Tunable Single-Phase White Light Emission from Complex Perovskite Sr3CaNb2O9: Dy3+/Eu3+ Phosphors

Abstract

Sr₃CaNb₂O₉:Dy³⁺/Eu³⁺ phosphors with a complex perovskite structure are prepared using a high-temperature solid- state reaction technique. These phosphors are doped either singly or in combination with Dy³⁺/Eu³⁺ ions, resulting in efficient energy transfer from Dy³⁺ to Eu³⁺ and thus tunable-color emission. Under 353 nm excitation, the Sr₃CaNb₂O₉:Dy³⁺ phosphor emits blue (492 nm), yellow (583 nm), and red (682 nm) light, with the optimal doping concentration of Dy³⁺ of 0.04%. When excited by 394 nm (⁷F₀ → ⁵L₆), the Sr₃CaNb₂O₉:Eu³⁺ phosphor exhibits two most intense emissions centered at 593 nm (⁵D₀ → ⁷F₁) and 614 nm (⁵D₀ → ⁷F₂). The decrease in luminescence intensity with increasing doping concentration of Dy³⁺ and Eu³⁺ is due to the cross-relaxation associated with electric dipole–dipole interaction. Photoluminescence emission measurements under excitations of 353 and 365 nm indicate that the Sr₃CaNb₂O₉:0.04Dy³⁺/0.05Eu³⁺ phosphor shows excellent thermal stability, even at a temperature of 150 °C, where the luminescence intensity preserves 79% of its initial value at room temperature. The electroluminescence performance of the Sr₃CaNb₂O₉:0.04Dy³⁺/0.05Eu³⁺ phosphor is tested with 365 nm LED chips for potential use in white LEDs. The results confirm that Sr₃CaNb₂O₉:0.04Dy³⁺/0.05Eu³⁺ phosphor has great potential for use in high-power white LED applications as a single matrix.