Internationale de I'Eclairage (CIE) color coordinates of (0.18,0.34) was obtained with a luminance of 190 cd/m(2) under I kHz pulse drive at 40 V above the threshold voltage. The luminance of the SrS:Ce,Rb EL device was improved to 220 cd/m(2) by annealing at 650degreesC while maintaining almost the same CIE color coordinates.