Photoluminescence and electroluminescence characteristics of CaSiN 2 :Eu phosphor

Abstract

Photoluminescence and electroluminescence of CaSiN 2 :Eu materials were investigated to develop a new phosphor for thin film electroluminescence (TFEL) device applications. Ca 3 N 2 and Si 3 N 4 powders were mixed to form CaSiN 2 host materials and Eu was added as the luminescent center. The mixed powder materials were cold pressed under the pressure of 1Kg/cm 2 to make pellets, and fired at 1400°C for 2 hours under N 2 /H 2 environment. The X-ray diffraction (XRD) patterns of synthesized materials were well matched with CaSiN 2 of joint committee for powder diffraction standards (JCPDS) card. When illuminated by ultraviolet rays, the new phosphors emitted very bright red light of peak wavelength centered at 620 nm. The TFEL devices with CaSiN 2 :Eu phosphor layers were grown by sputter deposition of CaSiN 2 :Eu target. Red light emission was observed when the peak amplitude of the applied voltage exceeded 116V. The luminance was shown to increase sharply with the increase of the applied voltage. The maximum luminance was 1.62 Cd/m 2 at the applied peak voltage of 276V. The red emission from CaSiN 2 :Eu TFEL device seems to result from electronic transition of Eu 3+ ions. The emission spectra of TFEL devices match well with the photoluminescence spectra of CaSiN 2 :Eu powders. The new devices structure and fabrication processes for the improvement of emission intensity of CaSiN 2 :Eu TFEL devices are under investigation.