Broadband conversion of ultraviolet to visible and near-infrared emission in Gd^{3 +}/Yb^{3 +}codoped germanate glass

Gd3 +/Yb3 +co-doped germanate glasses were fabricated using the melt-quenching method. Broadband visible emission was observed from the gadolinium doped germanate glasses under ultraviolet (UV) excitation, and white-light was obtained by modifying Yb3 +co-dopant concentration. Through this co-doped system, the white-light emission can be further converted into the near-infrared range which is matched well with the energy band gap of commercial silicon solar cell. The possible energy transfer processes involved are proposed and discussed according to the excitation, emission and fluorescence decay measurements. The effect of Yb3 +ion concentration with respect to fixed Gd3 +ions on the visible and near-infrared (NIR) emission has also been studied. The conversion efficiency from visible to near-infrared is as high as 69.3% in the GZN: 0.2Gd2O3-0.6Yb2O3sample. The results indicate that this material is potential in various applications, such as white LED, enhancing silicon solar cell efficiency, and so on.