Growth kinetics determine the polydispersity and size of PbS and PbSe nanocrystals

Abstract

A library of thio- and selenourea derivatives is used to adjust the kinetics of PbE (E = S, Se) nanocrystal formation across a 1000-fold range (kr = 10-1–10-4 s-1), at...

Persistent nucleation and size dependent attachment kinetics produce monodisperse PbS nanocrystals

“…Spectroscopic and X-ray scattering characterization of these solutes suggests a molecular complex with formula [(PbS)(Pb(oleate) 2 )] 2 . 14 Collectively, the NMR, UV-vis, and X-ray scattering kinetics data support a stepwise process where the lead oleate and thiourea are converted to solutes that accumulate and are then consumed by nanocrystal growth.…”

“…Reactions performed at lower temperatures display even longer nucleation times. 14 Interestingly, the nucleation rate decays as the solute concentration climbs to its maximum value. The inverse correlation between nucleation rate and solute concentration is counterintuitive, however, a variety of factors may directly or indirectly inuence the nucleation rate.…”

“…12 By modifying the chalcogenourea substitution pattern, the kinetics of solute generation can be precisely controlled over a wide range of temperatures. [12][13][14] These reagents have recently been used to study the temperature dependence of the crystal nucleation and growth steps, where in situ X-ray pair distribution function analysis demonstrated the formation of molecular solute intermediates. 14 Moreover, the precisely controlled solute supply is orthogonal to the crystal growth reaction and therefore ideally suited to explore the connection between the solute concentration and the kinetics of lead sulde nucleation and growth.…”

Chemical Considerations for Colloidal Nanocrystal Synthesis

“…Sugimoto and others solved this mass balance under the assumption of burst nucleation and found that the final particle number is proportional to Q and inversely proportional to the growth rate. − The above linear dependence on Q is valid for high growth rates. , For lower growth rates (e.g., in the presence of surfactants), a square root dependence is predicted . Such relations between precursor conversion rate and particle number have been confirmed by ample experimental data; ,,,,,,, see Figure C for an example of PbS nanocrystals.…”

“…(C) Relation between final number of particles and monomer generation rate, exemplified here with the concentration of PbS nanocrystals at different temperatures. Data replotted from ref .…”