Broadband spectral modification from visible light to near-infrared radiation using Ce3+–Er3+ codoped yttrium aluminium garnet

Broadband spectral conversion from visible light to near-infrared radiation in Ce(3+)-Er(3+) codoped yttrium aluminium garnet is reported. Excitation, emission, time-resolved luminescence spectra and fluorescence decay curves have been measured to prove the energy transfer from Ce(3+) to Er(3+). The broadband and strong absorption of Ce(3+), efficient energy transfer from Ce(3+) to Er(3+), and three-photon quantum cutting process in Er(3+) ions result in efficient near-infrared emission when excited by 400-500 nm broad visible light. The energy of the Er(3+) ((4)I(13/2)→(4)I(15/2)) transition matches well with the band gap of germanium (Eg ∼ 0.785 eV). Ce(3+)-Er(3+) codoped yttrium aluminium garnet is promising for the enhancement of conversion efficiency of germanium solar cells.