Luminance efficiency of a (La,Tb,Ce)PO4:Eu phosphor layer prepared with binary surface active organic molecules

Abstract

The effect of a binary surfactant on the luminance efficiency of a green phosphor was investigated with an emphasis on the chemical control of interactions between the suspension components. The dispersion system of the green phosphor paste was designed by an evaluation of the acid and base properties of the green phosphor and the surface active organic molecules by a non-aqueous titration method. Oleyl amine and 4-(1,1,3,3-tetramethylbutyl) phenyl-polyethylene phosphoric acid (hereafter SAIT7) were added into the green phosphor paste taking into account the ratio between the acid and base sites of the green phosphor particle's surface. This resulted in a higher maximum solid loading and a further decrease in the viscosity of the green phosphor paste compared to a single addition of SAIT7 and oleyl amine. The green phosphor paste with the binary surfactant exhibited a much improved photoluminescence intensity and homogeneity of the emission properties than a single addition of the dispersant.