Over the years, scientists have identified various synthetic "handles" while developing wet chemical protocols for achieving a high level of shape and compositional complexity in colloidal nanomaterials. Halide ions have emerged as one such handle which serve as important surface active species that regulate nanocrystal (NC) growth and concomitant physicochemical properties. Halide ions affect the NC growth kinetics through several means, including selective binding on crystal facets, complexation with the precursors, and oxidative etching. On the other hand, their presence on the surfaces of semiconducting NCs stimulates interesting changes in the intrinsic electronic structure and interparticle communication in the NC solids eventually assembled from them. Then again, halide ions also induce optoelectronic tunability in NCs where they form part of the core, through sheer composition variation. In this review, we describe these roles of halide ions in the growth of nanostructures and the physical changes introduced by them and thereafter demonstrate the commonality of these effects across different classes of nanomaterials.

中文翻译：

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胶体无机纳米晶体化学中卤化物离子的许多“方面”。

多年来，科学家们在开发湿化学方案以实现胶体纳米材料的高水平形状和成分复杂性的同时，已经确定了各种合成“手柄”。卤化物离子已经成为这样的一种手柄，它作为重要的表面活性物质来调节纳米晶体（NC）的生长和伴随的物理化学性质。卤化物离子通过多种方式影响NC生长动力学，包括选择性结合晶面、与前体络合以及氧化蚀刻。另一方面，它们在半导体NC表面上的存在刺激了最终由它们组装的NC固体中内在电子结构和颗粒间通信的有趣变化。另一方面，卤化物离子也通过纯粹的成分变化在NC中诱导光电可调性，它们形成核心的一部分。在这篇综述中，我们描述了卤化物离子在纳米结构生长中的作用以及它们引起的物理变化，然后证明了这些效应在不同类别的纳米材料中的共性。