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

Abstract

An optical spectroscopy investigation of zinc phosphate glasses activated with Tb3+/Dy3+ 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 Tb3+ content from 1.0 to 0.1mol% of Tb(PO3)3 upon Dy3+ excitation at 423nm. Such visible region luminescence is generated by 5D4→7F5 and 5D4→7F3 emissions of Tb3+ in addition to 4I15/2→6H15/2, 4F9/2→6H15/2, 4F9/2→6H13/2 and 4F9/2→6H11/2 emissions of Dy3+, so that Tb3+ emission is sensitized by Dy3+ through a non-radiative resonant energy transfer. A dominant 5D4→7F5 green emission is observed in detriment of the 5D3→7FJ blue emissions upon 282nm excitation, as well as an extended excitation range (280–500nm), due to multiple Dy3+ and Tb3+ transitions, which might contribute to enhance the spectral response of solar photovoltaic cells by down-shifting of the incident solar spectrum.