Near-infrared down-conversion and energy transfer mechanism of Ce³⁺-Yb³⁺ co-doped Ba₂Y(BO₃)₂Cl phosphors

Ce³⁺ and Yb³⁺ co-doped Ba₂Y(BO₃)₂Cl phosphors are synthesized via a conventional high-temperature solid-state method in CO atmosphere. The structure and luminescent properties of sample are characterized by X-ray diffraction (XRD) and photoluminescence excitation (PLE) and emission (PL) spectra. The phosphor has strong broad band absorption and strong near infrared (NIR) emission, which matches well with the Si-based solar response curve. As a function of Yb³⁺ concentration, the decay time curves of Ce³⁺ emission in Ba₂Y(BO₃)₂Cl: Ce³⁺, Yb³⁺ are measured to prove the occurrence of energy transfer (ET) from Ce³⁺ to Yb³⁺ and the energy transfer efficiency is also calculated. The energy transfer processes are also discussed, and possible transfer models are proposed. Results demonstrate that Ba₂Y(BO₃)₂Cl: Ce³⁺, Yb³⁺ phosphors might act as a promising down-conversion (DC) solar spectral convertor to enhance the efficiency of the silicon solar cell by utilizing the broadband absorption for solar spectrum.