Conversion of blue-green photon into NIR photons in Ho3+/Yb3+ co-doped zinc tellurite glasses

Ho3+/Yb3+ co-doped tellurite glasses with different concentrations were prepared by employing melt quenching technique. Enhancement of the emission intensities corresponding to the Yb3+: F-2(5/2) -> F-2(7/2) (950-1120 nm), Ho3+: I-5(6) -> I-5(8) (1197 nm) and I-5(7) -> I-5(8) (2000 nm) transitions were observed under excitation of Ho3+ at 453 and 547 nm. The luminescence enhancement is explained from the photoluminescence excitation, emission and decay analysis. Energy transfer efficiencies of the energy levels that are involved in the energy transfer mechanisms are evaluated from the decay curves of Ho3+ and Ho3+/Yb3+ tellurite glasses. The results suggest that these glasses are suitable as the spectral convertors in crystalline Si solar cells and efficient NIR emitters in the 1.2 and 2.0 mu m region. (C) 2019 Elsevier B.V. All rights reserved.