High-pressure study of non-radiative de-excitation mechanisms in perfluorinated organic erbium(III) phosphinates

Abstract

The excited state dynamics of Erbium(III) ions in perfluorinated compounds ErxY1−x[(p-CF3-C6F4)2PO2]3 has been studied using high pressure, over a range of temperatures. These fluorinated compounds have a long lifetime for the erbium 4I13/2 → 4I15/2 emission at λ ~ 1540 nm, but the lifetime increases with decreasing x. We have demonstrated the occurrence of energy migration and calculated the corresponding activation energy for the x = 0.3 and x = 1 samples. Using high pressure techniques, we also show that lifetime is reduced when reducing the Er-Er distance due to the enhancement of non-radiative de-excitation processes related to cross-relaxation. We also observe a pressure-induced phase transition at P ~ 2 GPa and a temperature-induced phase transition at T ~ 125 K. The general behaviour of the series is explained in terms of the occurrence of distance-dependent excitation transfer (excitation hopping and cross-relaxation). Findings for the Er series are compared with Yb[(p-CF3-C6F4)2PO2]3, in which only excitation migration takes place.