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A Modular Microfluidic Technology for Systematic Studies of Colloidal Semiconductor Nanocrystals
Published on: May 10, 2018
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Extended Nucleation and Superfocusing in Colloidal Semiconductor Nanocrystal Synthesis
P Tim Prins, Federico Montanarella, Kim Dümbgen1
1Physics and Chemistry of Nanostructures, Ghent University, B-9000 Gent, Belgium.
Nano Letters
|March 4, 2021
Summary
Hot-injection synthesis produces highly uniform semiconductor nanocolloids. Extended nucleation and reaction-limited growth, not diffusion, explain this size focusing, enabling rational production of monodisperse nanocolloids.
Area of Science:
- Materials Science
- Nanotechnology
- Chemical Synthesis
Background:
- Hot-injection synthesis is a key method for creating semiconductor nanocolloids with narrow size distributions.
- Existing theories attribute this uniformity to burst nucleation and diffusion-controlled growth, but experimental evidence is limited.
Purpose of the Study:
- To investigate the underlying mechanisms responsible for the narrow size dispersions achieved via hot-injection synthesis.
- To provide experimental evidence for the nucleation and growth dynamics in semiconductor nanocolloid formation.
Main Methods:
- In-situ X-ray scattering was employed to monitor the synthesis of Cadmium Selenide (CdSe) nanocolloids in real-time.
- Kinetic reaction simulations were performed to model nanocrystal growth dynamics.
Main Results:
- Nucleation was observed to be an extended process, overlapping with growth for 15-20% of the reaction time.
- Size focusing occurred faster than predicted by diffusion-limited growth models, indicating surface reactivity limitations.
- Simulations confirmed that surface reactivity-limited growth, termed 'superfocusing,' enhances size focusing and can extend nucleation.
Conclusions:
- The narrow size distribution in hot-injection synthesis arises from a combination of extended nucleation and reaction-limited size focusing.
- This study provides an evidence-based understanding, transforming hot injection into a predictable method for producing monodisperse semiconductor nanocolloids.
