Engineering topics

Im, Won Bin

Publications and source records attributed to Im, Won Bin.

3 records

DOE OSTI2021

Towards green synthesis of Mn 4+ -doped fluoride phosphors: a review

Mn 4+ -doped fluoride phosphors are attractive for application in white solid-state lighting devices because their distinct red emission can improve the color rendering index, while the earth-abundance of Mn 4+ ions can reduce the production cost. However, highly hazardous HF is used as the fluoride source in the synthesis processes, which requires extreme caution. In this review, we introduce various methods for synthesizing Mn 4+ -doped fluoride phosphors, categorized according to the presence or absence of HF in the synthesis. The underlying optical properties of the phosphors fabricated using the various methods are discussed. In addition, in the discussion of each method, we emphasize on the key factors and strategies for developing phosphors. Finally, this review highlights perspectives on and future directions for the safe synthesis of Mn 4+ -doped fluoride phosphors to achieve solid-state lighting devices with superior optical properties.

36 MATERIALS SCIENCE↗

DOE OSTI2018

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 Sr 2 LiAlO 4 , 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. Sr 2 LiAlO 4 is predicted and experimentally confirmed to be a thermodynamically and thermally stable phosphor host that can be excited with near-UV/blue sources. The Eu 2+ - and Ce 3+ -activated Sr 2 LiAlO 4 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 Sr 2 LiAlO 4 -based phosphors yields an excellent color-rendering index exceeding 90. Sr 2 LiAlO 4 therefore exhibits great potential for industrial applications in low-cost, high-color-quality WLEDs.

Wang, Zhenbin↗

DOE OSTI2012

Efficient and Color-Tunable Oxyfluoride Solid Solution Phosphors for Solid-State White Lighting

A solid solution strategy helps increase the efficiency of Ce{sup 3+} oxyfluoride phosphors for solid-state white lighting. The use of a phosphor-capping architecture provides additional light extraction. The accompanying image displays electroluminescence spectra from a 434-nm InGaN LED phosphor that has been capped with the oxyfluoride phosphor.

36 MATERIALS SCIENCE↗