Tunable white light in trivalent europium single doped tin fluorophosphates ultra-low melting glass

Abstract In recent years, low melting temperature glasses have received wide attention as the hosts of phosphor-converted light emitting diodes (pc-WLED). In this work, a series of trivalent europium doped tin fluorophosphates glasses were prepared by conventional melting method. Under ultraviolet excitation, the blue-green broadband emission from Sn 2+ activation centers in the glass matrix and the red emission of Eu 3+ ions together constituted a cool white luminescence. The spectra analysis was used to demonstrate the energy transfer between Sn 2+ centers and Eu 3+ ions. The results showed that Sn 2+ and Eu 3+ possessed independent intrinsic emission and mutual energy transfer simultaneously. The 5 D 4 and 5 G 2 excited states of Eu 3+ ion favored the energy transfer to Sn 2+ center, the 5 L 6 excited state of Eu 3+ ion would absorb more of the energy by the Sn 2+ ground state excitation to contribute on red emission. Therefore, the fluorescent glass can transform cool white light to warm white light by changing the excitation wavelength. The tunable white light is obtained in the WLED devices built with the glass and commercial UV chips.