Photoluminescence properties and Mn4+ → Tm3+ energy transfer of La0.557Li0.33TiO3: Mn4+, Tm3+ for thermometry and NIR-LED applications

Abstract

Over the span of years, Mn4+-doped red phosphors have been utilized to meaningful optoelectronic devices due to their outstanding optical properties, and Tm3+ usually is used for activator ion because of its efficient up-conversion emission, but the down-conversion processes are rarely used. Herein, we have successfully synthesized a series of novel La0.557Li0.33Ti1-xO3:xMn4+ (x = 0.1–7 %) phosphors. The photoluminescence properties have been analysis in detailed. Using Mn4+-Tm3+ co-doped strategy, we successfully synthesis La0.557-yLi0.33Ti0.993O3:0.7 %Mn4+, yTm3+ phosphors. Upon excitation with 360 nm light, this phosphor exhibits two distinct emission peaks at 729 nm and 806 nm. The emission intensity of Tm3+ is greatly improved after Mn4+ doping, which is attributed to the energy transfer of Mn4+ to Tm3+. In terms of potential applications, utilizing fluorescence intensity ratio technology, La0.551Li0.33Ti0.993O3:0.7 %Mn4+, 0.6 %Tm3+ exhibits maximum absolute and relative sensitivities of 3.25 % K−1 at 523 K and 3.49 % K−1 at 298 K, which demonstrating its potential for application in optical thermometry. Furthermore, The NIR-LED using phosphor and 365 nm chips reveals potential applications of the La0.551Li0.33Ti0.993O3:Mn4+, Tm3+ phosphor in NIR night vision and biosensing.