Augmenting cyan emission in vanadate garnets Dyactivation for light emitting devices and multi-mode optical thermometry.

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 VO center in the SrNaMgVO host is augmented activating with Dy ions. Dual emission from the SrNaMgVO:Dy system under 335 nm excitation is due to the energy transfer from VO to the Dy center. An increase in the ratio of yellow to blue bands (Y/B) is noted with the increase in the concentration of Dy. 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 SrNaMgVO:Dy 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 SrNaMgVO:Dy in multi-mode temperature sensing is also discussed. The maximum relative temperature sensitivity of 1.32, 0.41, and 1.9% K 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 Dy-based vanadate garnet phosphors for solid-state lighting and temperature sensing.