NIR Downconversion and Energy Transfer Mechanisms in Tb3+/Yb3+ Codoped Na5Lu9F32 Single Crystals.

Tb3+/Yb3+ codoped Na5Lu9F32 single crystals with near-infrared (NIR) emission are achieved by an improved Bridgman approach. Energy transfer from Tb3+ to Yb3+ ions is affirmed by the photoluminescence (PL) emission spectra and decay curves characterization. On the basis of the analysis of energy transfer rate dependence on the Yb3+ concentration, the interaction between Tb3+ and Yb3+ ions in Na5Lu9F32 single crystals is confirmed through the one-to-one energy transfer process. Results demonstrate that the prepared Na5Lu9F32 single crystals might be promising candidates to convert sunlight to improve the performance of the silicon solar cells.