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

Abstract

Broadband spectral conversion from visible light to near-infrared radiation in Ce³⁺–Er³⁺ 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 Ce³⁺ to Er³⁺. The broadband and strong absorption of Ce³⁺, efficient energy transfer from Ce³⁺ to Er³⁺, and three-photon quantum cutting process in Er³⁺ ions result in efficient near-infrared emission when excited by 400–500 nm broad visible light. The energy of the Er³⁺ (⁴I_13/2 → ⁴I_15/2) transition matches well with the band gap of germanium (Eg ∼ 0.785 eV). Ce³⁺–Er³⁺ codoped yttrium aluminium garnet is promising for the enhancement of conversion efficiency of germanium solar cells.