Development of Silicon Nanocrystals as High Energy White Phosphors

72497B03-I Organic, monolayer-stabilized silicon nanocrystals (2 to 10 nm in diameter), with photoluminescence quantum efficiencies exceeding 60%, could prove useful as the emissive phosphor layer in solid-state, light emitting diodes for general illumination purposes. They would offer better lifetimes, color shifts to the visible range, and higher efficiencies than existing phosphors for 380-400 nm pumped white light LEDs. This project will develop silicon nanocrystals as white phosphor materials for solid-state lighting applications. In Phase I, silicon nanocrystals will be synthesized using a newly developed approach in high-temperature, high-pressure solvents. Because a number of synthetic parameters contribute to the material properties of the silicon nanocrystals (including precursor chemistry, temperature, capping ligand chemistry, pressure, and concentration), a new, rapid throughput combinatorial approach will be employed to explore and optimize the reaction conditions for optimized light emission and color tunability. Phase II will improve the photoluminescent efficiency of the particles even further, as well as address device integration issues, such as optimizing LED package design and identifying host materials for maximum external light extraction. Commercial Applications and Other Benefits as described by awardee: The commercial application being pursued is lighting for the general illumination market. Solid-state lighting is said to be capable of saving $100 billion per year in electricity, with a corresponding savings of 200 billion tons of carbon emissions per year. This would be an enormous gain to society. Other marketing opportunities include flat panel displays, specialty lighting, biological sensors, quantum dot lasers, and novel floating gate memory structures.