Synthesis and Characterization of Quantum Dots: A Case Study Using PbS

A research project for senior undergraduates of chemistry has been developed to introduce syntheses of a series of monodispersed semiconductor PbS quantum dots (QDs) and their characterization methodologies. In this paper, we report the preparation of monodispersed semiconductor PbS QDs with sizes smaller than the exciton Bohr radius using a simple, one-step process, and the characterization of the QDs using a range of instruments, including Fourier-transform infrared spectroscopy, transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and energy-dispersive X-ray spectroscopy. Our synthesis approach involves dissolving powdered sulfur (as the S precursor) in 1-tetradecene and adding PbCl2 as the Pb precursor to the suspension as well as oleylamine as a capping ligand. The PbS QD project represents, we believe, an almost ideal opportunity to provide exposure of undergraduate students to nanotechnology research via syntheses and characterization of semiconductor nanoparticles.