Phosphine-free synthesis of metal chalcogenide quantum dots by means of in situ-generated hydrogen chalcogenides

We proved that various organic solvents react with elemental chalcogens (sulfur and selenium) by liberating hydrogen chalcogenide (H2X, X = S, Se) during the phosphine-free hot-matrix synthesis of quantum dots. The in situ-produced H2X reacts further with the metal salt to form the corresponding nanosized metal chalcogenide CdX. The effect of temperature on the rate of H2X generation was quantitatively studied in various organic solvents. We found that the organic amines reduce the reaction temperature of the phosphine-free quantum dots synthesis, being more effective in situ generators of H2S than the other tested organics at relatively low temperatures (140-170 degrees C).