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 ²F_5/2 → ²F_7/2 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.