Down-Shifting in the YAM: Ce + Yb System for Solar Cells.

In this work, we investigate Ce to Yb energy transfer in YAlO (YAM) for potential application in solar spectrum down-converting layers for photovoltaic devices. Photoluminescence properties set, of 10 samples, of the YAM host activated with Ce and Yb with varying concentrations are presented, and the Ce to Yb energy transfer is proven. Measurement of highly non-exponential luminescence decays of Ce 5d band allowed for the calculation of maximal theoretical quantum efficiency, of the expected down-conversion process, equal to 123%. Measurements of Yb emission intensity, in the function of excitation power, confirmed the predominantly single-photon downshifting character of Ce to Yb energy transfer. Favorable location of the Ce 5d bands in YAM makes this system a great candidate for down-converting, and down-shifting, luminescent layers for photovoltaics.