Limits...
Rational design of the gram-scale synthesis of nearly monodisperse semiconductor nanocrystals.

Protière M, Nerambourg N, Renard O, Reiss P - Nanoscale Res Lett (2011)

Bottom Line: On the basis of these results, the synthesis has been scaled up by a factor of 20.Using a 2-L batch reactor combined with a high-throughput peristaltic pump, different-sized samples of CdSe nanocrystals with yields of 2-3 g per synthesis have been produced without sacrificing the narrow size distribution.In a similar setup, the gram-scale synthesis of CdSe/CdS/ZnS core/shell/shell nanocrystals exhibiting a fluorescence quantum yield of 81% and excellent resistance of the photoluminescence in presence of a fluorescent quencher (aromatic thiol) has been achieved.PACS: 81.20.Ka, 81.07.Bc, 78.67.Bf.

View Article: PubMed Central - HTML - PubMed

Affiliation: DSM/INAC/SPrAM (UMR 5819 CEA-CNRS-UJF)/LEMOH, CEA-Grenoble - 17 rue des Martyrs - 38054 Grenoble cedex 9, France. peter.reiss@cea.fr.

ABSTRACT
We address two aspects of general interest for the chemical synthesis of colloidal semiconductor nanocrystals: (1) the rational design of the synthesis protocol aiming at the optimization of the reaction parameters in a minimum number of experiments; (2) the transfer of the procedure to the gram scale, while maintaining a low size distribution and maximizing the reaction yield. Concerning the first point, the design-of-experiment (DOE) method has been applied to the synthesis of colloidal CdSe nanocrystals. We demonstrate that 16 experiments, analyzed by means of a Taguchi L16 table, are sufficient to optimize the reaction parameters for controlling the mean size of the nanocrystals in a large range while keeping the size distribution narrow (5-10%). The DOE method strongly reduces the number of experiments necessary for the optimization as compared to trial-and-error approaches. Furthermore, the Taguchi table analysis reveals the degree of influence of each reaction parameter investigated (e.g., the nature and concentration of reagents, the solvent, the reaction temperature) and indicates the interactions between them. On the basis of these results, the synthesis has been scaled up by a factor of 20. Using a 2-L batch reactor combined with a high-throughput peristaltic pump, different-sized samples of CdSe nanocrystals with yields of 2-3 g per synthesis have been produced without sacrificing the narrow size distribution. In a similar setup, the gram-scale synthesis of CdSe/CdS/ZnS core/shell/shell nanocrystals exhibiting a fluorescence quantum yield of 81% and excellent resistance of the photoluminescence in presence of a fluorescent quencher (aromatic thiol) has been achieved.PACS: 81.20.Ka, 81.07.Bc, 78.67.Bf.

No MeSH data available.


Related in: MedlinePlus

Experimental setup. (a) Experimental setup used for the gram-scale synthesis of nearly monodisperse CdSe nanocrystals. (b) CdSe/CdS/ZnS core/shell/shell nanocrystals in the 2-L reactor at the final stage of synthesis. (c) Purification using a glass filter column retaining the precipitated nanocrystals, while the solvent and byproducts are collected in the round-bottom flask below.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211985&req=5

Figure 2: Experimental setup. (a) Experimental setup used for the gram-scale synthesis of nearly monodisperse CdSe nanocrystals. (b) CdSe/CdS/ZnS core/shell/shell nanocrystals in the 2-L reactor at the final stage of synthesis. (c) Purification using a glass filter column retaining the precipitated nanocrystals, while the solvent and byproducts are collected in the round-bottom flask below.

Mentions: A laboratory-scale synthesis as described in the last paragraphs yields approximately 100-200 mg of CdSe nanocrystals. Their potential technological applications make the scale-up of the synthesis highly desirable. Several attempts in this direction have been reported in the recent literature [32-35]. However, the detailed description of the experimental setup and the comparison of the results obtained with the gram scale and with the laboratory-scale synthesis are lacking in all cases. In a straightforward approach, we carried out the three synthesis protocols developed precedently in a 2-L reactor, after multiplying the quantities of all reagents by a factor of 20. Special care was taken concerning the stirring and the injection, both of which being of crucial importance for the size control of the nanocrystals. Figure 2a shows the experimental setup composed of the 2-L reactor, a mechanical stirrer, a 500-mL bottle containing the injection solution (TOPSe, ODE) and a Watson-Marlow 620 DI/RE peristaltic pump (Watson-Marlow and Bredel Products, La Queue Lez Yvelines, France) on the right, capable of injecting up to 500 mL within 3.5 seconds. The cover of the reactor contains five inlets used for the stirring bar, the condenser, the temperature probe, the injection tube, and for taking aliquots. The 500-mL bottle is equipped with a Teflon cap containing four inlets, allowing at the same time for the argon circulation and passage of the injection solution. The whole setup is connected to a vacuum line and can be used under inert atmosphere. While all other steps were carried out in the same way as during the laboratory-scale synthesis, purification was achieved by filtration rather than by centrifugation. It turned out to be impracticable to purify large quantities of nanocrystals by centrifugation due to the concomitant precipitation of large amounts of stearic acid. In order to avoid this phenomenon, the temperature of the reaction mixture is kept above 70°C after addition of acetone/ethanol. For the filtration, a standard glass filter (G3) is used, which allows carrying out the purification under inert atmosphere.


