Researchers from Japan's Hiroshima University developed a new technique to create efficient silicon quantum dots from recycled rice husks. Rice husk is a good source of high-purity silica (SiO2) and silicon powder.
The researchers created SiQDs that luminescence in the orange-red range with a high luminescence efficiency of over 20%. From the QDs the researchers created LEDs based on ITO glass substrates, using spin-coating to process the SiQDs.
To process the rice husk silica, the researchers used a combination of milling, heat treatments and chemical etching. Initially, they milled rice husks and obtained silica (SiO2) powders by burning off organic compounds in the milled rice husks.They then used an electric furnace to heat the resulting silica powder, resulting in Si powders through a reduction reaction. The final product was a purified Si powder that was chemically etched down to 3 nm in size. Lastly, its surface was chemically functionalized with 3 nm crystalline particles for high chemical stability and solvent dispersivity.