XAS study of local electronic structure of rare-earth doped NaYGdF4:Yb,Er compound to optimize up-conversion process

Crystalline particles made of fluoride materials and doped with rare earth (RE) ions are considered “photon recyclers”: they can absorb light with certain wavelengths, and through several luminescence mechanisms, emit light at different wavelengths afterward. This property is potentially handy for increasing the conversion efficiency of solar cells. The use of the NaYF4 matrix doped with a combination of a sensitizer ion (Yb) and an activator ion (Er) has been demonstrated as one of the most suitable luminescence systems; however, slight modifications in the sample composition and atomic concentration as well as synthesis parameters create variation in the crystal structure that may deeply affect the luminescence output. NaYGdF4:Yb − Er samples have been fabricated by hydrothermal synthesis and analyzed carefully through several structural and optical techniques. XAS study would allow us to pinpoint precisely the correlation between their luminescence performance and the local structure, electronic structure, and chemical composition induced by the growth condition.