Resonant energy transfer and near-infrared emission enhanced by tri-doped Sr2SiO4: Ce3+, Tb3+, Yb3+ phosphors for silicon solar cells

A novel tri-doped Sr2SiO4: Ce3+, Tb3+, Yb3+ phosphor was prepared using a conventional solid reaction. The resonant energy transfer (ET) with Ce3+→ Tb3+ through electric dipole-dipole interactions was demonstrated with luminescent spectra and decay lifetime curves. Upon UV photon excitation at 372 nm of Tb3+ ions and 350 nm of Ce3+ ions, Yb3+ emissions were detected in the near-infrared (NIR) region with a main peak at 977 nm, which belonged to the 2F5/2 → 2F7/2 transition and corresponding perfectly with silicon solar cell maximum spectral responses. The NIR emission intensity of Sr2SiO4: Ce3+, Tb3+, Yb3+ was almost 125 times greater than that of Sr2SiO4: Yb3+, which demonstrated that the 4f-5d luminescence of Ce3+ could be used to sensitize the Tb3+-Yb3+ down-conversion process. This tri-doped Ce3+−Tb3+−Yb3+ system offered potential applications for NIR down-conversion phosphors for silicon solar cells.