녹색 발광 Zn2SiO4:Mn2+ 분말 기반 전계발광소자의 광학전기적 특성 연구

Abstract

The alternating current driven large area powder electroluminescent device with Zn2SiO4:Mn2+ phosphor as emission layer was investigated. Single phase willemite crystal structure Zn2SiO4:Mn2+ phosphor was synthesized by solid-state reaction. This phosphor has R-3(148) space group. Transparent silver nanowire electrode, Zn2SiO4:Mn2+ emission layer, BaTiO3 dielectric layer structure were fabricated on metal brass electrode substrate. The silver nanowire transparent electrode showed a sheet resistance of 169 Ω/sq and over 95 % transmittance in visible region. The fabricated device showed luminescence phenomena as of 130 V AC applied voltage at 400 Hz sinusoidal wave. Main emission is around pure green color 525 nm. With increasing applied voltage, luminance was continuously increasing while 525 nm main emission peak and FWHM of 43 nm were not changed. Maximum luminance was 0.96 cd/m2 at 300 V, 400 Hz. Futhermore, luminance was linearly increased with increasing sinusoidal frequency at fixed 200 V, and also main emission peak and FWHM were still not changed. Device power consumption of 250 W/m2 at 420 Vp, 400 Hz and efficiency of 0.012 lm/W were obtained through charge density measurement. By temperature dependancy measurements upto 150 ℃, PL intensity was decreased as of 76 % of initial intensity. EL intensity rose about 166 % at 90 ℃, and got weak its value till 150 ℃. This increased EL intensity was due to dielectric property changes of BaTiO3 around Curie temperature(Tc) in this measurement range.