Tuning the Electronic Properties of Mesocrystals

Abstract

Colloidal crystals are arguably one of the most promising candidates when it comes to the fabrication of nanostructured metamaterials. Especially mesocrystals show exciting new properties that emerge from their inherent directional oriented assembly. With this work, the electrical conductivity of well‐defined micrometer‐sized platinum nanocube‐based mesocrystals is demonstrated and tuned through the variation of different capping agents. Herein, a method is presented to reproducibly quantify the intrinsic resistance of individual mesocrystals through electrical nanoprobing and focused ion beam deposition contacting. A thermally activated tunneling mechanism is identified as the main effect for electron propagation. In addition, the mesocrystals are altered through organically linking and mineral bridging the individual nanoparticles. This results in an increase in mesocrystal rigidity and, more importantly, conductivity by seven orders of magnitude while retaining shape, structure, and composition. In addition, these observations are transferred onto multicomponent superstructures in the form of binary mesocrystals. There, it is demonstrated that the electrical properties could be tuned through the ratio of nanoparticles incorporated into a mesocrystalline host system while simultaneously maintaining potential catalytic or superparamagnetic features of the guest particles.

Oriented attachment and aggregation as a viable pathway to self-assembled organic/inorganic hybrid materials

“…Reinforcement of the hybrid texture may be achieved by chemical crosslinking of organic segments and/ or the formation of mineral bridges between inorganic domains, as described in a recent study on mesocrystals of platinum nanocubes and fatty acids. 40 Such approaches will be subject of future work.…”

Direct Synthesis of CuPd Icosahedra Supercrystals studied by in situ X-ray Scattering

“…The self-assembly of nanocrystals into crystalline lattices constitutes a promising bottom-up route to such metamaterials, as it permits to tune the functional emergent properties of the outcoming supercrystals via engineering of the individual building blocks. [11][12][13][14][15][16] While recent improvements in the field of colloidal synthesis provide a high level of control of nanocrystal size, shape, and composition, [17][18][19][20][21][22] most synthetic schemes do not directly deliver supercrystals. Self-assembly procedures typically require several purification steps of the nanocrystal product and further rely on slow solvent evaporation or destabilization of the nanocrystal dispersion over a time up to many hours or days.…”

Shape-Mediated Oriented Assembly of Concave Nanoparticles under Cylindrical Confinement

“…Assembling colloidal nanoparticles into long-range ordered superlattices has been spotlighted as a promising pathway to creating structured materials with varying degrees of complexity and potentially programmable functionalities. , The properties of self-assembled materials rely heavily on the particle alignment and orientation, which profoundly influence their properties and applications in the field of optics, magnetics, and mechanics. − Nonspherical, anisotropic nanoparticles are appealing building blocks for constructing superlattices with both positioning and orientational order, due to the directional energetic and entropic interactions induced by particle shape. − Among various anisotropic building blocks, nanoparticles with concave features are of particular interest because of their rich phase behavior made possible by their distinct geometric curvature. − Manna and co-workers synthesized colloidal CdSe-CdS octapods and obtained three-dimensional (3D) superlattices comprising interlocked particle chains under appropriate assembly conditions . Murray and co-workers realized linear liquid-crystalline superlattices based on the unidirectional assembly of Gd 2 O 3 tripodal nanoplates, and the structural diversity of the resulting superlattices could be further enriched upon coassembly of shape-complementary tripodal and rhombic nanoplates …”