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Orange–Red Si Quantum Dot LEDs from Recycled Rice Husks

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journal contribution
posted on 28.01.2022, 14:36 authored by Shiho Terada, Honoka Ueda, Taisei Ono, Ken-ichi Saitow
Nanomaterial toxicity and environmental concerns inspired us to develop a scalable method for fabricating quantum dots with a positive environmental impact. Milling rice creates billions of kilograms of rice husks yearly, which are an excellent source for high-quality silica (SiO2) and value-added silicon (Si) powders. Herein, we synthesize SiO2, porous Si, and Si quantum dots (SiQDs) from rice husks containing 20 wt % SiO2 using a conventional chemical synthesis method and investigate the structure, optical, and optoelectrical properties. The extraction yields of SiO2 and Si powders from rice husks are 100 and 86%, respectively. The final product, decyl-passivated SiQDs, consists of 3 nm crystalline particles that are soluble in an organic solvent. A colloidal solution of the decyl-passivated SiQDs exhibits orange–red photoluminescence at a wavelength of 680 nm, with a 21% quantum yield. This colloidal solution is used to develop a SiQD LED, resulting in orange–red electroluminescence.