Multigram Scale, Solventless, and Diffusion-Controlled Route to Highly Monodisperse PbS Nanocrystals

Abstract

High-quality PbS nanocrystals were produced in multigram-scale quantities through a solventless, heterogeneous, and relatively green route. The heterogeneous nature of this reaction allows one to limit the diffusion in the system, allowing for unprecedented monodispersity and quality of the product demonstrated by a full-width at half-maximum of the photoluminescence peak (PL fwhm) as low as 52 meV, a Stokes shift as low as 10 meV, and a quantum yield (QY) of 40%. The growth of the nanocrystals is interpreted in the framework of a diffusion-controlled Ostwald growth in conditions of strong supersaturation.

Ultrathin Nanowires—A Materials Chemistry Perspective

“…Similarly, the morphology of Bi 2 S 3 [62] and Sb 2 S 3 [63] nanowires and nanotubes was also dependent on the precursor ratio, as reported by our group and by Son and coworkers. [64] Bi 2 S 3 nanowires were formed via a heterogenous nanocrystal route, [65] by reacting a bismuth citrate slurry in oleylamine with a sulfur solution in oleylamine [62] (Fig. 4b).…”

“…This is further confirmed by the ubiquitous 1.6 nm size in nanostructures formed from the isostructural Sb 2 S 3 . [64,65] This strong valley in the energy landscape would prevent the nanowire to grow sideways, and instead would foster growth along one direction only. Sb 2 S 3 nanowires and nanoplatelets could be formed with a thickness of $1.7 nm, by reacting antimony oleate with sulfur dissolved in oleylamine.…”

Temperature dependence of the photoluminescence emission from thiol-capped PbS quantum dots

“…6 Of the various nanocrystals, PbS-based QDs have emerged as promising candidates for optical applications in the near-infrared region of the electromagnetic spectrum. 5,[7][8][9] In particular, since the emission wavelength of PbS dots can be controlled and tailored within the spectroscopic window of 1.0-1.2 m of low absorption of biological systems, water soluble PbS nanocrystals have the potential to be used as biocompatible fluorescent labels and to replace traditional organic fluorescent dyes.The effect of temperature T on the optical properties of PbS quantum dots is of great importance for their use in room temperature ͑RT͒ applications. Recently, an unusually large linewidth ͑ϳ100 meV͒ for the RT photoluminescence ͑PL͒ emission from an individual PbS QD was reported.…”

Emerging strategies for the synthesis of highly monodisperse colloidal nanostructures

“…An XPS analysis of our PbS nanocrystals obtained from PbCl 2 revealed a sizeable amount of chloride ions on their surface, even after extensive purification procedures (Cademartiri et al 2006a). These ions are strongly bound and can be removed by reaction of the nanocrystals with oleic acid.…”

“…This reaction was later reproduced by other groups (Moreels et al 2009;Zhao et al 2009). Figure 5 shows an optical analysis of the growth kinetics, depending on the reaction conditions (Cademartiri et al 2006a). Figure 5a,b shows, respectively, the evolution of (i) the FWHM and (ii) the wavelength of the luminescence during growth for two different conditions: the filled symbols indicate low-concentration and low precursor ratio conditions that are usually found in most nanocrystal syntheses; the open symbols instead indicate a high concentration and a high precursor ratio regime, where the molarity of the 'solvent' and of the precursors are comparable.…”