Experimental evidence for quantum cutting co-operative energy transfer process in Pr 3+ /Yb 3+ ions co-doped fluorotellurite glass: dispute over energy transfer mechanism.

Pr3+ /Yb3+ doped materials have been widely reported as quantum-cutting materials in recent times. However, the question of the energy transfer mechanism in the Pr3+ /Yb3+ pair in light of the quantum-cutting phenomenon still remains unanswered. In view of that, we explored a series of Pr3+ /Yb3+ co-doped low phonon fluorotellurite glass systems to estimate the probability of different energy transfer mechanisms. Indeed, a novel and simple way to predict the probability of the proper energy transfer mechanism in the Pr3+ /Yb3+ pair is possible by considering the donor Pr3+ ion emission intensities and the relative ratio dependence in the presence of acceptor Yb3+ ions. Moreover, the observed results are very much in accordance with other estimated results that support the quantum-cutting phenomena in Pr3+ /Yb3+ pairs, such as sub-linear power dependence of Yb3+ NIR emission upon visible ∼450 nm laser excitation, integrated area of the donor Pr3+ ion's visible excitation spectrum recorded by monitoring the acceptor Yb3+ ion's NIR emission, and the experimentally obtained absolute quantum yield values using an integrating sphere setup. Our results give a simple way of estimating the probability of an energy transfer mechanism and the factors to be considered, particularly for the Pr3+ /Yb3+ pair.