Colloidal Self-Assembly of Inorganic Nanocrystals into Superlattice Thin-Films and Multiscale Nanostructures.

Hongseok Yun,Taejong Paik

doi:10.3390/nano9091243

Abstract

The self-assembly of colloidal inorganic nanocrystals (NCs) offers tremendous potential for the design of solution-processed multi-functional inorganic thin-films or nanostructures. To date, the self-assembly of various inorganic NCs, such as plasmonic metal, metal oxide, quantum dots, magnetics, and dielectrics, are reported to form single, binary, and even ternary superlattices with long-range orientational and positional order over a large area. In addition, the controlled coupling between NC building blocks in the highly ordered superlattices gives rise to novel collective properties, providing unique optical, magnetic, electronic, and catalytic properties. In this review, we introduce the self-assembly of inorganic NCs and the experimental process to form single and multicomponent superlattices, and we also describe the fabrication of multiscale NC superlattices with anisotropic NC building blocks, thin-film patterning, and the supracrystal formation of superlattice structures.

Highlights

In the past decades, colloidal inorganic nanocrystals (NCs) have received considerable attention in several research fields because of their interesting size-dependent properties, such as their quantum confinement effect and localized surface plasmonic effect, which are not be observed in the bulk [1,2]
binary NC superlattices (BNSLs) exhibit structural diversity for tuning NC–NC interactions through the choice of NC constituents or packing symmetry, and collective properties that are distinct from the sum Nanomaterials FOR PEER REVIEW
Uwael cwhailrlabctreoraisdtilcys.dIteisschriigbhelythiemspeolrft-aanstsetomubnldyeorsftacnodllothide asellNf-aCssse, minbcllyubdeihnagvtiohreoffaNbrCiscation methfoodr,thfoerdmevaetiloonpmmeencthoafnniosvmelomf asteelrfi-aalsssbeemcabulys,esotfruthcetiurrsaulpdeirvioerrsciotnytoroflBlaNbiSliLtys,inanmdatmereiasol dsceasilgens.tIrnucture of seltfh-iassrseevmiebwle, dwNe wCisllubpreoraldaltyticdees.cribe the self-assembly of colloidal NCs, including the fabrication method, formation mechanism of self-assembly, structural diversity of BNSLs, and mesoscale 2

Summary

Introduction

Colloidal inorganic nanocrystals (NCs) have received considerable attention in several research fields because of their interesting size-dependent properties, such as their quantum confinement effect and localized surface plasmonic effect, which are not be observed in the bulk [1,2]. One of the most interesting applications of NC building blocks is the colloidal self-assembly of NCs into ordered crystalline structures; that is, NC building blocks form various crystal structures, including face-centered cubic (fcc), body-centered cubic (bcc), and hexagonal close packed (hcp) structures, similar to how atoms or ions form crystalline structures [3,4]. The use of two different types of NCs can yield highly ordered binary NC superlattices (BNSLs) with various packing structures, such as NaCl, MgZn2, and NaZn13, depending on the size and concentration ratio [5]. Another method for the self-assembly of NCs involves the slow evaporation of the solvent from the NC solution, inducing the crystallization of the NCs [12]. An advantage of the liquid–air interface self-assembly technique is that it yields uniform NC superlattice thin-films over a large area within a short time

Self-Assembly of Spherical NCs

Findings

Perspectives