Generation of tunable luminescence via energy transfer dynamics in Tm3+/Dy3+co-doped antimony fluoroborate glasses for photonic applications

In this study, Tm³⁺ doped and Tm³⁺/Dy³⁺ bi-doped calcium antimony fluoroborate (CAFB) glasses were formed with the help of high-temperature melt-quenching procedure. To study the spectroscopic properties of the Tm³⁺/Dy³⁺bi-doped CAFB (CAFBTmDy) glass matrices, the optical absorption, photoluminescent, decay measurements as well as energy transfer (ET) mechanism were examined in detail. An intense emission peak around 454 nm was detected in the Tm³⁺ doped CAFB glasses under n-UV (358 nm) excitation and the optimized intensity for emission was noted to be 1.0 mol %. When the optimal concentration of Tm³⁺ ions was co-doped with the varying concentration values of present Dy³⁺ dopant ions, the intensity of emission peaks of Tm³⁺: ¹D₂ → ³F₄ (454 nm) diminished but upsurges for the Dy³⁺ ions: ⁴F_9/2 → ⁶H_15/2 (482 nm, blue), ⁴F_9/2 → ⁶H_13/2 (575 nm, yellow) and ⁴F_9/2 → ⁶H_11/2 (663 nm, red) indicating the process of energy transfer (ET) from the sensitizer (Tm³⁺) to the activator (Dy³⁺) ions. The ET expression of Dexter with Reisfeld's approximation validated this non-radiative transfer of energy process involving dipole-dipole (d-d) interaction amid these Tm³⁺ and Dy³⁺ ions. Furthermore, CAFBTmDy glasses can undergo tunable emission from blue to white light under the specific selected n-UV excitations. More importantly, the thermal stability of these CAFBTmDy glasses was demonstrated by temperature-dependent photoluminescence (TDPL) analysis. All the mentioned results validate that the prepared CAFBTmDy glass matrices are promising candidates to be utilized in n-UV-based w-LEDs and other photonic applications.