Luminescent properties and energy transfer of Tm3+/Dy3+ co-doped oxyfluoride borate glasses for white LEDs

Abstract

Tm3+/Dy3+ co-doped oxyfluoride borate glasses with composition of 25CaF2–25ZnO–6P2O5–44B2O3 (mol%) for white light-emitting diodes were synthesized by a conventional melting-quenching method. The glass structure, spectroscopic properties and decay time profiles were characterized by XRD and FT-IR, optical and fluorescence spectrum measurements. Under 354 nm excitation, the color tones change from light blue (0.3004, 0.2646) to warm white (0.3626, 0.3642) by increasing concentration of Tm3+. The shortening of the Dy3+ emission decay time in presence of Tm3+ suggests that Dy3+/Tm3+ non-radiative energy transfer occurs. By using the Inokuti–Hirayama model, it is inferred that an electric quadrupole–quadrupole interaction might be the dominant mechanism involved in the energy transfer. The results suggest that the as-prepared Tm3+/Dy3+ co-doped oxyfluoride borate glasses may be promising candidate in white LEDs and other display devices.