Augmenting cyan emission in vanadate garnets via Dy3+activation for light emitting devices and multi-mode optical thermometry

Abstract

Developing cyan-based phosphors is inevitable to bridge the cyan gap to generate white light with a high color rendering index. Herein, the blue-green emission from the VO₄³⁻ center in the Sr₂NaMg₂V₃O₁₂ host is augmented via activating with Dy³⁺ ions. Dual emission from the Sr₂NaMg₂V₃O₁₂:Dy³⁺ system under 335 nm excitation is due to the energy transfer from VO₄³⁻ to the Dy³⁺ center. An increase in the ratio of yellow to blue bands (Y/B) is noted with the increase in the concentration of Dy³⁺. Apart from the higher activation energy of 0.41 eV, excellent color stability with a small thermochromic shift is noted at elevated temperatures. The light emitting device fabricated based on the Sr₂NaMg₂V₃O₁₂:Dy³⁺ phosphor presents bright cyan emission with CIE coordinates of (0.250, 0.352), a CCT of 9826 K, and a CRI of 53 with stable emission even at higher input currents. The application of Sr₂NaMg₂V₃O₁₂:Dy³⁺ in multi-mode temperature sensing is also discussed. The maximum relative temperature sensitivity of 1.32, 0.41, and 1.9% K⁻¹ at 380, 300, and 460 K is obtained for the fluorescence, fluorescence intensity ratio and excitation intensity ratio methods. Thus, the present work details the capability of Dy³⁺-based vanadate garnet phosphors for solid-state lighting and temperature sensing.