Mining Unexplored Chemistries for Phosphors for High-Color-Quality White-Light-Emitting Diodes

There is a critical need for new earth-abundant phosphors to enable next-generation, highly efficient solid-state lighting. Here we report the discovery of Sr₂LiAlO₄, the first known Sr-Li-Al-O quaternary crystal, via a carefully targeted data-driven structure prediction and screening effort using density functional theory calculations. Sr₂LiAlO₄ is predicted and experimentally confirmed to be a thermodynamically and thermally stable phosphor host that can be excited with near-UV/blue sources. The Eu²⁺- and Ce³⁺-activated Sr₂LiAlO₄ phosphors exhibit broad emissions at λ_max ∼ 512 nm (green-yellow) and λ_max ∼ 434 nm (blue), respectively, with excellent thermal quenching resistance of >88% intensity at 150°C. A prototype phosphor-converted white LED utilizing Sr₂LiAlO₄-based phosphors yields an excellent color-rendering index exceeding 90. Sr₂LiAlO₄ therefore exhibits great potential for industrial applications in low-cost, high-color-quality WLEDs. Solid-state lighting based on phosphor-converted light-emitting diodes (pc-WLEDs) are highly efficient, environmentally friendly, and exhibit superior durability and reliability. For domestic lighting, a warm white-light LED with good quantum efficiency, resistance to thermal quenching, high color-rendering index (CRI), and low correlated color temperature is desired. Here, we report the discovery of an earth-abundant Sr₂LiAlO₄ phosphor host using data-driven structure prediction and screening of unexplored chemistries. The synthesized Sr₂LiAlO₄:Eu²⁺ and Sr₂LiAlO₄:Ce³⁺ phosphors exhibit broad green-yellow and blue emissions, respectively, with excellent thermal quenching resistance. A prototype pc-WLED utilizing Sr₂LiAlO₄:Eu²⁺ yields an excellent CRI > 90. This work highlights the effectiveness of an integrated in silico and experimental approach in the discovery of a technological material in a novel chemistry. The discovery of new phosphors is key to the development of highly efficient and environmentally friendly LED-based lighting. By applying data-driven structure prediction and quantum mechanics-based screening on unexplored chemistries, we identified a novel, earth-abundant phosphor host, Sr₂LiAlO₄, which was successfully synthesized and integrated into prototype LEDs with high color quality. © 2018 Elsevier Inc.