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Ce 3+ , Yb 3+ and Tb 3+ singly doped and Ce 3+ -Yb 3+ , Tb 3+ -Yb 3+ codoped Ca 3 (BO 3 ) 2 phosphors were prepared by a solid state reaction method. The photoluminescence excitation and emission spectra at room temperature were investigated. The emissions of Yb 3+ ion are at around 1000 nm, matching well with the optimal response of Si-based solar cells. When codoped with Ce 3+ or Tb 3+ ion, the absorption is greatly broadened in the ultraviolet-visible region. Energy transfer from Ce 3+ /Tb 3+ to Yb 3+ was investigated, the cooperative energy transfer process is proposed. [ABSTRACT FROM AUTHOR]

Yb 3+ and Tb 3+ singly doped and Tb 3+ –Yb 3+ co-doped Ca 5 (BO 3 ) 3 F phosphors were prepared by a solid state reaction method. The luminescence emission and excitation spectra as well as the luminescence decay curves were investigated. The emission bands of Yb 3+ ion are located around 1000 nm, matching well with the optimal response of Si-based solar cells. Tb 3+ can be a sensitizer for Yb 3+ in the host. The energy transfer from Tb 3+ to Yb 3+ was investigated, the energy transfer mechanism was proposed as cooperative energy transfer. Tb 3+ concentration dependent quantum efficiency was calculated and the maximum efficiency approached 115.5%. [ABSTRACT FROM AUTHOR]