Ligands as Universal Molecular Toolkit in Synthesis and Assembly of Semiconductor Nanocrystals
Successful exploitation of semiconductor nanocrystals (NCs) in commercial products has derived from the remarkable progress in the wet-chemical synthesis and controlled assembly of NCs. Central to the cadence of this progress is the capability to understand how NC growth and assembly can be controlled kinetically and thermodynamically. The arrested precipitation strategy offers a wide opportunity space for material selection, size uniformity, and morphology control. In this colloidal approach, capping ligands play an instrumental role in determining growth parameters and inter-NC interactions. Impetus for exquisite control over size and shape of NCs and orientation of NCs in ensemble has called for the use of two or more types of ligands in the system. In the multiple ligand approaches, ligands with different functionalities confer the extended tunability, hinting at the possibility of atomic-precision growth and long-range ordering of desired superlattices. Here, we highlight the progress in understanding the roles of ligands in size and shape control and assembly of NCs. We discuss the implication of the advances in the context of optoelectronic applications.