Intense infrared emission of Er3+ in Ca8Mg(SiO4)4Cl2 phosphor from energy transfer of Eu2+ by broadband down-conversion

We report on conversion of near-ultraviolet and visible radiation ranging from 250 to 500nm into near-infrared emission by a Ca8Mg(SiO4)(4)Cl-2: Eu2+, Er3+ phosphor. Efficient 1530-1560nm Er3+ emission (I-4(13/2)-> I-4(15/2)) was detected under the excitation of Eu2+ (4f -> 5d) absorption band as a result of energy transfer from Eu2+ to Er3+, which is confirmed by both steady state and time-resolved emission spectra. The laser power dependent emission intensity changes were investigated to analysis the energy transfer mechanism. Energy transfer from Eu2+ to Er3+ followed by a multi-photon quantum cutting of Er3+ is proposed. The result indicates that the phosphor has potential application in enhancement of conversion efficient of germanium solar cells because the energy difference of Er3+: I-4(13/2)-> I-4(15/2) transition matches well with the bandgap of Ge (Eg similar to 0.785 eV). (C) 2010 Optical Society of America