Design Rules for One-Step Seeded Growth of Nanocrystals: Threading the Needle between Secondary Nucleation and Ripening

Abstract

The heterogeneous growth of inorganic shells on seed nanocrystals is used to synthesize heterostructured nanocrystals such as core@shell quantum dots for applications ranging from biological imaging to solid-state lighting. Control over shelling reactions can be achieved through continuous or layer-by-layer growth methods that are tedious and time-consuming, particularly for the growth of complex, multishell heterostructures. Here, we leverage high-throughput synthesis along with a library of precursors with tunable reactivity to develop a comprehensive understanding of the role of precursor reactivity, ligands, and temperature in one-step, seeded growth reactions on CdSe quantum dots. These experiments reveal a narrow range of precursor reactivity and monomer solubility that fosters the uniform, purely heterogeneous growth of shell material on the seed particles. This narrow "ideal growth" regime in experimental parameter space is sandwiched between opposing regimes that lead to secondary nucleation or ripening during growth. We also report that, at high concentrations of tri-n-octylphosphine, shell growth reactions exhibit "digestive ripening", in which size distributions focus while particles dissolve. Coupled with kinetic simulations, these experiments reveal that the precursor reaction rate and monomer solubility are highly interdependent shell growth parameters that determine the balance between secondary nucleation and ripening. In contrast, the surface energy determines the evolution of the size and polydispersity of the heterostructures over time.

Breaking through the Size Control Dilemma of Silver Chalcogenide Quantum Dots via Trialkylphosphine-Induced Ripening: Leading to Ag2Te Emitting from 950 to 2100 nm

“…The introduction of TBP changed the equilibrium of coordination between OTT and Ag + , increasing the surface energy of silver chalcogenide QDs, especially for small-sized QDs to cause the dissolution. Such a ligand-induced change of surface energy of CdSe QDs has also been reported by Chan group …”

“…In fact, ligands should also play an important role in the growth of QDs. In the case of CdSe QDs, the addition of R 3 P ligands would cause the digestive ripening of CdSe QDs . R 3 P, as a soft base, can also coordinate with Ag + (soft acid) during the synthesis of Ag 2 Te QDs according to the “hard and soft acids and bases” (HSAB) theory .…”

Seeded Growth of Mesoscale Quantum-Confined Semiconductor Nanoplatelets

“…33,39,42 Additionally, these parameters are important for maintaining a regime of growth which outcompetes the critical supersaturation for nucleation and suppresses secondary nucleation. 33,43,44 We indeed find that the largest NPLs occur within a narrow range of optimized conditions and show how the experimental parameters of the slow injection seeded growth affect the extension in 3ML CdTe by isolating each variable individually (Figure 3). First, slightly elevated temperatures relative to the initial seed growth (210 ˚C) result in large extended NPLs, however this also results in a broadening of the size distribution.…”

Hybrid nanocapsules for in situ TEM imaging of gas evolution reactions in confined liquids

“…The ability to visualize the evolution of nanoscale reactions without labor-intensive fabrication will facilitate the direct testing of mechanistic theories, accelerating the development of new materials and helping to elucidate the complex reaction networks that produce them. [106][107][108]…”