High-yield green fabrication of colloidal silicon quantum dots by low-temperature thermal cracking of porous silicon

We developed high-yield green fabrication of colloidal silicon quantum dots (QDs) only by low-temperature treatment of porous silicon (PSi) flakes in a reactive organic solution. Heat treatment at ∼50 °C of the PSi flakes in unsaturated hydrocarbon solution mixed with hydrofluoric acid (HF) yields the organically self-surface-passivated Si QD, which exhibit efficient photoluminescence compared with the conventional PSi. The production yield of Si QDs is enhanced by increasing the heat-treatment temperature and HF concentration, and the best results were obtained at ∼50 °C and 50%, respectively. The dispersibility of the prepared Si QDs in the solvents can be controlled by using appropriate organic function groups. The efficient transformation into Si QDs without waste is based on thermal cracking of weakly interconnected Si cores of PSi. Performing a practical clean process, the present result provides a promising route for overcoming limitations in the conventional colloidal QD preparation methods.