Cooperative downconversion luminescence in Pr3+/Yb3+:SiO2-Al2O3-BaF2-GdF3 glasses

Oxyfluoride aluminosilicate glasses with compositions of 50SiO(2)-20Al(2)O(3)-20BaF(2)-10GdF(3)-0.5PrF(3)-xYbF(3) (x = 0, 1.0, 2.5, 5, 7.5, 10, 15, 20, 25, and 30 mol%) have been prepared to study their thermal and optical properties. From the differential thermal analysis (DTA) measurement, glass-transition temperatures and onset crystallization temperatures have been evaluated and from them, glass-stability factors against crystallization were calculated. Glass stabilities were decreased gradually with fluoride content increment in all the studied glasses. The photoluminescence and decay measurements have also been carried out for these glasses. In these glasses, an efficient near-infrared (NIR) quantum cutting with optimal quantum efficiency approaching 160% have been demonstrated, by exploring the cooperative downconversion mechanism from Pr3+ to Yb3+ with 481 nm (P-3(o) -> H-3(4)) excitation wave length. These glasses are promising materials to achieve high-efficiency silicon-base solar cells by means of downconversion in the visible part of the solar spectrum.