Characterizations and photoluminescence properties of a dual-functional La2LiNbO6:Bi3+, Eu3+ phosphor for WLEDs and ratiometric temperature sensing

Abstract

In recent years, color-tunable luminescent materials based on multi-emitting centers have attracted considerable attention owing to their potential applications in display, lighting and temperature sensor. In this research, we have designed a novel single-phased La2LiNbO6:Bi3+, Eu3+ phosphor with dual-emitting centers and investigated its band structure, luminescence property and temperature sensitive behaviors. The structural and morphological analysis confirmed that the as-synthesized phosphor crystallized in a monoclinic double-perovskite structure with well dispersed elemental composition and good crystallinity. Under NUV excitation, Bi3+ single-doped La2LiNbO6 phosphor exhibited a broad blue emission band in the range of 350–650 nm, which was assigned to the characteristic 3P1 →1S0 transition of Bi3+ ion. On the other hand, efficient energy transfer from Bi3+ to Eu3+ ions was observed in Bi3+/Eu3+ co-doped La2LiNbO6 phosphors, leading to the tunable emission color changing from blue to red with increasing Eu3+ concentration. Furthermore, from the emission spectra and critical distance, the energy transfer between Bi3+ and Eu3+ ions was deduced to be a dipole-dipole interaction mechanism. Based on the temperature-dependent PL spectra, the thermal stability and temperature sensing properties of the La2LiNbO6:Bi3+, Eu3+ phosphor were discussed and the main parameters related to the temperature sensing performance were calculated. Finally, we have preliminarily evaluated the performance of La2LiNbO6:Bi3+, Eu3+ phosphor in WLED through analyzing the photoelectric parameters of the fabricated LEDs.