Engineering the multifunctionality of Li3Y3Te2O12 garnets with Sm3+ and Tb3+ activators for solid-state lighting and luminescence thermometry†

Abstract

Tuning the photophysical response is indispensable in realizing the full potential of phosphors to meet the demands of multifunctional applications, such as solid-state lighting and optical thermometry. Herein, orange-red emission from an Sm³⁺-based Li₃Y₃Te₂O₁₂ system was studied for the first time with CIE coordinates of (0.488, 0.406), an internal quantum efficiency of 26%, T_1/2 of 500 K, CCT of 2346 K and color purity of 68%. The fabricated orange-emitting devices presented bright orange-red emission and superior color stability even at higher input currents suitable for plant growth and lighting applications with CIE coordinates of (0.444, 0.276) at 50 mA. The enhancement in temperature sensitivity of the system was achieved via a co-doping strategy by introducing Tb³⁺ ions. An improved relative temperature sensitivity of 1.8% K⁻¹ in the physiological temperature range was obtained based on the fluorescence intensity ratio method aided by the efficient energy transfer from Tb³⁺ to Sm³⁺. Thus, the present work demonstrates the multifunctional properties of the Li₃Y₃Te₂O₁₂:Tb³⁺/Sm³⁺ phosphor in solid-state lighting and ratiometric temperature sensing.