Europium-Activated Orthophosphate Phosphors For Energy-Efficient Solid-State Lighting: A Review

As a new class of inorganic phosphor, orthophosphate phosphors materials have received great interest because of their potential applications in solid-state lightings and displays. In this article, we focus on current developments in the synthesis, crystal structure and luminescence properties of orthophosphate phosphors for solid-state lightings. We discuss the synthesis of a family of orthophosphate phosphor doped with europium (Eu2+ and Eu3+) by traditional and novel methods. In the fluorescent lamp, phosphor materials convert UV radiation into visible radiation. Lamp phosphors are mostly white in color and they should not absorb the visible radiation. New phosphors that can absorb excitation energy from blue or near ultraviolet (n-UV) LEDs and generate visible emissions efficiently are desired. The criteria of choosing the best phosphors, for blue (450-480 nm) and n-UV (380-400 nm) LEDs, strongly depends on the absorption and emission of the phosphors. Here, we will review the status of phosphors for solid-state lightings and prospect the future development. The impacts of doping of europium and photoluminescence properties on orthophosphate phosphors were investigated and we propose a feasible interpretation.