Control of the energy transfer between Tm3+ and Yb3+ ions in ZnO nanowires for photovoltaic applications

摘要

We report on the mechanism of energy transfer between Tm^{3+ and Yb3+ ions in ZnO nanowires (NWs). We prepared Tm, Yb-codoped ZnO core-shell NWs grown by sputtering-assisted metalorganic chemical vapor deposition with different Tm/Yb concentrations, together with Tm- or Yb-doped ZnO core-shell NWs as a reference for comparison, and measured the lifetime of each rare-earth (RE) ion by time-resolved photoluminescence (PL) characterization. The PL spectra of Tm, Yb-codoped ZnO core-shell NWs exhibit characteristic luminescence from the intra 4f shell in Tm3+ ions at 488 nm, as well as 800 nm, and Yb3+ at 980 nm. The lifetime of each RE ion can vary by changing the concentration ratio of RE ions in the ZnO NWs, suggesting that the energy transfer between each RE ion in the ZnO NW can be controlled by altering the concentration ratio of RE ions which would enable the down conversion process towards photovoltaic applications.}