Crystallization kinetics of CdSe nanocrystals synthesized via the TOP–TOPO–HDA route

Xie, Chen; Hongxun, Hao; Chen, Wei; Wang, Jingkang

doi:10.1016/j.jcrysgro.2008.04.029

Cited by 18 publications

(33 citation statements)

References 26 publications

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“…Combining eqs and (), the growth rate acquires the form where constants a and b are connected by the simple relation: . Equation is valid as long as C 0 ≫ C eq so that the intrinsic size dependence of C eq via Gibbs–Thomson equation may be ignored. , Such an approximation seems to be reasonable especially in the very beginning of the colloidal synthetic procedure in which the supersaturation degree is usually high and, consequently, the particle growth is not significantly affected by coarsening. Indeed, in our syntheses of CdTe nanocrystals, the initial concentrations of both cadmium and tellurium precursors are of the order of mM while the equilibrium concentration is expected to be much smaller (∼μM, see the inset of Figure b).…”

Section: Resultsmentioning

confidence: 99%

Combined Theoretical–Experimental Approach to the Growth Kinetics of Colloidal Semiconductor Nanocrystals

Ferreira

Silva

et al. 2019

J. Phys. Chem. C

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A new theoretical analytical model is proposed in order to provide a quantitative description of the growth kinetics of colloidal semiconductor nanocrystals. The temporal evolution of the mean size of the nanocrystal ensemble in solution was determined by monitoring the variation of the absorption and photoluminescence spectra in the course of the chemical synthesis and then submitting the resulting optical data to a calculation procedure that generated the corresponding time-evolving particle size distribution. Two main problems were addressed and properly correlated: the size-dependence of the bandgap transition for a single semiconductor nanocrystal, which was treated within the framework of the finite-depth square-well effective mass approximation, and the inhomogeneous broadening of the optical spectra due to the distribution of nanocrystal sizes and hence the distribution of bandgaps. By application of the reported methodology to CdTe nanocrystals synthesized through a one-pot aqueous chemical route, growth curves (mean particle size as a function of time) were calculated for syntheses performed under various initial experimental conditions. Such kinetic results were interpreted in the sense of the well-established classical crystallization theories based on homogeneous nucleation and growth of spherical particles in solution, including a detailed study on the Ostwald ripening process. Specific growth modes were identified along with numerical estimates for their characteristic rate constants. The presented calculation method is easy to implement, and it can be used to access the size evolution of solution-grown nanocrystals of many other semiconductor materials, regardless of the adopted preparation procedure.

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Section: Resultsmentioning

confidence: 99%

Combined Theoretical–Experimental Approach to the Growth Kinetics of Colloidal Semiconductor Nanocrystals

Ferreira

Silva

et al. 2019

J. Phys. Chem. C

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“…Variations of this equation have been reported previously in literature. Those reported relationships have been expressed on a per-QD basis or have accounted for all QDs in a solution of known volume and concentration. ,, Equation includes terms for both growth and dissolution contributions to the time-dependent QD radius, r ( t ) and is a formulation based on a per-QD model with a per-QD unit volume of solution ( V u ). …”

Section: Resultsmentioning

confidence: 99%

“…These recent findings underline the need for a comprehensive data set of thermodynamic and kinetic properties that could guide the development of effective low-temperature synthesis routes for semiconductor QDs. Previous efforts in this direction have largely focused on experimental or theoretical determination of rate kinetics from a bottom-up perspective of nanocrystal formation. − For example, Rempel et al provide a kinetic model for nanocrystal growth and dissolution, investigating the impact of critical reaction parameters on nucleation, size distribution and size focusing . Experimental realization of these models is very difficult due to the rapid kinetics at high temperatures as well as competing processes including crystal nucleation, reaction- or diffusion-limited growth, and Ostwald ripening.…”

Section: Introductionmentioning

confidence: 99%

“…Experimental realization of these models is very difficult due to the rapid kinetics at high temperatures as well as competing processes including crystal nucleation, reaction- or diffusion-limited growth, and Ostwald ripening. These competing processes require assumptions of distinct formation and ripening mechanisms that complicate the modeling of an overall governing rate equation, which can lead to ambiguous results. ,, …”

Section: Introductionmentioning

confidence: 99%

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Experimental Evaluation of Kinetic and Thermodynamic Reaction Parameters of Colloidal Nanocrystals

et al. 2016

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The unique properties of colloidal semiconductor nanocrystals, or quantum dots, have attracted enormous interest in a wide range of applications, including energy, lighting, and biomedical fields. However, widespread implementation is hampered by the difficulty of developing large-scale and inexpensive synthesis routes, mainly due to our limited knowledge of formation reaction parameters. We report here a simple yet powerful method to experimentally determine critically important reaction parameters such as rate constants, activation barriers, equilibrium constants and reaction enthalpies. This method was applied to wurtzite cadmium selenide nanocrystals, yielding activation energies for growth and dissolution of 14 ± 6 kJ mol–1 and 27 ± 8 kJ mol–1, respectively, and a reaction enthalpy for nanocrystal growth of −15 ± 7 kJ mol–1. Moreover, the Gibbs free energy for growth was found to be negative at low temperatures, whereas dissolution becomes the spontaneous process above 150 °C.

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“…Of these, the most extensively investigated material is CdSe due to its potential applications in various optoelectronic devices such as low-cost and high-performance hybrid solar cells [1], photoelectrochemical cells [2], sensors [3] and green light-emitting diodes [4]. Amongst various methods for synthesis of CdSe thin films [5][6][7], the chemical bath deposition (CBD) [8] is found to be one of the relatively inexpensive, simple, and convenient techniques. Although a number of reports on synthesis and characterisation of nanocrystalline CdSe have already been published [9][10][11] only few works on structural parameters of these materials in nanocrystalline form are reported recently.…”

Section: Introductionmentioning

confidence: 99%

Structural analysis of chemically deposited nanocrystalline CdSe films

Borah¹,

Baruah²,

Chaliha³

et al. 2013

Journal of Experimental Nanoscience

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Nanocrystalline CdSe films are deposited on glass substrates by the chemical bath deposition method at different molarities and at room temperature. The structural parameters such as lattice constant, internal strain and dislocation density of CdSe nanocrystals are measured from X-ray diffractrograms using the Williamson-Hall plot. The average crystallite size of prepared films are found to be from 9.5 to 26 nm. The prepared films are found to be under compressive strain with very high dislocation density of the order of 10 17 line m À2.

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Crystallization kinetics of CdSe nanocrystals synthesized via the TOP–TOPO–HDA route

Cited by 18 publications

References 26 publications

Combined Theoretical–Experimental Approach to the Growth Kinetics of Colloidal Semiconductor Nanocrystals

Combined Theoretical–Experimental Approach to the Growth Kinetics of Colloidal Semiconductor Nanocrystals

Experimental Evaluation of Kinetic and Thermodynamic Reaction Parameters of Colloidal Nanocrystals

Structural analysis of chemically deposited nanocrystalline CdSe films

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