Preparation of stable blue-emitting silicon nanoparticles
This technology describes two methods to synthesize blue luminescent silicon nanoparticles. The first is a 3-phase process. In the first phase, laser decomposition of silane and wet chemical etching using a combination of acids (HF and HNO3) yields photoluminescent nanoparticles of diameter 10-15 nm. The second phase involves optimization of acid-combination proportions to produce high density of hydrogen and low density of oxygen on the nanoparticle surfaces. In the final phase, secondary atta chments of organic molecules (e.g. ethyl undecylenate) to the hydrogen terminators are done through photoinitiated hydrosilylation, resulting in silicon nanoparticles that display bright luminescence from red to green. Size separation is then done th rough chromatography to yield blue particles. The ethyl undecylenate used can be replaced with other capping chemicals also to yield the same results.
In the second method, a monomer with a terminal double bond (1-octadecene, styrene, 1-dodecene) is attached to the Silicon nanoparticles using hydrogen terminators and photoinitiated hydrosilylation as above. Oxidation at by heating at140 – 160 degrees Celsius or UV irradiation results in blue silicon nanoparticles.
The summary values of thi s technology are:
– Blue color-emitting luminescent Si nanoparticles of consistent size (~ 10 nm) have been synthesized; these are usually difficult to produce
– The second method does not require a size separation phase
– Usually oxidation of a n organic molecule leads to a red-shift in emission. In contrast, post-oxidation phase in the 2nd method above exhibits a blue shift. This phenomenon, if studied, could lead to interesting and useful results.
The technology has broad potential app
Categories: Optics, Nanotechnology
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