RESUMEN
Colloidal PbS/PbSe nanostructures with core-shell type morphology have been synthesized for the first time using a simple chemical procedure where template PbS nanocrystals (NCs) were treated with Se solution in tributylphosphine at elevated temperature. The Se-coated PbS NCs were structurally and optically characterized by high resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS) analysis, absorption and photoluminescence (PL) spectroscopy. Synthesized PbS/PbSe structures can be of particular importance in photovoltaic applications where fabrication of heterostructures with compositional modulation on the nanometer scale is essential.
RESUMEN
Alloy nanocrystals provide an additional degree of freedom in selecting desirable properties for nanoscale engineering because their physical and optical properties depend on both size and composition. We report the pyrolytic synthesis of homogeneously alloyed CdS(x)Se(1-x) nanocrystals in all proportions. The nanocrystals are characterized using UV-visible absorption spectroscopy, transmission electron microscopy, X-ray diffractrometry, and Rutherford backscattering spectrometry to determine precisely structure, size, and composition. The dependence of band gap on nanocrystal size and composition is elucidated, yielding a bowing constant of 0.29, in agreement with bulk values. In addition, the morphology of the resultant nanocrystals can be altered by changing the reaction conditions, generating structures ranging from homogeneous, spherical nanocrystals to one-dimensional gradient nanorods.