Temperature variable luminescence and color tuning of Eu2+/Mn2+-codoped strontium magnesium phosphates as promising red-emitting phosphors for light emitting diodes

Abstract

Eu²⁺ and Mn²⁺ codoped violet-/red-emitting strontium magnesium phosphates, SrMgP₂O₇, SrMg₂P₂O₈ and Sr₂Mg₃P₄O₁₅, were prepared and their emission properties, especially for color tuning with temperature variable luminescence, were investigated. Simply by changing the host composition of the SrO–MgO–P₂O₅ ternary system, we can control the Eu²⁺-sensitized Mn²⁺ emission efficiency as well as the thermal quenching of incorporated activators. We can realize that the overall luminescence behavior is induced by the Mn²⁺ center positioned at different coordination states with intermixed Sr²⁺/Mg²⁺ sites in various hosts, which resulted in widely tunable colors from violet-red through orange-red to pure red. Finally, bright and stable reddish color illuminated light emitting diodes (LEDs) can be obtained by combining the proposed phosphates with ultraviolet LEDs, demonstrating the potential red-emitting phosphors for ultraviolet-pumped phosphor converted white-LEDs.