Lattice Strain and Ligand Effects on the Formation of Cu2–xS/I-III-VI2 Nanorod Heterostructures through Partial Cation Exchange

Abstract

In the synthesis of anisotropic colloidal nanocrystal heterostructures, the interplay between many complicating factors such as interfacial chemistry, lattice strain, and coordinating ligands can make precise control over spatial distribution of composition extremely challenging. However, understanding how each complicating factor contributes to the growth mechanism can lead to otherwise difficult-to-achieve or unique structures and the means to tune their electronic/optical properties. Here, we report on the effects of lattice strain and the choice of ligands on the formation of Cu2–xS/I-III-VI2 colloidal nanorod heterostructures through partial cation exchange starting from Cu2–xS nanorods. Lattice strain can induce alternating Cu2–xS/CuGaS2 segments along a colloidal nanorod if CuGaS2 can nucleate easily from the sides of the nanorods. The choice in coordinating ligands can alter this preference to favor tip nucleation, in which case the resulting heterostructure has CuGaS2/Cu2–xS/CuGaS2 rod/rod/rod ge...