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Nanocrystal Precursor Incorporating Separated Reaction Mechanisms for Nucleation and Growth to Unleash the Potential of Heat-up Synthesis.

ACS nano (2020-08-14)
Joonhyuck Park, Arun Jayaraman, Xudong Wang, Jing Zhao, Hee-Sun Han
ABSTRACT

A heat-up method for quantum dots (QDs) synthesis holds distinctive benefits for large-scale production with its simplicity, scalability, and high reproducibility. Its applications, however, have been limited because it inevitably yields a strong overlap between the nucleation and the growth stages. We addressed this long-standing problem by introducing a precursor having separated reaction paths for nucleation and growth. Unlike existing precursors, which employ a shared intermediate for both reactions, 9-mercapto-9-borabicyclo[3.3.1]nonane (BBN-SH) induces growth via surface-assisted conversion and drives nucleation via cluster formation in solution. Furthermore, this precursor chemistry embeds an efficient mechanism to suppress nucleation during growth. As such, BBN-SH allows heat-up-based growth of high-quality shells that are comparable to those created by the injection method. It is also notable that BBN-SH-based heat-up synthesis shows mitigated sensitivity to temperature fluctuation; therefore, it is highly suitable for industrial-scale reactions. We established a simple, scalable, and economic scheme for core/shell QDs by streamlining quantitative core synthesis and heat-up-based shell growth and showed that the scheme produces QDs of comparable quality to those produced by the traditional method. Here, we introduce a precursor that drives a distinctive mode of nanoparticle growth. We anticipate our study to inspire the design of other precursors and unleash the full potential of heat-up synthesis.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
1,4-Diazabicyclo[2.2.2]octane, ReagentPlus®, ≥99%
Sigma-Aldrich
Trioctylphosphine, 97%
Sigma-Aldrich
Diphenylphosphine, 98%
Sigma-Aldrich
1-Octanethiol, ≥98.5%
Sigma-Aldrich
4-(Trifluoromethyl)pyridine, 97%