Li substituent tuning of LED phosphors with enhanced efficiency, tunable photoluminescence, and improved thermal stability.

Solid-state phosphor-converted white light-emitting diodes (pc-WLEDs) are currently revolutionizing the lighting industry. To advance the technology, phosphors with high efficiency, tunable photoluminescence, and high thermal stability are required. Here, we demonstrate that a simple lithium incorporation in NaAlSiO:Eu system enables the simultaneous fulfillment of the three criteria. The Li substitution at Al sites beside Na sites in NaAlSiO:Eu leads to an enhanced emission intensity/efficiency owing to an effective Eu to Eu reduction, an emission color tuning from yellow to green by tuning the occupation of different Eu sites, and an improvement of luminescence thermal stability as a result of the interplay with Li-related defects. A pc-WLED using the Li-codoped NaAlSiO:Eu as a green component exhibits improved performance. The phosphors with multiple activator sites can facilitate the positive synergistic effect on luminescence properties.