Downconversion luminescence in Ce3+, Yb2+, and Yb3+ co-doped low silica calcium aluminosilicate glasses: Potential for spectral conversion in solar cell technology

Yb–Ce co-doped LSCAS glasses melted under a vacuum atmosphere are free of OH− radicals presenting downconversion luminescence of interest for solar cell application. Absorption spectra showed an ultraviolet–visible broad band related to the 2F5/2, 2F7/2 → 5d transitions of the Ce3+. Time-resolved luminescence evidenced energy transfer from Ce3+ to Yb3+, and the contour maps spectra showed a decrease in Ce3+ emission with the increase of Yb concentration. Thermal lens results evidenced an increase in heat generation, suggesting the occurrence of nonradiative transitions due to the formation of Yb2+ or Ce4+ ions. The observed emissions are attributed to energy transfer from Ce3+ or Yb2+ to two Yb3+ ions by quantum cutting mechanism, emission from Ce3+ at 520 nm, and predominantly, a phonon-assisted energy transfer from Ce3+ or Yb2+ to one Yb3+ ion.