Size Selective Precipitation of CdSe Colloidal Quantum Dots

Ferreira, Diego Lourençoni; Silva, F. O.; Viol, L. C. S.; Schiavon, Marco A.; Licínio, Pedro; Valadares, M.; Cury, L. A.; Alves, J.L.A.; Caldas, M.P.; Studart, Nélson

doi:10.1063/1.3295425

Cited by 4 publications

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“…The hydrodynamic size of the nanocrystals has been measured by dynamic light scattering [ 33 - 35 ]. This technique allows for the statistical analysis of the fluctuations in the intensity of the light scattered by particles in solutions.…”

Section: Resultsmentioning

confidence: 99%

Effect of surface ligands on the optical properties of aqueous soluble CdTe quantum dots

et al. 2012

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We investigate systematically the influence of the nature of thiol-type capping ligands on the optical and structural properties of highly luminescent CdTe quantum dots synthesized in aqueous media, comparing mercaptopropionic acid (MPA), thioglycolic acid (TGA), 1-thioglycerol (TGH), and glutathione (GSH). The growth rate, size distribution, and quantum yield strongly depend on the type of surface ligand used. While TGH binds too strongly to the nanocrystal surface inhibiting growth, the use of GSH results in the fastest growth kinetics. TGA and MPA show intermediate growth kinetics, but MPA yields a much lower initial size distribution than TGA. The obtained fluorescence quantum yields range from 38% to 73%. XPS studies unambiguously put into evidence the formation of a CdS shell on the CdTe core due to the thermal decomposition of the capping ligands. This shell is thicker when GSH is used as ligand, as compared with TGA ligands.

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Section: Resultsmentioning

confidence: 99%

Effect of surface ligands on the optical properties of aqueous soluble CdTe quantum dots

et al. 2012

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“…31,32 Although the syntheses for MHP NCs like CsPbBr 3 , CsPbCl 3 , and CH 3 NH 3 PbBr 3 possessing different morphologies or sizes have been reported, 33−38 appropriate and versatile synthetic preparations for CsPbI 3 NCs with independent control of nucleation and growth have not yet been established. To overcome this challenge and generate NCs of appropriate quality for analysis, we have adopted a route using sizeselective precipitation 39,40 to divide several reactions into batches with relatively tight size distributions among the narrowest reported thus far for CsPbI 3 . This enables studies of size-dependent material properties, which we report here.…”

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“…The main challenge in the synthesis of CsPbX 3 , in general, is the rapid consumption of precursors during hot injection syntheses leading to poor control over nucleation and growth. , The typical size dispersion of CdSe or PbS quantum dots has been reduced to nearly 3% after decades of research; however, for MHP NCs, the size dispersion is typically >10%. , Although the syntheses for MHP NCs like CsPbBr 3 , CsPbCl 3 , and CH 3 NH 3 PbBr 3 possessing different morphologies or sizes have been reported, − appropriate and versatile synthetic preparations for CsPbI 3 NCs with independent control of nucleation and growth have not yet been established. To overcome this challenge and generate NCs of appropriate quality for analysis, we have adopted a route using size-selective precipitation , to divide several reactions into batches with relatively tight size distributions among the narrowest reported thus far for CsPbI 3 . This enables studies of size-dependent material properties, which we report here.…”

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Size-Dependent Lattice Structure and Confinement Properties in CsPbI₃ Perovskite Nanocrystals: Negative Surface Energy for Stabilization

et al. 2019

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(FA-acetate, 99%) were purchased from Sigma-Aldrich and used as received unless otherwise specified. CsPbI3 QD synthesis. The synthesis was performed following the method reported in our previous publications with slight modification. 1,2 First, 20 mL of ODE is mixed with 1.25 mL of OA containing 0.407 g of Cs2CO3. This was degassed at 120°C for 20 min under vacuum in a three-neck flask to form Cs-oleate. The Cs-oleate precursor was kept under N2 instead of vacuum after Cs2CO3 was completely dissolved in the solution. Then the PbI2 precursor was formed by mixing 0.5 g of PbI2 and 25 mL of ODE in a three-neck flask and heated at 120°C for 20 min under vacuum. A preheated mixture of OA and OAm (135°C, 2.5 mL each) was transferred into the PbI2 solution that was kept at 120°C under vacuum. After the PbI2 completely dissolved in the solution, the reaction flask was heated to the desired temperature (140, 160, or 180°C) under flowing N2. Then 2 mL of the Cs-oleate precursor was swiftly injected into the reaction flask. In general, smaller nanocrystals are obtained with lower growth and larger are obtained with higher temperature, but some sizes overlap this trend when using the size selective precipitation. Immediately after the reaction, the mixture was quenched by submerging the flask into an ice bath within 3 s after the injection. After cooling to room temperature, 70 mL of MeOAc was added into the colloidal solution and the mixed solution was centrifuged at 7500 rpm for 5 min.

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7.3.3 Quantum dots and nano crystals based on CdSe and its alloys

Klingshirn

2013

Growth and Structuring

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Size Selective Precipitation of CdSe Colloidal Quantum Dots

Cited by 4 publications

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Effect of surface ligands on the optical properties of aqueous soluble CdTe quantum dots

Effect of surface ligands on the optical properties of aqueous soluble CdTe quantum dots

Size-Dependent Lattice Structure and Confinement Properties in CsPbI₃ Perovskite Nanocrystals: Negative Surface Energy for Stabilization

7.3.3 Quantum dots and nano crystals based on CdSe and its alloys

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Size Selective Precipitation of CdSe Colloidal Quantum Dots

Cited by 4 publications

References 0 publications

Effect of surface ligands on the optical properties of aqueous soluble CdTe quantum dots

Effect of surface ligands on the optical properties of aqueous soluble CdTe quantum dots

Size-Dependent Lattice Structure and Confinement Properties in CsPbI3 Perovskite Nanocrystals: Negative Surface Energy for Stabilization

7.3.3 Quantum dots and nano crystals based on CdSe and its alloys

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Size-Dependent Lattice Structure and Confinement Properties in CsPbI₃ Perovskite Nanocrystals: Negative Surface Energy for Stabilization