Orange-Red Si Quantum Dot LEDs from Recycled Rice Husks

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.

Automated summary

This study developed a method for fabricating environmentally friendly quantum dots using rice husks, a byproduct of rice milling. The extracted SiO2 and Si powders from rice husks showed high yields and were used to synthesize decyl-passivated SiQDs with excellent photoluminescence properties. The colloidal solution of these SiQDs was further used to develop a SiQD LED with orange-red electroluminescence.