(136c) Size-Focused Growth of Indium Phosphide Nanocrystals By Tuning Precursor Reactivity

Colloidal quantum dots (QDs) of semiconductor materials are of particular interest for applications ranging from optoelectronics and photocatalysis to bioimaging technologies, due to their unique size, shape, and composition-dependent optical properties. Indium Phosphide (InP) nanocrystals have emerged as a promising alternative to heavy-metal-based colloidal QDs for optoelectronic applications. However, despite significant improvements in the synthetic chemistry of InP QDs, it still lags significantly behind the Cd-based materials, specifically with respect to the ability to control size homogeneity during nucleation and growth. Moreover, the underlying precursor conversion, nucleation, and growth mechanisms need to be better understood to achieve a size-focused growth of InP nanocrystals.

This presentation will focus on our recently developed approach towards size-focused growth of InP nanocrystals: tuning precursor reactivity by addition of trace water.^[1] Our findings indicate that by varying the amount of trace water (0.1-0.4% by volume) added to the reaction, the monomer supply rate during the growth can be significantly altered. Under optimal concentration of water added to the initial reaction mixture, a very rare size-focused growth of InP nanocrystals is observed. Further mechanistic investigation of the precursor conversion kinetics using phosphorous NMR revealed that very distinct kinetic regimes are achieved with varying concentration of water in the reaction mixture. Our findings suggest that although the presence of trace water is traditionally considered an impurity for the colloidal synthesis of most semiconductor nanocrystals, it can be used as a critical lever to enforce a very rare LaMer-like size-focused growth of semiconductor nanocrystals.

Reference:

[1] A. Vikram, A. Zahid, S.S. Bhargava, L.P. Keating, A. Sutrisno, A. Khare, P. Trefonas, M. Shim, P.J.A. Kenis, Mechanistic Insights into Size-Focused Growth of Indium Phosphide Nanocrystals in the Presence of Trace Water; Chemistry of Materials, 2020, Just Accepted.