Down-shifting by energy transfer in Tb3+/Dy3+ co-doped zinc phosphate glasses

Abstract An optical spectroscopy investigation of zinc phosphate glasses activated with Tb 3+ /Dy 3+ ions is carried out through photoluminescence spectra and decay time measurements. The emission color can be adjusted from yellow–green light, with CIE1931 chromaticity coordinates (0.36,0.44), toward the white light region (0.35,0.39) by decreasing the Tb 3+ content from 1.0 to 0.1 mol% of Tb(PO 3 ) 3 upon Dy 3+ excitation at 423 nm. Such visible region luminescence is generated by 5 D 4 → 7 F 5 and 5 D 4 → 7 F 3 emissions of Tb 3+ in addition to 4 I 15/2 → 6 H 15/2 , 4 F 9/2 → 6 H 15/2 , 4 F 9/2 → 6 H 13/2 and 4 F 9/2 → 6 H 11/2 emissions of Dy 3+ , so that Tb 3+ emission is sensitized by Dy 3+ through a non-radiative resonant energy transfer. A dominant 5 D 4 → 7 F 5 green emission is observed in detriment of the 5 D 3 → 7 F J blue emissions upon 282 nm excitation, as well as an extended excitation range (280–500 nm), due to multiple Dy 3+ and Tb 3+ transitions, which might contribute to enhance the spectral response of solar photovoltaic cells by down-shifting of the incident solar spectrum.