Potential substitutes for critical materials in white LEDs: Technological challenges and market opportunities

Abstract

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Facile Synthesis of Water-Stable Multicolor Carbonized Polymer Dots from a Single Unconjugated Glucose for Engineering White Light-Emitting Diodes with a High Color Rendering Index

“…Luminescent materials such as semiconductor quantum dots, , perovskite quantum dots, , rare earth-based nanoparticles, − and organic molecular fluorescent materials − have great potential for use in light-emitting diodes (LEDs). However, the application of these materials in LEDs is impeded by the complexity of their synthesis processes, as well as by their toxicity and photo-instability.…”

Drastic Ce3+ Insertion Enhancement in YAG Garnet Nanocrystals Through a Solvothermal Route

“…When micron-sized crystals are used, the absorption rate is not a problem as a low absorption coefficient can be easily compensated by the rise in matter (Waetzig et al, 2014). However, if one wants to limit the quantity of these phosphors which contain critical elements such as (Gaffuri et al, 2021) or to develop thin phosphor layer for the elaboration of nanostructured LEDs, it is essential to take into account the absorption capacity of these phosphors. Similar considerations have been done on YAG: Ce ceramics, (Yuan et al, 2018) where the absorption is adjusted by increasing the ceramic thickness.…”

Regulation of Local Site Structures to Stabilize Mixed-Valence Eu2+/3+ under a Reducing Atmosphere for Multicolor Photoluminescence

“…Among the lanthanide ions, both Eu 3+ and Eu 2+ can act as the luminescence center in the matrix lattice. Recently, Eu 2+/3+ has become the most commonly used luminescence activator in phosphors for white LEDs. − Eu 2+ -activated phosphors usually have wide and intense excitation bands due to the parity-allowed 4f–5d transition. , However, Eu 3+ is characterized by sharp red emission peaks caused by the 5 D 0 – 7 F J ( J = 0–4) transition. ,, In a single-phase phosphor, the valence-state transfer between Eu 2+ and Eu 3+ to synchronously obtain blue-green emissions from Eu 2+ and red emission from Eu 3+ is a promising method to realize warm white light emission. − However, Eu 2+ -activated phosphors generally require preparation in a reducing environment and/or a reductant for the Eu 3+ reduction to Eu 2+ in the raw Eu 2 O 3 material. Eu 3+ -activated phosphors can be obtained directly in air.…”