Exploring the Potential of Tb and Bi Doped LaF3 as a UV Absorber

Lanthanide-based nanophosphors are finding significant applicability in various fields such as LED, solar spectral convertors, lasers, biological sensors etc, owing to their superior stability and luminescence properties. However, their function as a UV protector hasn't evolved, possibly because of their limited absorption cross-section in the UV spectral region. Hence, to overcome this limitation, in this work, a strategy to utilize Bi ³⁺ ion as a co-dopant in LaF ₃ :Tb ³⁺ nanophosphor has been devised. These nanophosphors with uniform morphology and narrow particle size distribution were synthesized using hydrothermal method. Luminescence mechanism involving energy transfer from Bi ³⁺ to Tb ³⁺ were investigated. Excitation spectrum of LaF ₃ nanophosphor, co-doped with Bi and Tb, reveals distinct absorption bands. Absorption ascribed to Bi ³⁺ characterizes the UV range between 220–275 nm, whereas Tb ³⁺ is associated with absorption in another UV range spanning 280 to 380 nm. This shows the potential applicability of the Bi and Tb co-doped LaF ₃ nanophosphor as UV absorber. The cytotoxicity of these nanophosphors was tested on HaCaT cells, which indicates their potential applicability in health care field.