Energy transfer study between Ce3+ and Tb3+ ions in a calcium fluoride crystal for solar cell applications

Energy transfer from Ce3+ to Tb3+ ions in a single crystal of CaF2 has been analyzed for down-conversion application in Si solar cells. The nanophosphor samples were successfully synthesized by the co-precipitation method. Results obtained with x-ray diffraction indicated that the crystallite size were in the range of 30-40 nm. X-ray photoelectron spectroscopy confirmed the formation of the matrix and the presence of the dopants. The luminescence data obtained clearly indicated that energy transfer between Ce3+ and Tb3+ took place inside the crystalline matrix. The calculated energy transfer efficiency was relatively efficient at the high Tb3+ concentration. The results suggested that Ce3+ may therefore be used as an efficient sensitizer to feed the Tb3+ ions in a CaF2 crystal. UV light may be down shifted to the visible region for solar cell applications.