Size- and shape-controlled synthesis of PbSe and PbS nanocrystals via a facile method

The present study describes the synthesis of monodispersed PbSe and PbS nanocrystals by a facile, less hazardous and inexpensive approach. In this study, Se and S powder are used as chalcogenide precursors instead of trioctylphosphine-selenium (TOPSe) and hexamethyldisilthiane (TMS), which are toxic and expensive. The chalcogenide precursors used in this method are inexpensive and air-stable, which not only reduces the cost of the experiment, but also simplifies the synthesis process. Monodispersed PbSe and PbS nanocrystals with spherical, cubic and cuboctahedral shapes were obtained, and the size of the nanocrystals can be tuned in a wide range (6-25 nm for PbSe and 10-80 nm for PbS) via tuning the concentration of oleic acid (OA) and oleyamine (OAm). The mechanism of the size control and shape evolution is discussed. The concentration of OA and OAm is found to play an important role in deciding the size and shape of the nanocrystals in the nucleation and growth process.