Annina Moser, Olesya Yarema, Noemi Rusch, Nikola D Ord Ević, Weyde M M Lin, Deniz Bozyigit, Nuri Yazdani, Maksym Yarema, Mathieu Luisier, Vanessa Wood
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引用次数: 0
Abstract
Ag-In-Se/ZnSe core/shell nanocrystals exhibit good photoluminescence quantum yield (PLQY), yet intriguingly, the maximum PLQY is first reached after several days of storage. We hypothesize that this may be due to cationic rearrangement in the nanocrystal post-synthesis. To test this hypothesis, we computationally generated ternary Ag-In-Se and quaternary Ag-In-Zn-Se nanocrystals with varying degrees of cationic disorder, as quantified by the distribution of the metal cation valence electrons in the tetrahedra around Se anions. We then used density functional theory-parametrized tight-binding simulations to study the electronic structure and optical properties of these systems as a function of the homogeneity of the valence electron distribution in a tetrahedron. We found that homogeneous distribution of cations leads to a larger band gap and optical coupling, and that, in the presence of AgIn or InAg antisite defects, the introduction of intermediate valence Zn cations decreases the variance in valence electrons and improves the optical properties. We further simulated the impact of a Zn-gradient shell and rearrangement of cations in the outer layers of the nanocrystals and find that diffusion of Zn into the nanocrystal and cationic rearrangement can explain the post-synthetic increase of PLQY. This work highlights the importance of developing syntheses for multinary nanocrystals that result not only in size and composition uniformity but also in nanocrystals with a uniform distribution of charge.
期刊介绍:
ACS Nanoscience Au is an open access journal that publishes original fundamental and applied research on nanoscience and nanotechnology research at the interfaces of chemistry biology medicine materials science physics and engineering.The journal publishes short letters comprehensive articles reviews and perspectives on all aspects of nanoscience and nanotechnology:synthesis assembly characterization theory modeling and simulation of nanostructures nanomaterials and nanoscale devicesdesign fabrication and applications of organic inorganic polymer hybrid and biological nanostructuresexperimental and theoretical studies of nanoscale chemical physical and biological phenomenamethods and tools for nanoscience and nanotechnologyself- and directed-assemblyzero- one- and two-dimensional materialsnanostructures and nano-engineered devices with advanced performancenanobiotechnologynanomedicine and nanotoxicologyACS Nanoscience Au also publishes original experimental and theoretical research of an applied nature that integrates knowledge in the areas of materials engineering physics bioscience and chemistry into important applications of nanomaterials.