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Transition Metal-Doped Metal Oxide Nanocrystals: Efficient Substitutional Doping through a Continuous Growth Process

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journal contribution
posted on 10.09.2017, 00:00 by Adam W. Jansons, Kristopher M. Koskela, Brandon M. Crockett, James E. Hutchison
Doped oxide nanocrystals hold promise for a wide variety of applications if dopant-induced properties can be appropriately harnessed. However, synthesis of doped nanocrystals with precise control over composition and structure presents a significant challenge. With traditional thermal decomposition synthetic methods, nanocrystal composition is hard to control due to the differing reactivities of dopant and host precursors. Under decomposition conditions, the variety of dopant atoms that can be introduced is limited, and the efficacy of dopant atom incorporation is variable. Here, we show the slow-addition of metal oleates into hot, long-chain alcohol permits >90% dopant incorporation efficacy for a variety of first-row transition-metal dopants into an In2O3 lattice at dopant concentrations up to 20 atom %. X-ray photoelectron spectroscopy analysis indicates that dopants are distributed throughout the nanocrystal. Elemental composition analysis, shifts and intensity changes in the X-ray diffraction peaks, and electronic absorbance spectroscopy suggest that the guest cations are substitutionally doping in the host matrix. We demonstrate that the synthetic method allows access to previously unobtainable compositions and structures without significant investment into synthetic optimization and precursor selection. Synthetic approaches with such attributes will not only lead to faster development of applications from these materials but also aid in our understanding and optimization of their properties.