Colloidal Synthesis of Bulk-Bandgap Lead Selenide Nanocrystals

Abstract

Lead selenide quantum dots (QDs) are low-bandgap IV-VI semiconducting nanomaterials that have been studied for a variety of applications. Their preparation using colloidal methods can create small spherical to larger cubic nanocrystals, with an upper limit of ~17 nm reported to date. Here we describe methods for preparing cubic PbSe nanocrystals over a 20–40 nm size range using a twostep procedure. Specifically, ~10 nm PbSe QDs are generated using the rapid injection method, the products from which are overcoated with additional lead and selenium precursors. The use of two lead reagents were studied; lead oleate resulted in a maximum of 20 nm cubes, while more reactive lead hexyldecanoate resulted in much larger nanomaterials with bulk bandgaps. However, PbSe samples prepared with lead hexyldecanoate also contained agglomerates. Special care must be taken when characterizing larger strained nanomaterials with X-ray powder diffraction, for which the Scherrer equation is inadequate. A more rigorous approach using the Williamson–Hall method provides characterizations that are consistent with electron microscopy analysis.

Zinc Ferrite Nanoparticles: Unusual Growth Mechanism for Size‐Dependent Properties

“…Stress can broaden the diffraction peak and Scherrer equation often gives an underestimated particle size. In present work, the relatively intense diffraction peaks (220), (311), (222), (400), (422), (511), (440) of spinel phase were selected to determine the mean grain size by Williamson‐Hall equation (Equation 2 [30,31] …”

Strategies for enhancing conductivity of colloidal nanocrystals and their photoelectronic applications

“…nanocrystalline materials and the application range of NCs, especially the regulation of narrow size distribution, shape and composition, surface chemical modulation and diversified photoelectric applications. In recent years, although many excellent works on controllable synthesis of NCs and preparation of NCs photoelectronic devices have been reported, less work has focus on the study of NCs conductivity, which is a critical factor affecting the properties of photoelectric devices [34][35][36][37][38][39][40][41][42][43][44][45] . It is due to colloidal NCs surface ligands with electrical insulation, which must be processed to enable the application of NCs in optoelectronic devices.…”

Whole Specimen Analysis of Lead Chalcogenide Nanostructure Morphologies: Implications for Alternative Energy Generation

“…4,5 Lead selenide (PbSe) and lead sulfide (PbS) may be spherical or cubic depending on the size; furthermore, they may form platelets as well as straight or branched nanowires (NWs). 6,7 Materials may also be highly anisotropic as well, 6 which is known to affect the performance of the electrical devices that incorporate them. Furthermore, the size, shape, and homogeneity of nanomaterials are known to affect their performances in thermoelectrics, 8 conduction through solar cells, 9 and also multiple-exciton generation.…”

“…Our group reported a method to synthesize PbSe cubes to demonstrate enhanced conductivity in a device compared to smaller particles. 6 The procedure has a low tolerance concerning the reactive parameter space, producing massively inhomogeneous particles from a similar process. We typically use TEM measurements to differentiate the products; however, we prefer a method applicable at the whole specimen level.…”

“…It should be noted that WA analysis must only be performed on pure specimen diffraction profiles, especially during attempts to characterize materials larger than 20 nm. 6 These data are obtained by removing the effects of angle-dependent instrument broadening via deconvolution. Unfortunately, there are more nuances and pitfalls in the analysis than described here, and a detailed explanation of the algorithm, including instrument deconvolution, is available in the Supporting Information.…”