Low voltage, blue phosphor for highly efficient field emission display screens

Ce-doped yttrium orthosilicate, P47, is a blue phosphor used in a nonsulfur containing phosphor triad for field emission display (FED) displays. Its low luminous efficiency does not allow one to achieve the necessary light output. For the first time, a modified yttrium orthosilicate, nonsulfur containing blue phosphor has been synthesized and 4 in. phosphor screens with superior performance have been fabricated. This performance, 1.4 lm/W intrinsic luminous efficiency at 400 V and 5 μA/cm2, is significantly better than that of Nichia 1047 phosphor, which is 0.5 lm/W. Based on this blue phosphor and phosphor screen performance, a white light output of 4.5–5 lm/W is now possible in low-voltage FED displays. This performance is dramatically higher than that of compatible active matrix liquid crystal displays.