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Directional Carrier Transfer in Strongly Coupled Binary Nanocrystal Superlattice Films Formed by Assembly and in Situ Ligand Exchange at a Liquid-Air Interface
Journal article

Directional Carrier Transfer in Strongly Coupled Binary Nanocrystal Superlattice Films Formed by Assembly and in Situ Ligand Exchange at a Liquid-Air Interface

Yaoting Wu, Siming Li, Natalie Gogotsi, Tianshuo Zhao, Blaise Fleury, Cherie R. Kagan, Christopher B. Murray, Jason B. Baxter and Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Journal of physical chemistry. C, v 121(8), pp 4146-4157
02 Mar 2017

Abstract

Chemistry Chemistry, Physical Materials Science Materials Science, Multidisciplinary Nanoscience & Nanotechnology Physical Sciences Science & Technology Science & Technology - Other Topics Technology
Two species of monodisperse nanocrystals (NCs) can self-assemble into a variety of complex 2D and 3D periodic structures, or binary NC superlattice (BNSL) films, based on the relative number and size of the NCs. BNSL films offer great promise for both fundamental scientific studies and optoelectronic applications; however, the utility of as-assembled structures has been limited by the insulating ligands that originate from the synthesis of NCs. Here we report the application of an in situ ligand exchange strategy at a liquid air interface to replace the long synthesis ligands with short ligands while preserving the long-range order of BNSL films. This approach is demonstrated for BNSL structures consisting of PbSe NCs of different size combinations and ligands of interest for photovoltaic devices, infrared detectors, and light-emitting diodes. To confirm enhanced coupling introduced by ligand exchange, we show ultrafast (similar to 1 ps) directional carrier transfer across the type-1 heterojunction formed by NCs of different sizes within ligand-exchanged BNSL films. This approach shows the potential promise of functional BNSL films, where the local and long-range energy landscape and electronic coupling can be adjusted by tuning NC composition, size, and interparticle spacing.

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Domestic collaboration
Web of Science research areas
Chemistry, Physical
Materials Science, Multidisciplinary
Nanoscience & Nanotechnology
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