Rational design of the gram-scale synthesis of nearly monodisperse semiconductor nanocrystals.

Protière M, Nerambourg N, Renard O, Reiss P - Nanoscale Res Lett (2011)

Experimental setup. (a) Experimental setup used for the gram-scale synthesis of nearly monodisperse CdSe nanocrystals. (b) CdSe/CdS/ZnS core/shell/shell nanocrystals in the 2-L reactor at the final stage of synthesis. (c) Purification using a glass filter column retaining the precipitated nanocrystals, while the solvent and byproducts are collected in the round-bottom flask below.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211985&req=5

Figure 2: Experimental setup. (a) Experimental setup used for the gram-scale synthesis of nearly monodisperse CdSe nanocrystals. (b) CdSe/CdS/ZnS core/shell/shell nanocrystals in the 2-L reactor at the final stage of synthesis. (c) Purification using a glass filter column retaining the precipitated nanocrystals, while the solvent and byproducts are collected in the round-bottom flask below.
Mentions: A laboratory-scale synthesis as described in the last paragraphs yields approximately 100-200 mg of CdSe nanocrystals. Their potential technological applications make the scale-up of the synthesis highly desirable. Several attempts in this direction have been reported in the recent literature [32-35]. However, the detailed description of the experimental setup and the comparison of the results obtained with the gram scale and with the laboratory-scale synthesis are lacking in all cases. In a straightforward approach, we carried out the three synthesis protocols developed precedently in a 2-L reactor, after multiplying the quantities of all reagents by a factor of 20. Special care was taken concerning the stirring and the injection, both of which being of crucial importance for the size control of the nanocrystals. Figure 2a shows the experimental setup composed of the 2-L reactor, a mechanical stirrer, a 500-mL bottle containing the injection solution (TOPSe, ODE) and a Watson-Marlow 620 DI/RE peristaltic pump (Watson-Marlow and Bredel Products, La Queue Lez Yvelines, France) on the right, capable of injecting up to 500 mL within 3.5 seconds. The cover of the reactor contains five inlets used for the stirring bar, the condenser, the temperature probe, the injection tube, and for taking aliquots. The 500-mL bottle is equipped with a Teflon cap containing four inlets, allowing at the same time for the argon circulation and passage of the injection solution. The whole setup is connected to a vacuum line and can be used under inert atmosphere. While all other steps were carried out in the same way as during the laboratory-scale synthesis, purification was achieved by filtration rather than by centrifugation. It turned out to be impracticable to purify large quantities of nanocrystals by centrifugation due to the concomitant precipitation of large amounts of stearic acid. In order to avoid this phenomenon, the temperature of the reaction mixture is kept above 70°C after addition of acetone/ethanol. For the filtration, a standard glass filter (G3) is used, which allows carrying out the purification under inert atmosphere.

Bottom Line: On the basis of these results, the synthesis has been scaled up by a factor of 20.Using a 2-L batch reactor combined with a high-throughput peristaltic pump, different-sized samples of CdSe nanocrystals with yields of 2-3 g per synthesis have been produced without sacrificing the narrow size distribution.In a similar setup, the gram-scale synthesis of CdSe/CdS/ZnS core/shell/shell nanocrystals exhibiting a fluorescence quantum yield of 81% and excellent resistance of the photoluminescence in presence of a fluorescent quencher (aromatic thiol) has been achieved.PACS: 81.20.Ka, 81.07.Bc, 78.67.Bf.

View Article: PubMed Central - HTML - PubMed

Affiliation: DSM/INAC/SPrAM (UMR 5819 CEA-CNRS-UJF)/LEMOH, CEA-Grenoble - 17 rue des Martyrs - 38054 Grenoble cedex 9, France. peter.reiss@cea.fr.

ABSTRACT
We address two aspects of general interest for the chemical synthesis of colloidal semiconductor nanocrystals: (1) the rational design of the synthesis protocol aiming at the optimization of the reaction parameters in a minimum number of experiments; (2) the transfer of the procedure to the gram scale, while maintaining a low size distribution and maximizing the reaction yield. Concerning the first point, the design-of-experiment (DOE) method has been applied to the synthesis of colloidal CdSe nanocrystals. We demonstrate that 16 experiments, analyzed by means of a Taguchi L16 table, are sufficient to optimize the reaction parameters for controlling the mean size of the nanocrystals in a large range while keeping the size distribution narrow (5-10%). The DOE method strongly reduces the number of experiments necessary for the optimization as compared to trial-and-error approaches. Furthermore, the Taguchi table analysis reveals the degree of influence of each reaction parameter investigated (e.g., the nature and concentration of reagents, the solvent, the reaction temperature) and indicates the interactions between them. On the basis of these results, the synthesis has been scaled up by a factor of 20. Using a 2-L batch reactor combined with a high-throughput peristaltic pump, different-sized samples of CdSe nanocrystals with yields of 2-3 g per synthesis have been produced without sacrificing the narrow size distribution. In a similar setup, the gram-scale synthesis of CdSe/CdS/ZnS core/shell/shell nanocrystals exhibiting a fluorescence quantum yield of 81% and excellent resistance of the photoluminescence in presence of a fluorescent quencher (aromatic thiol) has been achieved.PACS: 81.20.Ka, 81.07.Bc, 78.67.Bf.

No MeSH data available.


Related in: MedlinePlus