Efficient near-infrared luminescence and energy transfer mechanism in Ca3Al2O6: Ce3+, Yb3+ phosphors

Abstract

Solar cells have been extensively studied as a means of green energy converters in recent decades, especially the silicon solar cells. However, the energy efficiency of crystalline solar cells is very low, which is due to the reason that they have a good absorption in 800–1100 nm region but a bad absorption in 300–500 nm region. Based on this, a series of Ce3+-Yb3+ codoped Ca3Al2O6 samples are synthesized by the conventional solid state method in reduced atmosphere. Energy transfer process from Ce3+ to Yb3+ is affirmed by the characterizations of photoluminescence, photoluminescence excitation spectra and decay curves in different temperatures. The photoluminescence intensity and lifetime of Ce3+ decrease with the increase of Yb3+ content. And as the temperature increases, the energy transfer efficiency increases. These results demonstrated that the near-infrared luminescence from 2F5/2 to 2F7/2 transition of Yb3+ is implemented via a multi-phonon assisted energy transfer process in the Ce3+-Yb3+ ions pair. These phosphors exhibit broadband absorption in the ultraviolet region with efficient near-infrared emission (centering at 976 nm), which has better spectral response for crystalline Si solar cells. The obtained results illustrated that the phosphors have potential applications as spectral conversion materials to enhance the performance of crystalline Si solar cells.