NaLaF4:Pr3+,Yb3+, an efficient blue to near infra-red quantum cutter

In order to reduce the thermalization losses in solar cells, down-conversion of blue photons into near infra-red photons is a promising solution. In the present paper, we analyse the energy transfer processes between Pr3+ and Yb3+ in NaLaF4 and we show that an efficient quantum-cutting process occurs. Nevertheless, we also show that a back transfer from Yb3+ toward the 1G4 level of Pr3+ ion leading to emission beyond 1 μm reduces the potentiality of this material as a quantum cutter for Si solar cells.