Growth kinetics of CdSe nanoparticles synthesized in reverse micelles using bis(trimethylsilyl) selenium precursor

Abstract

Abstract:We first focus on the kinetics of nanoparticle growth in a microemulsion synthesis of CdSe semiconductor nanocrystals. The process consists of a fast initial stage of typical time constant of the order of 10 3 s followed by a slow stage of time constant of the order of 10 4 s. Growth proceeds similarly to that described for the hot-matrix synthesis of CdSe, underlining the generality of the twostage growth mechanism, irrespective of the matrix type and synthesis conditions. However, the time constant of each stage in the microemulsion synthesis is much larger than in the hot-matrix one. Also, the ratio between the fast and slow time constant is appreciably bigger. We also prove that larger size reverse micelles, obtained by increasing the water:surfactant ratio, generally lead to larger CdSe nanoparticles. Bis(trimethylsilyl) selenium is the crucial precursor for the CdSe nanoparticle synthesis. An intermediate stage of the chemical reaction limiting the bis(trimethylsilyl) selenium production is described theoretically.

Study on Initial Kinetics of CdSe Nanocrystals by a Combination of in Situ X-ray Absorption Fine Structure and Microfluidic Reactor

“…We plot in Figure 5a the temporal evolution of NCs diameter within the whole time region of 0.0-8.1 s. The smallest nucleus size detected in our experiment was about D ≈ 1.3 nm at the reaction time of 1.1 s. This initial nuclei formation was immediately followed by a rapid increase in size within ca. 3 s. After that, the size growth was slowed, but the plateau-like growth at longer times, which has been observed frequently in the literature, [14][15][16][17][18][19] did not appear in our experiment due to the limited reaction time (<8.1 s). In fact, such a similar trend of size evolution has been predicted by very recent simulations.…”

“…At the initial stage after rapidly heating the raw materials solution, the NCs growth is governed by the reaction-driven mechanism. 13,16 In this case, the Cd concentration [Cd] t obeys the following equation: 15 Here, K is an interfacial rate constant that reflects the ratedetermining steps during deposition, and A(t) ) πD(t) 2 is the surface area of a particle with diameter D(t).…”

“…However, at the early stage of reaction immediately after injection of the hot reactant, a burst of nucleation frequently occurs, which makes the nucleation process dominant over the nuclei growth during this period. To date, the slow growth process and mechanism have been studied extensively, − but probing the burst nucleation process still remains a challenge, , because the nucleation step is very quick or even unobservable on the measurement time scale.…”

Synthesis, Characterization, and Self‐assembly of Colloidal Quantum Dots

“…Two popular micellar systems work well for preparation of metal and semiconductor nanoparticles [51]. Figure 1.4 shows absorption spectra and a TEM image of CdSe QDs synthesized in AOT micelles [53]. AOT reverse micelles are widely used for QD preparation because they produce relatively monodisperse QDs [52].…”

Nanosized CdSe Particles Synthesized by an Air Pressure Solution Process Using Ethylene‐Glycol‐Based Solvent

“…Nanoscale CdSe has attracted great attention in the past decade due to its unique properties supplying for potential luminescence and photoelectronic applications, such as biological fluorescent labels, 2,3 light‐emitting diodes, 4 lasers, 5 and solar cells 6 . Up to now, various chemical techniques, typically including coordinating solvent method, 7 thiol aqueous solution method, 8,9 microemulsion synthesis, 10–13 solvothermal, and hydrothermal methods 14–17 have been involved in the synthesis of CdSe nanocrystals. In the coordinating solvent methods, Murray et al 7 earlier made use of a reaction of dimethylcadmium Cd(CH 3 ) 2 with TOP–Se precursor solution in trioctylphosphine oxide solvent to generate high‐qualified monodisperse and uniform‐sized CdSe nanocrystals.…”