EFFECT OF MULTILAYERED SRS-SRS-CE-SRS PHOSPHOR PREPARED BY MULTISOURCE DEPOSITION METHOD ON THE THIN-FILM ELECTROLUMINESCENT DEVICES

Abstract

Single-layer SrS:Ce and multilayer SrS-SrS:Ce-SrS thin films have been grown by multi-source deposition method. The X-ray diffraction patterns of the films showed the typical diffraction patterns of the cubic SrS powder. Single-layer SrS:Ce thin films exhibited sulfur deficiency and their fluorescence spectra showed a broad red emission peak. The multilayer SrS-SrS:Ce-SrS electroluminescent device showed nearly stoichiometric composition and an electroluminescent device made of these layers displayed a green-emission intensified spectrum with peaks located at 493 and 523 nm. A distinct S-shaped pinching effect in the transferred charge versus applied voltage characteristics, similar to a hysteretic electroluminescent device, was observed in multilayer device. We interpret that the separation of the light-emitting SrS:Ce layer from the two interfacial SrS layers and the resulting nonuniform space charge in the middle SrS:Ce layer are responsible for the observed enhancement of luminance through the intensified hysteretic effect in the multilayer structure.