Tunable white-light emission from Pr3+/Dy3+ co-doped B2O3 - TeO2 - PbO - ZnO - Li2O - Na2O glasses

In this paper, structural and optical analysis of boro-tellurite based glasses co-doped with Dy3+ and Pr3+ ions has been carried out. The glasses were fabricated by traditional melt quenching technique. XRD results confirm the amorphous-like nature of the glasses. FTIR spectroscopy was applied to explore the functional groups and interactions for the samples. The transition temperatures of glasses were identified by TGA/DSC analysis. Optical absorption and emission spectra of all the glasses have been recorded in the UV-Vis-NIR spectral range. Tauc's method was applied to determine the direct and indirect optical band gaps. Luminescence spectra show intense emission bands at similar to 482 nm and similar to 574 nm wavelengths under lambda(exc) = 388 nm corresponding to Dy3+ : F-4(9/2) -> H-6(15/2) and F-4(9/2) -> H-6(13/2) transitions. Decay time data revealed the occurrence of a non-radiative energy transfer from Dy3+ to Pr3+ ions. Intense emission bands are identified at similar to 602 nm (orange), similar to 487 nm (blue) and similar to 574 nm (yellow) observed upon lambda(exc) = 437 nm, corresponding to Pr3+ : D-1(2) -> H-3(4), Pr3+ : P-3(0,1,2) -> H-3(4)/Dy3+ : F-4(9/2) -> H-6(13/2) and Dy3+: F-4(9/2) -> H-6(13/2) transitions, respectively, where the Dy3+ emissions are due to energy transfer from Pr3+ to Dy3+ ions. The CIE chromaticity results confirm that different colors can be generated by tuning the exciting wavelength, where all the glasses are capable to emit white light under lambda(exc) = 388 nm, while at lambda(exc) = 437 nm the samples (S2-S4) emit reddish orange light. Accordingly, it is plausible to suggest these glasses for white LED and SSL applications.