Concentration based multicolor upconversion emission of lanthanides Co -doped Ruddlesden-Popper type layered perovskites

Yb3+ ions initiated upconversion properties of Ruddlesden-Popper type layered materials were studied to elucidate the tunability of the visible emission under 980 nm excitation. The substitution of lanthanum ions in the host layer perovskites with different concentrations of Yb3+/Er3+ and Yb3+/Tm3+ as the sensitizer/activator pairs was performed via the solid-state procedure. The upconversion spectra of the samples have depicted that the materials relatively lower dopant concentrations of Yb3+/Er3+ have the green color, which was shifted to the red region due to both heavy activator and sensitizer concentrations because of the dominant F-4(9/2) -> I-4(15/2) transition rather than the H-2(11/2), S-4(3/2) -> I-4(15/2) transitions. The tunability of upconversion emission of Yb3+/ Tm3+ introduced materials was limited in the visible region compared to the Yb3+/Er3+ pair despite the fact that the wide variety of the lanthanide concentrations were studied and the layered materials were structured successfully. On the other hand, the first intense NIR emission was achieved for the layered perovskites co-doped with Yb3+/Tm3+ due to the H-3(4)-> H-3(6) relaxation.