Zero-thermal-quenching of LiAl5O8: Eu2+, Mn2+ phosphors by energy transfer and defects engineering

The photoluminescence behavior of inorganic phosphors is generally influenced by thermal stability, which determines the luminescence efficiency of the corresponding devices. Here, a series of Eu2+, Mn2+ co-doped LiAl5O8 blue-green-emitting phosphors with thermal robust are successfully fabricated. The concentration-dependent emission spectra and the decay curves of the as-obtained LiAl5O8: Eu2+, Mn2+ samples manifest the occurrence of the energy transfer from Eu2+ to Mn2+ ions via dipole-dipole interaction, and the corresponding emitted colors are gradually modulated from blue to green under the excitation of 310 nm. Moreover, the zero-thermal-quenching luminescence is observed when the operation temperature is up to 423 K, which is attributed to the energy release from the trapping centers to emitting centers (Eu2+ and Mn2+) at high temperature. Furthermore, a warm white light-emitting diodes (WLEDs) device with correlated color temperature of 5061 K, a color rendering index of 80.6 and long-term stability is fabricated by combining UV LED chip (λex = 310 nm), as-obtained LiAl5O8: Eu2+, Mn2+ phosphor, commercially available red phosphor and green phosphor. These results prove the potential application of the as-obtained LiAl5O8: Eu2+, Mn2+ phosphor for UV-pumped WLEDs devices.