Quantized Ostwald Ripening of Colloidal Nanoparticles

Controlling the growth of nanoparticles (NP) in nanotechnology is crucial to produce high-quality particles with narrow size distribution. This simulation investigates the growth of colloidal semiconductor NPs in the presence of two distinctly sized NPs in the so-called "bimodal growth regime". One of the sizes of the NPs is selected such that its radius falls below or close to the critical dissolution radius. These particles will act as sacrificial materials for a larger second size for the growth and size focusing. The bimodal distribution (or quantized Ostwald ripening) technique is found to be a slower process compared to the commonly used repeated injection technique to focus the size distribution of NPs. The slow growth condition could lead to a better reaction control over the NP synthesis. Slower growth will reduce the effect of inhomogeneous mixing in a scaled up production of NPs. The low monomer oversaturation over the growth could improve the overall quality of the NPs. The results presented here on colloidal NPs are potentially applicable to the size evolution of NPs on surfaces as well.